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Sample records for twin studies show

  1. Fullerton Virtual Twin Study.

    Science.gov (United States)

    Segal, Nancy L

    2006-12-01

    Virtual twins (VTs; same-age unrelated siblings reared together from early infancy) have been studied at California State University (CSU), Fullerton since 1991. The current sample includes over 130 pairs. Past and current research have research have focused on siblings' similarities and differences in general intelligence and body size. Future research in these areas will continue as new pairs continue to be identified. These studies will be supplemented by analyses of personality, social relations and adjustment using monozygotic (MZ) twins, dizygotic (DZ) twins, full siblings and friends, as well as new VTs, who have participated in Twins, Adoptees, Peers and Siblings (TAPS), a collaborative project conducted between CSU Fullerton and the University of San Francisco, from 2002 to 2006.

  2. The Twin Interdisciplinary Neuroticism Study

    NARCIS (Netherlands)

    Riese, Harriette; Rijsdijk, Fruehling V.; Snieder, Harold; Ormel, Johan

    The Twin Interdisciplinary Neuroticism Study (TWINS) is a three-wave study including >800 twin pairs from the northern part of the Netherlands. The aim of the study is to unravel why neuroticism reflects vulnerability to mental disorders. In this study, we focus on possible mechanisms underlying

  3. TWIN BLOCK (Studi Pustaka

    Directory of Open Access Journals (Sweden)

    Evie Lamtiur

    2015-08-01

    Full Text Available Young patients with class II skeletal malocclusion are often found. To avoid further discrepancy of this case, myofunctional therapy is one of the options. Functional appliance often used for such treatment. Functional appliance has been modified since activator was introduced by Andresen. With its bulky shape, activator makes difficulty for patient to speak and eat. Patient unable to wear it full time due to uncomfortness and negative facial appearance. In 1977, Clark developed twin block to overcome the weakness of previous appliances. A more simple design allows patient to be more comfortable and willing to wear it longer. Twin block is myofunctional appliance to reposition the mandible forward for skeletal class II correction with retruded mandible. This paper describes the design, clinical management effects of twin block treatment and brief case presentation using twin block appliance. Similar to the study reports found, this case revealed improvement of facial appearance, decrease overjet and overbite, improvement of molar relationship and good compliance of patient.

  4. A Twin Study of Perthes Disease

    DEFF Research Database (Denmark)

    Metcalfe, David; Van Dijck, Stephanie; Parsons, Nicolas

    2016-01-01

    and genetic associations with LCPD. METHODS: We extracted all twin pairs from the Danish Twin Registry (DTR) in which at least 1 individual had LCPD. The DTR captures every twin pair born alive in Denmark, and those with LCPD were identified by using health record linkage. Probanwise concordance.......00-0.18) for the dizygotic, and 0.18 (95% CI: 0.00-0.40) for the UZ twin pairs. CONCLUSIONS: This study found evidence of familial clustering in LCPD but did not show a genetic component. The absolute risk that a co-twin of an affected individual will develop LCPD is low, even in the case of monozygotic twin pairs.......BACKGROUND: Legg-Calvé-Perthes disease (LCPD) is an idiopathic avascular necrosis of the femoral head. Its etiology is poorly understood, although previous studies have implicated low birth weight and possible genetic determinants. The aim of this study was to identify potential birth weight...

  5. Twin Studies of Atopic Dermatitis

    DEFF Research Database (Denmark)

    Elmose, Camilla; Thomsen, Simon Francis

    2015-01-01

    Aim. The aim of this study was to conduct a systematic review of population-based twin studies of (a) the concordance and heritability of AD and (b) the relationship between AD and asthma and, furthermore, to reinterpret findings from previous twin studies in the light of the emerging knowledge a...

  6. Twin methodology in epigenetic studies

    DEFF Research Database (Denmark)

    Tan, Qihua; Christiansen, Lene; von Bornemann Hjelmborg, Jacob

    2015-01-01

    Since the final decades of the last century, twin studies have made a remarkable contribution to the genetics of human complex traits and diseases. With the recent rapid development in modern biotechnology of high-throughput genetic and genomic analyses, twin modelling is expanding from analysis ...

  7. Twin methodology in epigenetic studies.

    Science.gov (United States)

    Tan, Qihua; Christiansen, Lene; von Bornemann Hjelmborg, Jacob; Christensen, Kaare

    2015-01-01

    Since the final decades of the last century, twin studies have made a remarkable contribution to the genetics of human complex traits and diseases. With the recent rapid development in modern biotechnology of high-throughput genetic and genomic analyses, twin modelling is expanding from analysis of diseases to molecular phenotypes in functional genomics especially in epigenetics, a thriving field of research that concerns the environmental regulation of gene expression through DNA methylation, histone modification, microRNA and long non-coding RNA expression, etc. The application of the twin method to molecular phenotypes offers new opportunities to study the genetic (nature) and environmental (nurture) contributions to epigenetic regulation of gene activity during developmental, ageing and disease processes. Besides the classical twin model, the case co-twin design using identical twins discordant for a trait or disease is becoming a popular and powerful design for epigenome-wide association study in linking environmental exposure to differential epigenetic regulation and to disease status while controlling for individual genetic make-up. It can be expected that novel uses of twin methods in epigenetic studies are going to help with efficiently unravelling the genetic and environmental basis of epigenomics in human complex diseases.

  8. A twin study of ADHD symptoms in early adolescence: hyperactivity-impulsivity and inattentiveness show substantial genetic overlap but also genetic specificity

    NARCIS (Netherlands)

    Greven, C.U.; Rijsdijk, F.V.; Plomin, R.

    2011-01-01

    A previous paper in this journal revealed substantial genetic overlap between the ADHD dimensions of hyperactivity-impulsivity and inattentiveness in a sample of 8-year old twins drawn from a UK-representative population sample. Four years later, when the twins were 12 years old, more than 5,500 pai

  9. A Twin Study of ADHD Symptoms in Early Adolescence: Hyperactivity-Impulsivity and Inattentiveness Show Substantial Genetic Overlap but Also Genetic Specificity

    Science.gov (United States)

    Greven, Corina U.; Rijsdijk, Fruhling V.; Plomin, Robert

    2011-01-01

    A previous paper in this journal revealed substantial genetic overlap between the ADHD dimensions of hyperactivity-impulsivity and inattentiveness in a sample of 8-year old twins drawn from a UK-representative population sample. Four years later, when the twins were 12 years old, more than 5,500 pairs drawn from the same sample were rated again on…

  10. Utilizing twins as controls for non-twin case-materials in genome wide association studies.

    Directory of Open Access Journals (Sweden)

    Andrea Ganna

    Full Text Available Twin registries around the globe have collected DNA samples from large numbers of monozygotic and dizygotic twins. The twin sample collections are frequently used as controls in disease-specific studies together with non-twins. This approach is unbiased under the hypothesis that twins and singletons are comparable in terms of allele frequencies; i.e. there are no genetic variants associated with being a twin per se. To test this hypothesis we performed a genome-wide association study comparing the allele frequency of 572,352 single nucleotide polymorphisms (SNPs in 1,413 monozygotic (MZ and 5,451 dizygotic (DZ twins with 3,720 healthy singletons. Twins and singletons have been genotyped using the same platform. SNPs showing association with being a twin at P-value < 1 × 10(-5 were selected for replication analysis in 1,492 twins (463 MZ and 1,029 DZ and 1,880 singletons from Finland. No SNPs reached genome-wide significance (P-value < 5 × 10(-8 in the main analysis combining MZ and DZ twins. In a secondary analysis including only DZ twins two SNPs (rs2033541 close to ADAMTSL1 and rs4149283 close to ABCA1 were genome-wide significant after meta-analysis with the Finnish population. The estimated proportion of variance on the liability scale explained by all SNPs was 0.08 (P-value=0.003 when MZ and DZ were considered together and smaller for MZ (0.06, P-value=0.10 compared to DZ (0.09, P-value=0.003 when analyzed separately. In conclusion, twins and singletons can be used in genetic studies together with general population samples without introducing large bias. Further research is needed to explore genetic variances associated with DZ twinning.

  11. Brazilian Twin Registry: A Bright Future for Twin Studies/Twin Research: Twin Study of Alcohol Consumption and Mortality; Oxygen Uptake in Adolescent Twins/In the News: Superfecundated Twins In Vietnam; Adolescent Twin Relations; Twin and Triplet Co-Workers; A Special Twin Ultrasound; Monozygotic Twins With Different Skin Color; Identical Twin Returns from Space.

    Science.gov (United States)

    Segal, Nancy L

    2016-06-01

    The establishment of the Brazilian Twin Registry for the study of genetic, social, and cultural influences on behavior is one of eleven newly funded projects in the Department of Psychology at the University of São Paulo. These 11 interrelated projects form the core of the university's Center for Applied Research on Well-Being and Human Behavior. An overview of the planned twin research and activities to date is presented. Next, two recent twin studies are reviewed, one on the relationship between alcohol consumption and mortality, and the other on factors affecting maximal oxygen uptake. Twins cited in the media include the first identified superfecundated twins in Vietnam, adolescent twin relations, twins and triplets who work together, monozygotic twins with different skin tones and a co-twin control study that addresses the effects of space travel.

  12. A twin study of computer anxiety in Turkish adolescents.

    Science.gov (United States)

    Deryakulu, Deniz; Calışkan, Erkan

    2012-04-01

    The present study investigated computer anxiety within a sample of Turkish twins aged 10-18. A total of 185 twin-pairs participated in the study. Of the twins, 64 pairs (34.6 percent) were monozygotic (MZ) and 121 pairs (65.4 percent) were dizygotic (DZ). Of the 121 DZ twins, 54 pairs (44.63 percent) were same-sex twins and 67 pairs (55.37 percent) were opposite-sex twins. Computer anxiety was assessed using Computer Anxiety Rating Scale-Turkish Version (CARS-TV), one of the three main scales of "Measuring Technophobia Instruments" developed by Rosen and Weil. The results of paired t test comparisons showed no significant differences in MZ and same-sex DZ twin-pairs' levels of computer anxiety. On the other hand, a significant difference was found in opposite-sex DZ twin-pairs' level of computer anxiety. Interesting enough, males appeared to be more computer anxious than their female co-twins. In the present study, using Falconer's formula, heritability estimate for computer anxiety was derived from correlations based on MZ and DZ twins' mean scores on CARS-TV. The results showed that 57 percent of the variance in computer anxiety was from genetics and 41.5 percent was from nonshared environmental factors. Shared environmental influence, on the other hand, was very small and negligible. Interpretations of results and potential directions for future research are presented.

  13. Reared-Apart Chinese Twins: Chance Discovery/Twin-Based Research: Twin Study of Media Use; Twin Relations Over the Life Span; Breast-Feeding Opposite-Sex Twins/Print and Online Media: Twins in Fashion; Second Twin Pair Born to Tennis Star; Twin Primes; Twin Pandas.

    Science.gov (United States)

    Segal, Nancy L

    2017-04-01

    A January 2017 reunion of 10-year-old reared-apart Chinese twin girls was captured live on ABC's morning talk show Good Morning America, and rebroadcast on their evening news program Nightline. The twins' similarities and differences, and their participation in ongoing research will be described. This story is followed by reviews of twin research concerning genetic and environmental influences on media use, twin relations across the lifespan and the breast-feeding of opposite-sex twins. Popular interest items include twins in fashion, the second twin pair born to an internationally renowned tennis star, twin primes and twin pandas.

  14. Fullerton Virtual Twin Study: an update.

    Science.gov (United States)

    Segal, Nancy L; McGuire, Shirley A; Graham, Jamie L; Stohs, Joanne Hoven

    2013-02-01

    Virtual twins (VTs) are same-age unrelated siblings reared together from early infancy. These unique sibling sets replicate twinship, but without the genetic link. The first VT pair was identified and studied at the University of Minnesota in 1990, launching the development of the Fullerton Virtual Twin Study at California State University, Fullerton (CSUF) in 1991. The registry currently includes 151 pairs, mostly children, with new pairs identified on a continuous basis. Research with VTs includes studies of general intelligence, body size, interpersonal trust, social coordination, social networks, and parenting. In some cases, VTs have been studied in conjunction with pairs of monozygotic twins, dizygotic twins, full siblings, and friends as part of TAPS (Twins, Adoptees, Peers and Siblings), a collaborative project conducted between CSUF and the University of San Francisco, 2002-2006. VTs will also serve as a comparison group for epigenetic analyses of young Chinese twins reared apart and together.

  15. Twin Legacies: Victor and Vincent McKusick/Twin Studies: Twinning Rates I; Twinning Rates II; MZ Twin Discordance for Russell-Silver Syndrome; Twins' Language Skills/Headlines: Babies Born to Identical Twin Couples; Identity Exchange; Death of Princess Ashraf (Twin); Yahoo CEO Delivers Identical Twins.

    Science.gov (United States)

    Segal, Nancy L

    2016-04-01

    The lives of the illustrious monozygotic (MZ) twins, Victor A. and Vincent L. McKusick, are described. Victor earned the distinction as the 'Father of Medical Genetics', while Vincent was a legendary Chief Justice of the Maine Supreme Court. This dual biographical account is followed by two timely reports of twinning rates, a study of MZ twin discordance for Russell-Silver Syndrome (RSS) and a study of twins' language skills. Twin stories in the news include babies born to identical twin couples, a case of switched identity, the death of Princess Ashraf (Twin) and a new mother of twins who is also Yahoo's CEO.

  16. Colorado Longitudinal Twin Study of Reading Disability

    Science.gov (United States)

    Wadsworth, Sally J.; DeFries, John C.; Olson, Richard K.; Willcutt, Erik G.

    2007-01-01

    The primary objectives of the present study are to introduce the Colorado Longitudinal Twin Study of Reading Disability, the first longitudinal twin study in which subjects have been specifically selected for having a history of reading difficulties, and to present some initial assessments of the stability of reading performance and cognitive…

  17. A Danish Twin Study of Schizophrenia Liability

    DEFF Research Database (Denmark)

    Kläning, Ulla; Trumbetta, Susan L; Gottesman, Irving I

    2016-01-01

    We studied schizophrenia liability in a Danish population-based sample of 44 twin pairs (13 MZ, 31 DZ, SS plus OS) in order to replicate previous twin study findings using contemporary diagnostic criteria, to examine genetic liability shared between schizophrenia and other disorders, and to explo...

  18. Twin studies: A unique epidemiological tool

    Directory of Open Access Journals (Sweden)

    Monalisha Sahu

    2016-01-01

    Full Text Available Twin studies are a special type of epidemiological studies designed to measure the contribution of genetics as opposed to the environment, to a given trait. Despite the facts that the classical twin studies are still being guided by assumptions made back in the 1920s and that the inherent limitation lies in the study design itself, the results suggested by earlier twin studies have often been confirmed by molecular genetic studies later. Use of twin registries and various innovative yet complex software packages such as the (SAS and their extensions (e.g., SAS PROC GENMOD and SAS PROC PHREG has increased the potential of this epidemiological tool toward contributing significantly to the field of genetics and other life sciences.

  19. Genetics of dietary habits and obesity - a twin study

    DEFF Research Database (Denmark)

    Hasselbalch, Ann Louise

    2010-01-01

    equation modelling of twin data from the Danish Twin Registry with special focus on the GEMINAKAR twin study that was performed in 1997-2000. In this study, anthropometric traits of the twin pairs were measured and habitual dietary intake was assessed through a food frequency questionnaire (FFQ). When...... residual genetic influence existed. Based on information about habitual diet from the FFQ the genetic influence on total energy intake, macronutrient intake, as well as intake of energy from 20 food groups, was estimated. The proportion of variation in dietary intake explained by variation in genes....... The study showed, however, consistent positive associations between intake of sugar-sweetened soft drink and BMI, FMI and waist circumference in men. Gene-environment interaction models showed that while high physical activity is associated with a down-regulation of genes predisposing to obesity...

  20. Twins eye study in Tasmania (TEST): rationale and methodology to recruit and examine twins.

    Science.gov (United States)

    Mackey, David A; Mackinnon, Jane R; Brown, Shayne A; Kearns, Lisa S; Ruddle, Jonathan B; Sanfilippo, Paul G; Sun, Cong; Hammond, Christopher J; Young, Terri L; Martin, Nicholas G; Hewitt, Alex W

    2009-10-01

    Visual impairment is a leading cause of morbidity and poor quality of life in our community. Unravelling the mechanisms underpinning important blinding diseases could allow preventative or curative steps to be implemented. Twin siblings provide a unique opportunity in biology to discover genes associated with numerous eye diseases and ocular biometry. Twins are particularly useful for quantitative trait analysis through genome-wide association and linkage studies. Although many studies involving twins rely on twin registries, we present our approach to the Twins Eye Study in Tasmania to provide insight into possible recruitment strategies, expected participation rates and potential examination strategies that can be considered by other researchers for similar studies. Five separate avenues for cohort recruitment were adopted: (1) piggy-backing existing studies where twins had been recruited, (2) utilizing the national twin registry, (3) word-of-mouth and local media publicity, (4) directly approaching schools, and finally (5) collaborating with other research groups studying twins.

  1. Cooperative Research Twin Trawl Sweep Comparison Study

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The "Twin-Trawl Sweep Efficiency Study" was intended to compare the sweep efficiency and selectivity of the NEFSC standardized bottom trawl to that of a standardized...

  2. Spectroscopic study of solar twins and analogues

    CERN Document Server

    Datson, Juliet; Portinari, Laura

    2014-01-01

    Context. Many large stellar surveys have been and are still being carried out, providing huge amounts of data, for which stellar physical parameters will be derived. Solar twins and analogues provide a means to test the calibration of these stellar catalogues because the Sun is the best-studied star and provides precise fundamental parameters. Solar twins should be centred on the solar values. Aims. This spectroscopic study of solar analogues selected from the Geneva-Copenhagen Survey (GCS) at a resolution of 48,000 provides effective temperatures and metallicities for these stars. We test whether our spectroscopic parameters, as well as the previous photometric calibrations, are properly centred on the Sun. In addition, we search for more solar twins in our sample. Methods. The methods used in this work are based on literature methods for solar twin searches and on methods we developed in previous work to distinguish the metallicity-temperature degeneracies in the differential comparison of spectra of solar ...

  3. The Danish political twin study

    DEFF Research Database (Denmark)

    Klemmensen, Robert; Hobolt, Sara B; Dinesen, Peter Thisted

    2012-01-01

    We compare a recent Danish twin survey on political attitudes and behaviors to a nationally representative survey covering similar topics. We find very similar means and variances for most of our constructed scales of political attitudes and behaviors in the two surveys, although even small...

  4. The Finnish Twin Cohort Study: an update.

    Science.gov (United States)

    Kaprio, Jaakko

    2013-02-01

    In 2002 and 2006, review papers have described the Finnish Twin Cohort and studies conducted on these population-based, longitudinal data sets with extensive follow-up data. Three cohorts have been established: the older twin cohort in the 1970s, and the Finntwin12 and Finntwin16 studies initiated in the 1990s. The present review provides on update on the latest data collections conducted since the previous review. These cover the fourth waves of data collection in the older cohort (twins born before 1958) and Finntwin12 (twins born 1983-1987). The fifth wave of data collection in Finntwin16 (twins born 1975-1979) also included assessments of their spouses/partners. An analysis of mortality in the older cohort from 1975 to 2009 indicates that the mortality of adult twins (as individuals) does not differ from the population at large. Based on the cohorts, many sub-studies with more detailed phenotyping and collection of omics data have been conducted or are in progress. We also contribute to numerous national and international collaborations.

  5. Estimating heritability for cause specific mortality based on twin studies

    DEFF Research Database (Denmark)

    Scheike, Thomas; Holst, Klaus Kähler; von Bornemann Hjelmborg, Jacob

    2014-01-01

    There has been considerable interest in studying the magnitude and type of inheritance of specific diseases. This is typically derived from family or twin studies, where the basic idea is to compare the correlation for different pairs that share different amount of genes. We here consider data from...... the Danish twin registry and discuss how to define heritability for cancer occurrence. The key point is that this should be done taking censoring as well as competing risks due to e.g.  death into account. We describe the dependence between twins on the probability scale and show that various models can...... be used to achieve sensible estimates of the dependence within monozygotic and dizygotic twin pairs that may vary over time. These dependence measures can subsequently be decomposed into a genetic and environmental component using random effects models. We here present several novel models that in essence...

  6. How does the inclusion of twins conceived via fertility treatments influence the results of twin studies?

    Science.gov (United States)

    Burt, S Alexandra; Klump, Kelly L

    2012-12-01

    Rates of twinning have risen dramatically over the last 30 years, from 1 in 53 births in 1980 to 1 in 30 births in 2009 (Martin et al. (January 2012). Three decades of twin births in the United States, 1980-2009. Atlanta, GA: Centers for Disease Control and Prevention, National Center for Health Statistics). This increase is largely attributable to increases in the use of fertility treatments (i.e., ovulation induction and in vitro fertilization) combined with delays in parenthood. Although this increase means that more twins are available for recruitment into twin studies, it also has potential consequences for the heritability estimates obtained in these studies. This study sought to evaluate this possibility, making use of the ongoing Michigan Twins Project (N = 7,261 families with twins aged 3-17 years), an arm of the Michigan State University Twin Registry. Results revealed that, on average, twins conceived via fertility treatments had lower rates of behavior problems than those conceived naturally, although these behavioral differences could be explained largely by demographic and socio-economic differences across the two types of twin families. Twin similarity did not meaningfully differ across fertility treatment status. We thus conclude that estimates of genetic and environmental influences obtained from twin studies over the last 10-15 years are more or less unaffected by the inclusion of twins conceived via fertility treatments in their samples.

  7. Twin and grain boundary in InP: A synchrotron radiation study

    Energy Technology Data Exchange (ETDEWEB)

    Han, Y.; Liu, X.; Jiao, J.; Lin, L. [Chinese Academy of Sciences, Beijing (China). Inst. of Semiconductors; Jiang, J.; Wang, Z.; Tian, Y. [Chinese Academy of Sciences, Beijing (China). Beijing Synchrotron Radiation Lab.

    1998-12-31

    Experimentally observed X-ray reflectivity curves show bi-crystal(twin) characteristics. The study revealed that there was defect segregation at the twin boundary. Stress was relaxed at the edge of the boundary. Relaxation of the stress resulted in formation of twin and other defects. As a result of formation of such defects, a defect-free and stress-free zone or low defect density and small stress zone is created around the defects. So a twin model was proposed to explain the experimental results. Stress(mainly thermal stress), chemical stoichiometry deviation and impurities nonhomogeneous distributions are the key factors that cause twins in LEC InP crystal growth. Twins on (111) face in LEC InP crystal were studied. Experimental evidence of above mentioned twin model and suggestions on how to get twin-free LEC InP single crystals will be discussed.

  8. Twin studies in auto-immune disease.

    Science.gov (United States)

    Leslie, R D; Hawa, M

    1994-01-01

    Immune-mediated diseases affect up to 5% of the population and are a major cause of morbidity and mortality. These diseases can be organ specific, such as insulin-dependent diabetes (IDDM) and non-organ specific, such as Rheumatoid Arthritis (RA). Identical and non-identical twins have been used to establish whether these diseases are determined by genetic or environmental factors. The results of these studies have been collated in a new section of the Mendel Institute in Rome. Diseases included in these studies included IDDM, RA, Systemic Lupus Erythematosus (SLE), Multiple Sclerosis (MS) and Myasthenia. Striking differences in concordance rates between identical and non-identical twins in all these studies suggest that genetic factors are important in causing these diseases. All the diseases are known to be associated with HLA genes on chromosome 6 which may account for some or all of the genetic susceptibility. However, in the majority of pairs the affected twin has an unaffected co-twin. These observations suggest that non-genetically determined factors, probably environmental factors and not somatic mutations, are critical. The study of unaffected co-twins, who are at high disease-risk, has allowed the identification of changes which precede and predict the clinical disease. The immune-mediated destruction in many of these diseases is probably caused by T-lymphocytes. Twin studies have shown the importance of genetic factors in determining T-cell responses. Identical twins should, therefore, provide the perfect test bed to assess the role of T-cells in immune-mediated diseases.

  9. The first large population based twin study of coeliac disease

    Science.gov (United States)

    Greco, L; Romino, R; Coto, I; Di Cosmo, N; Percopo, S; Maglio, M; Paparo, F; Gasperi, V; Limongelli, M G; Cotichini, R; D'Agate, C; Tinto, N; Sacchetti, L; Tosi, R; Stazi, M A

    2002-01-01

    Background and aims: The genetic load in coeliac disease has hitherto been inferred from case series or anecdotally referred twin pairs. We have evaluated the genetic component in coeliac disease by estimating the concordance rate for the disease among twin pairs in a large population based study. Methods: The Italian Twin Registry was matched with the membership lists of a patient support group. Forty seven twin pairs were recruited and screened for antiendomysial (EMA) and antihuman-tissue transglutaminase (anti-tTG) antibodies; zygosity was verified by DNA fingerprinting and twins were typed for HLA class II DRB1 and DQB1 molecules. Results: Concordance rates for coeliac disease differ significantly between monozygotic (MZ) (0.86 probandwise and 0.75 pairwise) and dizygotic (DZ) (0.20 probandwise and 0.11 pairwise) twins. This is the highest concordance so far reported for a multifactorial disease. A logistic regression model, adjusted for age, sex, number of shared HLA haplotypes, and zygosity, showed that genotypes DQA1*0501/DQB1*0201 and DQA1*0301/DQB1*0302 (encoding for heterodimers DQ2 and DQ8, respectively) conferred to the non-index twin a risk of contracting the disease of 3.3 and 1.4, respectively. The risk of being concordant for coeliac disease estimated for the non-index twin of MZ pairs was 17 (95% confidence interval 2.1–134), independent of the DQ at risk genotype. Conclusion: This study provides substantial evidence for a very strong genetic component in coeliac disease, which is only partially due to the HLA region. PMID:11950806

  10. Effect of co-twin gender on neurodevelopmental symptoms: a twin register study.

    Science.gov (United States)

    Eriksson, Jonna Maria; Lundström, Sebastian; Lichtenstein, Paul; Bejerot, Susanne; Eriksson, Elias

    2016-01-01

    Autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) are neurodevelopmental disorders thought to have both genetic and environmental causes. It has been hypothesized that exposure to elevated levels of prenatal testosterone is associated with elevated traits of ASD and ADHD. Assuming that testosterone levels from a dizygotic male twin fetus may lead to enhanced testosterone exposure of its co-twins, we aimed to test the prenatal testosterone hypothesis by comparing same-sex with opposite-sex dizygotic twins with respect to neurodevelopmental symptoms. Neuropsychiatric traits were assessed in a population-based twin cohort from the Child and Adolescent Twin Study in Sweden (CATSS). Parental interviews were conducted for 16,312 dizygotic twins, 9 and 12 years old, with the Autism-Tics, ADHD, and other Comorbidities inventory (A-TAC). Girls with a female co-twin had an increased risk of reaching the cut-off score for ADHD compared with girls with a male co-twin. Both boys and girls with a female co-twin displayed a larger number of traits related to attention deficit and repetitive and stereotyped behaviors than those with a male twin. In girls, this also extended to social interaction and the combined measures for ASD and ADHD, however, with small effect sizes. Our results are reverse to what would have been expected from the prenatal testosterone hypothesis but consistent with a previous study of ASD and ADHD traits in dizygotic twins. The seemingly protective effect for girls of having a twin brother may be an effect of parent report bias, but may also be an unexpected effect of sharing the intrauterine environment with a male co-twin.

  11. Social Determinants of Smoking Behavior: The Healthy Twin Study, Korea

    OpenAIRE

    Kim, Youn Sik; Ko, Hansoo; Yoon, Changgyo; Lee, Dong-Hun; Sung, Joohon

    2012-01-01

    Objectives The purpose of this study was to identify any influence of socioeconomic status on smoking and smoking cessation in a situation where genetic factors are controlled. Methods The sample for this study was 2502 members of the twins and families cohort who participated in the Korean Healthy Twins Study from 2005 to 2009. Groups of brothers or sisters, including twins and fraternal twins, were compared in terms of smoking and smoking cessation behaviors according to differences in soci...

  12. A Multivariate Twin Study of Early Literacy in Japanese "Kana"

    Science.gov (United States)

    Fujisawa, Keiko K.; Wadsworth, Sally J.; Kakihana, Shinichiro; Olson, Richard K.; DeFries, John C.; Byrne, Brian; Ando, Juko

    2013-01-01

    This first Japanese twin study of early literacy development investigated the extent to which genetic and environmental factors influence individual differences in prereading skills in 238 pairs of twins at 42 months of age. Twin pairs were individually tested on measures of phonological awareness, "kana" letter name/sound knowledge,…

  13. Comparison of Naturally Conceived and IVF-DZ Twins in the Netherlands Twin Registry: A Developmental Study

    Directory of Open Access Journals (Sweden)

    Catharina E. M. van Beijsterveldt

    2011-01-01

    Full Text Available In a large set of twin pairs, we compared twins born after IVF to naturally conceived twins with respect to birth characteristics, growth, attainment of motor milestones, and emotional and behavioral problems. Twin families were registered with the Netherlands Twin Register. We included 1534 dizygotic (DZ twins born after IVF, 5315 naturally conceived (NC DZ twins, and 1504 control NC DZ twins who were matched to the IVF twins based on maternal age, maternal educational level, smoking during pregnancy, gestational age, and offspring sex. Data were obtained by longitudinal surveys sent to fathers, mothers, and teachers at ages 1, 2, 3, 7, 10, and 12 years. Results showed no differences in growth, in attainment of motor milestones, and in behavioral development between IVF and matched NC twins. It can be concluded that for nearly all aspects, development in IVF and NC children is similar.

  14. A registry of adult African American twins: the Carolina African American Twin Study of Aging.

    Science.gov (United States)

    Whitfield, Keith E

    2013-02-01

    Twin studies have seldom addressed ethnicity as one of the possible factors that create unique combinations of genetic and environmental influences. The major objective of the Carolina African American Twin Study of Aging is to identify the proportion of the genetic and environmental sources of individual variation in measures of health and behavioral factors in a sample of adult African Americans. Drawn from birth records from the State of North Carolina, this in-person study used public records to identify a cohort of twins between 22 and 92 years of age (X = 49.82 yrs, SD = 14.62), 39.7% of which were men. Members of non-intact twin pairs and siblings were also recruited to explore alternative models to the classic twin design. To date, the project has contributed to knowledge about blood pressure, forced expiratory volume, chronic illness, body mass index, and waist-hip ratio memory, personality, social, and demographic factors, mortality, and mental health.

  15. Late prematurity in twins: a Polish multicenter study.

    Science.gov (United States)

    Kosinska-Kaczynska, Katarzyna; Szymusik, Iwona; Bomba-Opon, Dorota; Madej, Anna; Oleszczuk, Jan; Patro-Malysza, Jolanta; Marciniak, Beata; Breborowicz, Grzegorz; Drews, Krzysztof; Seremak-Mrozikiewicz, Agnieszka; Szymankiewicz, Marta; Zimmer, Mariusz; Pomorski, Michal; Olejek, Anita; Slawska, Helena; Wielgos, Mirosław

    2014-10-01

    The study aimed at investigating the impact of late prematurity (LPT) on neonatal outcome in twins and neonatal morbidity and mortality within LPT with regard to the completed weeks of gestation. The study was conducted in six tertiary obstetric departments from different provinces of Poland (Warsaw, Lublin, Poznan, Wroclaw, Bytom). It included 465 twin deliveries in the above centers in 2012. A comparative analysis of maternal factors, the course of pregnancy and delivery and neonatal outcome between LPT (34 + 0-36 + 6 weeks of gestation) and term groups (completed 37 weeks) was performed. The neonatal outcome included short-term morbidities. The analysis of neonatal complication rates according to completed gestational weeks was carried out. Out of 465 twin deliveries 213 (44.8%) were LPT and 156 (33.55%) were term. There were no neonatal deaths among LPT and term twins. One-third of LPT newborns suffered from respiratory disorders or required antibiotics, 40% had jaundice requiring phototherapy, and 30% were admitted to NICU. The analysis of neonatal morbidity with regard to each gestational week at delivery showed that most analyzed complications occurred less frequently with the advancing gestational age, especially respiratory disorders and NICU admissions. The only two factors with significant influence on neonatal morbidity rate were neonatal birth weight (OR = 0.43, 95% CI = 0.2-0.9, p = .02) and gestational age at delivery (OR = 0.62, 95% CI = 0.5-0.8, p twins. Gestational age and neonatal birth weight seem to play a crucial role in neonatal outcome in twins.

  16. CLINICAL STUDY OF LABOUR IN TWIN PREGNANCY

    Directory of Open Access Journals (Sweden)

    Amudha

    2015-07-01

    Full Text Available OBJECTIVES: The objective of the present study is to analyse the incidence of preterm labour, intrapartum complications, incidence of operative delivery both vaginal and cesarean and indications for such interventions. METHODOLOGY: A total of 150 cases of twin pregnancy were analyzed between the period of September 2012 to February 2014. These cases were stud ied with respect to period of gestation at the onset of labour, fetal presentations at the onset of labour, route and mode of delivery, indications in cases of cesarean delivery, intrapartum complications and delivery interval between twins. OBSERVATIONS A ND RESULTS: In the present study there was increased incidence of preterm labour (52.6%, fetal malpresentations (43.3%, operative vaginal delivery (29.5%, cesarean delivery (17.3%. CONCLUSION: In this study it is observed that above mentioned labour ev ents and complications double up in the event of a twin pregnancy. Regular antenatal visits, planned delivery and anticipation and identification of complications will help for better pregnancy outcome.

  17. Twin studies in psychiatry and psychology: science or pseudoscience?

    Science.gov (United States)

    Joseph, Jay

    2002-01-01

    Twin studies are frequently cited in support of the influence of genetic factors for a wide range of psychiatric conditions and psychological trait differences. The most common method, known as the classical twin method, compares the concordance rates or correlations of reared-together identical (MZ) vs. reared-together same-sex fraternal (DZ) twins. However, drawing genetic inferences from MZ-DZ comparisons is problematic due to methodological problems and questionable assumptions. It is argued that the main theoretical assumption of the twin method--known as the "equal environment assumption"--is not tenable. The twin method is therefore of doubtful value as an indicator of genetic influences. Studies of reared-apart twins are discussed, and it is noted that these studies are also vulnerable to methodological problems and environmental confounds. It is concluded that there is little reason to believe that twin studies provide evidence in favor of genetic influences on psychiatric disorders and human behavioral differences.

  18. A study of asthma severity in adult twins

    DEFF Research Database (Denmark)

    Thomsen, Simon Francis; van der Sluis, Sophie; Kyvik, Kirsten Ohm

    2012-01-01

    twins from the Danish Twin Registry, a total of 575 subjects (256 intact pairs and 63 single twins) who themselves and/or their co-twins reported a history of asthma at a questionnaire survey were clinically examined. The severity of asthma symptoms was graded according to a clinical interview...... of asthma symptoms and objectively measured asthma-related traits, respectively, seem to differ. Please cite this paper as: Thomsen SF, van der Sluis S, Kyvik KO and Backer V. A study of asthma severity in adult twins. Clin Respir J 2011; DOI:10.1111/j.1752-699X.2011.00273.x....

  19. Knowledge data base system for twins study.

    Science.gov (United States)

    Reina, S; Miozza, F

    1994-01-01

    The medical research on twins, carried out at the Gregor Mendel Institute for Medical Genetics and Twin Study in Rome over the past four decades, has resulted in a vast collection of clinical paper records. A challenge was presented by the need for a more secure method of storage to preserve this enormously valuable historical and scientific patrimony and to render its contents more easily accessible for research purposes. We met the challenge by planning and developing the computerization of this material. New concepts, currently being explored in biomedical informatics, were applied to build a Knowledge Data Base System, using a fourth-generation language (SQL). This architecturally innovative computer system enables its users to manipulate data supplied, rather than just simply storing it. Based on heuristic relational criteria between variables and parameters, the system is employed to solve problems of sibling design analysis typically arising from twins' records, but is also equipped to meet future data base requirements. Another feature of the system is its users' ability to pull off data in the form of regular automated reports, which are distributed through a Local Area Network (LAN). Through a Bulletin Board System (BBS) and modem, any scientist (outside as well as within the Institute) is thus able to access data and exchange scientific information.

  20. Mutagen sensitivity has high heritability: evidence from a twin study.

    Science.gov (United States)

    Wu, Xifeng; Spitz, Margaret R; Amos, Christopher I; Lin, Jie; Shao, Lina; Gu, Jian; de Andrade, Mariza; Benowitz, Neal L; Shields, Peter G; Swan, Gary E

    2006-06-15

    Despite numerous studies showing that mutagen sensitivity is a cancer predisposition factor, the heritability of mutagen sensitivity has not been clearly established. In this report, we used a classic twin study design to examine the role of genetic and environmental factors on the mutagen sensitivity phenotype. Mutagen sensitivity was measured in peripheral blood lymphocytes from 460 individuals [148 pairs of monozygotic (MZ) twins, 57 pairs of dizygotic (DZ) twins, and 50 siblings]. The intraclass correlation coefficients were all significantly higher in MZ twins than in dizygotes (DZ pairs and MZ-sibling pairs combined) for sensitivity to four different mutagen challenges. Applying biometric genetic modeling, we calculated a genetic heritability of 40.7%, 48.0%, 62.5%, and 58.8% for bleomycin, benzo[a]pyrene diol epoxide, gamma-radiation, and 4-nitroquinoline-1-oxide sensitivity, respectively. This study provides the strongest and most direct evidence that mutagen sensitivity is highly heritable, thereby validating the use of mutagen sensitivity as a cancer susceptibility factor.

  1. 'Biracial'-Looking Twins: A New Twin Type?/Twin Research: Twins with Cystic Teratomas; Sleep Quality and Body Mass Index; Previable Membrane Rupture/Print and Online Reports: Twins Born to a Sister Surrogate; NASA Twin Study; African-Cosmopolitan Twin Fashion Inspirations; Triplet Hockey Stars.

    Science.gov (United States)

    Segal, Nancy L

    2017-06-01

    Dizygotic (DZ) co-twins born to mothers and fathers from different racial or ethnic backgrounds often resemble one parent much more than the other. As such, these pairs comprise a unique subset of twins for investigating how others' responses to their different looks may affect their personalities and self-esteem. This article describes some of these twin pairs and some challenges of raising them, and suggests ways they may be used in research. Next, recent twin research on cystic teratomas, relations between sleep quality and body mass index, and previable membrane rupture is described. The final section concerns twins, twin studies, and related events in the media, namely: twins born to a sister surrogate, the NASA twin investigation, inspiring African-Cosmopolitan twins in fashion, and triplet Hockey Stars.

  2. A twin study of weight loss and metabolic efficiency.

    Science.gov (United States)

    Hainer, V; Stunkard, A; Kunesová, M; Parízková, J; Stich, V; Allison, D B

    2001-04-01

    To assess the genetic contribution to determinants of therapeutic weight loss in obese female identical twins. Subjects were studied for 40 days on an inpatient unit in three phases: 7 baseline days; 28 days of weight reduction by a very low calorie diet (1.6 MJ per day); and 5 days after weight reduction. Fourteen pairs of premenopausal obese female identical twins (age: 39.0+/-1.7 y; body weight (BW): 93.9+/-21.2 kg; body mass index (BMI): 34.2+/-7.8 kg/m2). : Body composition by hydrodensitometry and resting metabolic rate by indirect calorimetry were assessed before and after weight loss. : There was great variability among pairs in loss of weight (5.9-12.4 kg) and body fat (3.1-12.4 kg). By contrast, the intraclass correlation (ICC) within twin pairs was 0.85, P<0.001 for weight and 0.88, P<0.001 for body fat. A measure of metabolic efficiency, calculated as the difference between 'estimated' and 'measured' energy deficit showed high intrapair correlation (ICC=0.77; P<0.001). The high correlation in metabolic efficiency within twin pairs in response to therapeutic weight loss suggests a strong genetic contribution.

  3. Highlights from the 15th International Congress of Twin Studies/Twin Research: Differentiating MZ Co-twins Via SNPs; Mistaken Infant Twin-Singleton Hospital Registration; Narcolepsy With Cataplexy; Hearing Loss and Language Learning/Media Mentions: Broadway Musical Recalls Conjoined Hilton Twins; High Fashion Pair; Twins Turn 102; Insights From a Conjoined Twin Survivor.

    Science.gov (United States)

    Segal, Nancy L

    2015-02-01

    Highlights from the 15th International Congress of Twin Studies are presented. The congress was held November 16-19, 2014 in Budapest, Hungary. This report is followed by summaries of research addressing the differentiation of MZ co-twins by single nucleotide polymorphisms (SNPs), an unusual error in infant twin-singleton hospital registration, twins with childhood-onset narcolepsy with cataplexy, and the parenting effects of hearing loss in one co-twin. Media interest in twins covers a new Broadway musical based on the conjoined twins Violet and Daisy Hilton, male twins becoming famous in fashion, twins who turned 102 and unique insights from a conjoined twin survivor. This article is dedicated to the memory of Elizabeth (Liz) Hamel, DZA twin who met her co-twin for the first time at age seventy-eight years. Liz and her co-twin, Ann Hunt, are listed in the 2015 Guinness Book of Records as the longest separated twins in the world.

  4. The genetic and environmental influences on childhood obesity: a systematic review of twin and adoption studies

    DEFF Research Database (Denmark)

    Silventoinen, K; Rokholm, B; Kaprio, J;

    2010-01-01

    of obesity. Except the two twin studies from the Korean population, all studies represented Caucasian populations. In a meta-analysis of these twin studies, we found that genetic factors had a strong effect on the variation of body mass index (BMI) at all ages. The common environmental factors showed...... and their biological offspring, further supporting the importance of genetic factors. In the future, more studies implementing genetic and environmental measures into twin models are needed as they allow estimation of the proportion of total genetic variation explained by candidate genes and analyses of gene......In this systematic review, we aimed to collect together all previous twin and adoption studies on childhood and adolescent obesity up to the age of 18 years. Using several sources, we identified nine twin and five adoption studies; all of these studies had used relative weight as an indicator...

  5. “That Show You Like Might Be Coming Back in Style”: How Twin Peaks Changed the Face of Contemporary Television

    Directory of Open Access Journals (Sweden)

    Moldovan Raluca

    2015-06-01

    Full Text Available The present study revisits one of American television’s most famous and influential shows, Twin Peaks, which ran on ABC between 1990 and 1991. Its unique visual style, its haunting music, the idiosyncratic characters and the mix of mythical and supernatural elements made it the most talked-about TV series of the 1990s and generated numerous parodies and imitations. Twin Peaks was the brainchild of America’s probably least mainstream director, David Lynch, and Mark Frost, who was known to television audiences as one of the scriptwriters of the highly popular detective series Hill Street Blues. When Twin Peaks ended in 1991, the show’s severely diminished audience were left with one of most puzzling cliffhangers ever seen on television, but the announcement made by Lynch and Frost in October 2014, that the show would return with nine fresh episodes premiering on Showtime in 2016, quickly went viral and revived interest in Twin Peaks’ distinctive world. In what follows, I intend to discuss the reasons why Twin Peaks was considered a highly original work, well ahead of its time, and how much the show was indebted to the legacy of classic American film noir; finally, I advance a few speculations about the possible plotlines the series might explore upon its return to the small screen.

  6. STUDY OF OBSTETRIC COMPLICATIONS & OUTCOME OF TWIN PREGNANCY

    Directory of Open Access Journals (Sweden)

    Swati

    2014-10-01

    Full Text Available : INTRODUCTION: Twin pregnancy is a rare phenomenon and significantly related to increased maternal & fetal morbidity and mortality as compared to singleton pregnancy. It is important that every physician must know the complications related to twin pregnancy and how to manage these complications. DESIGN: Prospective observational study AIMS AND OBJECTIVE: (1 To study incidence of various obstetric complications in twin pregnancy (2 To study outcome of twin pregnancy in terms of average duration of gestation, mode of delivery & neonatal outcome. METHODS: 59 Patients with sonographically confirmed twin pregnancy attending ante-natal care outpatient department (ANC OPD & labor room at a tertiary care hospital in our Unit in specified period of 18 months as mentioned above were enrolled in this study and followed till delivery and thereafter in the neonatal period. RESULTS: In this study twin pregnancies were slightly more in multigravida. The rate of preterm delivery was 77.9%.PIH & Anaemia was more common in primigravida. Monochorionic twins had more complications than dichorionic twins. NICU admission rate in this study was 23.6%, perinatal mortality rate was 16.9% and neonatal mortality rate was 12.2%. CONCLUSION: Twinning in pregnancy is a high risk factor which can cause various maternal as well fetal complications. Prompt ANC care and timely intervention is required to avoid these complications.

  7. Class - III malocclusion: Genetics or environment? A twins study

    Directory of Open Access Journals (Sweden)

    Jena A

    2005-03-01

    Full Text Available Etiology of class-III malocclusion is generally believed to be genetic. A wide range of environmental factors have been suggested as contributing factors for the development of class-III malocclusion. Twin study is one of the most effective methods available for investigating genetically determined variables of malocclusion. Discordancy for class-III malocclusion is a frequent finding in dizygotic twins. However, class-III malocclusion discordancy in monozygotic twins is a rare finding. The purpose of this study of monozygotic twins is to assess the genetic and environmental components of variation within the cranio-dento-facial complex.

  8. Class - III malocclusion: Genetics or environment? A twins study

    OpenAIRE

    Jena A; Duggal R; Mathur V; Parkash H

    2005-01-01

    Etiology of class-III malocclusion is generally believed to be genetic. A wide range of environmental factors have been suggested as contributing factors for the development of class-III malocclusion. Twin study is one of the most effective methods available for investigating genetically determined variables of malocclusion. Discordancy for class-III malocclusion is a frequent finding in dizygotic twins. However, class-III malocclusion discordancy in monozygotic twins is a rare finding. The p...

  9. CoSMoS and TwinPaW: initial report on two new German twin studies.

    Science.gov (United States)

    Spinath, Frank M; Wolf, Heike

    2006-12-01

    After briefly recapitulating two earlier German twin studies (BiLSAT and GOSAT), we present two new German twin studies with a longitudinal perspective: CoSMoS and TwinPaW. The twin study on Cognitive ability, Self-reported Motivation and School performance (CoSMoS) aims to investigate predictors and influences of school performance in a genetically sensitive design, beginning with children in late elementary school. The Twin study on Personality And Wellbeing (TwinPaW) focuses on adult personality and its relation to physical health as well as health-related behavior in an adult sample of twins. Both studies are characterized by an effort to recruit new large twin samples through a novel recruitment procedure aimed at reducing self-selective sampling. In two German federal states, contact information on persons born on the same day and with the same name was retrieved from record sections. From the resulting pool of more than 36,000 addresses we contacted approximately 2000 parents of twins aged 9 and 10 for CoSMoS, as well as 2000 adult twin pairs for TwinPaW by telephone and mail. Personal contact by telephone proved to be more efficient with agreement rates of 63% in the children sample and 65% in the adult sample. In this article we briefly describe the rationale and the study aims of CoSMoS and TwinPaW as well as the characteristics of the sample we have recruited so far.

  10. Twin studies on obsessive-compulsive disorder: a review

    NARCIS (Netherlands)

    Grootheest, van D.S.; Cath, D.C.; Beekman, A.T.F.; Boomsma, D.I.

    2005-01-01

    Genetic factors have historically been thought of as important in the development of obsessive-compulsive disorder (OCD). For the estimation of the relative importance of genetic and environmental factors, twin studies are an obvious approach. Twin studies of OCD have a long history, starting in 192

  11. Twin studies on obsessive-compulsive disorder: a review

    NARCIS (Netherlands)

    Grootheest, van D.S.; Cath, D.C.; Beekman, A.T.F.; Boomsma, D.I.

    2005-01-01

    Genetic factors have historically been thought of as important in the development of obsessive-compulsive disorder (OCD). For the estimation of the relative importance of genetic and environmental factors, twin studies are an obvious approach. Twin studies of OCD have a long history, starting in

  12. Twinning in Iranian Holstein Dairy Cattle: A Study of Risk Factors and Production and Reproduction Consequences

    Directory of Open Access Journals (Sweden)

    abolfazl mahnani

    2016-08-01

    Full Text Available Introduction Cattle are a monotocous species meaning that, under most circumstances, a successful pregnancy results in the birth of one calf. Twinning rate has been reported in dairy cows from 3 to 5 percent, which can be influenced by maternal age.The birth of twins is detrimental to the majority of beef and dairy cattle producer. Financial loss arising from any of twinning has been reported in Europe between 109 to 201 dollars in recent years. Because it is associated with undesirable consequences such as reduced survival, calf, cow increased removal rate and poor performance. This also reduces pregnancy rates and profitability herds. One of the effects of twinning severe is reduction of the number of calves for replacement fertility in dairy cows. This is a loss arising from an increase in infant mortality and a gender bias in bull calves homo zygote.Twinning rate increases significantly the incidence of reproductive abnormalities, including the retained placenta, dystocia, stillbirth and abortion. Many studies have been done on the effect of multiple pregnancies in cattle production and reproduction. Higher milk production for cows twin issue is controversial as some studies have shown that there is a positive correlation between the rate of twinning in dairy cattle and milk production. But in the next lactation, production for cows that have been the twin of the infected cow metabolic disease in the previous period was lower. In a study reported that cows spend fewer days in the twin peak production. The results of the study on the effect of twinning on reproductive traits of Holstein cows-Farzin showed that only half of the twin cows are prone to reproduce in the next period. It is also reported a greater number of insemination per conception in twin compared to single cows. In addition, it has been reported that the twin was more than 15 days from calving to first services. Average twin cows experiencing 1.7 times more death and removal

  13. Genetic influences on dietary variety - Results from a twin study

    NARCIS (Netherlands)

    Scheibehenne, Benjamin; Todd, Peter M.; van den Berg, Stéphanie Martine; Hatemi, Peter K.; Eaves, Lindon J.; Vogler, Christian

    2014-01-01

    The heritability of variety seeking in the food domain was estimated from a large sample (N = 5,543) of middle age to elderly monozygotic and dizygotic twins from the “Virginia 30,000” twin study. Different dietary variety scores were calculated based on a semi-quantitative food choice questionnaire

  14. Paternal age and twinning in the Jerusalem Perinatal Study

    Science.gov (United States)

    Kleinhaus, Karine; Perrin, Mary C.; Manor, O; Friedlander, Yehiel; Calderon-Margalit, Ronit; Harlap, Susan; Malaspina, Dolores

    2008-01-01

    Objective To investigate whether incidence of twin deliveries is related to father's age, independently of mother's age, and whether it differs for same-sex or opposite-sex twin sets. Study Design In a program of research on effects of paternal age, this study used data from a prospective cohort of 92,408 offspring born in Jerusalem from 1964-1976. Of the 91,253 deliveries in the Jerusalem Perinatal Study, 1,115 were twin deliveries. The data were analyzed with General Estimate Equations to inform unconditional logistic regression. Results After controlling for maternal age, Odds Ratios (OR) and 95% Confidence Intervals (95% CI) associated with father's ages 25-34 and 35+ were 1.3 (1.1, 1.7) and 1.5 (1.2, 2.1) respectively, compared with fathers <25 years old. The effect of maternal age was partly explained by paternal age. The ORs for opposite-sex twin sets and male-male twin sets increased slightly with paternal age, while the OR for same-sex and female-female twin decreased. Conclusion Studies of twins are used to estimate effects of genes and environment in a variety of diseases. Our findings highlight the need to consider paternal as well as maternal age when analyzing data on twins to explore etiology of diseases. PMID:18771839

  15. Disease-Concordant Twins Empower Genetic Association Studies

    DEFF Research Database (Denmark)

    Tan, Qihua; Li, Weilong; Vandin, Fabio

    2017-01-01

    Genome-wide association studies with moderate sample sizes are underpowered, especially when testing SNP alleles with low allele counts, a situation that may lead to high frequency of false-positive results and lack of replication in independent studies. Related individuals, such as twin pairs...... concordant for a disease, should confer increased power in genetic association analysis because of their genetic relatedness. We conducted a computer simulation study to explore the power advantage of the disease-concordant twin design, which uses singletons from disease-concordant twin pairs as cases...... and ordinary healthy samples as controls. We examined the power gain of the twin-based design for various scenarios (i.e., cases from monozygotic and dizygotic twin pairs concordant for a disease) and compared the power with the ordinary case-control design with cases collected from the unrelated patient...

  16. Twins for epigenetic studies of human aging and development

    DEFF Research Database (Denmark)

    Tan, Qihua; Christiansen, Lene; Thomassen, Mads

    2013-01-01

    , our understanding of genetic and environmental influences on the epigenetic processes remains limited. Twins are of special interest for genetic studies due to their genetic similarity and rearing-environment sharing. The classical twin design has made a great contribution in dissecting the genetic...... and environmental contributions to human diseases and complex traits. In the era of functional genomics, the valuable sample of twins is helping to bridge the gap between gene activity and the environments through epigenetic mechanisms unlimited by DNA sequence variations. We propose to extend the classical twin...... design to study the aging-related molecular epigenetic phenotypes and link them with environmental exposures especially early life events. Different study designs and application issues will be highlighted and novel approaches introduced with aim at making uses of twins in assessing the environmental...

  17. Heritability of neck pain: a population-based study of 33,794 Danish twins

    DEFF Research Database (Denmark)

    Fejer, R; Hartvigsen, J; Kyvik, K O

    2006-01-01

    OBJECTIVES: To determine the heritability of neck pain in a large population-based study of twins. METHODS: Data on lifetime prevalence of neck pain from a population-based cross-sectional survey of Danish twins were used. To assess twin similarity, the probandwise concordance rates, zygosity......-specific odds ratios and tetrachoric correlations were calculated and compared for monozygotic and dizygotic twins. Using biometric modelling (structural equation modelling), the genetic and environmental contributions of the liability to neck pain were estimated. RESULTS: A total of 33,794 twins (response rate...... 73%) answered the questions regarding neck pain. Probandwise concordance rates, zygosity-specific odds ratios and tetrachoric correlations showed a significant genetic effect on neck pain. An overall additive genetic component of 44% was found. The genetic effect decreased with age, accounting...

  18. Heredity and environment in schizophrenia, revisited. The contribution of twin and high-risk studies.

    Science.gov (United States)

    Stabenau, J R; Pollin, W

    1993-05-01

    Life history study of monozygotic (MZ) twins discordant for schizophrenia led to the 1967 hypothesis that phenotypic schizophrenia was an expression of genotypic vulnerability interacting with prenatal and/or perinatal environmental experience. This report is a selected review of partial answers to five questions facing research efforts that have attempted to clarify the interactive gene-environment model of schizophrenia. Follow-up study of the offspring of MZ twins with a diagnosis of schizophrenia and their MZ co-twins without schizophrenia demonstrated equal rates of schizophrenia; hence, each group of offspring carried equal genetic vulnerability for schizophrenia. Magnetic resonance imaging study of MZ discordant twins found that phenotypic schizophrenia was characterized by brain ventricular enlargement and hippocampal reduction in 87-93% of the schizophrenic twins, when compared with their nonschizophrenic co-twins. A longitudinal study of teenage children at differential risk for schizophrenia showed that brain ventricular enlargement in adulthood correlated significantly and positively with genetic risk for schizophrenia and number of perinatal complications, and negatively with birth weight. Significantly greater dysmorphological hand skin signs among schizophrenic MZ twins when compared with their nonschizophrenic co-twins have suggested an in utero second trimester fetal developmental abnormality for the schizophrenic subjects. Simultaneous neuroanatomic, neurophysiological, and neurocognitive evaluation of MZ twin pairs discordant for schizophrenia demonstrated decreased prefrontal physiological cerebral blood flow activation during Wisconsin Card Sorting Test for affected twins correlated with decreased hippocampal volume determined by magnetic resonance imaging. These neurocognitive studies have suggested that schizophrenia involves neocortical-limbic pathology and dysfunction implicated in performance of cognitive tasks requiring working memory

  19. Musical activity and emotional competence – a twin study

    Directory of Open Access Journals (Sweden)

    Tores PG Theorell

    2014-07-01

    Full Text Available The hypothesis was tested that musical creative achievement and musical practice are associated with lower alexithymia. 8000 Swedish twins aged 27-54 were studied. Alexithymia was assessed using the Toronto Alexithymia Scale (TAS-20. Musical achievement was rated on a 7-graded scale. Participants estimated number of hours of music practice during different ages throughout life. A total life estimation of number of accumulated hours was made. They were also asked about ensemble playing. In addition, twin modelling was used to explore the genetic architecture of the relation between musical practice and alexithymia. Alexithymia was negatively associated with (i musical creative achievement, (ii having played a musical instrument as compared to never having played, and – for the subsample of participants that had played an instrument – (iii total hours of musical training (r = -.12 – in men and -.10 in women. Ensemble playing added significant variance. Twin modelling showed that alexithymia had a moderate heritability of 36% and that the association with musical practice could be explained by shared genetic influences. Associations between musical training and alexithymia remained significant when controlling for education, depression, and intelligence. Musical achievement and musical practice are associated with lower levels of alexithymia in both men and women. Musical engagement thus appears to be associated with higher emotional competence, although effect sizes are small. The association between musical training and alexithymia appears to be entirely genetically mediated, suggesting genetic pleiotropy.

  20. Musical activity and emotional competence - a twin study.

    Science.gov (United States)

    Theorell, Töres P; Lennartsson, Anna-Karin; Mosing, Miriam A; Ullén, Fredrik

    2014-01-01

    The hypothesis was tested that musical activities may contribute to the prevention of alexithymia. We tested whether musical creative achievement and musical practice are associated with lower alexithymia. 8000 Swedish twins aged 27-54 were studied. Alexithymia was assessed using the Toronto Alexithymia Scale-20. Musical achievement was rated on a 7-graded scale. Participants estimated number of hours of music practice during different ages throughout life. A total life estimation of number of accumulated hours was made. They were also asked about ensemble playing. In addition, twin modelling was used to explore the genetic architecture of the relation between musical practice and alexithymia. Alexithymia was negatively associated with (i) musical creative achievement, (ii) having played a musical instrument as compared to never having played, and - for the subsample of participants that had played an instrument - (iii) total hours of musical training (r = -0.12 in men and -0.10 in women). Ensemble playing added significant variance. Twin modelling showed that alexithymia had a moderate heritability of 36% and that the association with musical practice could be explained by shared genetic influences. Associations between musical training and alexithymia remained significant when controlling for education, depression, and intelligence. Musical achievement and musical practice are associated with lower levels of alexithymia in both men and women. Musical engagement thus appears to be associated with higher emotional competence, although effect sizes are small. The association between musical training and alexithymia appears to be entirely genetically mediated, suggesting genetic pleiotropy.

  1. Association between physical and motor development in childhood: a longitudinal study of Japanese twins.

    Science.gov (United States)

    Silventoinen, Karri; Pitkäniemi, Janne; Latvala, Antti; Kaprio, Jaakko; Yokoyama, Yoshie

    2014-06-01

    Length and weight in infancy are associated with neurodevelopment, but less is known about growth in other anthropometric measures. In this study we analyzed how the development in length, weight, head circumference, and chest circumference over infancy is associated with motor development in early childhood, using a twin study design. Information on physical development over infancy and the age at achievement of eight developmental milestones over early childhood was collected for 370 Japanese twin pairs. Linear mixed models were used to analyze how physical development is associated with motor development between individual twins, as well as within twin pairs, adjusting the results for shared maternal and postnatal environmental factors. Delayed motor development was associated with smaller body size over infancy, and we also found some suggestive evidence that it was associated with catch-up growth as well. When studying the associations within twin pairs discordant for motor development, similar associations were found. However, chest circumference showed the most robust association within discordant twin pairs. Smaller body size and rapid catch-up growth are associated with delayed motor development. When studying these associations within twin pairs and thus adjusting the results for gestational age as well as many other maternal and postnatal environmental factors, chest circumference showed the most robust association. Chest circumference, rarely used in developed countries, can offer additional information on prenatal conditions relevant for further motor development not achieved by more traditional anthropometric measures.

  2. Genetic and environmental influences on blood pressure variability: a study in twins.

    Science.gov (United States)

    Xu, Xiaojing; Ding, Xiuhua; Zhang, Xinyan; Su, Shaoyong; Treiber, Frank A; Vlietinck, Robert; Fagard, Robert; Derom, Catherine; Gielen, Marij; Loos, Ruth J F; Snieder, Harold; Wang, Xiaoling

    2013-04-01

    Blood pressure variability (BPV) and its reduction in response to antihypertensive treatment are predictors of clinical outcomes; however, little is known about its heritability. In this study, we examined the relative influence of genetic and environmental sources of variance of BPV and the extent to which it may depend on race or sex in young twins. Twins were enrolled from two studies. One study included 703 white twins (308 pairs and 87 singletons) aged 18-34 years, whereas another study included 242 white twins (108 pairs and 26 singletons) and 188 black twins (79 pairs and 30 singletons) aged 12-30 years. BPV was calculated from 24-h ambulatory blood pressure recording. Twin modeling showed similar results in the separate analysis in both twin studies and in the meta-analysis. Familial aggregation was identified for SBP variability (SBPV) and DBP variability (DBPV) with genetic factors and common environmental factors together accounting for 18-40% and 23-31% of the total variance of SBPV and DBPV, respectively. Unique environmental factors were the largest contributor explaining up to 82-77% of the total variance of SBPV and DBPV. No sex or race difference in BPV variance components was observed. The results remained the same after adjustment for 24-h blood pressure levels. The variance in BPV is predominantly determined by unique environment in youth and young adults, although familial aggregation due to additive genetic and/or common environment influences was also identified explaining about 25% of the variance in BPV.

  3. Twin studies in behavioral research: a skeptical view.

    Science.gov (United States)

    Kamin, Leon J; Goldberger, Arthur S

    2002-02-01

    We review in detail two major ongoing research projects that employ samples of twins reared apart (and in one case, twins reared together). The studies attempt, via model fitting, to estimate proportions of genetic and environmental variance for many human traits. We discuss problems concerning the representativeness of samples, the accuracy and reliability of the data, the extent of contact of nominally separated twins, the measurement of selective placement effects, and the particular model-fitting procedures. The two studies agree in their conclusions, but we do not find the conclusions to be convincing. We suggest that no scientific purpose is served by the flood of heritability estimates generated by these studies.

  4. Relationship between Refractive Error and Ocular Biomet-rics in Twin Children:the Guangzhou Twin Eye Study

    Institute of Scientific and Technical Information of China (English)

    Decai Wang; Bin Liu; Shengsong Huang; Wenyong Huang; Mingguang He

    2014-01-01

    Purpose:.A cross-sectional study was conducted to explore the relationship between refractive error and ocular biometrics in children from the Guangzhou twin eye study.Methods:.Twin participants aged 7-15 years were selected from Guangzhou Twin Eye Study..Ocular examinations included vi-sual acuity measurement, ocular motility evaluation, autore-fraction under cycloplegia, and anterior segment, media, and fundus examination...Axial length (AL),..anterior cham ber depth (ACD), and corneal curvature radius were measured us-ing partial coherence laser interferometry. A multivariate linear regression model was used for statistical analysis.Results:.Twin children from Guangzhou city showed a de-creased spherical equivalent with age,.whereas both AL and ACD were increased and corneal curvature radius remained unchanged. When adjusted by age and gender, the data from 77% of twins presenting with spherical equivalent changes in-dicated that these were caused by predictable variables. (R2=0.77, P<0.001). Primary factors affecting children's refraction included axial length (β=-0.97,P<0.001), ACD (β=0.33,P<0.001), and curvature radius (β=2.10,P<0.001). Girls had a higher tendency for myopic status than did boys (β=-0.26,P<0.001)..Age exerted no effect upon the changes in refraction (β=-0.01, P=0.25).Conclusion:.Refraction is correlated with ocular biometrics. Refractive status is largely determined by axial length as the major factor. (Eye Science 2014; 29:129-133)

  5. The genetic and environmental influences on childhood obesity: a systematic review of twin and adoption studies

    DEFF Research Database (Denmark)

    Silventoinen, K; Rokholm, B; Kaprio, J

    2010-01-01

    In this systematic review, we aimed to collect together all previous twin and adoption studies on childhood and adolescent obesity up to the age of 18 years. Using several sources, we identified nine twin and five adoption studies; all of these studies had used relative weight as an indicator...... a substantial effect in mid-childhood, but this effect disappeared at adolescence. Adoption studies supported the role of family environment in childhood obesity as correlations were found between adoptees and adoptive parents; however, correlations were substantially stronger between parents...... of obesity. Except the two twin studies from the Korean population, all studies represented Caucasian populations. In a meta-analysis of these twin studies, we found that genetic factors had a strong effect on the variation of body mass index (BMI) at all ages. The common environmental factors showed...

  6. Genetics of dietary habits and obesity - a twin study.

    Science.gov (United States)

    Hasselbalch, Ann Louise

    2010-09-01

    were measured and habitual dietary intake was assessed through a food frequency questionnaire (FFQ). When studying body fat mass in population-based studies, the phenotype used is often the body mass index (BMI). This measure does, however, not specify whether excess body mass is due to excess fat mass and how the body fat is distributed. Studying the genetic and environmental correlations between the anthropometry measures in the GEMINAKAR sample showed that the genetic correlations between BMI, fat mass index (FMI) and waist circumference were high in men and that the genetic correlations between BMI, FMI, waist and hip circumference were high in women. For all anthropometric phenotypes, significant residual genetic influence existed. Based on information about habitual diet from the FFQ the genetic influence on total energy intake, macronutrient intake, as well as intake of energy from 20 food groups, was estimated. The proportion of variation in dietary intake explained by variation in genes differed between the dietary traits under study but for the majority of dietary variables the genetic influence was 20-50%. Accordingly, both diet and anthropometry is influenced by genetic variation. In order to control for potential confounding by genetic variation and shared environment on the association between habitual diet and body fat, the monozygotic twin pairs were selected and the associations between intrapair differences in dietary intake and intrapair differences in anthropometry were studied. For the majority of dietary traits, no associations or only weak associations were found. The study showed, however, consistent positive associations between intake of sugar-sweetened soft drink and BMI, FMI and waist circumference in men. Gene-environment interaction models showed that while high physical activity is associated with a down-regulation of genes predisposing to obesity, such effects were not found for protein intake. In conclusion, the studies included in this

  7. Disease-Concordant Twins Empower Genetic Association Studies.

    Science.gov (United States)

    Tan, Qihua; Li, Weilong; Vandin, Fabio

    2017-01-01

    Genome-wide association studies with moderate sample sizes are underpowered, especially when testing SNP alleles with low allele counts, a situation that may lead to high frequency of false-positive results and lack of replication in independent studies. Related individuals, such as twin pairs concordant for a disease, should confer increased power in genetic association analysis because of their genetic relatedness. We conducted a computer simulation study to explore the power advantage of the disease-concordant twin design, which uses singletons from disease-concordant twin pairs as cases and ordinary healthy samples as controls. We examined the power gain of the twin-based design for various scenarios (i.e., cases from monozygotic and dizygotic twin pairs concordant for a disease) and compared the power with the ordinary case-control design with cases collected from the unrelated patient population. Simulation was done by assigning various allele frequencies and allelic relative risks for different mode of genetic inheritance. In general, for achieving a power estimate of 80%, the sample sizes needed for dizygotic and monozygotic twin cases were one half and one fourth of the sample size of an ordinary case-control design, with variations depending on genetic mode. Importantly, the enriched power for dizygotic twins also applies to disease-concordant sibling pairs, which largely extends the application of the concordant twin design. Overall, our simulation revealed a high value of disease-concordant twins in genetic association studies and encourages the use of genetically related individuals for highly efficiently identifying both common and rare genetic variants underlying human complex diseases without increasing laboratory cost. © 2016 John Wiley & Sons Ltd/University College London.

  8. A study on twin-tungsten TIG welding method

    Institute of Scientific and Technical Information of China (English)

    Leng Xuesong; Zhang Guangjun; Gao Hongming; Wu Lin

    2006-01-01

    A new twin-tungsten TIG (T-TIG) welding method was studied. This method differs from the conventional TIG method, it places two electrodes insulated from each other in the same welding torch, and a coupling arc is generated from the two electrodes. The coupling arc pressure was measured and preliminary welding experiment was made. The results show that the coupling arc can keep arc pressure at a low level compared with conventional TIG arc, and welding can be achieved under higher current and high travel speed with sound appearance of weld. Therefore, this new method can applied widely in high efficiency welding.

  9. Exploring the origins of asthma: Lessons from twin studies

    Science.gov (United States)

    2014-01-01

    This thesis explores the contribution of twin studies, particularly those studies originating from the Danish Twin Registry, to the understanding of the aetiology of asthma. First, it is explored how twin studies have established the contribution of genetic and environmental factors to the variation in the susceptibility to asthma, and to the variation in several aspects of the clinical expression of the disease such as its age at onset, its symptomatology, its intermediate phenotypes, and its relationship with other atopic diseases. Next, it is explored how twin studies have corroborated theories explaining asthma's recent increase in prevalence, and last, how these fit with the explanations of the epidemiological trends in other common chronic diseases of modernity. PMID:26557247

  10. Genetic influence on bone mineral density in Korean twins and families: the healthy twin study.

    Science.gov (United States)

    Park, J-H; Song, Y-M; Sung, J; Lee, K; Kim, Y S; Park, Y S

    2012-04-01

    Bone mineral density (BMD), a representative marker of osteoporosis risk, is found to be highly heritable in this Korean study, which is very consistent with the findings in Western populations. This finding strongly supports that genetic factors are significant determinants of osteoporosis risk along with individual biological and behavioral factors. Although genetic factors are known to contribute significantly to variations in BMD in Western populations, such an association has not been fully evaluated in an Asian population. This study was conducted to determine the role of genetic factors on BMD in Korean population. The study participants were 2,728 men and women consisting of 497 monozygotic (MZ) twin pairs, 119 dizygotic (DZ) twin pairs, and 1,496 first-degree relatives from the Healthy Twin Study. BMD was measured using dual-energy X-ray absorptiometry. Quantitative genetic analysis based on a variance decomposition model was performed. Age and the measured covariates accounted for 17~61% of the variation in BMD, depending on the sites of measurement. After accounting for the covariate effects, the heritability of BMD at the whole body, thoracic and lumbar spine, whole ribs, whole pelvis, whole arms, and whole legs were 0.76, 0.72, 0.73, 0.71, 0.51, and 0.75, respectively. The pair-wise correlation of BMD was the highest within MZ twin pairs, followed by DZ twin pairs, sibling pairs, and parents-child pairs. Cross-trait correlation analysis revealed a positive genetic correlation between BMDs at different sites, ranging from 0.80 (arm and leg BMD) to 0.50 (pelvis and arm BMD). The high heritability of BMD in this Korean population similar to those found in Western populations and the significant common genetic basis between BMDs at different sites strongly supports a significant role of genetic determinants on the risk of osteoporosis.

  11. In Situ Studies on Twin-Thickness-Dependent Distribution of Defect Clusters in Heavy Ion-Irradiated Nanotwinned Ag

    Science.gov (United States)

    Li, Jin; Chen, Y.; Wang, H.; Zhang, X.

    2017-03-01

    Recent studies have shown that twin boundaries are effective defect sinks in heavy ion irradiated nanotwinned (nt) metals. Prior in situ radiation studies on nt Ag at room temperature indicate that the accumulative defect concentration is higher in center areas in the 60-nm-thick twins, and twin boundaries are distorted and self-heal during the absorption of different types of defect clusters. In this follow-up study, we show that the spatial distribution of accumulative defect concentrations in nt metals has a clear dependence on twin thickness, and in certain cases, the trend of spatial distribution is reversed. Potential mechanisms for the counterintuitive findings are discussed.

  12. Discordant tooth agenesis and peg-shaped in a pair of monozygotic twins: Clinical and molecular study.

    Science.gov (United States)

    Antunes, Lívia Azeredo Alves; Küchler, Erika Calvano; Costa, Marcelo de Castro; Antunes, Leonardo Santos; Granjeiro, José Mauro

    2013-11-01

    The present report aimed to study an uncommon case of a pair of twins that presented a discordant dental phenotype. Family investigation, clinical, radiographic examination and molecular analysis were performed in both girls. Molecular analysis confirmed the monozygosity by deoxyribonucleic acid chip technology. One twin presented tooth agenesis in left upper lateral incisor and peg-shaped on the contra lateral side while the other twin had no dental alterations. The dental casts study employed digital caliper to compare morphological dimensions and showed alteration only in peg-shaped tooth. In conclusion, this study provide support that one or more mutated gene could cause discordances in dental phenotype in these monozygotic twins.

  13. A prospective study of twinning and perinatal mortality in urban Guinea-Bissau

    DEFF Research Database (Denmark)

    Bjerregaard-Andersen, Morten; Lund, Najaaraq; Jepsen, Frida Staarup

    2012-01-01

    ABSTRACT: BACKGROUND: Despite twinning being common in Africa, few prospective twin studies have been conducted. We studied twinning rate, perinatal mortality and the clinical characteristics of newborn twins in urban Guinea-Bissau. METHODS: The study was conducted at the Bandim Health Project (B...

  14. A phenomenological study on twin screw extruders

    NARCIS (Netherlands)

    Janssen, L.P.B.M.

    1976-01-01

    Although more and more twin screw extruders are being used in the polymer industry, the theoretical background is relatively undeveloped. The literature abounds in contradictions and often informs the reader that all extrusion problems can be solved if a certain new design is considered. The develop

  15. Prognostic and survival analysis of presbyopia: The healthy twin study

    Science.gov (United States)

    Lira, Adiyani; Sung, Joohon

    2015-12-01

    Presbyopia, a vision condition in which the eye loses its flexibility to focus on near objects, is part of ageing process which mostly perceptible in the early or mid 40s. It is well known that age is its major risk factor, while sex, alcohol, poor nutrition, ocular and systemic diseases are known as common risk factors. However, many other variables might influence the prognosis. Therefore in this paper we developed a prognostic model to estimate survival from presbyopia. 1645 participants which part of the Healthy Twin Study, a prospective cohort study that has recruited Korean adult twins and their family members based on a nation-wide registry at public health agencies since 2005, were collected and analyzed by univariate analysis as well as Cox proportional hazard model to reveal the prognostic factors for presbyopia while survival curves were calculated by Kaplan-Meier method. Besides age, sex, diabetes, and myopia; the proposed model shows that education level (especially engineering program) also contribute to the occurrence of presbyopia as well. Generally, at 47 years old, the chance of getting presbyopia becomes higher with the survival probability is less than 50%. Furthermore, our study shows that by stratifying the survival curve, MZ has shorter survival with average onset time about 45.8 compare to DZ and siblings with 47.5 years old. By providing factors that have more effects and mainly associate with presbyopia, we expect that we could help to design an intervention to control or delay its onset time.

  16. Nature, nurture, and ethnocentrism in the Minnesota twin study.

    Science.gov (United States)

    Orey, Byron D'Andra; Park, Hyung

    2012-02-01

    The preponderance of research on the study of ethnocentrism has primarily attributed such attitudes to learned behavior. The research here advances the argument that both socialization and genetic inheritance contribute to the development of ethnocentric attitudes and behavior. This analysis employs the Minnesota Twins Political Survey data consisting of 596 complete twin pairs. Using the classical twin design, we employed structural equation modeling to model the covariance of twins in regards to additive genetic effects, shared environmental effects, and unique environmental effects (i.e., the classic ACE model). The findings reveal that genetic inheritance is significant in explaining the variance in genetic attitudes. Specifically, genetic inheritance explains 18% of the variance, with the overwhelming 82% being explained by the unique environment.

  17. Heritability of retinal vascular fractals: a twin study

    DEFF Research Database (Denmark)

    Vergmann, Anna Stage; Broe, Rebecca; Kessel, Line

    Purpose: To determine the genetic contribution to the pattern of retinal vascular branching expressed by its fractal dimension. Methods: This was a cross-sectional study of 50-degree, disc-centred fundus photographs from 59 monozygotic and 55 dizygotic, same-sex twin pairs aged 20-46 years....... The retinal vascular fractal dimension was measured using the box-counting method and compared within monozygotic and dizygotic twin pairs using Pearson correlation coefficents. Falconer´s formula and quantitative genetic models were used to determine the genetic component of variation. Results: The retinal...... for quantitative analysis of heritability. The intrapair correlation was markedly higher (0.505, p=0.0002) in monozygotic twins than in dizygotic twins (0.108, p=0.46), corresponding to a heritability h2 for the fractal dimension of 0.79. In quantitative genetic models, 54% of the variation was explained...

  18. Twins for epigenetic studies of human aging and development

    DEFF Research Database (Denmark)

    Tan, Qihua; Christiansen, Lene; Thomassen, Mads

    2013-01-01

    Most of the complex traits including aging phenotypes are caused by the interaction between genome and environmental conditions and the interface of epigenetics may be a central mechanism. Although modern technologies allow us high-throughput profiling of epigenetic patterns already at genome level......, our understanding of genetic and environmental influences on the epigenetic processes remains limited. Twins are of special interest for genetic studies due to their genetic similarity and rearing-environment sharing. The classical twin design has made a great contribution in dissecting the genetic...... and environmental contributions to human diseases and complex traits. In the era of functional genomics, the valuable sample of twins is helping to bridge the gap between gene activity and the environments through epigenetic mechanisms unlimited by DNA sequence variations. We propose to extend the classical twin...

  19. Secular change in 13 metabolic phenotypes: A Chinese longitudinal twin study

    DEFF Research Database (Denmark)

    Li, Shuxia; Pang, Zengchang; Zhang, Dongfeng

    Aims: The genetic and environmental influences on metabolic phenotypes have been intensively studied by twin modeling in different populations. However, twin studies on secular change in metabolic phenotypes have been rare due to high expenses, losses of follow up, and long waiting time...... in prospective investigations. Based on Chinese twin data collected from Danish-Chinese collaboration research, we perform twin modeling on 13 metabolic phenotypes (total cholesterol; triglyceride; high density lipoprotein (HDL); low density lipoprotein (LDL); urine acid (UA); glucose; weight; body mass index...... environmental factors. Secular changes in all phenotypes are under moderate to high (e2: 0.45 - 0.79) control by unique environmental factors. Conclusions: Variations in secular change in the 13 metabolic phenotypes show limited genetic control. Our results emphasize the special importance of unique environment...

  20. Strong Genetic Contribution to Peer Relationship Difficulties at School Entry: Findings from a Longitudinal Twin Study

    Science.gov (United States)

    Boivin, Michel; Brendgen, Mara; Vitaro, Frank; Dionne, Ginette; Girard, Alain; Perusse, Daniel; Tremblay, Richard E.

    2013-01-01

    This study assessed the genetic and environmental contributions to peer difficulties in the early school years. Twins' peer difficulties were assessed longitudinally in kindergarten (796 twins, "M"[subscript age] = 6.1 years), Grade 1 (948 twins, "M"[subscript age] = 7.1 years), and Grade 4 (868 twins, "M"[subscript…

  1. Paternal age and telomere length in twins

    DEFF Research Database (Denmark)

    Hjelmborg, Jacob B; Dalgård, Christine; Mangino, Massimo

    2015-01-01

    . Based on two independent (discovery and replication) twin studies, comprising 889 twin pairs, we show an increase in the resemblance of leukocyte telomere length between dizygotic twins of older fathers, which is not seen in monozygotic twins. This phenomenon might result from a paternal age...

  2. In situ nanoindentation study on plasticity and work hardening in aluminium with incoherent twin boundaries.

    Science.gov (United States)

    Bufford, D; Liu, Y; Wang, J; Wang, H; Zhang, X

    2014-09-10

    Nanotwinned metals have been the focus of intense research recently, as twin boundaries may greatly enhance mechanical strength, while maintaining good ductility, electrical conductivity and thermal stability. Most prior studies have focused on low stacking-fault energy nanotwinned metals with coherent twin boundaries. In contrast, the plasticity of twinned high stacking-fault energy metals, such as aluminium with incoherent twin boundaries, has not been investigated. Here we report high work hardening capacity and plasticity in highly twinned aluminium containing abundant Σ3{112} incoherent twin boundaries based on in situ nanoindentation studies in a transmission electron microscope and corresponding molecular dynamics simulations. The simulations also reveal drastic differences in deformation mechanisms between nanotwinned copper and twinned aluminium ascribed to stacking-fault energy controlled dislocation-incoherent twin boundary interactions. This study provides new insight into incoherent twin boundary-dominated plasticity in high stacking-fault energy twinned metals.

  3. Accounting for the relationship between low education and dementia: a twin study.

    Science.gov (United States)

    Gatz, Margaret; Mortimer, James A; Fratiglioni, Laura; Johansson, Boo; Berg, Stig; Andel, Ross; Crowe, Michael; Fiske, Amy; Reynolds, Chandra A; Pedersen, Nancy L

    2007-09-10

    We evaluated whether the association between low education and greater risk of dementia is explained by genetic influences, using three different types of analyses. The HARMONY study (Swedish for "health" (Hälsa), "genes" (ARv), "environment" (Miljö), "and" (Och), and "new" (NY)) includes members of the Swedish Twin Registry who were aged 65 and older and alive in 1998, and who were screened and clinically assessed for dementia. There were 394 cases with dementia and 7786 unrelated controls. Analyses included co-twin control, tests for association between education and a measured genotype, and bivariate twin modeling. Low education was a significant risk factor for dementia both in case-control analyses (odds ratio=1.77, 95% confidence interval 1.38 to 2.28) and co-twin control analyses with monozygotic twin pairs (odds ratio=3.17, 95% confidence interval 1.26 to 7.93). Apolipoprotein E genotype was not associated with education and did not account for the relationship between education and dementia. Bivariate twin modeling showed that the association between education and dementia was not mediated by genetic influences in common between education and dementia. The association was mediated by shared environmental influences that were related to both dementia and to education. Low education is confirmed as a risk factor for dementia. Findings from three different analytic approaches showed that genetic influences did not explain this association.

  4. Personality and birth order in monozygotic twins adopted apart: a test of Sulloway's theory; Research Reviews: twin births and cancer risk in mothers, male sexual dysfunction, twin study of ultimatum game behavior; Human Interest: 'The Land of Twins', twin-like reunion-I, twin-like reunion-II.

    Science.gov (United States)

    Segal, Nancy L

    2008-02-01

    A brief overview of Sulloway's (1996) theory of birth order and personality is presented. A reared apart twin approach for testing his personality findings regarding openness to experience and conscientiousness in first borns and later borns is described. This is followed by summaries of three recent twin studies. The topics include cancer risk in mother of twins, sexual dysfunction in males and responder behavior during ultimatum games. This article concludes with a discussion of twinning rates and rituals among the Yoruba of western Nigeria, and descriptions of two unusual reunions between siblings and twins.

  5. In Situ Studies on the Irradiation-Induced Twin Boundary-Defect Interactions in Cu

    Science.gov (United States)

    Fan, C.; Li, Jin; Fan, Zhe; Wang, H.; Zhang, X.

    2017-08-01

    Polycrystalline Cu films with nanoscale annealing twins are subjected to in situ Kr++ ion irradiation at room temperature inside a transmission electron microscope up to a dose of 1 displacement-per-atom. Radiation induces prominent migration of incoherent twin boundaries. Depending on twin thickness, three types of twin boundary evolutions are observed, including rapid detwinning, gradual detwinning, and self-healing. The mechanism of twin thickness-dependent evolution of microstructures is discussed. This study provides further evidence on twin boundary-defect interactions and may assist the design of radiation-tolerant twinned metallic materials.

  6. The contribution of twins to the study of cognitive ageing and dementia: the Older Australian Twins Study.

    Science.gov (United States)

    Sachdev, Perminder S; Lee, Teresa; Wen, Wei; Ames, David; Batouli, Amir H; Bowden, Jocelyn; Brodaty, Henry; Chong, Elizabeth; Crawford, John; Kang, Kristan; Mather, Karen; Lammel, Andrea; Slavin, Melissa J; Thalamuthu, Anbupalam; Trollor, Julian; Wright, Margie J

    2013-12-01

    The Older Australian Twins Study (OATS) is a major longitudinal study of twins, aged ≥ 65 years, to investigate genetic and environmental factors and their interactions in healthy brain ageing and neurocognitive disorders. The study collects psychiatric, neuropsychological, cardiovascular, metabolic, biochemical, neuroimaging, genomic and proteomic data, with two-yearly assessments, and is currently in its third wave. The initial cohort comprises 623 individuals (161 monozygotic and 124 dizygotic twin pairs; 1 MZ triplets; 27 single twins and 23 non-twin siblings), of whom 426 have had wave 2 assessment. A number of salient findings have emerged thus far which assist in the understanding of genetic contributions to cognitive functions such as processing speed, executive ability and episodic memory, and which support the brain reserve hypothesis. The heritability of brain structures, both cortical and subcortical, brain spectroscopic metabolites and markers of small vessel disease, such as lacunar infarction and white matter hyperintensities, have been examined and can inform future genetic investigations. Work on amyloid imaging and functional magnetic resonance imaging is proceeding and epigenetic studies are progressing. This internationally important study has the potential to inform research into cognitive ageing in the future, and offers an excellent resource for collaborative work.

  7. Adult body height of twins compared with that of singletons: a register-based birth cohort study of Norwegian males.

    Science.gov (United States)

    Eriksen, Willy; Sundet, Jon M; Tambs, Kristian

    2013-05-01

    In the present study, we evaluated whether childhood differences in body height between singletons and twins persist into adulthood. Data from the Medical Birth Register of Norway were linked with data from the Norwegian National Conscript Service. This study used data on the 457,999 males who were born alive and without physical anomalies in single or twin births in Norway during 1967-1984 and who were examined at the mandatory military conscription (age 18-20 years; 1985-2003). For sibling comparisons, the authors selected the 1,721 sibships of full brothers that included at least 1 male born in a single birth and at least 1 male born in a twin birth (4,520 persons, including 2,493 twins and 2,027 singletons). An analysis of the total study population using generalized estimating equations showed that the twins were 0.6 cm (95% confidence interval: 0.4, 0.7) shorter than were the singletons after adjustment for a series of background factors. The fixed-effects regression analysis of the sibships that included both twins and singletons showed that the twins were 0.9 cm (95% confidence interval: 0.6, 1.2) shorter than were their singleton brothers. The study suggests that male twins born in Norway during 1967-1984 were slightly shorter in early adulthood than were singletons.

  8. Recurrence risk for offspring of twins discordant for oral cleft: a population-based cohort study of the Danish 1936-2004 cleft twin cohort

    DEFF Research Database (Denmark)

    Grosen, Dorthe; Bille, Camilla; Pedersen, Jacob Krabbe;

    2010-01-01

    Our objective in this Danish population-based cohort study was to estimate the recurrence risk of isolated oral cleft (OC) for offspring of the unaffected co-twins of OC discordant twin pairs and to compare this risk to the recurrence risk in the offspring of the affected co-twin as well...... as to the risk in the background population. During 1936-2004, 207 twin pairs were ascertained, among whom at least one twin had an OC. The index persons were twins discordant for OC who had children (N=117), and their offspring (N=239). The participants were ascertained by linkage between The Danish Facial...... Cleft Database, The Danish Twin Registry and The Danish Civil Registration System. In the study OC recurrence risk for offspring of the affected and unaffected twin and relative risk were compared to the background prevalence. We found that among 110 children of the 54 OC affected twins, two (1...

  9. Weak phonon scattering effect of twin boundaries on thermal transmission.

    Science.gov (United States)

    Dong, Huicong; Xiao, Jianwei; Melnik, Roderick; Wen, Bin

    2016-01-29

    To study the effect of twin boundaries on thermal transmission, thermal conductivities of twinned diamond with different twin thicknesses have been studied by NEMD simulation. Results indicate that twin boundaries show a weak phonon scattering effect on thermal transmission, which is only caused by the additional twin boundaries' thermal resistance. Moreover, according to phonon kinetic theory, this weak phonon scattering effect of twin boundaries is mainly caused by a slightly reduced average group velocity.

  10. Weak phonon scattering effect of twin boundaries on thermal transmission

    OpenAIRE

    Huicong Dong; Jianwei Xiao; Roderick Melnik; Bin Wen

    2016-01-01

    To study the effect of twin boundaries on thermal transmission, thermal conductivities of twinned diamond with different twin thicknesses have been studied by NEMD simulation. Results indicate that twin boundaries show a weak phonon scattering effect on thermal transmission, which is only caused by the additional twin boundaries’ thermal resistance. Moreover, according to phonon kinetic theory, this weak phonon scattering effect of twin boundaries is mainly caused by a slightly reduced averag...

  11. Zygosity differences in height and body mass index of twins from infancy to old age: A study of the CODATwins project

    Science.gov (United States)

    Jelenkovic, Aline; Yokoyama, Yoshie; Sund, Reijo; Honda, Chika; Bogl, Leonie H; Aaltonen, Sari; Ji, Fuling; Ning, Feng; Pang, Zengchang; Ordoñana, Juan R; Sánchez-Romera, Juan F; Colodro-Conde, Lucia; Burt, S Alexandra; Klump, Kelly L; Medland, Sarah E; Montgomery, Grant W; Kandler, Christian; McAdams, Tom A; Eley, Thalia C; Gregory, Alice M; Saudino, Kimberly J; Dubois, Lise; Boivin, Michel; Tarnoki, Adam D; Tarnoki, David L; Haworth, Claire MA; Plomin, Robert; Öncel, Sevgi Y; Aliev, Fazil; Stazi, Maria A; Fagnani, Corrado; D'Ippolito, Cristina; Craig, Jeffrey M; Saffery, Richard; Siribaddana, Sisira H; Hotopf, Matthew; Sumathipala, Athula; Rijsdijk, Fruhling; Spector, Timothy; Mangino, Massimo; Lachance, Genevieve; Gatz, Margaret; Butler, David A; Bayasgalan, Gombojav; Narandalai, Danshiitsoodol; Freitas, Duarte L; Maia, José Antonio; Harden, K Paige; Tucker-Drob, Elliot M; Kim, Bia; Chong, Youngsook; Hong, Changhee; Shin, Hyun Jung; Christensen, Kaare; Skytthe, Axel; Kyvik, Kirsten O; Derom, Catherine A; Vlietinck, Robert F; Loos, Ruth JF; Cozen, Wendy; Hwang, Amie E; Mack, Thomas M; He, Mingguang; Ding, Xiaohu; Chang, Billy; Silberg, Judy L; Eaves, Lindon J; Maes, Hermine H; Cutler, Tessa L; Hopper, John L; Aujard, Kelly; Magnusson, Patrik KE; Pedersen, Nancy L; Aslan, Anna K Dahl; Song, Yun-Mi; Yang, Sarah; Lee, Kayoung; Baker, Laura A; Tuvblad, Catherine; Bjerregaard-Andersen, Morten; Beck-Nielsen, Henning; Sodemann, Morten; Heikkilä, Kauko; Tan, Qihua; Zhang, Dongfeng; Swan, Gary E; Krasnow, Ruth; Jang, Kerry L; Knafo-Noam, Ariel; Mankuta, David; Abramson, Lior; Lichtenstein, Paul; Krueger, Robert F; McGue, Matt; Pahlen, Shandell; Tynelius, Per; Duncan, Glen E; Buchwald, Dedra; Corley, Robin P; Huibregtse, Brooke M; Nelson, Tracy L; Whitfield, Keith E; Franz, Carol E; Kremen, William S; Lyons, Michael J; Ooki, Syuichi; Brandt, Ingunn; Nilsen, Thomas Sevenius; Inui, Fujio; Watanabe, Mikio; Bartels, Meike; van Beijsterveldt, Toos CEM; Wardle, Jane; Llewellyn, Clare H; Fisher, Abigail; Rebato, Esther; Martin, Nicholas G; Iwatani, Yoshinori; Hayakawa, Kazuo; Sung, Joohon; Harris, Jennifer R; Willemsen, Gonneke; Busjahn, Andreas; Goldberg, Jack H; Rasmussen, Finn; Hur, Yoon-Mi; Boomsma, Dorret I; Sørensen, Thorkild IA; Kaprio, Jaakko; Silventoinen, Karri

    2015-01-01

    A trend towards greater body size in dizygotic (DZ) than in monozygotic (MZ) twins has been suggested by some but not all studies, and this difference may also vary by age. We analyzed zygosity differences in means and variances of height and body mass index (BMI) among male and female twins from infancy to old age. Data were derived from an international database of 54 twin cohorts participating in the CODATwins project and included 842,951 height and BMI measurements from age 1 to 102 years. The results showed that DZ twins were consistently taller than MZ twins, with differences of up to 2.0 cm in childhood and adolescence and up to 0.9 cm in adulthood. Likewise, a greater mean BMI of up to 0.3 kg/m2 in childhood and adolescence and up to 0.2 kg/m2 in adulthood was observed in DZ twins, although the pattern was less consistent. DZ twins presented up to 1.7% greater height and 1.9% greater BMI than MZ twins; these percentage differences were largest in middle and late childhood and decreased with age in both sexes. The variance of height was similar in MZ and DZ twins at most ages. In contrast the variance of BMI was significantly higher in DZ than in MZ twins particularly in childhood. In conclusion, DZ twins were generally taller and had greater BMI than MZ twins, but the differences decreased with age in both sexes. PMID:26337138

  12. Studies of twins indicate that genetics influence dietary intake

    DEFF Research Database (Denmark)

    Hasselbalch, Ann Louise; Heitmann, Berit L; Kyvik, Kirsten O

    2008-01-01

    Habitual dietary intake is a complex behavior that may have both biological and nonbiological bases. We estimated the contribution of genetic and environmental influences on dietary intake in a large population-based sample of healthy twins. Data originated from a cross-sectional study of 600 mal...

  13. A prospective study of twinning and perinatal mortality in urban Guinea-Bissau

    Science.gov (United States)

    2012-01-01

    Background Despite twinning being common in Africa, few prospective twin studies have been conducted. We studied twinning rate, perinatal mortality and the clinical characteristics of newborn twins in urban Guinea-Bissau. Methods The study was conducted at the Bandim Health Project (BHP), a health and demographic surveillance site in Bissau, the capital of Guinea-Bissau. The cohort included all newborn twins delivered at the National Hospital Simão Mendes and in the BHP study area during the period September 2009 to August 2011 as well as singleton controls from the BHP study area. Data regarding obstetric history and pregnancy were collected at the hospital. Live children were examined clinically. For a subset of twin pairs zygosity was established by using genetic markers. Results Out of the 5262 births from mothers included in the BHP study area, 94 were twin births, i.e. a community twinning rate of 18/1000. The monozygotic rate was 3.4/1000. Perinatal mortality among twins vs. singletons was 218/1000 vs. 80/1000 (RR = 2.71, 95% CI: 1.93-3.80). Among the 13783 hospital births 388 were twin births (28/1000). The hospital perinatal twin mortality was 237/1000. Birth weight twin mortality. Male sex (RR = 1.38, CI: 0.97-1.96), unawareness of twin pregnancy (RR = 1.64, CI: 0.97-2.78) and high blood pressure during pregnancy (RR = 1.77, CI: 0.88-3.57) were borderline non-significant. Sixty-five percent (245/375) of the mothers who delivered at the hospital were unaware of their twin pregnancy. Conclusions Twins had a very high perinatal mortality, three-fold higher than singletons. A birth weight twin pregnancy was common. Urgent interventions are needed to lower perinatal twin mortality in Guinea-Bissau. PMID:23216795

  14. Twin Supernova Studies with SNe Ia from SNfactory

    Science.gov (United States)

    Fakhouri, Hannah; Aldering, G.; Aragon, C.; Hsiao, E.; Loken, S.; Nugent, P.; Perlmutter, S.; Runge, K.; Thomas, R. C.; Antilogous, P.; Bongard, S.; Canto, A.; Pain, R.; Wu, C.; Chotard, N.; Copin, Y.; Gangler, E.; Pereira, R.; Smadja, G.; Pecontal, E.; Baltay, C.; Rabinowitz, D.; Scalzo, R.; Buton, C.; Kerschhaggl, M.; Kowalski, M.; Paech, K.; Tao, C.

    2011-01-01

    We present a study of twin supernovae with spectrophotometric timeseries of nearby Type Ia supernova from the Nearby Supernova Factory (Aldering, et al. 2002). One advantage of "twins” is they offer the best opportunity for having objects with the same intrinsic luminosities and colors, ostensibly leaving only extrinsic factors such as dust to explain any observed differences in brightness and color. Using well-sampled timeseries data for over 100 nearby Hubble-flow SNe Ia, we study the impact of dust on the brightness differences of SN Ia twins in order to improve the standardization of these standardizable candles that have been and will continue to be a primary tool in the determination of cosmological parameters. Specifically we are able to solve for the relative extinction and RV needed to bring the twins into near-perfect agreement. We will present a study of the resulting distribution of RV. In searching for twin supernovae we have found groups of SNe, again differing only by a dust law that accounts for the brightness differences. These groups allow us to look for similarities in subsets of SNe and explore spectrophotometric differences from group to group.

  15. Genetic and environmental influences on applied creativity: A reared-apart twin study.

    Science.gov (United States)

    Velázquez, Jaime A; Segal, Nancy L; Horwitz, Briana N

    2015-03-01

    Applied creativity involves bringing innovation to real-life activities. The first reared-apart twin study assessing genetic and environmental origins of applied creativity, via Draw-a-House (DAH) and Draw-a-Person (DAP) tasks, is presented. Participants included 69 MZA and 53 DZA twin pairs from the Minnesota Study of Twins Reared Apart. Drawings were evaluated by four artists and four non-artists. Genetic effects were demonstrated for the DAP (.38-.47), but not for the DAH. Creative personality showed genetic effects (.50), and modest, but significant correlations with scores on the two drawings (rs = .17-.26). Both genetic and nonshared environmental influences underlie variance in applied creativity. Individuals concerned with enhancing creativity among students and others may better understand individual differences in performance and training.

  16. Family study of monozygotic twins affected by pemphigus vulgaris.

    Science.gov (United States)

    Salathiel, Adriana Martinelli; Brochado, Maria José Franco; Kim, Olivia; Deghaide, Neifi Hassan Saloum; Donadi, Eduardo Antonio; Roselino, Ana Maria

    2016-07-01

    Rare are the family studies that include siblings affected by pemphigus vulgaris (PV) and in whom HLA class II alleles are related. HLA-DR and -DQ genotyping and profiling of antibodies against desmogleins (Dsg) 1 and Dsg3 were performed in ten members of a family including monozygotic twins affected by PV. The twin sisters were heterozygotes; they presented the haplotypes most commonly associated with increased susceptibility to PV (DRB1∗04:02-DQA1∗03:01-DQB1∗03:02 and DRB1∗14:04-DQA1∗01:01-DQB1∗05:03). Their parents and five siblings had only one or none of these two haplotypes in combination with the alleles or haplotypes associated with resistance to PV (DRB1∗07:01-DQA1∗02:01-DQB1∗02:02 and DRB1∗13:01-DQA1∗01:03-DQB1∗06:03). Only the monozygotic twins presented IgG antibodies against both Dsg1 and Dsg3. According to our knowledge based on a review of published literature on the topic, this is the first report of PV affecting monozygotic twins.

  17. Genetic contribution to the relationship between social role function and depressive symptoms in Japanese elderly twins: a twin study.

    Science.gov (United States)

    Nishihara, Reiko; Inui, Fujio; Kato, Kenji; Tomizawa, Rie; Hayakawa, Kazuo

    2011-03-01

    Social role function is the capacity to maintain interpersonal relationships and is essential for being independent in the community. Limitations in social role function often coexist with depressive symptoms, suggesting a possible common mechanistic basis. We investigated whether the observed association between these traits is mainly a result of genetic or environmental influences. In 2008, a questionnaire was sent to 745 male twins aged 65 years and older. Our sample included 397 male twins. The number of monozygotic twins was 302, and dizygotic was 95. Among the twin pairs for whom data were available for both twins, 75 twin pairs (150 individuals) were monozygotic and 28 pairs (56 individuals) were dizygotic. Social role function was assessed using the Tokyo Metropolitan Institute of Gerontology Index of Competence. Depressive symptoms were measured by the 15-item version of the Geriatric Depression Scale. Relative importance of genes and environments for the phenotypes was calculated using structural equation analyses. Our results show that genetic influence was the major contributor to the relationship between social role function and depressive symptoms, and non-shared environmental influence was important for overall variation in each trait. We concluded that focusing on a non-shared environment is an essential approach for maintaining social role function and psychological well-being. It is suggested that treatments specific to depressive symptoms are more effective than indirect intervention targeting social role function. © 2011 The Authors. Psychogeriatrics © 2011 Japanese Psychogeriatric Society.

  18. The Heritability of Breast Cancer among women in the Nordic Twin Study of Cancer

    DEFF Research Database (Denmark)

    Möller, Sören; Mucci, Lorelei A; Harris, Jennifer R;

    2016-01-01

    and heritability of breast cancer among 21,054 monozygotic and 30,939 dizygotic female twin pairs from the Nordic Twin Study of Cancer, the largest twin study of cancer in the world. We accounted for left-censoring, right-censoring, as well as the competing risk of death. Results From 1943 through 2010, 3...

  19. Prevalence and heritability of skin picking in an adult community sample: a twin study.

    Science.gov (United States)

    Monzani, Benedetta; Rijsdijk, Fruhling; Cherkas, Lynn; Harris, Juliette; Keuthen, Nancy; Mataix-Cols, David

    2012-07-01

    Skin-picking disorder (SPD) is a disabling psychiatric condition that can lead to skin damage and other medical complications. Epidemiological data is scarce and its causes are unknown. The present study examined the prevalence and heritability of skin-picking symptoms in a large sample of twins. A total of 2,518 twins completed a valid and reliable self-report measure of skin-picking behavior. The prevalence of clinically significant skin picking was established using empirically derived cut-offs. Twin modeling methods were employed to decompose the variance in the liability to skin picking into additive genetic and shared and non-shared environmental factors. A total of 1.2% of twins scored above the cut-off, indicative of clinically significant skin picking. All these participants were women. Univariate model-fitting analyses (female twins only, N = 2,191) showed that genetic factors accounted for approximately 40% (95% CI 19-58%) of the variance in skin picking, with non-shared environmental factors and measurement error accounting for the remaining variance (60% [95% CI 42-81%]). Shared environmental factors were negligible. It is concluded that pathological skin picking is relatively prevalent problem, particularly among women, and that it tends to run in families primarily due to genetic factors. Non-shared environmental factors are also likely to play an important role in its etiology.

  20. Abnormal N400 Semantic Priming Effect May Reflect Psychopathological Processes in Schizophrenia: A Twin Study

    Directory of Open Access Journals (Sweden)

    Anuradha Sharma

    2017-01-01

    Full Text Available Objective. Activation of semantic networks is indexed by the N400 effect. We used a twin study design to investigate whether N400 effect abnormalities reflect genetic/trait liability or are related to psychopathological processes in schizophrenia. Methods. We employed robust linear regression to compare N400 and behavioral priming effects across 36 monozygotic twin pairs (6 pairs concordant for schizophrenia/schizoaffective disorder, 11 discordant pairs, and 19 healthy control pairs performing a lexical decision task. Moreover, we examined the correlation between Brief Psychiatric Rating Scale (BPRS score and the N400 effect and the influence of medication status on this effect. Results. Regression yielded a significant main effect of group on the N400 effect only in the direct priming condition (p=0.003. Indirect condition and behavioral priming effect showed no significant effect of group. Planned contrasts with the control group as a reference group revealed that affected concordant twins had significantly reduced N400 effect compared to controls, and discordant affected twins had a statistical trend for reduced N400 effect compared to controls. The unaffected twins did not differ significantly from the controls. There was a trend for correlation between reduced N400 effect and higher BPRS scores, and the N400 effect did not differ significantly between medicated and unmedicated patients. Conclusions. Reduced N400 effect may reflect disease-specific processes in schizophrenia implicating frontotemporal brain network in schizophrenia pathology.

  1. A prospective study of twinning and perinatal mortality in urban Guinea-Bissau

    Directory of Open Access Journals (Sweden)

    Bjerregaard-Andersen Morten

    2012-12-01

    Full Text Available Abstract Background Despite twinning being common in Africa, few prospective twin studies have been conducted. We studied twinning rate, perinatal mortality and the clinical characteristics of newborn twins in urban Guinea-Bissau. Methods The study was conducted at the Bandim Health Project (BHP, a health and demographic surveillance site in Bissau, the capital of Guinea-Bissau. The cohort included all newborn twins delivered at the National Hospital Simão Mendes and in the BHP study area during the period September 2009 to August 2011 as well as singleton controls from the BHP study area. Data regarding obstetric history and pregnancy were collected at the hospital. Live children were examined clinically. For a subset of twin pairs zygosity was established by using genetic markers. Results Out of the 5262 births from mothers included in the BHP study area, 94 were twin births, i.e. a community twinning rate of 18/1000. The monozygotic rate was 3.4/1000. Perinatal mortality among twins vs. singletons was 218/1000 vs. 80/1000 (RR = 2.71, 95% CI: 1.93-3.80. Among the 13783 hospital births 388 were twin births (28/1000. The hospital perinatal twin mortality was 237/1000. Birth weight  Conclusions Twins had a very high perinatal mortality, three-fold higher than singletons. A birth weight 

  2. What Twin Studies Tell Us About the Heritability of Brain Development, Morphology, and Function: A Review

    NARCIS (Netherlands)

    A.G. Jansen (Arija G.); S.E. Mous (Sabine); T.J.H. White (Tonya); D. Posthuma (Danielle); T.J.C. Polderman (Tinca)

    2015-01-01

    textabstractThe development of brain structure and function shows large inter-individual variation. The extent to which this variation is due to genetic or environmental influences has been investigated in twin studies using structural and functional Magnetic Resonance Imaging (MRI). The current rev

  3. Circadian system heritability as assessed by wrist temperature: a twin study.

    Science.gov (United States)

    Lopez-Minguez, Jesus; Ordoñana, Juan R; Sánchez-Romera, Juan F; Madrid, Juan A; Garaulet, Marta

    2015-02-01

    Previous research shows that wrist temperature (WT) is a good marker to assess the circadian system health in different circumstances. However, no studies have been performed in order to know the genetic component of this circadian marker. For this purpose, the aim was to determine, using classical twin models, the relative genetic and environmental influences on WT. The study was performed in 53 pairs of female twins (28 monozygotic (MZ) and 25 dizygotic (DZ)), with a body mass index 25.9 ± 3.78 and mean age 52 ± 6 years. The sample was selected from the Murcia Twin Register. Circadian patterns were studied by analyzing WT during one week every 10 min "Circadianware®". Genetic influences to WT variability were estimated by comparing correlations of MZ and DZ twin pairs and fitting genetic structural equation models to measured variables. MZ twins showed higher intra-pair correlations than DZ twins for most of the parameters. Genetic factors were responsible for between 46% and 70% of variance (broad sense heritability) in parameters such as mean temperature, mesor, acrophase, Rayleigh test, percentage of rhythmicity and five hours of maximum temperature. The pattern of correlations and the genetic models point to moderate to high heritability for most of the WT parameters, suggesting a relevant genetic influence. The presence of these genetic factors points to endogenicity as the main cause of the coincidence of the WT rhythms. However, some WT parameters are still dependent on environment to a relevant extent and, hence, more amenable to change through external interventions.

  4. A Monozygotic Twin Difference Study of Friends' Aggression and Children's Adjustment Problems

    Science.gov (United States)

    Vitaro, Frank; Brendgen, Mara; Boivin, Michel; Cantin, Stephane; Dionne, Ginette; Tremblay, Richard E.; Girard, Alain; Perusse, Daniel

    2011-01-01

    This study used the monozygotic (MZ) twin difference method to examine whether differences in friends' aggression increased the differences in MZ twins' aggression and depressive symptoms from kindergarten to Grade 1 and whether perceived victimization by the friend played a mediating role in this context. Participants were 223 MZ twin pairs.…

  5. Bidirectional Influences between Maternal Parenting and Children's Peer Problems: A Longitudinal Monozygotic Twin Difference Study

    Science.gov (United States)

    Yamagata, Shinji; Takahashi, Yusuke; Ozaki, Koken; Fujisawa, Keiko K.; Nonaka, Koichi; Ando, Juko

    2013-01-01

    This twin study examined the bidirectional relationship between maternal parenting behaviors and children's peer problems that were not confounded by genetic and family environmental factors. Mothers of 259 monozygotic twin pairs reported parenting behaviors and peer problems when twins were 42 and 48 months. Path analyses on monozygotic twin…

  6. The Fourth International Network of Twin Registries: Overview from Osaka/Research Reviews: Familial Fraternal Twinning; Twin Study of Masculine Faces; Physical Aggression and Epigenetics; Prenatal Education for Parents of Twins/Current Events: 2016 Guinness Book of World Records; Oldest Living Male Twins; Twins Reunited at Sixty-Nine; Panda Twins; Twins.com.

    Science.gov (United States)

    Segal, Nancy L

    2015-12-01

    The 4th International Network of Twin Registries (INTR) Consortium Meeting took place in Osaka, Japan, September 28-29, 2015. The venue was the Osaka Medical Center for Medical Innovation and Translational Research. An overview of presentations and other activities is provided. Next, 1930s research on familial fraternal twinning, preference for masculine faces, physical aggression and epigenetics, and a prenatal education program for parents of multiples are described. Current twin-related events include the 2016 Guinness Book of World Records (GWR), the oldest living male twins, newly reunited twins, the birth of panda twins and a controversial twin-based website.

  7. Familial aggregation of atrial fibrillation: a study in Danish twins

    DEFF Research Database (Denmark)

    Christophersen, Ingrid Elisabeth; Ravn, Lasse Steen; Budtz-Joergensen, Esben

    2009-01-01

    BACKGROUND: Heritability may play a role in nonfamilial atrial fibrillation (AF). We hypothesized that a monozygotic (MZ) twin whose co-twin was diagnosed with AF would have an increased risk of the disease compared with a dizygotic (DZ) twin in the same situation. METHODS AND RESULTS: A sample...... of 1137 same-sex twin pairs (356 MZ and 781 DZ pairs) in which one or both members were diagnosed with AF were identified in The Danish Twin Registry. Concordance rates were twice as high for MZ pairs than for DZ pairs regardless of sex (22.0% versus 11.6%, P...-free survival times, we compared the time span between occurrences of disease in MZ and DZ twins. The unaffected twin was included when his or her twin-sibling (the index twin) was diagnosed with AF. After adjustment for age at entry, MZ twins had a significantly shorter event-free survival time (hazard ratio...

  8. Twins reunited: scientific and personal perspectives/twin research studies: multiple birth effects on IQ and body size; life style, muscles, and metabolism; monochorionic dizygotic twin with blood chimerism; amniocentesis for twins/twins in the media: identical doctors; freedom fighter for twins; twin scholarships; Auguste and Jean-Felix Piccard; twins born apart.

    Science.gov (United States)

    Segal, Nancy L; Mulligan, Christy A

    2014-04-01

    A reunion of 38-year-old female monozygotic twins took place in Daegu, South Korea, on January 14, 2014. Scientific and personal perspectives on this extraordinary event are provided. A review of timely twin research follows, covering the effects of multiple births on IQ and body size, lifestyle and physical fitness associations, a rare case of a dizygotic twin with blood chimerism and definitional issues surrounding amniocentesis-related loss in multiple birth pregnancies. Interesting and informative mention of twins in the media includes twin doctors, a twin freedom fighter, the availability of college scholarships for twins, a new book about the Piccard family (two of whose members were twins), and co-twins born before and after the new year. A follow-up to a previous mention of identical twin biatheletes is also provided.

  9. Current twin studies in Germany: report on CoSMoS, SOEP, and ChronoS.

    Science.gov (United States)

    Hahn, Elisabeth; Gottschling, Juliana; Spinath, Frank M

    2013-02-01

    This article summarizes the status of three recent German twin studies: CoSMoS, SOEP, and ChronoS. The German twin study on Cognitive Ability, Self-Reported Motivation, and School Achievement (CoSMoS) is a three-wave longitudinal study of monozygotic and dizygotic twins reared together, and aims to investigate predictors of and influences on school performance. In the first wave of the data collection in 2005, 408 pairs of twins aged between 7 and 11 as well as their parents participated in CoSMoS. The SOEP twin study is an extended twin study, which has combined data from monozygotic and dizygotic twins reared together with additional data from full sibling pairs, mother-child, and grandparent-child dyads who participated in the German Socio-Economic Panel (GSOEP) study. The SOEP twin project comprises about 350 twin and 950 non-twin pairs aged between 17 and 70. Data were collected between 2009 and 2010, with a focus on personality traits, wellbeing, education, employment, income, living situation, life-satisfaction, and several attitudes. The aim of the Chronotype twin study (ChronoS) was to examine genetic and environmental influences on chronotype (morningness and eveningness), coping strategies, and several aspects of the previous SOEP twin project in a sample of 301 twin pairs aged between 19 and 76 years, recruited in 2010 and 2011. Part of the ChronoS twin sample also participated in the earlier SOEP twin study, representing a second wave of assessments. We briefly describe the design and contents of these three studies as well as selected recent findings.

  10. Evidence for shared genetic risk between ADHD symptoms and reduced mathematics ability: a twin study.

    Science.gov (United States)

    Greven, Corina U; Kovas, Yulia; Willcutt, Erik G; Petrill, Stephen A; Plomin, Robert

    2014-01-01

    Attention-deficit/hyperactivity disorder (ADHD) symptoms and mathematics ability are associated, but little is known about the genetic and environmental influences underlying this association. Data came from more than 6,000 twelve-year-old twin pairs from the UK population-representative Twins Early Development Study. Parents rated each twin's behaviour using a DSM-IV-based 18-item questionnaire of inattentive and hyperactive-impulsive ADHD symptoms. Mathematics tests based on the UK National Curriculum were completed by each twin. The twins also completed standardised tests of reading and general cognitive ability. Multivariate twin model fitting was applied. Inattentive and hyperactive-impulsive ADHD symptoms were highly heritable (67% and 73% respectively). Mathematics ability was moderately heritable (46%). Mathematics ability and inattentiveness showed a significantly greater phenotypic correlation (r(p) = -.26) and genetic correlation (r(A) = -.41) than mathematics ability and hyperactivity-impulsivity (r(p) = -.18; r(A) = -.22). The genetic correlation between inattentiveness and mathematics ability was largely independent from hyperactivity-impulsivity, and was only partially accounted for by genetic influences related to reading and general cognitive ability. Results revealed the novel finding that mathematics ability shows significantly stronger phenotypic and genetic associations with inattentiveness than with hyperactivity-impulsivity. Genetic associations between inattentiveness and mathematics ability could only partially be accounted for by hyperactivity-impulsivity, reading and general cognitive ability. Results suggest that mathematics ability is associated with ADHD symptoms largely because it shares genetic risk factors with inattentiveness, and provide further evidence for considering inattentiveness and hyperactivity-impulsivity separately. DNA markers for ADHD symptoms (especially inattentiveness) may also be candidate risk factors for

  11. A possible genetic influence in parenchyma and small airway changes in COPD: a pilot study of twins using HRCT.

    Science.gov (United States)

    Tarnoki, D L; Tarnoki, A D; Lazar, Zs; Korom, Cs; Berczi, V; Horvath, I; Karlinger, K

    2014-06-01

    Genetic effects that contribute to the risk of developing chronic obstructive pulmonary disease (COPD) have been reported. Our purpose was to estimate the possible genetic influence on CT features related to COPD in twins. Two COPD-discordant and one COPD-concordant monozygotic (MZ) twin pair, in addition to 2 control dizygotic (DZ) twin pairs underwent a low-dose high resolution computer tomography (HRCT) in inspiration and expiration (Philips Brilliance 16). Monozygotic twins were more similar in lung volume expiration and in air trapping score compared to dizygotics (382 cm(3) vs. 2303 cm(3) and 17.6% vs. 26.6%, respectively). In general, MZ twin pairs showed almost identical HRCT features independently of smoking attitude and COPD status. The dizygotic twin pairs showed larger differences in HRCT features compared to MZ twins. Lung parenchymal and small airway changes (lung density, presence of bronchial wall thickening, bronchiectasis and/or mucus plug formation, air trapping and emphysema score) seem to be genetically associated traits, independently of smoking/COPD history. A future study with a larger sample size should confirm our findings.

  12. Twin Binaries: Studies of Stability, Mass Transfer, and Coalescence

    CERN Document Server

    Lombardi, James C; Dooley, Katherine L; Gearity, Kyle; Kalogera, Vassiliki; Rasio, Frederic A

    2010-01-01

    Motivated by suggestions that binaries with almost equal-mass components ("twins") play an important role in the formation of double neutron stars and may be rather abundant among binaries, we study the stability of synchronized close and contact binaries with identical components in circular orbits. In particular, we investigate the dependency of the innermost stable circular orbit on the core mass, and we study the coalescence of the binary that occurs at smaller separations. For twin binaries composed of convective main-sequence stars, subgiants, or giants with low mass cores (M_c ~0.15M), we find that stable contact configurations exist at all separations down to the Roche limit, when mass shedding through the outer Lagrangian points triggers a coalescence of the envelopes and leaves the cores orbiting in a central tight binary. We discuss the implications of our results to the formation of binary neutron stars.

  13. Hyperpolarizability studies of some nonconjugated twin donor–acceptor molecules

    Indian Academy of Sciences (India)

    Elizabeth Chirackal Varkey; Krishnapillai Sreekumar

    2011-07-01

    Extensive theoretical calculation on the effects of spacer length enhancement on the second-order NLO properties of twin donor acceptor molecules having two amide units bridged by the CH2 spacers was performed. The role of such aliphatic bridges on the Donor–Acceptor groups was computed by ZINDO/CV quantum chemical formalism. The odd-even effects were observed in twin donor acceptor systems (with two aliphatic units) linked by an alkyl spacer of varying length from = 1 to = 12. The system considered for the present study was ,'-alkane-(1, ) diyl bis-4-hydroxy hexanamides. For an odd number of CH2 spacers, the value was an order of magnitude higher than that for the even number of CH2 spacers. The origin for such oscillation is attributed to the similar oscillations in the dipole moment difference between the ground state and the dipole allowed state and to some extent on the variation in the oscillator strength.

  14. Attachment to Inanimate Objects and Early Childcare: A Twin Study

    Directory of Open Access Journals (Sweden)

    Keren eFortuna

    2014-05-01

    Full Text Available Extensive nonmaternal childcare plays an important role in children's development. This study examined a potential coping mechanism for dealing with daily separation from caregivers involved in childcare experience—children's development of attachments toward inanimate objects. We employed the twin design to estimate relative environmental and genetic contributions to the presence of object attachment, and assess whether childcare explains some of the environmental variation in this developmental phenomenon. Mothers reported about 1122 3-year-old twin pairs. Variation in object attachment was accounted for by heritability (48% and shared environment (48%, with childcare quantity accounting for 2.2% of the shared environment effect. Children who spent half-days in childcare were significantly less likely to attach to objects relative to children who attended full-day childcare.

  15. Heredity In Sarcoidosis - A Registry-Based Twin Study

    DEFF Research Database (Denmark)

    Sverrild, Asger; Backer, Vibeke; Kyvik, Kirsten Ohm

    2008-01-01

    of sarcoidosis in order to assess the overall contribution of genetic factors to the disease susceptibility. METHODS: Monozygotic and dizygotic twins enrolled in either the Danish or the Finnish population-based, national Twin Cohorts (61,662 pairs in total) were linked to diagnostic information on sarcoidosis...... obtained from the Danish National Patient Registry or the Social Insurance Institution, Finland, registry of re-imbursed medication using the 8th and 10th editions of the International Classification of Diseases. Fisher's exact test was used to compare probandwise concordance rates in different zygosity.......45-0.80). CONCLUSIONS: This study suggests that genetic factors play an important role in the susceptibility to sarcoidosis. This result should encourage the search for molecular genetic markers of the susceptibility to disease....

  16. A twin study of perfume-related respiratory symptoms.

    Science.gov (United States)

    Elberling, J; Lerbaek, A; Kyvik, K O; Hjelmborg, J

    2009-11-01

    Respiratory symptoms from environmental perfume exposure are main complaints in patients with multiple chemical sensitivities and often coincide with asthma and or eczema. In this population-based twin study we estimate the heritability of respiratory symptoms related to perfume and if co-occurrences of the symptoms in asthma, atopic dermatitis, hand eczema or contact allergy are influenced by environmental or genetic factors common with these diseases. In total 4,128 twin individuals (82%) responded to a questionnaire. The heritability of respiratory symptoms related to perfume is 0.35, 95%CI 0.14-0.54. Significant associations (pperfume-related respiratory symptoms and asthma, atopic dermatitis, hand eczema or contact allergy are not attributable to shared genetic or shared environmental/familial factors, except possibly for atopic dermatitis where genetic pleiotropy with respiratory symptoms to perfume is suggested by an estimated genetic correlation of 0.39, 95%CI 0.09-0.72.

  17. A twin study of perfume-related respiratory symptoms

    DEFF Research Database (Denmark)

    Elberling, J; Lerbaek, A; Kyvik, K O

    2009-01-01

    Respiratory symptoms from environmental perfume exposure are main complaints in patients with multiple chemical sensitivities and often coincide with asthma and or eczema. In this population-based twin study we estimate the heritability of respiratory symptoms related to perfume and if co......-occurrences of the symptoms in asthma, atopic dermatitis, hand eczema or contact allergy are influenced by environmental or genetic factors common with these diseases. In total 4,128 twin individuals (82%) responded to a questionnaire. The heritability of respiratory symptoms related to perfume is 0.35, 95%CI 0.......14-0.54. Significant associations (psymptoms and asthma, atopic dermatitis, hand eczema or contact allergy are not attributable to shared genetic or shared environmental/familial factors, except possibly for atopic dermatitis where genetic pleiotropy with respiratory symptoms...

  18. Twin study on transplacental-acquired antibodies and attention deficit/hyperactivity disorder - A pilot study

    DEFF Research Database (Denmark)

    Bilenberg, Niels; Hougaard, David; Norgaard-Pedersen, Bent

    2011-01-01

    in the lower scoring twin (P=0.04). CONCLUSION: Although the study provides no strong support for the hypothesis, infection or immunological factors may be one among several causes of ADHD. The genetic control obtained in a twin design may reduce the exposure contrast and a larger sample is needed to further...

  19. Comparative study on twinning characteristics during two post-weld compression paths and their effects on joint enhancement

    Science.gov (United States)

    Liu, Zhe; Xin, Renlong; Li, Dongrong; Sun, Liyun; Liu, Qing

    2016-12-01

    Friction stir welding (FSW) has promising application potential in Mg alloys. However, the texture distribution in stir zone (SZ) is usually complicated for Mg alloys, which deterioriates the joint performance. In this study, the texture distribution in SZ was tailored by applying two kinds of post-weld compression deformation along normal direction (ND) or welding direction (WD) of the FSWed AZ31 Mg alloy plates. The twinning behavior and texture change in the various regions of SZ were then evaluated by electron back scatter diffraction (EBSD) characterization. The effect of texture change on the joint performance was discussed in terms of Schmid factors (SFs) for basal slip and extension twinning. The results showed that profuse extension twins were formed through the whole SZ for the sample subjected to compression along ND, whereas they were observed mainly in SZ-side for the sample compressed along WD. Most of the twins were present in the forms of twin bands or chains. The directions of the twin bands or chains were related to the habit plane traces of selected twin variants. The ND post-weld compression had better strengthening effects on the joints compared to the WD compression, and the underline mechanism was discussed.

  20. NOTE: Increasing cardiac output and decreasing oxygenation sequence in pump twins of acardiac twin pregnancies

    Science.gov (United States)

    van Gemert, Martin J. C.; Umur, Asli; van den Wijngaard, Jeroen P. H. M.; Van Bavel, Ed; Vandenbussche, Frank P. H. A.; Nikkels, Peter G. J.

    2005-02-01

    An acardiac twin pregnancy is a rare but serious complication of monochorionic twinning and consists of an acardiac twin and a pump twin. The acardiac twin is a severely malformed fetus that lacks most organs, particularly a heart, but grows during pregnancy because it is perfused by the developmentally normal pump twin via a set of arterioarterial and venovenous placental anastomoses. Pump twins die intrauterine or neonatally in about 50% of the cases. Because the effects of an acardiac mass on the pump twin's development are incompletely known, methods for outcome prognosis are currently not available. We sought to derive simple relations for the pump twin's excess cardiac output and decreased oxygenation and to use available clinical cases for a preliminary test of the model. As a method, we used a theoretical flow model to represent the fetoplacental circulation of an acardiac twin pregnancy and estimated blood deoxygenation and reoxygenation following perfusion of the two bodies and placentas, respectively. The results show the pump twin's excess cardiac output and decrease of venous oxygen saturation to depend on the ratio of pump twin to acardiac twin umbilical blood flow, whose ratio can be measured by ultrasonography. The clinical cases show a decreasing umbilical flow ratio with gestation. In conclusion, prospective serial study is necessary to test whether measurement of umbilical flow ratios allows monitoring the pump twin's pathophysiologic development, possibly resulting in a guideline for prognosis of pump twin survival.

  1. Increasing cardiac output and decreasing oxygenation sequence in pump twins of acardiac twin pregnancies

    Energy Technology Data Exchange (ETDEWEB)

    Gemert, Martin J C van [Laser Center and Department of Obstetrics and Gynecology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam (Netherlands); Umur, Asli [Laser Center and Department of Obstetrics and Gynecology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam (Netherlands); Wijngaard, Jeroen P H M van den [Laser Center and Department of Obstetrics and Gynecology, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam (Netherlands); VanBavel, Ed [Department of Medical Physics, Academic Medical Center, University of Amsterdam, Amsterdam (Netherlands); Vandenbussche, Frank P H A [Department of Obstetrics, Leiden University Medical Center, Leiden (Netherlands); Nikkels, Peter G J [Department of Pathology, University Medical Center, Utrecht (Netherlands)

    2005-02-07

    An acardiac twin pregnancy is a rare but serious complication of monochorionic twinning and consists of an acardiac twin and a pump twin. The acardiac twin is a severely malformed fetus that lacks most organs, particularly a heart, but grows during pregnancy because it is perfused by the developmentally normal pump twin via a set of arterioarterial and venovenous placental anastomoses. Pump twins die intrauterine or neonatally in about 50% of the cases. Because the effects of an acardiac mass on the pump twin's development are incompletely known, methods for outcome prognosis are currently not available. We sought to derive simple relations for the pump twin's excess cardiac output and decreased oxygenation and to use available clinical cases for a preliminary test of the model. As a method, we used a theoretical flow model to represent the fetoplacental circulation of an acardiac twin pregnancy and estimated blood deoxygenation and reoxygenation following perfusion of the two bodies and placentas, respectively. The results show the pump twin's excess cardiac output and decrease of venous oxygen saturation to depend on the ratio of pump twin to acardiac twin umbilical blood flow, whose ratio can be measured by ultrasonography. The clinical cases show a decreasing umbilical flow ratio with gestation. In conclusion, prospective serial study is necessary to test whether measurement of umbilical flow ratios allows monitoring the pump twin's pathophysiologic development, possibly resulting in a guideline for prognosis of pump twin survival. (note)

  2. The Role of Nature and Nurture for Individual Differences in Primary Emotional Systems: Evidence from a Twin Study.

    Directory of Open Access Journals (Sweden)

    Christian Montag

    Full Text Available The present study investigated for the first time the relative importance of genetics and environment on individual differences in primary emotionality as measured with the Affective Neuroscience Personality Scales (ANPS by means of a twin-sibling study design. In N = 795 participants (n = 303 monozygotic twins, n = 172 dizygotic twins and n = 267 non-twin full siblings, moderate to strong influences of genetics on individual differences in these emotional systems are observed. Lowest heritability estimates are presented for the SEEKING system (33% and highest for the PLAY system (69%. Further, multivariate genetic modeling was applied to the data showing that associations among the six ANPS scales were influences by both, a genetic as well as an environmental overlap between them. In sum, the study underlines the usefulness of the ANPS for biologically oriented personality psychology research.

  3. Discordant tooth agenesis and peg-shaped in a pair of monozygotic twins: Clinical and molecular study

    Directory of Open Access Journals (Sweden)

    Lívia Azeredo Alves Antunes

    2013-01-01

    Full Text Available The present report aimed to study an uncommon case of a pair of twins that presented a discordant dental phenotype. Family investigation, clinical, radiographic examination and molecular analysis were performed in both girls. Molecular analysis confirmed the monozygosity by deoxyribonucleic acid chip technology. One twin presented tooth agenesis in left upper lateral incisor and peg-shaped on the contra lateral side while the other twin had no dental alterations. The dental casts study employed digital caliper to compare morphological dimensions and showed alteration only in peg-shaped tooth. In conclusion, this study provide support that one or more mutated gene could cause discordances in dental phenotype in these monozygotic twins.

  4. Sex differences in jealousy: a population-based twin study in Sweden.

    Science.gov (United States)

    Walum, Hasse; Larsson, Henrik; Westberg, Lars; Lichtenstein, Paul; Magnusson, Patrik K E

    2013-10-01

    According to the theory of evolved sex differences in jealousy, the challenge for women to ensure paternal investment increased their jealousy response to emotional infidelity, whereas paternal uncertainty exerted selective pressures that shaped men to become more distressed by sexual infidelity. Several studies have investigated whether the effect of these sexually dimorphic selection pressures can be detected in contemporary human populations, with conflicting results. To date, no genetically informed studies of sex differences in jealousy have been conducted. We used data from the Screening Across the Lifespan of Twins Younger (SALTY) sample, containing information concerning self-rated jealousy from 3,197 complete twin pairs collected by the Swedish Twin Registry. Intra-class correlations and structural equation models were used to assess the genetic influence on jealousy and to investigate sex differences at genetic level. We saw a highly significant sex effect on the relationship between infidelity types, indicating that men, relative to women, reported greater jealousy in response to sexual infidelity than in response to emotional infidelity. The twin models revealed significant heritabilities for both sexual (32%) and emotional (26%) jealousy. The heritabilities were of a similar magnitude in both sexes, and no qualitative sex differences could be detected. We show for the first time that variance in jealousy is to some extent explained by genetic factors. Even though our results from the mean value analyses are in line with the theory of evolved sex differences in jealousy, we could not identify any sex differences on a genetic level.

  5. Twin-Twin Transfusion Syndrome: study protocol for developing, disseminating, and implementing a core outcome set.

    Science.gov (United States)

    Khalil, Asma; Perry, Helen; Duffy, James; Reed, Keith; Baschat, Ahmet; Deprest, Jan; Hecher, Kurt; Lewi, Liesbeth; Lopriore, Enrico; Oepkes, Dick

    2017-07-14

    Twin-Twin Transfusion Syndrome (TTTS) is associated with an increased risk of perinatal mortality and morbidity. Several treatment interventions have been described for TTTS, including fetoscopic laser surgery, amnioreduction, septostomy, expectant management, and pregnancy termination. Over the last decade, fetoscopic laser surgery has become the primary treatment. The literature to date reports on many different outcomes, making it difficult to compare results or combine data from individual studies, limiting the value of research to guide clinical practice. With the advent and ongoing development of new therapeutic techniques, this is more important than ever. The development and use of a core outcome set has been proposed to address these issues, prioritising outcomes important to the key stakeholders, including patients. We aim to produce, disseminate, and implement a core outcome set for TTTS. An international steering group has been established to oversee the development of this core outcome set. This group includes healthcare professionals, researchers and patients. A systematic review is planned to identify previously reported outcomes following treatment for TTTS. Following completion, the identified outcomes will be evaluated by stakeholders using an international, multi-perspective online modified Delphi method to build consensus on core outcomes. This method encourages the participants towards consensus 'core' outcomes. All key stakeholders will be invited to participate. The steering group will then hold a consensus meeting to discuss results and form a core outcome set to be introduced and measured. Once core outcomes have been agreed, the next step will be to determine how they should be measured, disseminated, and implemented within an international context. The development, dissemination, and implementation of a core outcome set in TTTS will enable its use in future clinical trials, systematic reviews and clinical practice guidelines. This is

  6. A twin-sibling study on the relationship between exercise attitudes and exercise behavior.

    Science.gov (United States)

    Huppertz, Charlotte; Bartels, Meike; Jansen, Iris E; Boomsma, Dorret I; Willemsen, Gonneke; de Moor, Marleen H M; de Geus, Eco J C

    2014-01-01

    Social cognitive models of health behavior propose that individual differences in leisure time exercise behavior are influenced by the attitudes towards exercise. At the same time, large scale twin-family studies show a significant influence of genetic factors on regular exercise behavior. This twin-sibling study aimed to unite these findings by demonstrating that exercise attitudes can be heritable themselves. Secondly, the genetic and environmental cross-trait correlations and the monozygotic (MZ) twin intrapair differences model were used to test whether the association between exercise attitudes and exercise behavior can be causal. Survey data were obtained from 5,095 twins and siblings (18-50 years). A genetic contribution was found for exercise behavior (50 % in males, 43 % in females) and for the six exercise attitude components derived from principal component analysis: perceived benefits (21, 27 %), lack of skills, support and/or resources (45, 48 %), time constraints (25, 30 %), lack of energy (34, 44 %), lack of enjoyment (47, 44 %), and embarrassment (42, 49 %). These components were predictive of leisure time exercise behavior (R(2) = 28 %). Bivariate modeling further showed that all the genetic (0.36 < |rA| < 0.80) and all but two unique environmental (0.00 < |rE| < 0.27) correlations between exercise attitudes and exercise behavior were significantly different from zero, which is a necessary condition for the existence of a causal effect driving the association. The correlations between the MZ twins' difference scores were in line with this finding. It is concluded that exercise attitudes and exercise behavior are heritable, that attitudes and behavior are partly correlated through pleiotropic genetic effects, but that the data are compatible with a causal association between exercise attitudes and behavior.

  7. An 11-year follow-up study of neonatal-onset, bath-induced alternating hemiplegia of childhood in twins.

    Science.gov (United States)

    Incorpora, Gemma; Pavone, Piero; Polizzi, Agata; Cocuzza, Mariadonatella; Privitera, Michael; Pavone, Lorenzo; Ruggieri, Martino

    2012-05-01

    The authors previously reported on the initial manifestations in a set of female twins, who presented soon after birth with bath-induced paroxysmal events each time they were immersed in a warm water bath. These episodes progressively ceased by the age of 36 months, replaced by paroxysmal episodes of alternating hemiplegia unrelated to water immersion. By age 4 years, the twins developed the classic features of alternating hemiplegia of childhood. Clinical outcomes at the age of 11 years are now reported. Standard and video-electroencephalograms showed a large, slow background activity followed by lower amplitude waves without focal abnormalities or other abnormal findings. This represents the first report on (a) alternating hemiplegia of childhood started with bath-induced paroxysmal episodes; (b) this condition in monozygotic twins; and (c) an 11-year follow-up study in which the twins continue to experience episodes of alternating hemiplegia in the setting of baseline cognitive impairment without epileptic episodes.

  8. Twin-twin transfusion syndrome - diagnosis and prognosis

    Directory of Open Access Journals (Sweden)

    Hajrić-Egić Amira

    2003-01-01

    Full Text Available Twin-twin transfusion syndrome is a serious complication of monozygotic, monochorionic, diamniotic twins resulting from transplacental vascular communications. In this syndrome blood is thought to be shunted from one twin - donor,who develops anaemia,growth retardation and oligoamnios, to the other twin - recipient,who becomes plethoric,macrosomic and develops polyhydroamnios. The incidence of twin-twin transfusion syndrome ranges from 5-15% of all twin pregnancies. If this condition develops in the second trimester, it is usually associated with spontaneous abortion and death of one or both fetuses before viability. Developing the syndrome in the third trimester has better perinatal outcome. Mortality rates ranging from 56%-100%, depending on gestational age and severity of the syndrome. The ultrasound criterias for diagnosis, in this study,were the presence of twins of the same sex with discordant growth, with oligohydroamnios in one twin sac and polyhydroamnios in the other one, one placenta and thin membrane between twins. The present study shows clinical course of 14 cases and value of Doppler ultrasound to analyze the usefulness of umbilical artery blood flow velocimetry for predicting the risk of twin-twin transfusion syndrome. 14 twin pregnancies with twin-twin transfusion syndrome were diagnosed during the last four years period and prospectivelly followed. 9 cases were diagnosed before the completion od 28 weeks of gestation.The mean gestational age was 21,6_+4,2 weeks at diagnosis and 23,2+_3,6 weeks at delivery. 5 cases were diagnosed after 28 weeks of gestation. The mean gestational age in this group was 29,6+_2,1 weeks at diagnosis and 33+_3,3 weeks at delivery. The survival rate in this study was 29%(8/28.9 cases ended in spontaneous abortion between 18th and 27th weeks of pregnancy (table 1 and 5 in premature labor (table 2.There were 7 intrauterine death (5 at admission and 2 few days after admission and 13 neonatal deaths

  9. Family and twin studies in inflammatory bowel disease

    Institute of Scientific and Technical Information of China (English)

    Leena Halme; Paulina Paavola-Sakki; Ulla Turunen; Maarit Lappalainen; Martti F(a)rkkil(a); Kimmo Kontula

    2006-01-01

    Studies examining the inheritance of inflammatory bowel disease (IBD) within different family groups have been the basis for recent molecular advances in the genetics of IBD. The derived heritability in Crohn's disease (CD) is higher than in many other complex diseases. The risk of IBD is highest in first-degree relatives of a CD proband,but first-degree relatives of a proband suffering from ulcerative colitis (UC) and more distant relatives are also at increased risk. Disease concordance rates in IBD have been examined in multiplex families and in three large European twin studies.

  10. Recurrence risk for offspring of twins discordant for oral cleft: a population-based cohort study of the Danish 1936-2004 cleft twin cohort.

    Science.gov (United States)

    Grosen, Dorthe; Bille, Camilla; Pedersen, Jacob Krabbe; Skytthe, Axel; Murray, Jeffrey C; Christensen, Kaare

    2010-10-01

    Our objective in this Danish population-based cohort study was to estimate the recurrence risk of isolated oral cleft (OC) for offspring of the unaffected co-twins of OC discordant twin pairs and to compare this risk to the recurrence risk in the offspring of the affected co-twin as well as to the risk in the background population. During 1936-2004, 207 twin pairs were ascertained, among whom at least one twin had an OC. The index persons were twins discordant for OC who had children (N=117), and their offspring (N=239). The participants were ascertained by linkage between The Danish Facial Cleft Database, The Danish Twin Registry and The Danish Civil Registration System. In the study OC recurrence risk for offspring of the affected and unaffected twin and relative risk were compared to the background prevalence. We found that among 110 children of the 54 OC affected twins, two (1.8%) children had OC corresponding to a significantly increased relative risk (RR=10; 95% CI 1.2-35) when compared to the frequency in the background population. Among the 129 children of the 63 unaffected twins, three (2.3%) children were affected, corresponding to a significantly increased relative risk (RR=13; 95% CI 2.6-36) when compared the background prevalence. We concluded that in OC discordant twin pairs similar increased recurrence risks were found among offspring of both OC affected and OC unaffected twins. This provides further evidence for a genetic component in cleft etiology and is useful information for genetic counseling of twin pairs discordant for clefting. Copyright © 2010 Wiley-Liss, Inc.

  11. Shared genetic influence on frailty and chronic widespread pain: a study from TwinsUK.

    Science.gov (United States)

    Livshits, Gregory; Ni Lochlainn, Mary; Malkin, Ida; Bowyer, Ruth; Verdi, Serena; Steves, Claire J; Williams, Frances M K

    2017-07-07

    frailty is an increased vulnerability to adverse health outcomes, across multiple physiological systems, with both environmental and genetic drivers. The two most commonly used measures are Rockwood's frailty index (FI) and Fried's frailty phenotype (FP). the present study included 3626 individuals from the TwinsUK Adult Twin Registry. We used the classical twin model to determine whether FI and FP share the same latent aetiological factors. We also investigated the relationship between frailty and chronic widespread musculoskeletal pain (CWP), another holistic age-related condition with significant clinical impact. FP and FI shared underlying genetic and environmental aetiology. CWP was associated with both frailty measures, and health deficits appeared to mediate the relationship between phenotypic frailty and pain. Latent genetic factors underpinning CWP were shared with frailty. While frailty was increased in the twins reporting pain, co-twin regression analysis indicated that the relationship between CWP and frailty is reduced after accounting for shared genetic and environmental factors. both measures of frailty tap the same root causes, thus this work helps unify frailty research. We confirmed a strong association between CWP and frailty, and showed a large and significant shared genetic aetiology of both phenomena. Our findings argue against pain being a significant causative factor in the development of frailty, favouring common causation. This study highlights the need to manage CWP in frail individuals and undertake a Comprehensive Geriatric Assessment in individuals presenting with CWP. Finally, the search for genetic factors underpinning CWP and frailty could be aided by integrating measures of pain and frailty.

  12. Risk factors for asthma in young adults: a co-twin control study

    DEFF Research Database (Denmark)

    Thomsen, S F; Ulrik, C S; Kyvik, K O;

    2006-01-01

    BACKGROUND: The liability to asthma is influenced both by genetic and environmental factors. The objective of this study was to identify risk factors for asthma in young adult twin pairs during an 8-year period. METHODS: From the birth cohorts 1953-1982 of the Danish Twin Registry, 6,090 twin pairs...... who were initially unaffected with respect to asthma at a nationwide questionnaire-based study in 1994 participated in a similar follow-up study in 2002. Subjects were regarded incident asthma cases when responding affirmatively to the question 'Do you have, or have you ever had asthma'? in 2002....... Pairs in which only one twin developed asthma -- discordant pairs -- were identified and conditional logistic regression was applied to detect effects of risk factors. RESULTS: A total of 126 monozygotic (MZ) and 273 dizygotic (DZ) discordant twin pairs were identified. In MZ twins hay fever (OR = 3...

  13. A twin and molecular genetics study of sleep paralysis and associated factors.

    OpenAIRE

    Denis, Dan; French, Christopher C.; Rowe, Richard; Zavos, Helena M S; Nolan, Patrick M.; Parsons, Michael J.; Gregory, Alice M

    2015-01-01

    Sleep paralysis is a relatively common but under-researched phenomenon. In this paper we examine prevalence in a UK sample and associations with candidate risk factors. This is the first study to investigate the heritability of sleep paralysis in a twin sample and to explore genetic associations between sleep paralysis and a number of circadian expressed single nucleotide polymorphisms. Analyses are based on data from the Genesis1219 twin/sibling study, a community sample of twins/siblings fr...

  14. A twin and molecular genetics study of sleep paralysis and associated factors.

    OpenAIRE

    Denis, Dan; French, Christopher C.; Rowe, Richard; Zavos, Helena M. S.; Nolan, Patrick M.; Parsons, Michael J.; Gregory, Alice M.

    2015-01-01

    Sleep paralysis is a relatively common but under-researched phenomenon. In this paper we examine prevalence in a UK sample and associations with candidate risk factors. This is the first study to investigate the heritability of sleep paralysis in a twin sample and to explore genetic associations between sleep paralysis and a number of circadian expressed single nucleotide polymorphisms. Analyses are based on data from the Genesis1219 twin/sibling study, a community sample of twins/siblings fr...

  15. Born to Lead? A Twin Design and Genetic Association Study of Leadership Role Occupancy.

    Science.gov (United States)

    De Neve, Jan-Emmanuel; Mikhaylov, Slava; Dawes, Christopher T; Christakis, Nicholas A; Fowler, James H

    2013-02-01

    We address leadership emergence and the possibility that there is a partially innate predisposition to occupy a leadership role. Employing twin design methods on data from the National Longitudinal Study of Adolescent Health, we estimate the heritability of leadership role occupancy at 24%. Twin studies do not point to specific genes or neurological processes that might be involved. We therefore also conduct association analysis on the available genetic markers. The results show that leadership role occupancy is associated with rs4950, a single nucleotide polymorphism (SNP) residing on a neuronal acetylcholine receptor gene (CHRNB3). We replicate this family-based genetic association result on an independent sample in the Framingham Heart Study. This is the first study to identify a specific genotype associated with the tendency to occupy a leadership position. The results suggest that what determines whether an individual occupies a leadership position is the complex product of genetic and environmental influences; with a particular role for rs4950.

  16. Genetic Influences on Suicide and Nonfatal Suicidal Behavior: Twin Study Findings

    Science.gov (United States)

    Pedersen, Nancy L.

    2015-01-01

    It has been well established that suicidal behavior is familial. Twin studies provide a unique opportunity to distinguish genetic effects from other familial influences. Consistent with findings from previous twin studies, including case series and selected samples, data from the population-based Swedish Twin Registry clearly demonstrate the importance of genetic influences on suicide. Twin studies of suicidal ideation and suicide attempts also implicate genetic influences, even when accounting for the effects of psychopathology. Future work is needed to evaluate the possibility of age and gender differences in heritability of suicide and nonfatal suicidal behavior. PMID:20444580

  17. Maternal distancing strategies toward twin sons, one with mild hearing loss: a case study.

    Science.gov (United States)

    Muñoz-Silva, Alicia; Sánchez-García, Manuel

    2004-01-01

    The authors apply descriptive and sequential analyses to a mother's distancing strategies toward her 3-year-old twin sons in puzzle assembly and book reading tasks. One boy had normal hearing and the other a mild hearing loss (threshold: 30 dB). The results show that the mother used more distancing behaviors with the son with a hearing loss, and thus gave greater encouragement to this son's cognitive development. These results differ from those of previous studies of deaf or hard of hearing children, whose participants generally had severe or profound hearing loss. In those studies, parents of deaf children used more low-level distancing than parents of normally hearing children. The results of the present study are discussed in terms of their implications for the parenting of twins and of children with mild hearing loss.

  18. [Study of intellectual activity in twins. I. Developmental features].

    Science.gov (United States)

    Kantonistova, N S

    1980-01-01

    The investigation of 234 twins and 100 singletons at the age from 7 till 16 years old was carried out by WISC method. The intellectual development of twins was established to fall behind singletons at the expense of lower level of verbal intellectual functions. It is due to organic changes of nervous system, arising as the result of the action of unfavourable factors during antenatal period. Slight asphyxia and prematurity as well as the order of birth do not exert essential effect on intellectual development of twins. Low weight at birth combines with lower intellectual index only in cases when lowering of weight is due to the action of unfavourable factors during intrauterine period. "Twins situation" apparently renders positive influence on twins intellectual activity during school are, distracting children's attention in cases of unfavourable psychological situation in family. Intellectual environment renders positive influence on intellectual development of twins.

  19. Tuning the thermal conductivity of silicon carbide by twin boundary: a molecular dynamics study

    Science.gov (United States)

    Liu, Qunfeng; Luo, Hao; Wang, Liang; Shen, Shengping

    2017-02-01

    Silicon carbide (SiC) is a semiconductor with excellent mechanical and physical properties. We study the thermal transport in SiC by using non-equilibrium molecular dynamics simulations. The work is focused on the effects of twin boundaries and temperature on the thermal conductivity of 3C-SiC. We find that compared to perfect SiC, twinned SiC has a markedly reduced thermal conductivity when the twin boundary spacing is less than 100 nm. The Si-Si twin boundary is more effective to phonon scattering than the C-C twin boundary. We also find that the phonon scattering effect of twin boundary decreases with increasing temperature. Our findings provide insights into the thermal management of SiC-based electronic devices and thermoelectric applications.

  20. A Danish population-based twin study on autism spectrum disorders

    DEFF Research Database (Denmark)

    Nordenbaek, Claudia; Jorgensen, Meta; Kyvik, Kirsten Ohm

    2014-01-01

    Genetic epidemiological studies of Autism Spectrum Disorders (ASDs) based on twin pairs ascertained from the population and thoroughly assessed to obtain a high degree of diagnostic validity are few. All twin pairs aged 3-14 years in the nationwide Danish Twin Registry were approached. A three...... based on 36 pairs. The probandwise concordance rate for ASD was 95.2 % in monozygotic (MZ) twins (n = 13 pairs) and 4.3 % in dizygotic (DZ) twins (n = 23 pairs). The high MZ and low DZ concordance rate support a genetic aetiology to ASDs....... standard" diagnostic research procedures including diagnostic interview, observation and cognitive examination. Classification was based on DSM-IV-TR criteria. The initial sample included 7,296 same-sexed twin pairs and, after two phases of screening and clinical assessment, the final calculations were...

  1. Twin-to-twin delivery time: neonatal outcome of the second twin.

    Science.gov (United States)

    Schneuber, Susanne; Magnet, Eva; Haas, Josef; Giuliani, Albrecht; Freidl, Thomas; Lang, Uwe; Bjelic-Radisic, Vesna

    2011-12-01

    To examine the effect of twin-to-twin delivery time (TTDT) on neonatal outcome. We evaluated twin deliveries >34 weeks of gestation. Twin pregnancies with both twins delivered by cesarean section and pregnancies with antenatal complications were excluded. We analyzed TTDT and neonatal outcomes of the second twin (umbilical arterial pH value (pH(art)), Apgar scores at 1, 5 and 10 minutes, need for intensive care). The study population was divided into two homogenous groups based on the mode of delivery: (A) vertex presentation and vaginal delivery of both twins, (B) vertex presentation and vaginal or vaginal operative delivery of twin I, breech or transverse presentation and vaginal breech delivery or cesarean section (CS) of twin II. A total of 207 twin pairs were included in our study. In Group A (n = 151) there were no significant correlations between TTDT and pH(art) or Apgar scores at 1,5 and 10 minutes of twin II (p = .156; 0.861; 0.151 and 0.384, respectively). In Group B (n = 56), the mean pH(art) of twin II was inversely correlated to TTDT, but not significantly (p = .417). TTDT was inversely related to 1-min and 5-min Apgar scores, but not significantly (p = .330; p = .138, respectively). The 10-min Apgar score showed no correlation with TTDT (p = .638). Increasing TTDT was not associated with adverse fetal outcome. Expectant management of the second twin appears possible and elapsed time alone does not appear to be an indication for intervention.

  2. A twin-study of genetic contributions to morningness-eveningness and depression.

    Science.gov (United States)

    Toomey, Rosemary; Panizzon, Matthew S; Kremen, William S; Franz, Carol E; Lyons, Michael J

    2015-04-01

    Circadian rhythms are associated with the preference for sleep-wake timing, also known as morningness-eveningness (ME). Both circadian rhythms and ME are influenced by genetic factors. Studies show an association between eveningness and depression. This study investigates the heritability of ME and whether ME and depression share common genetic influences. Study participants (n = 1237) were from the Vietnam Era Twin Study of Aging, a longitudinal study of aging with a baseline in midlife. Participants received the Morningness-Eveningness Questionnaire (MEQ) and the Center for Epidemiologic Studies Depression (CES-D) Scale as part of an extensive neurocognitive and psychosocial assessment. MEQ correlations between members of twin pairs were 0.41 (95% CI 0.31-0.49) for monozygotic (MZ) twins and 0.28 for dizygotic (DZ) twins (95% CI 0.19-0.41). CES-D correlations were 0.38 (95% CI 0.28-0.46) for MZ twins and 0.24 (95% CI 0.14-0.36) for DZ twins. Greater eveningness (i.e. lower MEQ scores) was significantly related to more depression symptoms (phenotypic correlation = -0.15 (95% CI -0.21 to -0.09). In the best fitting model, the heritability estimates are 0.42 for the MEQ and 0.37 for the CES-D. A significant genetic correlation of -0.21 indicated that ME and depression share a significant amount of their underlying genetic variance. The genetic covariance between ME and depression accounted for 59.1% of the phenotypic correlation. Of the CES-D sub-scales, Depressed Mood and Interpersonal Difficulties were significantly heritable, while only Well-Being had a significant genetic correlation with ME. ME and depression are both heritable (ME 0.42, depression 0.37) and share common genetic factors, suggesting an overlap in etiology and the relevance of circadian rhythms to depression. Further study of this relationship may help elucidate etiological factors in depression and targets for treatment.

  3. Traits of ADHD and autism in girls with a twin brother: a Mendelian randomization study

    DEFF Research Database (Denmark)

    Attermann, Jorn; Obel, Carsten; Bilenberg, Niels

    2012-01-01

    It has been hypothesized that prenatal exposure to testosterone may be associated with traits of attention-deficit/hyperactivity disorder (ADHD) or autism spectrum disorder (ASD). We conducted a population-based study of dizygotic female twins to elucidate this hypothesis, assuming that the sex...... in females. In conclusion, we found that female twins with a twin brother scored significantly lower in parent-reported traits of ADHD and ASD than those with a twin sister. The reason for this may be parental reporting bias, or confounding by unmeasured variables, or a causal effect of an intrauterine...

  4. The seroprevalence of antithyroid peroxidase antibodies in bipolar families and bipolar twins: results from two longitudinal studies.

    Science.gov (United States)

    Snijders, G; de Witte, L; Mesman, E; Kemner, S; Vonk, R; Brouwer, R; Nolen, W A; Drexhage, H A; Hillegers, M H J

    2017-12-01

    Previous studies of our group among bipolar offspring and bipolar twins showed significant higher prevalence's and levels of antithyroid peroxidase antibodies (TPO-Abs) in offspring and co-twins (without a mood disorder) compared to controls, suggesting that TPO-Abs might be considered as vulnerability factor (trait marker) for BD development. Here we elucidate, in the same cohorts, but now after 12- and 6-year follow-up, whether TPO-abs should be considered as a 'trait' marker for BD. The present study aims to investigate whether TPO-Abs (1) are stable over time, (2) are associated with lithium-exposure, (3) share a common genetic background with BD and are related to psychopathology. In bipolar offspring and twins, the prevalence of TPO-Abs is stable over time (r s = .72 p bipolar offspring (10,4% versus 4%) and higher TPO-abs titers were still present in co-twins of bipolar cases compared to control twins [mean 1.06 IU/ml (SD .82) versus mean .82 IU/ml (SD .67)], although statistical significance was lost. Although our results show a trend toward an increased inherited risk of the co-occurrence of BD and thyroid autoimmunity, large-scale studies can only draw final conclusions. Nationwide epidemiological and GWAS studies reach such numbers and support the view of a possible common (autoimmune) etiology of severe mood disorders and chronic recurrent infections and autoimmunity, including thyroid autoimmunity.

  5. Aging Trajectories in Different Body Systems Share Common Environmental Etiology: The Healthy Aging Twin Study (HATS).

    Science.gov (United States)

    Moayyeri, Alireza; Hart, Deborah J; Snieder, Harold; Hammond, Christopher J; Spector, Timothy D; Steves, Claire J

    2016-02-01

    Little is known about the extent to which aging trajectories of different body systems share common sources of variance. We here present a large twin study investigating the trajectories of change in five systems: cardiovascular, respiratory, skeletal, morphometric, and metabolic. Longitudinal clinical data were collected on 3,508 female twins in the TwinsUK registry (complete pairs:740 monozygotic (MZ), 986 dizygotic (DZ), mean age at entry 48.9 ± 10.4, range 18-75 years; mean follow-up 10.2 ± 2.8 years, range 4-17.8 years). Panel data on multiple age-related variables were used to estimate biological ages for each individual at each time point, in linear mixed effects models. A weighted average approach was used to combine variables within predefined body system groups. Aging trajectories for each system in each individual were then constructed using linear modeling. Multivariate structural equation modeling of these aging trajectories showed low genetic effects (heritability), ranging from 2% in metabolic aging to 22% in cardiovascular aging. However, we found a significant effect of shared environmental factors on the variations in aging trajectories in cardiovascular (54%), skeletal (34%), morphometric (53%), and metabolic systems (53%). The remainder was due to environmental factors unique to each individual plus error. Multivariate Cholesky decomposition showed that among aging trajectories for various body systems there were significant and substantial correlations between the unique environmental latent factors as well as shared environmental factors. However, there was no evidence for a single common factor for aging. This study, the first of its kind in aging, suggests that diverse organ systems share non-genetic sources of variance for aging trajectories. Confirmatory studies are needed using population-based twin cohorts and alternative methods of handling missing data.

  6. Study on heat source model in twin-arc GMAW with a common weld pool

    Institute of Scientific and Technical Information of China (English)

    Zhao Pengcheng; Wang Lulu; Liu Chunting; Huang Shisheng

    2009-01-01

    The heat input from arcs to weld pool in twin-arc gas metal arc welding (GMAW) with a common weld pool is investigated by high-speed photography. The characteristics of arc shapes and droplet transfer are studied and then the models for heat flux distribution on top surface of weld pool and enthalpy distribution of metal droplets transferred into weld pool are established. By using the model, 3-D geometries of weld pools in twin-arc GMAW with a common weld pool are predicted. Corresponding welding experiments on mild steel plates are carried out and the results indicate that the predicted shape of weld bead on cross section shows good agreement with measured one.

  7. Longitudinal Associations Among Reading-Related Skills and Reading Comprehension: A Twin Study.

    Science.gov (United States)

    Erbeli, Florina; Hart, Sara A; Taylor, Jeanette

    2017-06-01

    This study investigated the etiology of longitudinal relations among kindergarten prereading skills, first-grade word level reading skills, and seventh-grade reading comprehension in 265 monozygotic and 459 dizygotic twin pairs (Mage  = 6.29 years in kindergarten) from the Florida Twin Project on Reading. Using a quadvariate Cholesky decomposition, results showed genetic, shared, and nonshared environmental overlap among prereading skills, word level reading skills, and reading comprehension. In addition, genetic and shared environmental overlap was indicated among word level reading skills and reading comprehension, outside the influence of prereading skills. After accounting for overlapping, there remained moderate genetic and nonshared environmental influence specific to reading comprehension. Implications for reading education are discussed. © 2017 The Authors. Child Development © 2017 Society for Research in Child Development, Inc.

  8. A simulation study of the low-speed characteristics of a light twin with an engine-out

    Science.gov (United States)

    Stewart, E. C.; Moul, T. M.; Brown, P. W.

    1983-01-01

    Potential safety advantages provided by the two engines on a light twin aircraft are not realized in practice as evidenced by recent engine-failure accident statistics. These statistics showed twice the fatality rate from engine failure for twins as for single-engine aircraft. The statistics showed also that one-half of the fatal engine-out accidents involved a stall. An improvement of the low-speed engine-out characteristics is, therefore, needed. An investigation of the engine-out characteristics of light twin-engine aircraft is currently being conducted as part of the comprehensive stall/spin program for general aviation aircraft. The present study is concerned with the first phase of this program. The primary objective of this study is to advance the understanding of the basic flight dynamics and piloting problems for an engine-out condition. An all-digital computer system was used in the conducted simulation study.

  9. The Netherlands twin register biobank: A resource for genetic epidemiological studies

    NARCIS (Netherlands)

    Willemsen, G.; Geus, E.J.C. de; Bartels, M.; Beijsterveldt, C.E.M.T. van; Brooks, A.I.; Estourgie-van Burk, G.F.; Fugman, D.A.; Hoekstra, C.; Hottenga, J.-J.; Kluft, K.; Meijer, P.; Montgomery, G.W.; Rizzu, P.; Sondervan, D.; Smit, A.B.; Spijker, S.; Suchiman, H.E.D.; Tischfield, J.A.; Lehner, T.; Slagboom, P.E.; Boomsma, D.I.

    2010-01-01

    In 2004 the Netherlands Twin Register (NTR) started a large scale biological sample collection in twin families to create a resource for genetic studies on health, lifestyle and personality. Between January 2004 and July 2008, adult participants from NTR research projects were invited into the study

  10. A Twin-Family Study of General IQ

    Science.gov (United States)

    van Leeuwen, Marieke; van den Berg, Stephanie M.; Boomsma, Dorret I.

    2008-01-01

    In this paper we assess the presence of assortative mating, gene-environment interaction and the heritability of intelligence in childhood using a twin family design with twins, their siblings and parents from 112 families. We evaluate two competing hypotheses about the cause of assortative mating in intelligence: social homogamy and phenotypic…

  11. A Twin-Family Study of General IQ

    Science.gov (United States)

    van Leeuwen, Marieke; van den Berg, Stephanie M.; Boomsma, Dorret I.

    2008-01-01

    In this paper we assess the presence of assortative mating, gene-environment interaction and the heritability of intelligence in childhood using a twin family design with twins, their siblings and parents from 112 families. We evaluate two competing hypotheses about the cause of assortative mating in intelligence: social homogamy and phenotypic…

  12. A Danish Twin Study of Schizophrenia Liability: Investigation from Interviewed Twins for Genetic Links to Affective Psychoses and for Cross-Cohort Comparisons.

    Science.gov (United States)

    Kläning, Ulla; Trumbetta, Susan L; Gottesman, Irving I; Skytthe, Axel; Kyvik, Kirsten O; Bertelsen, Aksel

    2016-03-01

    We studied schizophrenia liability in a Danish population-based sample of 44 twin pairs (13 MZ, 31 DZ, SS plus OS) in order to replicate previous twin study findings using contemporary diagnostic criteria, to examine genetic liability shared between schizophrenia and other disorders, and to explore whether variance in schizophrenia liability attributable to environmental factors may have decreased with successive cohorts exposed to improvements in public health. ICD-10 diagnoses were determined by clinical interview. Although the best-fitting, most parsimonious biometric model of schizophrenia liability specified variance attributable to additive genetic and non-shared environmental factors, this model did not differ significantly from a model that also included non-additive genetic factors, consistent with recent interview-based twin studies. Schizophrenia showed strong genetic links to other psychotic disorders but much less so for the broader category of psychiatric disorders in general. We also observed a marginally significant decline in schizophrenia variance attributable to environmental factors over successive Western European cohorts, consistent perhaps with improvements in diagnosis and in prenatal and perinatal care and with a secular decline in the prevalence of schizophrenia in that region.

  13. Genetics of dietary habits and obesity - a twin study

    DEFF Research Database (Denmark)

    Hasselbalch, Ann Louise

    2010-01-01

    exposures as well as genetic differences between individuals, resulting in differentiated susceptibility to environmental exposures. The evidence for genetic influence on anthropometry has previously been established and has been estimated to be 60-70% based on twin studies. These inter...... mass, but only limited evidence for associations between habitual dietary intake and anthropometry exists. Differences in habitual dietary intake are also partly determined by differences in genes influencing smell and taste preferences. But, so far, only few studies have investigated genetic...... influences on dietary intake in adults and the interplay between diet, genes and obesity. The focus of the thesis was to investigate the genetic and environmental influence on habitual diet and obesity as well as the association between habitual diet and anthropometry. The thesis is based on structural...

  14. Genetics of dietary habits and obesity - a twin study

    DEFF Research Database (Denmark)

    Hasselbalch, Ann Louise

    2010-01-01

    exposures as well as genetic differences between individuals, resulting in differentiated susceptibility to environmental exposures. The evidence for genetic influence on anthropometry has previously been established and has been estimated to be 60-70% based on twin studies. These inter......Obesity has become a major health concern due to the increased risk of co-morbidities, resulting in decreased quality of life, stigmatization, reduced working ability and early death. This causes a great challenge for the health care systems and results in increased direct costs related...... mass, but only limited evidence for associations between habitual dietary intake and anthropometry exists. Differences in habitual dietary intake are also partly determined by differences in genes influencing smell and taste preferences. But, so far, only few studies have investigated genetic...

  15. Genetic influences on Chronic Obstructive Pulmonary Disease - a twin study.

    Science.gov (United States)

    Ingebrigtsen, Truls; Thomsen, Simon F; Vestbo, Jørgen; van der Sluis, Sophie; Kyvik, Kirsten O; Silverman, Edwin K; Svartengren, Magnus; Backer, Vibeke

    2010-12-01

    Genes that contribute to the risk of developing Chronic Obstructive Pulmonary Disease (COPD) have been identified, but an attempt to accurately quantify the total genetic contribution to COPD has to our knowledge never been conducted. Hospital discharge diagnoses data on COPD were analysed in 22,422 Danish twin pairs, 20-71 years of age. The analyses were replicated in a population of 27,668 Swedish twin pairs, 45-108 years of age. A Cox-regression model was applied to the discordant time from the age at first hospital admission for COPD in the co-twin of an affected twin. Latent factor models were used to estimate genetic and environmental effects. The probandwise concordance rate for COPD was higher in monozygotic (MZ) than in dizygotic (DZ) twins, 0.19 vs. 0.07 (p = 0.08) in the Danish population, and 0.20 vs. 0.08 (p = 0.006) in the Swedish population. After adjusting for sex, smoking and age at first hospital admission the risk of developing COPD in the co-twin of an affected twin was higher in MZ than in DZ twins, with hazards ratio 4.3 (95% confidence interval 1.2-15.8, p = 0.03) in Danish twins and 3.4 (1.5-7.7, p = 0.004) in Swedish twins. According to the most parsimonious model, additive genetic factors explained 63% (46-77%) of the individual COPD-susceptibility in the Danish population and 61% (48-72%) in the Swedish population. The susceptibility to develop severe COPD, as defined by hospitalizations, is strongly influenced by genetic factors. Approximately 60% of the individual susceptibility can be explained by genetic factors. Copyright © 2010 Elsevier Ltd. All rights reserved.

  16. Inertia-Controlled Twinning in Ni-Mn-Ga Actuators: A Discrete Twin-Boundary Dynamics Study

    Science.gov (United States)

    Faran, Eilon; Riccardi, Leonardo; Shilo, Doron

    2017-07-01

    A discrete twin-boundary modeling approach is applied for simulating the dynamic magnetomechanical response of a Ni-Mn-Ga actuator over a wide frequency range. The model is based on experimentally measured kinetic relation of individual twin boundaries and takes into account inertial forces due to acceleration of the actuator's mass. The calculated results show good agreement with experimental measurements performed on a specially designed Ni-Mn-Ga linear spring-mass actuator. In addition, the simulation reveals several new effects that have not been considered before and can be applied to the design of improved actuators. It is identified that the demagnetization effect plays a role of an "effective spring" and results in a resonance-type response. The effects of the actuator's mass and the twin-boundary density on the resonance response and the actuator performance are explored numerically. In particular, it is shown that mass-inertia poses an inherent upper limit over the actuator's bandwidth, which is approximately constant and equals to about 200 Hz.

  17. Genetic and Environmental Effects on Stuttering: A Twin Study from Finland

    Science.gov (United States)

    Rautakoski, Pirkko; Hannus, Therese; Simberg, Susanna; Sandnabba, N. Kenneth; Santtila, Pekka

    2012-01-01

    The present study explored the prevalence of self-reported stuttering in a Finnish twin population and examined the extent to which the variance in liability to stuttering was attributable to genetic and environmental effects. We analyzed data of 1728 Finnish twins, born between 1961 and 1989. The participants were asked to complete a…

  18. Bruxism is associated with nicotine dependence: a nationwide Finnish twin cohort study

    NARCIS (Netherlands)

    Rintakoski, K.; Ahlberg, J.; Hublin, C.; Broms, C.; Madden, P.; Könönen, M.; Koskenvuo, M.; Lobbezoo, F.; Kaprio, J.

    2010-01-01

    Objectives: To investigate the association of smoking with bruxism while controlling for genetic and environmental factors using a co-twin-control design. Especially, the role of nicotine dependence was studied in this context. Methods: The material derives from the Finnish Twin Cohort consisting of

  19. Genetic and Environmental Effects on Stuttering: A Twin Study from Finland

    Science.gov (United States)

    Rautakoski, Pirkko; Hannus, Therese; Simberg, Susanna; Sandnabba, N. Kenneth; Santtila, Pekka

    2012-01-01

    The present study explored the prevalence of self-reported stuttering in a Finnish twin population and examined the extent to which the variance in liability to stuttering was attributable to genetic and environmental effects. We analyzed data of 1728 Finnish twins, born between 1961 and 1989. The participants were asked to complete a…

  20. Evidence for Shared Genetic Risk between ADHD Symptoms and Reduced Mathematics Ability: A Twin Study

    Science.gov (United States)

    Greven, Corina U.; Kovas, Yulia; Willcutt, Erik G.; Petrill, Stephen A.; Plomin, Robert

    2013-01-01

    Background: Attention-deficit/hyperactivity disorder (ADHD) symptoms and mathematics ability are associated, but little is known about the genetic and environmental influences underlying this association. Methods: Data came from more than 6,000 twelve-year-old twin pairs from the UK population-representative Twins Early Development Study. Parents…

  1. Sleep quality and body mass index: a co-twin study.

    Science.gov (United States)

    Madrid-Valero, Juan J; Martínez-Selva, José M; Ordoñana, Juan R

    2017-08-01

    There is a consistent relationship between body mass index and sleep quality. However, the directionality and possible confounding factors of this relationship are unclear. Our aim is to confirm the association between sleep quality and body mass index, independent of possible genetic confounding, as well as to provide some indirect inferences about the directionality of this association. The co-twin study design was used to analyse the body mass index-sleep relationship in a sample of 2150 twins. We selected two parallel sub-samples of twins discordant for body mass index (n = 430 pairs), or discordant for sleep quality (n = 316 pairs). Sleep quality and body mass index showed an inverse relationship (b = 0.056, P = 0.032) in the global sample. When twins discordant for body mass index were selected, this association maintained a similar effect size and statistical significance, at all levels of the case-control analysis (all discordant pairs b = 0.173, P body mass index and sleep quality appeared weaker and lost significance (b = 0.021, P = 0.508). The analyses including only dizygotic (b = 0.028, P = 0.526) or monozygotic (b = 0.001, P = 0.984) pairs produced similar non-significant results. Our results confirm the relationship between sleep quality and body mass index, even after applying high levels of control, including genetic factors. Moreover, this study suggests a possible directionality of this relationship, such that sleep quality would strongly affect body mass index, while the opposite would be less robust and consistent in non-clinical samples. © 2017 European Sleep Research Society.

  2. The Qingdao Twin Registry

    DEFF Research Database (Denmark)

    Duan, Haiping; Ning, Feng; Zhang, Dongfeng;

    2013-01-01

    In 1998, the Qingdao Twin Registry was initiated as the main part of the Chinese National Twin Registry. By 2005, a total of 10,655 twin pairs had been recruited. Since then new twin cohorts have been sampled, with one longitudinal cohort of adolescent twins selected to explore determinants...... of metabolic disorders and health behaviors during puberty and young adulthood. Adult twins have been sampled for studying heritability of multiple phenotypes associated with metabolic disorders. In addition, an elderly twin cohort has been recruited with a focus on genetic studies of aging-related phenotypes...

  3. Revisiting the Association between Reading Achievement and Antisocial Behavior: New Evidence of an Environmental Explanation from a Twin Study

    Science.gov (United States)

    Trzesniewski, Kali H.; Moffitt, Terrie E.; Caspi, Avshalom; Taylor, Alan; Maughan, Barbara

    2006-01-01

    Previous studies have reported, but not explained, the reason for a robust association between reading achievement and antisocial behavior. This association was investigated using the Environmental Risk (E-Risk) Longitudinal Twin Study, a nationally representative 1994-1995 birth cohort of 5 and 7 year-olds. Results showed that the association…

  4. A twin study of the trough plasma steady-state concentration of metformin

    DEFF Research Database (Denmark)

    Stage, Tore B; Damkier, Per; Pedersen, Rasmus S;

    2015-01-01

    OBJECTIVE: The aim of this study was to determine the intrapair similarity in trough steady-state plasma concentrations of metformin in monozygotic and dizygotic twin pairs. METHODS: We included 16 twin pairs (eight monozygotic and eight dizygotic twin pairs) for this study after contacting 524...... twin pairs. They were dosed with metformin to steady state (1 g twice daily) for 6 days and on day 7, the trough concentration of metformin was determined 12 h after the last dose. RESULTS: There was no strong intrapair similarity in trough steady-state plasma concentrations of metformin in either...... dizygotic or monozygotic twin pairs. CONCLUSION: The trough steady-state plasma concentration of metformin does not appear to be tightly genetically regulated. The interpretation of this finding is limited by the small sample size....

  5. Using Twins to Better Understand Sibling Relationships.

    Science.gov (United States)

    Mark, Katharine M; Pike, Alison; Latham, Rachel M; Oliver, Bonamy R

    2017-03-01

    We compared the nature of the sibling relationship in dyads of varying genetic relatedness, employing a behavioural genetic design to estimate the contribution that genes and the environment have on this familial bond. Two samples were used-the Sisters and Brothers Study consisted of 173 families with two target non-twin children (mean ages = 7.42 and 5.22 years respectively); and the Twins, Family and Behaviour study included 234 families with two target twin children (mean age = 4.70 years). Mothers and fathers reported on their children's relationship with each other, via a postal questionnaire (the Sisters and Brothers Study) or a telephone interview (the Twins, Family and Behaviour study). Contrary to expectations, no mean level differences emerged when monozygotic twin pairs, dizygotic twin pairs, and non-twin pairs were compared on their sibling relationship quality. Behavioural genetic analyses also revealed that the sibling bond was modestly to moderately influenced by the genetic propensities of the children within the dyad, and moderately to substantially influenced by the shared environment common to both siblings. In addition, for sibling negativity, we found evidence of twin-specific environmental influence-dizygotic twins showed more reciprocity than did non-twins. Our findings have repercussions for the broader application of results from future twin-based investigations.

  6. Experimental study of aerodynamic interference effects on aerostatic coefficients of twin deck bridges

    Institute of Scientific and Technical Information of China (English)

    Zhiwen LIU; Zhengqing CHEN; Gao LIU; Xinpeng SHAO

    2009-01-01

    The aerodynamic interference effects on aero-static coefficients of twin deck bridges with large span were investigated in detail by means of wind tunnel test.The distances between the twin decks and wind attack angles were changed during the wind tunnel test to study the effects on aerodynamic interferences of aerostatic coefficients of twin decks. The research results have shown that the drag coefficients of the leeward deck are much smaller than that of a single leeward deck. The drag coefficients of a windward deck decrease slightly com-pared with that of a single deck. The lift and torque coefficients of windward and leeward decks are also affected slightly by the aerodynamic interference of twin decks. And the aerodynamic interference effects on lift and torque coefficients of twin decks can be neglected.

  7. Study Shows How Zika Attacks Infant Brain

    Science.gov (United States)

    ... gov/news/fullstory_162514.html Study Shows How Zika Attacks Infant Brain Virus can copy itself thousands ... New research paints a chilling portrait of how Zika ravages the infant brain. Scientists from the U.S. ...

  8. The morphology of the sella turcica in monozygotic twins.

    Science.gov (United States)

    Brock-Jacobsen, Mette T; Pallisgaard, Carsten; Kjaer, Inger

    2009-12-01

    The purpose was to compare the sella turcica morphology of individuals within pairs of monozygotic twins with normal karyotype and to analyze the similarity between the observed morphology and the morphology of non-twins at the same age with normal karyotype. Profile radiographs from 84 individuals of 42 twin pairs (18 male and 24 female pairs, aged 18-23 years) comprised the material. Sella turcica measurements from non-twins aged 6-21 years were used as normal reference. Length, depth and diameter of the sella turcica were measured and controlled by re-measurements. Pearson's correlation coefficient was used for comparison of individuals within twin pairs. For comparison of twins and non-twins, normal standard values for length, depth and diameter were subtracted from the twin values. For the mean values of these differences, confidence limits p values and t values were calculated. The study showed that the size of the sella turcica may be partly similar and partly dissimilar within the pair of monozygotic twins. Statistical evaluation of the data showed correlations between length, depth and diameter of the sella turcica between the two twin individuals in the same twin pair. Differences in sizes are observed between individuals in the twin material and individuals in the non-twin material. As a conclusion, the twin males were more similar within the twin pair, but deviated more from the non-twin material than the females. Female twins had more discrepancy within the twin pair, but deviated less from the non-twin material than the males.

  9. Perinatal Outcome of Second Twin with Respect to Mode of Delivery: An Observational Study

    Science.gov (United States)

    Nadkarni, Trupti K

    2016-01-01

    Introduction With the advent of assisted reproductive techniques, multi-fetal pregnancies are on the rise. While caesarean section is the defined mode of delivery for triplets and higher order pregnancies, the picture for twin delivery is not so clear. While a trial for vaginal delivery is attempted, the second twin is considered vulnerable to complications. Whether this translates into worsened perinatal outcomes is not well defined. Aim To study the perinatal outcome and to identify the various factors influencing the perinatal outcome of second twin with respect to mode of delivery. Materials and Methods Data was collected from hospital birth records regarding the mode of delivery of viable twins (period of gestation >28 weeks) and outcome of second twin with respect to APGAR scores, NICU stay, neonatal morbidity and mortality, over a period of 12 months. Results Of the 93 pairs of twins delivered, in 21(22.6%) pregnancies both twins were delivered vaginally, in 70(75.2%) pregnancies both were delivered by caesarean section and in 2 (1.8%) pregnancies 1st twin was delivered by vaginal route and 2nd by caesarean. In the vaginal delivery group, 85.7% times both twins were in vertex position. In the caesarean group, vertex/non-vertex (38.57%) was the most common presentation followed by non-vertex /non-vertex (25.71%) and vertex/vertex (24.28%). Comparing the perinatal outcome of second twin in both groups, the odds for APGAR score ≤7 was 3.385 times (OR-3.384, 95% CI 1.2099- 9.4684, p=0.02) in the vaginal group compared to the caesarean group. There was no association (OR-1.054, 95% CI 0.3344- 3.3268, p=0.9) between neonatal morbidity of second twin compared to mode of delivery. All 3 perinatal deaths were in the vaginal group (all between 28-32 weeks of gestation). Conclusion There is an increased preference for caesarean delivery in twin pregnancies except in cases where both the twins are in vertex position and not associated with any other maternal or fetal

  10. A polynomial chaos expansion based molecular dynamics study for probabilistic strength analysis of nano-twinned copper

    Science.gov (United States)

    Mahata, Avik; Mukhopadhyay, Tanmoy; Adhikari, Sondipon

    2016-03-01

    Nano-twinned structures are mechanically stronger, ductile and stable than its non-twinned form. We have investigated the effect of varying twin spacing and twin boundary width (TBW) on the yield strength of the nano-twinned copper in a probabilistic framework. An efficient surrogate modelling approach based on polynomial chaos expansion has been proposed for the analysis. Effectively utilising 15 sets of expensive molecular dynamics simulations, thousands of outputs have been obtained corresponding to different sets of twin spacing and twin width using virtual experiments based on the surrogates. One of the major outcomes of this work is that there exists an optimal combination of twin boundary spacing and twin width until which the strength can be increased and after that critical point the nanowires weaken. This study also reveals that the yield strength of nano-twinned copper is more sensitive to TBW than twin spacing. Such robust inferences have been possible to be drawn only because of applying the surrogate modelling approach, which makes it feasible to obtain results corresponding to 40 000 combinations of different twin boundary spacing and twin width in a computationally efficient framework.

  11. Study of the twinned dendrite tip shape II: Experimental assessment

    Energy Technology Data Exchange (ETDEWEB)

    Salgado-Ordorica, M.A., E-mail: mario.salgado@novelis.com [Laboratoire de Simulation des Materiaux LSMX, Ecole Polytechnique Federale de Lausanne, Station 12, 1015 Lausanne (Switzerland); Burdet, P.; Cantoni, M. [Centre Interdisciplinaire de Microscopie Electronique CIME, Ecole Polytechnique Federale de Lausanne, Station 12, 1015 Lausanne (Switzerland); Rappaz, M. [Laboratoire de Simulation des Materiaux LSMX, Ecole Polytechnique Federale de Lausanne, Station 12, 1015 Lausanne (Switzerland)

    2011-08-15

    The favorable growth kinetics of twinned dendrites can be explained by their complex morphology, multiple side branching mechanisms, growth undercooling and tip morphology. Three models were proposed for the twinned dendrite tip shape: (i) a grooved tip satisfying the Smith condition at the triple line; (ii) a doublon , i.e. a double-tip dendrite that grows with a narrow and deep liquid channel in its center; and (iii) a pointed (or edgy) tip, with consideration of the solid-liquid interfacial energy anisotropy. In the first part of this work, phase field simulations of half a twinned dendrite with an appropriate boundary condition to reproduce the Smith condition supported the doublon conjecture, with a narrow liquid channel ending its solidification with the formation of small liquid droplets. In this part, experimental observations of twinned dendrite tips reveal the presence of a small, but well-defined, groove, thus definitely eliminating the edged tip hypothesis. Focused ion beam nanotomography and energy-dispersive spectroscopy chemical analysis in a transmission electron microscope reveal the existence of a positive solute gradient in a region localized within 2 {mu}m around the twin plane. In Al-Zn specimens, small particles aligned within the twin plane further support the doublon conjecture and the predicted formation of small liquid droplets below the doublon root.

  12. Examination of the Relationship between Oral Health and Arterial Sclerosis without Genetic Confounding through the Study of Older Japanese Twins.

    Directory of Open Access Journals (Sweden)

    Yuko Kurushima

    Full Text Available Although researchers have recently demonstrated a relationship between oral health and arterial sclerosis, the genetic contribution to this relationship has been ignored even though genetic factors are expected to have some effect on various diseases. The aim of this study was to evaluate oral health as a significant risk factor related to arterial sclerosis after eliminating genetic confounding through study of older Japanese twins.Medical and dental surveys were conducted individually for 106 Japanese twin pairs over the age of 50 years. Maximal carotid intima-media thickness (IMT-Cmax was measured as a surrogate marker of arterial sclerosis. IMT-Cmax > 1.0 mm was diagnosed as arterial sclerosis. All of the twins were examined for the number of remaining teeth, masticatory performance, and periodontal status. We evaluated each measurement related with IMT-Cmax and arterial sclerosis using generalized estimating equations analysis adjusted for potential risk factors. For non-smoking monozygotic twins, a regression analysis using a "between within" model was conducted to evaluate the relationship between IMT-Cmax and the number of teeth as the environmental factor controlling genetic and familial confounding.We examined 91 monozygotic and 15 dizygotic twin pairs (males: 42, females: 64 with a mean (± standard deviation age of 67.4 ± 10.0 years. Out of all of the oral health-related measurements collected, only the number of teeth was significantly related to arterial sclerosis (odds ratio: 0.72, 95% confidence interval: 0.52-0.99 per five teeth. Regression analysis showed a significant association between the IMT-Cmax and the number of teeth as an environmental factor (p = 0.037.Analysis of monozygotic twins older than 50 years of age showed that having fewer teeth could be a significant environmental factor related to arterial sclerosis, even after controlling for genetic and familial confounding.

  13. Examination of the Relationship between Oral Health and Arterial Sclerosis without Genetic Confounding through the Study of Older Japanese Twins.

    Science.gov (United States)

    Kurushima, Yuko; Ikebe, Kazunori; Matsuda, Ken-Ichi; Enoki, Kaori; Ogata, Soshiro; Yamashita, Motozo; Murakami, Shinya; Maeda, Yoshinobu

    2015-01-01

    Although researchers have recently demonstrated a relationship between oral health and arterial sclerosis, the genetic contribution to this relationship has been ignored even though genetic factors are expected to have some effect on various diseases. The aim of this study was to evaluate oral health as a significant risk factor related to arterial sclerosis after eliminating genetic confounding through study of older Japanese twins. Medical and dental surveys were conducted individually for 106 Japanese twin pairs over the age of 50 years. Maximal carotid intima-media thickness (IMT-Cmax) was measured as a surrogate marker of arterial sclerosis. IMT-Cmax > 1.0 mm was diagnosed as arterial sclerosis. All of the twins were examined for the number of remaining teeth, masticatory performance, and periodontal status. We evaluated each measurement related with IMT-Cmax and arterial sclerosis using generalized estimating equations analysis adjusted for potential risk factors. For non-smoking monozygotic twins, a regression analysis using a "between within" model was conducted to evaluate the relationship between IMT-Cmax and the number of teeth as the environmental factor controlling genetic and familial confounding. We examined 91 monozygotic and 15 dizygotic twin pairs (males: 42, females: 64) with a mean (± standard deviation) age of 67.4 ± 10.0 years. Out of all of the oral health-related measurements collected, only the number of teeth was significantly related to arterial sclerosis (odds ratio: 0.72, 95% confidence interval: 0.52-0.99 per five teeth). Regression analysis showed a significant association between the IMT-Cmax and the number of teeth as an environmental factor (p = 0.037). Analysis of monozygotic twins older than 50 years of age showed that having fewer teeth could be a significant environmental factor related to arterial sclerosis, even after controlling for genetic and familial confounding.

  14. Examination of the Relationship between Oral Health and Arterial Sclerosis without Genetic Confounding through the Study of Older Japanese Twins

    Science.gov (United States)

    Kurushima, Yuko; Ikebe, Kazunori; Matsuda, Ken-ichi; Enoki, Kaori; Ogata, Soshiro; Yamashita, Motozo; Murakami, Shinya; Maeda, Yoshinobu

    2015-01-01

    Objective Although researchers have recently demonstrated a relationship between oral health and arterial sclerosis, the genetic contribution to this relationship has been ignored even though genetic factors are expected to have some effect on various diseases. The aim of this study was to evaluate oral health as a significant risk factor related to arterial sclerosis after eliminating genetic confounding through study of older Japanese twins. Subjects and Methods Medical and dental surveys were conducted individually for 106 Japanese twin pairs over the age of 50 years. Maximal carotid intima-media thickness (IMT-Cmax) was measured as a surrogate marker of arterial sclerosis. IMT-Cmax > 1.0 mm was diagnosed as arterial sclerosis. All of the twins were examined for the number of remaining teeth, masticatory performance, and periodontal status. We evaluated each measurement related with IMT-Cmax and arterial sclerosis using generalized estimating equations analysis adjusted for potential risk factors. For non-smoking monozygotic twins, a regression analysis using a “between within” model was conducted to evaluate the relationship between IMT-Cmax and the number of teeth as the environmental factor controlling genetic and familial confounding. Results We examined 91 monozygotic and 15 dizygotic twin pairs (males: 42, females: 64) with a mean (± standard deviation) age of 67.4 ± 10.0 years. Out of all of the oral health-related measurements collected, only the number of teeth was significantly related to arterial sclerosis (odds ratio: 0.72, 95% confidence interval: 0.52-0.99 per five teeth). Regression analysis showed a significant association between the IMT-Cmax and the number of teeth as an environmental factor (p = 0.037). Conclusions Analysis of monozygotic twins older than 50 years of age showed that having fewer teeth could be a significant environmental factor related to arterial sclerosis, even after controlling for genetic and familial confounding

  15. Art for twins: Yorùbá artists and their statues/twin research studies: twins' education and conceptions; diurnal preference; inherited eye diseases; ultrasound counseling when twins are conjoined/popular twin reports: twin sisters (the film); rare pregnancy; diet test; French twins reared apart and reunited.

    Science.gov (United States)

    Segal, Nancy L

    2014-06-01

    The Yorùbá of Nigeria are well known for their high twinning rate and the statues they create to commemorate deceased twins. An impressive collection of this artwork was displayed at the University of California's Fowler Museum in Los Angeles between October 13, 2013 and March 2, 2014. An overview of this exhibit is provided. Next, twin research on maternal education and conception, diurnal preference, inherited eye diseases, and ultrasound counseling for couples with conjoined twins are briefly summarized. This article concludes with a discussion of media-based items related to twins. The topics include an award-winning twin film, a rare pregnancy, a diet test, and the separation and chance reunion of monozygotic female twins.

  16. The Nature and Nurture of Melody: A Twin Study of Musical Pitch and Rhythm Perception.

    Science.gov (United States)

    Seesjärvi, Erik; Särkämö, Teppo; Vuoksimaa, Eero; Tervaniemi, Mari; Peretz, Isabelle; Kaprio, Jaakko

    2016-07-01

    Both genetic and environmental factors are known to play a role in our ability to perceive music, but the degree to which they influence different aspects of music cognition is still unclear. We investigated the relative contribution of genetic and environmental effects on melody perception in 384 young adult twins [69 full monozygotic (MZ) twin pairs, 44 full dizygotic (DZ) twin pairs, 70 MZ twins without a co-twin, and 88 DZ twins without a co-twin]. The participants performed three online music tests requiring the detection of pitch changes in a two-melody comparison task (Scale) and key and rhythm incongruities in single-melody perception tasks (Out-of-key, Off-beat). The results showed predominantly additive genetic effects in the Scale task (58 %, 95 % CI 42-70 %), shared environmental effects in the Out-of-key task (61 %, 49-70 %), and non-shared environmental effects in the Off-beat task (82 %, 61-100 %). This highly different pattern of effects suggests that the contribution of genetic and environmental factors on music perception depends on the degree to which it calls for acquired knowledge of musical tonal and metric structures.

  17. Bruxism Is Associated With Nicotine Dependence: A Nationwide Finnish Twin Cohort Study

    Science.gov (United States)

    Ahlberg, J.; Hublin, C.; Broms, U.; Madden, P. A. F.; Könönen, M.; Koskenvuo, M.; Lobbezoo, F.; Kaprio, J.

    2010-01-01

    Objectives: To investigate the association of smoking with bruxism while controlling for genetic and environmental factors using a co-twin-control design. Especially, the role of nicotine dependence was studied in this context. Methods: The material derives from the Finnish Twin Cohort consisting of 12,502 twin individuals who responded to a questionnaire in 1990 (response rate of 77%). All were born in 1930–1957, the mean age being 44 years. The questionnaire covered 103 multiple choice questions, 7 dealing with tobacco use and 22 with sleep and vigilance matters, including perceived bruxism. In addition, a subsample derived from the Nicotine Addiction Genetics Finland Study containing 445 twin individuals was studied. Results: In age- and gender-controlled multinomial logistic regression, both monthly and rarely reported bruxism associated with both current cigarette smoking (odds ratio [OR] = 1.74 and 1.64) and former cigarette smoking (OR = 1.64 and 1.47). Weekly bruxism associated with current smoking (OR = 2.85). Current smokers smoking 20 or more cigarettes a day reported weekly bruxism more likely (OR = 1.61–1.97) than those smoking less. Among twin pairs (N = 142) in which one twin was a weekly bruxer and the cotwin a never bruxer, there were 13 monozygotic pairs in which one twin was a current smoker and the other twin was not. In all cases, the bruxer was the smoker (p = .0003). Nicotine dependence associated significantly with bruxism. Conclusions: Our twin study provides novel evidence for a possible causal link between tobacco use and bruxism among middle-aged adults. Nicotine dependence may be a significant predisposing factor for bruxism. PMID:21041838

  18. A longitudinal study of epigenetic variation in twins

    Science.gov (United States)

    Caspi, Avshalom; Williams, Benjamin; Craig, Ian W; Houts, Renate; Ambler, Antony; Moffitt, Terrie E; Mill, Jonathan

    2010-01-01

    DNA methylation is a key epigenetic mechanism involved in the developmental regulation of gene expression. Alterations in DNA methylation are established contributors to inter-individual phenotypic variation and have been associated with disease susceptibility. The degree to which changes in loci-specific DNA methylation are under the influence of heritable and environmental factors is largely unknown. In this study, we quantitatively measured DNA methylation across the promoter regions of the dopamine receptor 4 gene (DRD4), the serotonin transporter gene (SLC6A4/SERT) and the X-linked monoamine oxidase A gene (MAOA) using DNA sampled at both ages 5 and 10 years in 46 MZ twinpairs and 45 DZ twin-pairs (total n = 182). Our data suggest that DNA methylation differences are apparent already in early childhood, even between genetically identical individuals, and that individual differences in methylation are not stable over time. Our longitudinal-developmental study suggests that environmental influences are important factors accounting for interindividual DNA methylation differences, and that these influences differ across the genome. The observation of dynamic changes in DNA methylation over time highlights the importance of longitudinal research designs for epigenetic research. PMID:20505345

  19. Effects of asthma on stability of Wisconsin card sorting test measures A twin study

    Institute of Scientific and Technical Information of China (English)

    Yixiao Fu; Huaqing Meng; Hengshu Zhang; Lu Jia; Qinghua Luo

    2008-01-01

    BACKGROUND:The four measures used to assess the stability of the Wisconsin card sorting test (WEST),that is,the number of preservative errors,percentage of preservative errors,number of categories completed,and the number of trials to complete the first category,reflect the function of the frontal lobe.OBJECTIVE:This study was designed to investigate the effects of asthma on the stability of WCST measurements through the use of a twin study,and to analyze whether egg-type difference exists.DESIGN:A cohort study.SETTING:Mental Health Center,the First Affiliated Hospital of Chongqing Medical University.PARTICIPANTS:Fifty-nine pairs of twins,aged 6-16 years,were primarily selected from schools between August 2005 and February 2007 and the WeST and Zygosity identification test was applied.Twins with achromatopsia,severe upper limb diseases,somatic diseases,or mental disorders were excluded.According to disease history of asthmatic attack,children were assigned into asthma(n=16)and non-asthma(n=43)groups.METHODS:Four WCST measurements were determined in the 59 pairs of twins,and egg-type differences were identified in conjunction.RESULTS:All 59 pairs of twins were included in the final analysis.Among the pairs of twins,28 (48.5%)were monozygotic twins,and 31(52%)were dizygotic twins.Among the monozygotic and dizygotic twins,the number of preservative errors and percentage of preservative errors were significantly higher in the asthma group than in the non-asthma group(P0.05).CONCLUSION:Asthma may affect the stability of WCST measures,but egg-type differences do not exist.

  20. Relative Genetic and Environmental Contributions to Variations in Human Retinal Electrical Responses Quantified in a Twin Study.

    Science.gov (United States)

    Bhatti, Taha; Tariq, Ambreen; Shen, Ting; Williams, Katie M; Hammond, Christopher J; Mahroo, Omar A

    2017-08-01

    To estimate heritability of parameters of human retinal electrophysiology and to explore which parameters change with age. Prospective, classic twin study. Adult monozygotic and dizygotic twin pairs recruited from the TwinsUK cohort. Electroretinogram responses were recorded using conductive fiber electrodes in response to stimuli incorporating standards set by the International Society for the Clinical Electrophysiology of Vision. These parameters were extracted; in addition, photopic negative-response (PhNR; originating from retinal ganglion cells) and i-wave components were extracted from responses to the photopic single flash. Parameter values were averaged from both eyes. Mean values were calculated for the cohort. Correlation coefficients with age were calculated (averaging parameters from both twins from each pair). Coefficients of intrapair correlation were calculated for monozygotic and dizygotic twins. Age-adjusted heritability estimates were derived using standard maximum likelihood structural equation twin modeling. Responses were recorded from 210 participants in total (59 monozygotic and 46 dizygotic twin pairs). Ninety-three percent were women. Mean age for the cohort was 62.4 years (standard deviation, 11.4 years). In general, response amplitudes correlated negatively, and implicit times positively, with age. Correlations were statistically significant (P 0.35) for the following parameters: scotopic standard and bright-flash a-wave implicit times, photopic 30-Hz flicker and single-flash b-wave implicit times, and PhNR and i-wave implicit times. Intrapair correlations were higher for monozygotic than dizygotic twins, suggesting important genetic influences. Age-adjusted estimates of heritability were significant for all parameters (except scotopic dim-flash b-wave implicit time), ranging from 0.34 to 0.85. Highest estimates were for photopic single-flash a-wave and b-wave amplitudes (0.84 and 0.85, respectively). This study explored heritability of

  1. Evidence that BMI and type 2 diabetes share only a minor fraction of genetic variance: a follow-up study of 23,585 monozygotic and dizygotic twins from the Finnish Twin Cohort Study.

    Science.gov (United States)

    Lehtovirta, M; Pietiläinen, K H; Levälahti, E; Heikkilä, K; Groop, L; Silventoinen, K; Koskenvuo, M; Kaprio, J

    2010-07-01

    We investigated whether BMI predicts type 2 diabetes in twins and to what extent that is explained by common genetic factors. This was a population-based twin cohort study. Monozygotic (n = 4,076) and dizygotic (n = 9,109) non-diabetic twin pairs born before 1958 answered a questionnaire in 1975, from which BMI was obtained. Information on incident cases of diabetes was obtained by linkage to nationwide registers until 2005. Altogether, 1,332 twins (6.3% of men, 5.1% of women) developed type 2 diabetes. The HR for type 2 diabetes increased monotonically with a mean of 1.22 (95% CI 1.20-1.24) per BMI unit and of 1.97 (95% CI 1.87-2.08) per SD of BMI. The HRs for lean, overweight, obese and morbidly obese participants were 0.59, 2.96, 6.80 and 13.64 as compared with normal weight participants. Model heritability estimates for bivariate variance due to an additive genetic component and non-shared environmental component were 75% (men) and 71% (women) for BMI, and 73% and 64%, respectively for type 2 diabetes. The correlations between genetic variance components (r (g)) indicated that one fifth of the covariance of BMI and type 2 diabetes was due to shared genetic influences. Although the mean monozygotic concordance for type 2 diabetes was approximately twice the dizygotic one, age of onset of diabetes within twin pair members varied greatly, irrespective of zygosity. A 28-year follow-up of adult Finnish twins showed that despite high trait heritability estimates, only a fraction of covariation in BMI and incident type 2 diabetes was of genetic origin.

  2. Genetic and environmental influences on the relationship between ADHD symptoms and internalizing problems: A Chinese twin study.

    Science.gov (United States)

    Chen, Tian-Jiao; Ji, Cheng-Ye; Wang, Shang-Shang; Lichtenstein, Paul; Larsson, Henrik; Chang, Zheng

    2016-10-01

    Several twin studies have investigated the overlap between attention deficit hyperactivity disorder (ADHD) and externalizing problems; however, limited information is known regarding the genetic and environmental contribution to the overlap between ADHD and internalizing problems. This study examined the genetic and environmental influences on the variation in and covariation between ADHD symptoms and internalizing problems by using the Child Behavior Checklist (CBCL). We investigated 1,316 child and adolescent twins, including 780 monozygotic twins and 536 dizygotic twins, aged 6 years to 18 years from the Chinese Child and Adolescent Twin Registry. ADHD symptoms and internalizing problems were quantified through parent rating by using the Attention Problems Scale and other three scales, which include Anxious/Depressed, Withdrawn, and Somatic Complaints of CBCL. Genetic and environmental susceptibilities common to ADHD symptoms and internalizing problems were examined through bivariate twin modeling. Results showed that genetic factors substantially influenced the ADHD symptoms with a heritability of 72%. Modest genetic influences and substantial shared environmental influences (20-77%) were observed in the three internalizing problem scales. Common genetic and shared environmental influences were essential for the overlap between ADHD and the three internalizing problems respectively. Approximately one-fifth of the genetic variance of ADHD symptoms was shared with anxiety/depression. In conclusion, substantial genetic and shared environmental influences on ADHD symptoms and internalizing problems were observed in Chinese children and adolescents. Our finding supports a common etiology between ADHD and internalizing problems. This finding can also help explain the co-existence of these behavior problems. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  3. Anorexia and Bulimia Nervosa in Same-Sex and Opposite-Sex Twins : Lack of Association With Twin Type in a Nationwide Study of Finnish Twins

    NARCIS (Netherlands)

    Raevuori, Anu; Kaprio, Jaakko; Hoek, Hans W.; Sihvola, Elina; Rissanen, Aila; Keski-Rahkonen, Anna

    2008-01-01

    Objective: The authors tested the hypothesis that either prenatal feminization or masculinization hormone influences in utero or later socialization affects the risk for anorexia and bulimia nervosa and disordered eating in members of opposite-sex twin pairs. Method: Finnish twins (N=2,426 women, N=

  4. Anorexia and Bulimia Nervosa in Same-Sex and Opposite-Sex Twins : Lack of Association With Twin Type in a Nationwide Study of Finnish Twins

    NARCIS (Netherlands)

    Raevuori, Anu; Kaprio, Jaakko; Hoek, Hans W.; Sihvola, Elina; Rissanen, Aila; Keski-Rahkonen, Anna

    2008-01-01

    Objective: The authors tested the hypothesis that either prenatal feminization or masculinization hormone influences in utero or later socialization affects the risk for anorexia and bulimia nervosa and disordered eating in members of opposite-sex twin pairs. Method: Finnish twins (N=2,426 women,

  5. Anorexia and Bulimia Nervosa in Same-Sex and Opposite-Sex Twins : Lack of Association With Twin Type in a Nationwide Study of Finnish Twins

    NARCIS (Netherlands)

    Raevuori, Anu; Kaprio, Jaakko; Hoek, Hans W.; Sihvola, Elina; Rissanen, Aila; Keski-Rahkonen, Anna

    2008-01-01

    Objective: The authors tested the hypothesis that either prenatal feminization or masculinization hormone influences in utero or later socialization affects the risk for anorexia and bulimia nervosa and disordered eating in members of opposite-sex twin pairs. Method: Finnish twins (N=2,426 women, N=

  6. Experimental and Numerical Study of Twin Underexpanded Impinging Jets

    Institute of Scientific and Technical Information of China (English)

    Minoru Yaga; Minoru Okano; Masumi Tamashiro; Kenyu Oyakawa

    2003-01-01

    In this paper, the dual underexpanded impinging jets are experimentally and numerically studied. The experiments were performed by measuring the unsteady and averaged wall static pressures and by visualizing density fields using schlieren method. Numerical calculations were also conducted by solving unsteady three dimensional compressible Navier-Stokes equations with Baldwin-Lomax turbulence model. The main parameters for the dual jets are the non-dimensional distance between the two nozzle centers H/D covering 1.5, 2.0, the nozzle to plate separation L/D 2.0, 3.0,4.0 and 5.0 and the pressure ratio defined by Po/Pb 1.0~6.0, where D is the diameter of each nozzle exit, Po the stagnation pressure and Pb the back pressure. It is found that the agreement between the experiments and the calculations is good. The fountain flow at the middle of the two jets is observed both in the experiments and the calculation. According to FFT analysis of the experiments for the twin jets,relatively low frequency (up to 5 kHz) is dominant for H/D =1.5, L/D =2.0 and pressure ratio Po/Pb =3.0 and 5.0,which is confirmed by the experiments.

  7. Study on twin stacking faults in vaterite tablets of freshwater lacklustre pearls

    Science.gov (United States)

    Qiao, L.; Feng, Q. L.

    2007-06-01

    Twin stacking faults have been observed in vaterite tablets of freshwater lacklustre pearls for the first time. The detailed characteristic of stacking faults was studied by high-resolution transmission electron microscope (HRTEM) with selected area electron diffraction (SAED). It is found that stacking faults along [0 0 1] mainly consist of micro-twins with the twin plane (0 0 1). The stacking faults in vaterite crystals may lower energy for crystal growth, and at the same time make vaterite crystals more stable than the other polymorphs of calcium carbonate. At last, the formation mechanism of stacking faults was discussed.

  8. Twin Higgs WIMP Dark Matter

    CERN Document Server

    García, Isabel García; March-Russell, John

    2015-01-01

    Dark matter (DM) without a matter asymmetry is studied in the context of Twin Higgs (TH) theories in which the LHC naturalness problem is addressed. These possess a twin sector related to the Standard Model (SM) by a (broken) $\\mathbb{Z}_2$ symmetry, and interacting with the SM via a specific Higgs portal. We focus on the minimal realisation of the TH mechanism, the Fraternal Twin Higgs, with only a single generation of twin quarks and leptons, and $SU(3)'\\times SU(2)'$ gauge group. We show that a variety of natural twin-WIMP DM candidates are present (directly linked to the weak scale by naturalness), the simplest and most attractive being the $\\tau^\\prime$ lepton with a mass $m_{\\tau^\\prime} > m_{\\rm Higgs}/2$, although spin-1 $W^{\\prime\\pm}$ DM and multicomponent DM are also possible (twin baryons are strongly disfavoured by tuning). We consider in detail the dynamics of the possibly (meta)stable glueballs in the twin sector, the nature of the twin QCD phase transition, and possible new contributions to th...

  9. The Norwegian Twin Registry.

    Science.gov (United States)

    Nilsen, Thomas S; Brandt, Ingunn; Magnus, Per; Harris, Jennifer R

    2012-12-01

    Norway has a long-standing tradition in twin research, but the data collected in several population-based twin studies were not coordinated centrally or easily accessible to the scientific community. In 2009, the Norwegian Twin Registry was established at the Norwegian Institute of Public Health (NIPH) in Oslo with the purpose of creating a single research resource for Norwegian twin data. As of today, the Norwegian Twin Registry contains 47,989 twins covering birth years 1895-1960 and 1967-1979; 31,440 of these twins consented to participate in health-related research. In addition, DNA from approximately 4,800 of the twins is banked at the NIPH biobank and new studies are continually adding new data to the registry. The value of the Norwegian twin data is greatly enhanced by the linkage opportunities offered by Norway's many nationwide registries, spanning a broad array of medical, demographic, and socioeconomic information.

  10. Renal albumin excretion: twin studies identify influences of heredity, environment, and adrenergic pathway polymorphism

    DEFF Research Database (Denmark)

    Rao, Fangwen; Wessel, Jennifer; Wen, Gen

    2007-01-01

    Albumin excretion marks early glomerular injury in hypertension. This study investigated heritability of albumin excretion in twin pairs and its genetic determination by adrenergic pathway polymorphism. Genetic associations used single nucleotide polymorphisms at adrenergic pathway loci spanning......, diagnosis, and treatment....

  11. Small effect of genetic factors on neck pain in old age: a study of 2,108 Danish twins 70 years of age and older

    DEFF Research Database (Denmark)

    Hartvigsen, Jan; Petersen, Hans Christian; Frederiksen, Henrik;

    2005-01-01

    environmental risk factors (rheumatoid arthritis, osteoarthritis, disc prolapse, and coronary heart disease) showed no significant additive genetic, dominant genetic, or common environmental effects. CONCLUSION: Genetic factors do not play an important role in the liability to neck pain in persons 70 years......STUDY DESIGN: Classic twin study. OBJECTIVES: To determine the heritability of neck pain in persons 70 years of age and older. SUMMARY OF BACKGROUND DATA: Previous studies have shown a moderate effect of genetic factors on back pain in the elderly. Genetic influence on neck pain in old age...... is unknown. METHODS: Data on the 1-month prevalence of neck pain from twin pairs participating in the population based Longitudinal Study of Aging Danish Twins formed the basis of this analysis. To assess twin similarity, probandwise concordance rates, odds ratios, and tetrachoric correlations were...

  12. Profile of asymmetrical retinopathy of prematurity in twins

    Directory of Open Access Journals (Sweden)

    Azad Rajvardhan

    2010-01-01

    Full Text Available Background: In twin births, both babies have the same gestational age and pre-natal conditions. However, twins may develop a varied retinopathy of prematurity (ROP course depending on birth weight and other systemic factors. Objective: To study the profile of asymmetric ROP in twins Design: Retrospective study Setting: Tertiary ROP referral eye hospital. Materials and Methods: The profile of 56 pairs of twins with ROP were studied and analyzed for differences in zone or need for treatment, while studying possible causes for the varied outcome. Results: In 45 pairs of twins (80% the disease progressed identically in both eyes, while in 11 pairs (20% the ROP showed differences in zone or need for treatment. Four of these pairs were discordant. In 3 of these 4 pairs, the heavier birth weight twin had a more severe ROP course. Conclusions: Twins can present with asymmetric ROP course, and it is therefore essential to examine both twins as per screening protocols.

  13. EXPERIMENTAL STUDY ON THE FLOW FIELD CHARACTERISTICS IN THE MIXING REGION OF TWIN JETS

    Institute of Scientific and Technical Information of China (English)

    YIN Zhao-qin; ZHANG Hong-jun; LIN Jian-zhong

    2007-01-01

    Twin jets flow, generated by two identical parallel axisymmetric nozzles, has been experimentally investigated. The dimensionless spacing (B) between two nozzles were set at 1.89, 1.75 and 1.5. Measurements have been carried out at several free-stream velocities ranging from 10 m/s to 25 m/s or Reynolds numbers (based on the nozzle diameter of 44 mm) ranging from 3.33×104 to 8.33×104. The results show that the twin jets attract each other. With the increasing Reynolds number, the turbulence energy grows, which indicates that the twin jets attract acutely. The jet flow field and the merging process of two jets vary with B. The width of the twin jets flow spreads linearly downstream and grows with B. The merging between two jets occurs at the location closer to the nozzle exit for the cases with smaller spacing between nozzles and higher Reynolds number.

  14. Fingerprint recognition with identical twin fingerprints.

    Directory of Open Access Journals (Sweden)

    Xunqiang Tao

    Full Text Available Fingerprint recognition with identical twins is a challenging task due to the closest genetics-based relationship existing in the identical twins. Several pioneers have analyzed the similarity between twins' fingerprints. In this work we continue to investigate the topic of the similarity of identical twin fingerprints. Our study was tested based on a large identical twin fingerprint database that contains 83 twin pairs, 4 fingers per individual and six impressions per finger: 3984 (83*2*4*6 images. Compared to the previous work, our contributions are summarized as follows: (1 Two state-of-the-art fingerprint identification methods: P071 and VeriFinger 6.1 were used, rather than one fingerprint identification method in previous studies. (2 Six impressions per finger were captured, rather than just one impression, which makes the genuine distribution of matching scores more realistic. (3 A larger sample (83 pairs was collected. (4 A novel statistical analysis, which aims at showing the probability distribution of the fingerprint types for the corresponding fingers of identical twins which have same fingerprint type, has been conducted. (5 A novel analysis, which aims at showing which finger from identical twins has higher probability of having same fingerprint type, has been conducted. Our results showed that: (a A state-of-the-art automatic fingerprint verification system can distinguish identical twins without drastic degradation in performance. (b The chance that the fingerprints have the same type from identical twins is 0.7440, comparing to 0.3215 from non-identical twins. (c For the corresponding fingers of identical twins which have same fingerprint type, the probability distribution of five major fingerprint types is similar to the probability distribution for all the fingers' fingerprint type. (d For each of four fingers of identical twins, the probability of having same fingerprint type is similar.

  15. A study of diabetes mellitus within a large sample of Australian twins

    DEFF Research Database (Denmark)

    Condon, Julianne; Shaw, Joanne E; Luciano, Michelle;

    2008-01-01

    with type 2 diabetes (T2D), 41 female pairs with gestational diabetes (GD), 5 pairs with impaired glucose tolerance (IGT) and one pair with MODY. Heritabilities of T1D, T2D and GD were all high, but our samples did not have the power to detect effects of shared environment unless they were very large......Twin studies of diabetes mellitus can help elucidate genetic and environmental factors in etiology and can provide valuable biological samples for testing functional hypotheses, for example using expression and methylation studies of discordant pairs. We searched the volunteer Australian Twin...... Registry (19,387 pairs) for twins with diabetes using disease checklists from nine different surveys conducted from 1980-2000. After follow-up questionnaires to the twins and their doctors to confirm diagnoses, we eventually identified 46 pairs where one or both had type 1 diabetes (T1D), 113 pairs...

  16. Sex differences and heritability of two indices of heart rate dynamics: a twin study.

    Science.gov (United States)

    Snieder, Harold; van Doornen, Lorenz J P; Boomsma, Dorret I; Thayer, Julian F

    2007-04-01

    We investigated whether women show larger heart rate variability (HRV) than men after controlling for a large number of health-related covariates, using two indices of HRV, namely respiratory sinus arrhythmia (RSA) and approximate entropy (ApEn). In a twin design, the heritability of both indices was examined. The covariation between RSA and ApEn, a measure of heart rate dynamics derived from nonlinear dynamical systems theory, was decomposed into genetic and environmental components. Subjects were 196 male and 210 female middle-aged twins. Females showed larger HRV than men before (ApEn: p RSA: p = .052) and after adjustment for covariates (ApEn: p RSA: p = .015). This sex difference was confirmed by significant intrapair differences in the opposite-sex twin pairs for both ApEn (p RSA (p = .03). In addition to sex, only heart period and age (both p RSA was also influenced by respiration rate and smoking (both p RSA and ApEn, respectively. Oral contraceptive use and menopausal status had no effect on HRV. Genetic model fitting yielded moderate heritability estimates for RSA (30%) and ApEn (40%) for both males and females. The correlation between RSA and ApEn (r = .60) could be attributed to genetic factors (48%), environmental factors (36%) and age (16%). The present study found support for a gender difference in HRV with women having greater HRV than men even after controlling for a large number of potential confounders. Indices of heart rate dynamics derived from nonlinear dynamical systems theory are moderately heritable and may be more sensitive than traditional indices of HRV to reveal subtle sex differences with important implications for health and disease.

  17. Predicting Individual Differences in Reading Comprehension: A Twin Study

    Science.gov (United States)

    Harlaar, Nicole; Cutting, Laurie; Deater-Deckard, Kirby; DeThorne, Laura S.; Justice, Laura M.; Schatschneider, Chris; Thompson, Lee A.; Petrill, Stephen A.

    2010-01-01

    We examined the Simple View of reading from a behavioral genetic perspective. Two aspects of word decoding (phonological decoding and word recognition), two aspects of oral language skill (listening comprehension and vocabulary), and reading comprehension were assessed in a twin sample at age 9. Using latent factor models, we found that overlap…

  18. Twin-domain size and bulk oxygen in-diffusion kinetics of YBa2Cu3O6+x studied by neutron powder diffraction and gas volumetry

    DEFF Research Database (Denmark)

    Poulsen, H.F.; Andersen, N.H.; Lebech, B.

    1991-01-01

    distribution. At higher temperatures, tau is activated with activation energies 0.55 and 0.25 eV in the tetragonal and orthorhombic phases, respectively. Comparison between twin-domain sizes and bulk oxygen in-diffusion time constants indicates that the twin-domain boundaries may contribute to the effective......We report experimental results of twin-domain size and bulk oxygen in-diffusion kinetics of YBa2Cu3O6+x, which supplement a previous and simultaneous study of the structural phase diagram and oxygen equilibrium partial pressure. Analysis of neutron powder diffraction peak broadening show features...... which are identified to result from temperature independent twin-domain formation in to different orthorhombic phases with domain sizes 250 and 350 angstrom, respectively. The oxygen in-diffusion flow shows simple relaxation type behaviour J = J0 exp(-t/tau) despite a rather broad particle size...

  19. Heritability of eleven metabolic phenotypes in Danish and Chinese twins

    DEFF Research Database (Denmark)

    Li, Shuxia; Duan, Hongmei; Pang, Zengchang

    2013-01-01

    A twin-based comparative study on the genetic influences in metabolic endophenotypes in two populations of substantial ethnic, environmental, and cultural differences was performed. Design and Methods: Data on 11 metabolic phenotypes including anthropometric measures, blood glucose, and lipids...... levels as well as blood pressure were available from 756 pairs of Danish twins (309 monozygotic and 447 dizygotic twin pairs) with a mean age of 38 years (range: 18-67) and from 325 pairs of Chinese twins (183 monozygotic and 142 dizygotic twin pairs) with a mean age of 40.5 years (range: 18-69). Twin...... similar heritability patterns in the two samples with body weight showing only a slight difference. Higher genetic influences were estimated for fasting blood glucose level in Chinese twins, whereas the Danish twins showed more genetic regulation over most lipids phenotypes. Systolic blood pressure...

  20. EFFECTS OF LONG-TERM PHYSICAL ACTIVITY ON CARDIAC STRUCTURE AND FUNCTION: A TWIN STUDY

    Directory of Open Access Journals (Sweden)

    Urho M.Kujala

    2009-12-01

    Full Text Available Previous studies have shown that athletic training or other physical activity causes structural and functional adaptations in the heart, but less is known how long-term physical activity affects heart when genetic liability and childhood environment are taken into account. The aim of this study was to investigate the effects of long-term physical activity vs. inactivity on cardiac structure and function in twin pairs discordant for physical activity for 32 years. Twelve same-sex twin pairs (five monozygotic and seven dizygotic, 50-67 years were studied as a part of the TWINACTIVE study. Discordance in physical activity was initially determined in 1975 and it remained significant throughout the follow-up. At the end of the follow-up in 2007, resting echocardiographic and electrocardiographic measurements were performed. During the follow-up period, the active co-twins were on average 8.2 (SD 4.0 MET hours/day more active than their inactive co-twins (p < 0.001. At the end of the follow-up, resting heart rate was lower in the active than inactive co-twins [59 (SD 5 vs. 68 (SD 10 bpm, p=0.03]. The heart rate-corrected QT interval was similar between the co-twins. Also, there was a tendency for left ventricular mass per body weight to be greater and T wave amplitude in lead II to be higher in the active co-twins (18% and 15%, respectively, p=0.08 for both. Similar trends were found for both monozygotic and dizygotic twin pairs. In conclusion, the main adaptation to long- term physical activity is lowered resting heart rate, even after partially or fully controlling for genetic liability and childhood environment

  1. Timing of Colonization of Caries-Producing Bacteria: An Approach Based on Studying Monozygotic Twin Pairs

    OpenAIRE

    Bockmann, Michelle R.; Harris, Abbe V.; Bennett, Corinna N.; Ruba Odeh; Hughes, Toby E.; Townsend, Grant C

    2011-01-01

    Findings are presented from a prospective cohort study of timing of primary tooth emergence and timing of oral colonization of Streptococcus mutans (S. mutans) in Australian twins. The paper focuses on differences in colonization timing in genetically identical monozygotic (MZ) twins. Timing of tooth emergence was based on parental report. Colonization timing of S. mutans were established by plating samples of plaque and saliva on selective media at 3 monthly intervals and assessing colony mo...

  2. The roots of autism and ADHD twin study in Sweden (RATSS)

    OpenAIRE

    2014-01-01

    Neurodevelopmental disorders affect a substantial minority of the general population. Their origins are still largely unknown, but a complex interplay of genetic and environmental factors causing disturbances of the central nervous system's maturation and a variety of higher cognitive skills is presumed. Only limited research of rather small sample size and narrow scope has been conducted in neurodevelopmental disorders using a twin-differences design. The Roots of Autism and ADHD Twin Study ...

  3. Cohort Profile: Swedish Twin Study on Prediction and Prevention of Asthma (STOPPA).

    Science.gov (United States)

    Almqvist, Catarina; Örtqvist, Anne K; Ullemar, Vilhelmina; Lundholm, Cecilia; Lichtenstein, Paul; Magnusson, Patrik K E

    2015-06-01

    Asthma is a common childhood disease and several risk factors have been identified; however, the impact of genes and environment is not fully understood. The aim of the Swedish Twin study On Prediction and Prevention of Asthma (STOPPA) is to identify environmental (birth characteristics and early life) and genetic (including epigenetic) factors as determinants for asthmatic disease. Based on the Child and Adolescent Twin Study in Sweden (CATSS) (parental interview at 9 or 12 years, N ~23,900) and an asthma and/or wheezing algorithm, we identified a sample of monozygotic (MZ) and dizygotic (DZ) same-sexed twin pairs. The twin pairs were classified as asthma concordant (ACC), asthma discordant (ADC) and healthy concordant (HCC). A sample of 9- to 14-year-old twins and their parents were invited to participate in a clinical examination. Background characteristics were collected in questionnaires and obtained from the National Health Registers. A clinical examination was performed to test lung function and capacity (spirometry with reversibility test and exhaled nitric oxide) and collect blood (serology and DNA), urine (metabolites), feces (microbiota), and saliva (cortisol). In total, 376 twin pairs (752 individual twins) completed the study, response rate 52%. All participating twins answered the questionnaire and >90% participated in lung function testing, blood-, and saliva sampling. This article describes the design, recruitment, data collection, measures, and background characteristics, as well as ongoing and planned analyses in STOPPA. Potential gains of the study include the identification of biomarkers, the emergence of candidates for drug development, and new leads for prevention of asthma and allergic disease.

  4. Cold welding of copper nanowires with single-crystalline and twinned structures: A comparison study

    Science.gov (United States)

    Huang, Rao; Shao, Gui-Fang; Wen, Yu-Hua

    2016-09-01

    In this article, molecular simulations were adopted to explore the cold welding processes of copper nanowires with both single-crystalline and fivefold twinned structures. It was verified that the twinned nanowires exhibited enhanced strength but lowered elastic limit and ductility. Both nanowires could be successfully welded through rather small loadings, although their stress-strain responses toward compression were different. Meanwhile, more stress was accumulated in the twinned nanowire due to repulsive force of the twin boundaries against the nucleation and motions of dislocations. Moreover, by characterizing the structure evolutions in the welding process, it can be ascertained that perfect atomic order was finally built at the weld region in both nanowires. This comparison study will be of great importance to future mechanical processing of metallic nanowires.

  5. Twin study of heritability of eating bread in Danish and Finnish men and women

    DEFF Research Database (Denmark)

    Hasselbalch, Ann Louise; Silventoinen, Karri; Keskitalo, Kaisu;

    2010-01-01

    cohorts included 575 Danish (age range 18-67 years) and 2009 Finnish (age range 22-27 years) adult twin pairs. Self-reported frequency of eating bread was obtained by food frequency questionnaires. Univariate models based on linear structural equations for twin data were used to estimate the relative......Bread is an elementary part of the western diet, and especially rye bread is regarded as an important source of fibre. We investigated the heritability of eating bread in terms of choice of white and rye bread and use-frequency of bread in female and male twins in Denmark and Finland. The study...... influence on intake of white bread was moderate (24-31%), while the genetic influence on intake of rye bread was higher in men (41-45%) than in women (24-33%). Environmental influences shared by the twins were not significant. Consumption of bread as well as choice of bread is influenced by genetic...

  6. Dialysis for twins

    DEFF Research Database (Denmark)

    Gramkow, Ann-Maria; Aarup, Michael; Andersen, L. L. T.

    2014-01-01

    A 32-year-old woman with known stage-4 chronic kidney disease due to lupus nephritis presented with twin pregnancy after in vitro fertilization at a gestational age of 24 weeks + 3 days because of imminent preterm labour. Repeated ultrasound evaluations confirmed intrauterine growth restriction...... in both twins and polyhydramnios as the cause of imminent preterm labour. After initiation of haemodialysis treatment, ultrasound evaluation showed a significant decrease in amniotic fluids, and also reduction in blood urea nitrogen and in clinical complaints could be observed. At a gestational age of 28...... weeks + 4 days, delivery was performed by Caesarean section. This case study shows that effective treatment of elevated uraemic toxins significantly reduced the morbidity risks of the twins....

  7. Psychiatric outcomes of bullying victimization: A study of discordant monozygotic twins

    Science.gov (United States)

    Silberg, Judy L.; Copeland, William; Linker, Julie; Moore, Ashlee A.; Roberson-Nay, Roxann; York, Timothy P.

    2016-01-01

    Background Bullying victimization in childhood is associated with a broad array of serious mental health disturbances, including anxiety, depression, and suicidal ideation and behavior. The key goal of this study was to evaluate whether bullying victimization is a true environmental risk factor for psychiatric disturbance using data from 145 bully-discordant monozygotic (MZ) juvenile twin pairs from the Virginia Twin Study of Adolescent Behavioral Development (VTSABD) and their follow-up into young adulthood. Method Since MZ twins share an identical genotype and familial environment, a higher rate of psychiatric disturbance in a bullied MZ twin compared to their non-bullied MZ co-twin would be evidence of an environmental impact of bullying victimization. Environmental correlations between being bullied and the different psychiatric traits were estimated by fitting structural equation models to the full sample of MZ and DZ twins (N = 2824). Environmental associations were further explored using the longitudinal data on the bullying-discordant MZ twins. Results Being bullied was associated with a wide range of psychiatric disorders in both children and young adults. The analysis of data on the MZ-discordant twins supports a genuine environmental impact of bullying victimization on childhood social anxiety [odds ratio (OR) 1.7], separation anxiety (OR 1.9), and young adult suicidal ideation (OR 1.3). There was a shared genetic influence on social anxiety and bullying victimization, consistent with social anxiety being both an antecedent and consequence of being bullied. Conclusion Bullying victimization in childhood is a significant environmental trauma and should be included in any mental health assessment of children and young adults. PMID:26979565

  8. Do twins share the same dress code? Quantifying relative genetic and environmental contributions to subjective perceptions of "the dress" in a classical twin study.

    Science.gov (United States)

    Mahroo, Omar A; Williams, Katie M; Hossain, Ibtesham T; Yonova-Doing, Ekaterina; Kozareva, Diana; Yusuf, Ammar; Sheriff, Ibrahim; Oomerjee, Mohamed; Soorma, Talha; Hammond, Christopher J

    2017-01-01

    The phenomenon of contrasting color perceptions of "the dress" photograph has gained scientific interest. The mechanism underlying why individuals differ is yet to be fully explained. We use the powerful twin model design to ascertain the relative contribution of genetic and environmental factors on perception variation. A sample of 466 twins from the British TwinsUK registry were invited to report what color they saw in a standard image of the dress in standard illumination. The mean age of the participants was 49.5 (SD = 17.8) years, and 85% were female. When asked to choose between white and gold (WG) or blue and black (BB), 328 reported WG (70.4%) and 135 (29.0%) reported BB. Subjects choosing WG were significantly older (p twins were more concordant in their responses than dizygotic (DZ) twins (0.46 vs. 0.36). Twin modeling revealed that genetic factors accounted for 34% (95% confidence interval, 5%-59%) of variation in the reported color of the dress when adjusted for age, whereas environmental factors contributed 66% (95% CI, 41%-95%). This study suggests environmental factors play a significant role in how an individual perceives the color of "the dress."

  9. Genetic and environmental influences on sleep quality in middle-aged men: a twin study.

    Science.gov (United States)

    Genderson, Margo R; Rana, Brinda K; Panizzon, Matthew S; Grant, Michael D; Toomey, Rosemary; Jacobson, Kristen C; Xian, Hong; Cronin-Golomb, Alice; Franz, Carol E; Kremen, William S; Lyons, Michael J

    2013-10-01

    Poor sleep quality is a risk factor for a number of cognitive and physiological age-related disorders. Identifying factors underlying sleep quality are important in understanding the etiology of these age-related health disorders. We investigated the extent to which genes and the environment contribute to subjective sleep quality in middle-aged male twins using the classical twin design. We used the Pittsburgh Sleep Quality Index to measure sleep quality in 1218 middle-aged twin men from the Vietnam Era Twin Study of Aging (mean age = 55.4 years; range 51-60; 339 monozygotic twin pairs, 257 dizygotic twin pairs, 26 unpaired twins). The mean PSQI global score was 5.6 [SD = 3.6; range 0-20]. Based on univariate twin models, 34% of variability in the global PSQI score was due to additive genetic effects (heritability) and 66% was attributed to individual-specific environmental factors. Common environment did not contribute to the variability. Similarly, the heritability of poor sleep-a dichotomous measure based on the cut-off of global PSQI>5-was 31%, with no contribution of the common environment. Heritability of six of the seven PSQI component scores (subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, and daytime dysfunction) ranged from 0.15 to 0.31, whereas no genetic influences contributed to the use of sleeping medication. Additive genetic influences contribute to approximately one-third of the variability of global subjective sleep quality. Our results in middle-aged men constitute a first step towards examination of the genetic relationship between sleep and other facets of aging. © 2013 European Sleep Research Society.

  10. Register-based research on twins

    DEFF Research Database (Denmark)

    Christensen, Kaare; Ohm Kyvik, Kirsten; Holm, Niels V

    2011-01-01

    Introduction: The Danish Twin Registry (DTR) has for more than 50 years been based on surveys and clinical investigations and over the two last decades also on register linkage. Currently these two approaches are merged within Statistics Denmark. Research topics: Here we report on three major...... groups of register-based research in the DTR that used the uniqueness of twinning. First, we focus on the ''long-term prognosis'' of being a twin compared with being a singleton and show that Danish twins have health trajectories in adulthood similar to singletons, which is a result of interest for twins...... and their families as well as a test of the fetal origins hypothesis that states that fetal growth restriction has long-term health consequences. Secondly, we summarise some of the most important register-based ''classical twin studies'', e.g. heritability studies on lifespan and exceptional longevity. Finally, we...

  11. Optimal timing for term delivery of twin pregnancies: a population-based study.

    Science.gov (United States)

    Vilchez, Gustavo A; Dai, Jing; Hoyos, Luis R; Chelliah, Anushka; Bahado-Singh, Ray; Sokol, Robert J

    2015-04-01

    The objective of this study was to examine the risk of adverse neonatal outcomes after twin delivery according to gestational age. The U.S. Natality Database from 2007 to 2010 was reviewed. Inclusion criteria were twin deliveries and gestational age of 37 to 42 weeks. Exclusion criteria were congenital anomalies and missing/incomplete data. Cases were subdivided by gestational age into early term, term, and late term. Singleton pregnancies matched by delivery time and location were selected as controls. Outcome variables included were low Apgar score, assisted ventilation, neonatal intensive care unit admission, surfactant/antibiotic use, seizures, and birth injury. Logistic regression analysis was used to calculate adjusted odds ratios according to gestational age and plurality, using singleton term as reference. A total of 220,169 twin and 270,540 singleton deliveries were identified. The risk of adverse neonatal outcomes for twins was higher than for singletons. For twins, the distribution of the risks of the composite of adverse neonatal outcomes was linear, being the lowest at early term and the highest at late term, whereas the distribution for singletons was u-shaped being lowest at term compared with early and late term. Twins are at higher risk of suboptimal neonatal outcomes than singletons, but do better when delivered at early term rather than term or late term. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  12. Physical activity attenuates genetic effects on BMI: Results from a study of Chinese adult twins.

    Science.gov (United States)

    Wang, Biqi; Gao, Wenjing; Lv, Jun; Yu, Canqing; Wang, Shengfeng; Pang, Zengchang; Cong, Liming; Dong, Zhong; Wu, Fan; Wang, Hua; Wu, Xianping; Jiang, Guohong; Wang, Xiaojie; Wang, Binyou; Cao, Weihua; Li, Liming

    2016-03-01

    This study aimed to examine the gene-environment interaction of physical activity and body mass index (BMI) using the Chinese National Twin Registry (CNTR). A total of 19,308 same-sex adult twins from CNTR were included in the analysis. Twin zygosity was determined by self-reported questionnaire. Height and weight were measured using self-reported questionnaire. The vigorous physical activity was defined as greater or equal to five times a week of at least 30 min moderate- or high-intensity physical activity. A twin structural equation model was used to analyze the gene-environment interaction of vigorous exercise with BMI among 13,506 monozygotic twins and 5,802 dizygotic twins. A structural equation model adjusting for age and sex found vigorous exercise significantly moderated the additive genetic effects (P genetic contributions to BMI were significantly lower for people who adopted a physically active lifestyle [h(2) = 40%, 95% confidence interval (CI): 35%-46%] than those who were relative sedentary (h(2) = 59%, 95% CI: 52%-66%). The observed gene-physical activity interaction was more pronounced in men than women. Our results suggested that adopting a physically active lifestyle may help to reduce the genetic influence on BMI among the Chinese population. © 2016 The Obesity Society.

  13. Research from the NASA Twins Study and Omics in Support of Mars Missions

    Science.gov (United States)

    Kundrot, C.; Shelhamer, M.; Scott, G.

    2015-01-01

    The NASA Twins Study, NASA's first foray into integrated omic studies in humans, illustrates how an integrated omics approach can be brought to bear on the challenges to human health and performance on a Mars mission. The NASA Twins Study involves US Astronaut Scott Kelly and his identical twin brother, Mark Kelly, a retired US Astronaut. No other opportunity to study a twin pair for a prolonged period with one subject in space and one on the ground is available for the foreseeable future. A team of 10 principal investigators are conducting the Twins Study, examining a very broad range of biological functions including the genome, epigenome, transcriptome, proteome, metabolome, gut microbiome, immunological response to vaccinations, indicators of atherosclerosis, physiological fluid shifts, and cognition. A novel aspect of the study is the integrated study of molecular, physiological, cognitive, and microbiological properties. Major sample and data collection from both subjects for this study began approximately six months before Scott Kelly's one year mission on the ISS, continue while Scott Kelly is in flight and will conclude approximately six months after his return to Earth. Mark Kelly will remain on Earth during this study, in a lifestyle unconstrained by this study, thereby providing a measure of normal variation in the properties being studied. An overview of initial results and the future plans will be described as well as the technological and ethical issues raised for spaceflight studies involving omics.

  14. Heritability of optic disc diameters: a twin study

    DEFF Research Database (Denmark)

    Drobnjak, Dragana; Taarnhøj, Nina Charlotte; Mitchell, Paul

    2011-01-01

    Purpose: To assess the relative influence of genetic and environmental factors on optic disc size and cup/disc ratio in healthy eyes. Methods: A sample of 55 monozygotic and 50 dizygotic healthy twin pairs aged 20-46, all having the same sex within pairs (47 pairs were male) had optic discs......: 20-45%). For cup/disc ratio, additive genetic and unshared environmental factors explained 66% (95% CI: 48-77%) and 34% (95% CI: 23-52%) of the variations, respectively. Discussion: In this healthy twin sample, we found that three quarters of the variations in vertical optic disc and optic cup...... measured from colour fundus photographs according to the Wisconsin Protocol. Structural equation modelling was used to estimate the relative contribution of genetic and environmental factors to the phenotype. Results: Disc dimensions did not vary significantly by age or sex. After adjusting for age and sex...

  15. Predicting individual differences in reading comprehension: a twin study

    OpenAIRE

    Harlaar, Nicole; Cutting, Laurie; Deater-Deckard, Kirby; DeThorne, Laura S.; Justice, Laura M.; Schatschneider, Chris; Thompson, Lee A.; Petrill, Stephen A.

    2010-01-01

    We examined the Simple View of reading from a behavioral genetic perspective. Two aspects of word decoding (phonological decoding and word recognition), two aspects of oral language skill (listening comprehension and vocabulary), and reading comprehension were assessed in a twin sample at age 9. Using latent factor models, we found that overlap among phonological decoding, word recognition, listening comprehension, vocabulary, and reading comprehension was primarily due to genetic influences....

  16. Genetic covariance between central corneal thickness and anterior chamber volume: a Hungarian twin study.

    Science.gov (United States)

    Toth, Georgina Zsofia; Racz, Adel; Tarnoki, Adam Domonkos; Tarnoki, David Laszlo; Szekelyhidi, Zita; Littvay, Levente; Suveges, Ildiko; Nemeth, Janos; Nagy, Zoltan Zsolt

    2014-10-01

    Few, and inconsistent, studies have showed high heritability of some parameters of the anterior segment of the eye; however, no heritability of anterior chamber volume (ACV) has been reported, and no study has been performed to investigate the correlation between the ACV and central corneal thickness (CCT). Anterior segment measurements (Pentacam, Oculus) were obtained from 220 eyes of 110 adult Hungarian twins (41 monozygotic and 14 same-sex dizygotic pairs; 80% women; age 48.6 ± 15.5 years) obtained from the Hungarian Twin Registry. Age- and sex-adjusted heritability of ACV was 85% (bootstrapped 95% confidence interval; CI: 69% to 93%), and 88% for CCT (CI: 79% to 95%). Common environmental effects had no influence, and unshared environmental factors were responsible for 12% and 15% of the variance, respectively. The correlation between ACV and CCT was negative and significant (r ph = -0.35, p covariance significantly (0.934; CI: 0.418, 1.061) based on the bivariate Cholesky decomposition model. These findings support the high heritability of ACV and central corneal thickness, and a strong genetic covariance between them, which underscores the importance of identification of the specific genetic factors and the family risk-based screening of disorders related to these variables, such as open-angle and also angle closure glaucoma and corneal endothelial alterations.

  17. Relativistic twins or sextuplets?

    CERN Document Server

    Sheldon, E S

    2003-01-01

    A recent study of the relativistic twin 'paradox' by Soni in this journal affirmed that 'A simple solution of the twin paradox also shows anomalous behaviour of rigidly connected distant clocks' but entailed a pedagogic hurdle which the present treatment aims to surmount. Two scenarios are presented: the first 'flight-plan' is akin to that depicted by Soni, with constant-velocity segments, while the second portrays an alternative mission undertaken with sustained acceleration and deceleration, illustrated quantitatively for a two-way spacecraft flight from Earth to Polaris (465.9 light years distant) and back.

  18. Situs Inversus Totalis in Twins: A Brief Review and a Life History / Twin Research: Twin Studies of Trisomy 21; Monozygotic Twin Concordance for Bilateral Coronoid Hyperplasia; Prenatal Hormonal Effects in Mixed-Sex Non-Human Primate Litters; Insurance Mandates and Twinning After In Vitro Fertilization / News Reports: First Report of Identical Twin Puppies; Twins Sisters Turn 100; Remembering an Identical Twin Production Designer; New York City Marathon Quadruplets.

    Science.gov (United States)

    Segal, Nancy L

    2017-02-01

    The presence of situs inversus totalis (full reversal of internal organs) in twins is briefly reviewed. Information gathered from 35-year-old monozygotic (MZ) female twin pair discordant for this condition is presented. This is followed by summaries of research on the frequency of trisomy 21 (Down syndrome) in twins, the first case of MZ twin concordance for bilateral coronoid hyperplasia, prenatal hormonal effects in mixed-sex non-human primate litters, and links between insurance mandates and twinning following in vitro fertilization. The final section of this article describes twin-related events reported in the news, namely, the first recorded birth of identical twin puppies; the 100th birthday celebration of a pair of fraternal female twins, the passing of an award-winning identical twin production designer, and the first running of the New York City Marathon by a set of quadruplets.

  19. Twin Baryogenesis

    CERN Document Server

    Farina, Marco; Shin, Chang Sub

    2016-01-01

    In the context of Twin Higgs models, we study a simple mechanism that simultaneously generates asymmetries in the dark and visible sector through the out-of-equilibrium decay of a TeV scale particle charged under a combination of baryon and twin baryon number. We predict the dark matter to be a 5 GeV twin baryon, which is easy to achieve because of the similarity between the two confinement scales. Dark matter is metastable and can decay to three quarks, yielding indirect detection signatures. The mechanism requires the introduction of a new colored particle, typically within the reach of the LHC, of which we study the rich collider phenomenology, including prompt and displaced dijets, multi-jets, monojets and monotops.

  20. Anorexia and bulimia nervosa in same-sex and opposite-sex twins: lack of association with twin type in a nationwide study of Finnish twins.

    Science.gov (United States)

    Raevuori, Anu; Kaprio, Jaakko; Hoek, Hans W; Sihvola, Elina; Rissanen, Aila; Keski-Rahkonen, Anna

    2008-12-01

    The authors tested the hypothesis that either prenatal feminization or masculinization hormone influences in utero or later socialization affects the risk for anorexia and bulimia nervosa and disordered eating in members of opposite-sex twin pairs. Finnish twins (N=2,426 women, N=1,962 men with known zygosity) from birth cohorts born 1974-1979 were assessed at age 22 to 28 years with a questionnaire for eating disorder symptoms. Based on the questionnaire screen, women (N=292), men (N=53), and their cotwins were interviewed to assess diagnoses of anorexia nervosa and bulimia nervosa (per DSM-IV and broad criteria). In women from opposite-sex twin pairs, the prevalence of DSM-IV or broad anorexia nervosa was not significantly different than that of women from monozygotic pairs or same-sex dizygotic pairs. Of the five male anorexia nervosa probands, only one was from an opposite-sex twin pair. Bulimia nervosa in men was too rare to be assessed by zygosity; the prevalence of DSM-IV or broad bulimia nervosa did not differ in women from opposite- versus same-sex twin pairs. In both sexes, the overall profile of indicators on eating disorders was rather similar between individuals from opposite- and same-sex pairs. The authors found little evidence that the risk for anorexia nervosa, bulimia nervosa, or disordered eating was associated with zygosity or sex composition of twin pairs, thus making it unlikely that in utero femininization or masculinization or socialization effects of growing up with an opposite-sex twin have a major influence on the later development of eating disorders.

  1. Comparison of academic performance of twins and singletons in adolescence

    DEFF Research Database (Denmark)

    Christensen, Kaare; Petersen, Inge; Skytthe, Axel

    2006-01-01

    OBJECTIVES: To determine whether twins in recent cohorts show similar academic performance in adolescence to singletons and to test the effect of birth weight on academic performance in twins and singletons. DESIGN: Follow-up study. SETTING: Denmark. PARTICIPANTS: All twins (n=3411) and a 5% random...... increase in birth weight. CONCLUSIONS: Although older cohorts of twins have been found to have lower mean IQ scores than singletons, twins in recent Danish cohorts show similar academic performance in adolescence to that of singletons. Birth weight has a minimal effect on academic performance in recent...

  2. Al-Ti Particulate Composite: Processing and Studies on Particle Twinning, Microstructure, and Thermal Stability

    Science.gov (United States)

    Yadav, Devinder; Bauri, Ranjit; Kauffmann, Alexander; Freudenberger, Jens

    2016-08-01

    The present investigation shows that alternate to the ceramic particles, hard metallic particles can be used as reinforcement in an aluminum matrix to achieve a good strength-ductility combination in a composite. Titanium particles were incorporated into aluminum by friction stir processing (FSP) to process an Al-Ti particulate composite. FSP led to uniform distribution of the particles in the stir zone without any particle-matrix reaction, thereby retaining the particles in their elemental state. Fracture and twinning of the Ti particles with different frequency of occurrence on the advancing and retreating sides of the stir zone was observed. Twinning of the particles was studied by focused ion beam-assisted transmission electron microscopy. The processed Al-Ti composite exhibited a significant improvement in strength and also retained appreciable amount of ductility. The thermal stability of the fine-grained structure against abnormal grain growth (AGG) was improved by the Ti particles. The AGG in the Al-Ti composite occurred at 713 K (440 °C) compared to 673 K (400 °C) in the unreinforced aluminum processed under the same conditions. On the other hand, the particle-matrix reaction occurred only at 823 K (550 °C), and hence the Ti particles were thermally more stable compared to the matrix grain structure.

  3. Experimental study on the wave loads of twin-plate breakwater under oblique waves

    Institute of Scientific and Technical Information of China (English)

    GU Qian; HUANG Guoxing; ZHANG Ningchuan; LI Longxiang; SHAO Zhongan

    2016-01-01

    In this study, systematic physical model tests were performed to investigate the wave forces on the twin-plate breakwater under irregular waves. Based on the experimental results, the effects of the relative plate widthB/L, wave heightHs/D and incident angleθ0 on the wave forces were analyzed and discussed. The results showed that: (1) The envelopes of the total wave pressure were generally symmetrical along the direction of plate width under the incident angles (θ0) being 0°, 15°, 30°, 45° and 60°. In particular, the envelopes of wave pressure atθ0=30° were larger than all other cases. (2) The synchronous pressure distribution of the breakwater under oblique wave action was more complicated comparing to the normal incident waves. (3) Based on data analysis, an empirical formula was obtained to estimate the total vertical force of the twin-plate breakwater. This empirical formula can be a good reference for the design basis of engineering applications under specified wave conditions.

  4. Impact of adolescent marijuana use on intelligence: Results from two longitudinal twin studies.

    Science.gov (United States)

    Jackson, Nicholas J; Isen, Joshua D; Khoddam, Rubin; Irons, Daniel; Tuvblad, Catherine; Iacono, William G; McGue, Matt; Raine, Adrian; Baker, Laura A

    2016-02-02

    Marijuana is one of the most commonly used drugs in the United States, and use during adolescence--when the brain is still developing--has been proposed as a cause of poorer neurocognitive outcome. Nonetheless, research on this topic is scarce and often shows conflicting results, with some studies showing detrimental effects of marijuana use on cognitive functioning and others showing no significant long-term effects. The purpose of the present study was to examine the associations of marijuana use with changes in intellectual performance in two longitudinal studies of adolescent twins (n = 789 and n = 2,277). We used a quasiexperimental approach to adjust for participants' family background characteristics and genetic propensities, helping us to assess the causal nature of any potential associations. Standardized measures of intelligence were administered at ages 9-12 y, before marijuana involvement, and again at ages 17-20 y. Marijuana use was self-reported at the time of each cognitive assessment as well as during the intervening period. Marijuana users had lower test scores relative to nonusers and showed a significant decline in crystallized intelligence between preadolescence and late adolescence. However, there was no evidence of a dose-response relationship between frequency of use and intelligence quotient (IQ) change. Furthermore, marijuana-using twins failed to show significantly greater IQ decline relative to their abstinent siblings. Evidence from these two samples suggests that observed declines in measured IQ may not be a direct result of marijuana exposure but rather attributable to familial factors that underlie both marijuana initiation and low intellectual attainment.

  5. Heritability of Biomarkers of Oxidized Lipoproteins: Twin Pair Study.

    Science.gov (United States)

    Rao, Fangwen; Schork, Andrew J; Maihofer, Adam X; Nievergelt, Caroline M; Marcovina, Santica M; Miller, Elizabeth R; Witztum, Joseph L; O'Connor, Daniel T; Tsimikas, Sotirios

    2015-07-01

    To determine whether biomarkers of oxidized lipoproteins are genetically determined. Lipoprotein(a) (Lp[a]) is a heritable risk factor and carrier of oxidized phospholipids (OxPL). We measured oxidized phospholipids on apolipoprotein B-containing lipoproteins (OxPL-apoB), Lp(a), IgG, and IgM autoantibodies to malondialdehyde-modified low-density lipoprotein, copper oxidized low-density lipoprotein, and apoB-immune complexes in 386 monozygotic and dizygotic twins to estimate trait heritability (h(2)) and determine specific genetic effects among traits. A genome-wide linkage study followed by genetic association was performed. The h(2) (scale: 0-1) for Lp(a) was 0.91±0.01 and for OxPL-apoB 0.87±0.02, which were higher than physiological, inflammatory, or lipid traits. h(2) of IgM malondialdehyde-modified low-density lipoprotein, copper oxidized low-density lipoprotein, and apoB-immune complexes were 0.69±0.04, 0.67±0.05, and 0.80±0.03, respectively, and for IgG malondialdehyde-modified low-density lipoprotein, copper oxidized low-density lipoprotein, and apoB-immune complexes 0.62±0.05, 0.52±0.06, and 0.53±0.06, respectively. There was an inverse correlation between the major apo(a) isoform and OxPL-apoB (R=-0.49; Plipoprotein and copper oxidized low-density lipoprotein, and apoB-immune complexes. Sib-pair genetic linkage of the Lp(a) trait revealed that single nucleotide polymorphism rs10455872 was significantly associated with OxPL-apoB after adjusting for Lp(a). OxPL-apoB and other biomarkers of oxidized lipoproteins are highly heritable cardiovascular risk factors that suggest novel genetic origins of atherothrombosis. © 2015 American Heart Association, Inc.

  6. The Danish Twin Register

    DEFF Research Database (Denmark)

    Kyvik, K O; Christensen, Kaare; Skytthe, A;

    1996-01-01

    BACKGROUND: Population based twin registers represent a valuable tool for genetic epidemiological research, since twin studies aim at separating the effect of genes and environment for complex traits. The Danish Twin Register's history, size, ascertainment and completeness of data, as well as data...... accessibility and availability are described. RESULTS: The Danish Twin Register comprises 14,051 twin pairs born 1870-1930, representing all twins surviving to age six years, and 20,888 twin pairs born 1953-1982, representing 75% of those born 1953-1967 and 95% of those born 1968-1982. The birth cohorts 1931......-1952 og 1983-1993 are being ascertained at the moment. The register is available for research given certain conditions are fulfilled. CONCLUSION: This register will in a few years be the most comprehensive twin register in the world. It is a very valuable Danish research resource....

  7. The Danish Twin Register

    DEFF Research Database (Denmark)

    Kyvik, K O; Christensen, Kaare; Skytthe, A

    1996-01-01

    BACKGROUND: Population based twin registers represent a valuable tool for genetic epidemiological research, since twin studies aim at separating the effect of genes and environment for complex traits. The Danish Twin Register's history, size, ascertainment and completeness of data, as well as data...... accessibility and availability are described. RESULTS: The Danish Twin Register comprises 14,051 twin pairs born 1870-1930, representing all twins surviving to age six years, and 20,888 twin pairs born 1953-1982, representing 75% of those born 1953-1967 and 95% of those born 1968-1982. The birth cohorts 1931......-1952 og 1983-1993 are being ascertained at the moment. The register is available for research given certain conditions are fulfilled. CONCLUSION: This register will in a few years be the most comprehensive twin register in the world. It is a very valuable Danish research resource....

  8. Alanine aminotransferase, gamma-glutamyltransferase (GGT) and all-cause mortality: results from a population-based Danish twins study alanine aminotransferase, GGT and mortality in elderly twins

    DEFF Research Database (Denmark)

    Fraser, Abigail; Thinggaard, Mikael; Christensen, Kaare

    2009-01-01

    Abstract Background/Aims: Alanine aminotransferase (ALT) and gamma-glutamyltransferase (GGT) are widely used markers of liver disease. Several population-based cohort studies have found associations of these liver enzymes with all-cause mortality. None of these studies controlled for genetic...... variation as well as fetal and early life exposure, whether environmental or genetic. Methods: We studied the associations of ALT and GGT with all-cause mortality using data for 686 twins (73-94 years old) included in the Longitudinal Study of Aging Danish Twins. Results: An increase in 1 logged U/L of GGT...... for potential confounders and existing diabetes and cardiovascular disease. Environmental developmental origins may explain the association, but larger twin studies are required to replicate our findings....

  9. The Twins Study: NASA's First Foray into 21st Century Omics Research

    Science.gov (United States)

    Kundrot, C. E.; Shelhamer, M.; Scott, G. B. I.

    2015-01-01

    The full array of 21st century omics-based research methods should be intelligently employed to reduce the health and performance risks that astronauts will be exposed to during exploration missions beyond low Earth Orbit. In March of 2015, US Astronaut Scott Kelly will launch to the International Space Station for a one year mission while his twin brother, Mark Kelly, a retired US Astronaut, remains on the ground. This situation presents an extremely rare flight opportunity to perform an integrated omics-based demonstration pilot study involving identical twin astronauts. A group of 10 principal investigators has been competitively selected, funded, and teamed together to form the Twins Study. A very broad range of biological function are being examined including the genome, epigenome, transcriptome, proteome, metabolome, gut microbiome, immunological response to vaccinations, indicators of atherosclerosis, physiological fluid shifts, and cognition. The plans for the Twins Study and an overview of initial results will be described as well as the technological and ethical issues raised for such spaceflight studies. An anticipated outcome of the Twins Study is that it will place NASA on a trajectory of using omics-based information to develop precision countermeasures for individual astronauts.

  10. Familial resemblance in religiousness in a secular society: a twin study.

    Science.gov (United States)

    Hvidtjørn, Dorte; Petersen, Inge; Hjelmborg, Jacob; Skytthe, Axel; Christensen, Kaare; Hvidt, Niels C

    2013-04-01

    It is well known that human behavior and individual psychological traits are moderately to substantially heritable. Over the past decade, an increasing number of studies have explored the genetic and environmental influence on religiousness. These studies originate predominantly from countries generally considered more religious than the very secular northern European countries. Comparisons of the results are complicated by diverse definitions of religiousness, but several studies indicate that the influence of the family environment is most predominant in early life, whereas genetic influences increase with age. We performed a population-based twin study of religiousness in a secular society using data from a Web-based survey sent to 6,707 Danish twins born 1970-1989, who were identified in the Danish Twin Registry. We applied Fishman's three conceptual dimensions of religiousness: cognition, practice, and importance. In all polygenic models and biometric analyses, we controlled for gender and age. The study sample comprised 2,237 same sex twins, a response rate of 45%. We found high correlations within both monozygotic and dizygotic twin pairs in most items of religiousness, indicating a large influence from shared environmental factors. Personal religiousness such as praying to God, believing in God, and finding strength and comfort in religion were more influenced by genetic factors than were social forms of religiousness such as church attendance. We found a small tendency for increasing genetic influence with increasing age for some religious items, but not for all.

  11. STD studies show spermicides protect against Chlamydia.

    Science.gov (United States)

    1986-01-01

    Evidence which suggests that spermicides provide protection against sexually transmitted diseases (STDs) is accumulating. Laboratory tests have repeatedly demonstrated that spermicides are capable of killing the bacteria responsible for several types of STDs, as well as the virus responsible for acquired immunodeficiency syndrome. Recently, studies conducted in Bangkok, Thailand and in New York City suggest that these protective effects are not confined to the laboratory but that they also occur among women who use spermicides in the real world. In the New York City study, Family Health International (FHI), using data collected by Planned Parenthood of New York City, compared STD prevalence rates for women using different contraceptive methods. Women who used spermicides, in comparison with women who used oral contraceptives (OCs), were 20% less likely to have contracted a STD, 30% less likely to have gonorrhea, and 60% less likely to have chlamydia. In the Thai study, conducted jointly by the FHI and the Ministry of Health, women at high risk of STDs were allocated either to a group which was instructed to use a vaginal sponge impregnated with nonoxynol-9 during intercourse or to a control group which received no vaginal contraceptives. All the women were either sterilized or using OCs, IUDs, or injectable contraceptives. Preliminary results suggest that the women who used the vaginal sponges were significantly less likely to contract chlamydia than the control group. In regard to the incidence of gonorrhea, no differences between the 2 groups was detected. In the Thai study methodological problems forced the researchers to redesign the study. In accordance with the new design, the women in the 2 groups will be crossed over after 6 weeks. This will allow the researchers to examine the effect of using or not using a vaginal spermicide on specific individuals. The findings of the 2 studies have special relevance given the increasing prevalence of STDs in many

  12. Discordant tooth agenesis and peg-shaped in a pair of monozygotic twins: Clinical and molecular study

    OpenAIRE

    Lívia Azeredo Alves Antunes; Erika Calvano Küchler; Marcelo de Castro Costa; Leonardo Santos Antunes; José Mauro Granjeiro

    2013-01-01

    The present report aimed to study an uncommon case of a pair of twins that presented a discordant dental phenotype. Family investigation, clinical, radiographic examination and molecular analysis were performed in both girls. Molecular analysis confirmed the monozygosity by deoxyribonucleic acid chip technology. One twin presented tooth agenesis in left upper lateral incisor and peg-shaped on the contra lateral side while the other twin had no dental alterations. The dental casts study employ...

  13. The Southern Illinois Twins and Siblings Study (SITSS): description and update.

    Science.gov (United States)

    Dilalla, Lisabeth Fisher; Gheyara, Sufna; Bersted, Kyle

    2013-02-01

    This update on the Southern Illinois Twins and Siblings Study (SITSS) documents some of the follow-up studies that have been conducted and results that have been obtained from this sample. At the current time, 283 twin pairs, 8 triplet families, 98 non-twin sibling pairs, and 287 singletons have been enrolled in SITSS. Twins and triplets are tested as young as 1 year of age and then every year on their birthday through age 5 years. A variety of follow-up studies have been conducted for SITSS children through age 20. Results thus far have demonstrated significant genetic influences on social behaviors such as aggression, victimization, and attention toward facial expressions. Interesting interactions have been documented between the dopamine receptor D4 gene (DRD4) and the social environment (parental sensitivity or peer aggression) as they predict children's aggressive behaviors. In addition, increased difficulty with social interactions has been noted for twins versus singletons. Thus, this multi-trait, multi-method behavior genetic data set contributes to our understanding of the etiology of social behaviors in preschoolers and to predictors of similar behaviors through adolescence.

  14. Twin-Based DNA Methylation Analysis Takes the Center Stage of Studies of Human Complex Diseases

    Institute of Scientific and Technical Information of China (English)

    Dongfeng Zhang; Shuxia Li; Qihua Tan; Zengchang Pang

    2012-01-01

    The etiology of complex diseases is characterized by the interaction between the genome and environmental conditions and the interface of epigenetics may be a central mechanism.Current technologies already allow us high-throughput profiling of epigenetic patterns at genome level.However,our understanding of the epigenetic processes remains limited.Twins are special samples in genetic studies due to their genetic similarity and rearing-environment sharing.In the past decades,twins have made a great contribution in dissecting the genetic and environmental contributions to human diseases and complex traits.In the era of functional genomics,the valuable samples of twins are helping to bridge the gap between gene activity and environmental conditions through epigenetic mechanisms unlimited to DNA sequence variations.We review the recent progresses in using twins to study disease-related molecular epigenetic phenotypes and link them with environmental exposures especially early life events.Various study designs and application issues will be highlighted and discussed with aim at making uses of twins in assessing the environmental impact on epigenetic changes during the development of complex diseases.

  15. Neonatal morbidity in growth-discordant monochorionic twins: comparison between the larger and the smaller twin.

    Science.gov (United States)

    Lopriore, Enrico; Sluimers, Carolien; Pasman, Suzanne A; Middeldorp, Johanna M; Oepkes, Dick; Walther, Frans J

    2012-08-01

    Fetal growth restriction in singletons has been shown to enhance fetal lung maturation and reduce the risk of respiratory distress syndrome due to increased endogenous steroid production. However, data on lung maturation in growth-discordant monochorionic (thus, identical) twins are lacking. Our objective was to compare the risk of severe neonatal morbidity between the larger and the smaller twin in monochorionic twins with birth weight discordance (BWD). We included in the study all consecutive monochorionic diamniotic pregnancies with severe BWD (≥25%) and two live-born twins delivered at our center (n=47 twin pairs). We compared the incidence of neonatal morbidity, particularly respiratory distress syndrome (RDS), and cerebral lesions between the larger and the smaller co-twin. The incidence of severe neonatal morbidity in the larger and smaller twin was 38% (18/47) and 19% (9/47), respectively (odds ratio (OR) 2.66, 95% confidence interval (CI) 0.94-7.44) and was due primarily to the higher incidence of RDS, 32% (15/47) and 6% (3/47), respectively (OR 6.88, 95% CI 1.66-32.83). In conclusion, this study shows that the larger twin in monochorionic twin pairs with BWD is at increased risk of severe neonatal morbidity, particularly RDS, compared to the smaller twin.

  16. Heritability and environmental effects for self-reported periods with stuttering: A twin study from Denmark

    DEFF Research Database (Denmark)

    Fagnani, Corrado; Fibiger, Steen; Skytthe, Axel;

    2011-01-01

    Genetic influence for stuttering was studied based on adult self-reporting. Using nation-wide questionnaire answers from 33,317 Danish twins, a univariate biometric analysis based on the liability threshold model was performed in order to estimate the heritability of stuttering. The self......-reported incidences for stuttering were from less than 4% for females to near 9% for males. Both probandwise concordance rate and tetrachoric correlation were substantially higher for monozygotic compared to dizygotic pairs, indicating substantial genetic influence on individual liability. Univariate biometric...... analyses showed that additive genetic and unique environmental factors best explained the observed concordance patterns. Heritability estimates for males/females were 0.84/0.81. Moderate unique environmental effects were also found. Genetic influence for stuttering was studied based on adult self...

  17. Heritability and environmental effects for self-reported periods with stuttering: A twin study from Denmark

    DEFF Research Database (Denmark)

    Fagnani, Corrado; Fibiger, Steen; Skytthe, Axel

    2011-01-01

    Genetic influence for stuttering was studied based on adult self-reporting. Using nation-wide questionnaire answers from 33,317 Danish twins, a univariate biometric analysis based on the liability threshold model was performed in order to estimate the heritability of stuttering. The self......-reported incidences for stuttering were from less than 4% for females to near 9% for males. Both probandwise concordance rate and tetrachoric correlation were substantially higher for monozygotic compared to dizygotic pairs, indicating substantial genetic influence on individual liability. Univariate biometric...... analyses showed that additive genetic and unique environmental factors best explained the observed concordance patterns. Heritability estimates for males/females were 0.84/0.81. Moderate unique environmental effects were also found. Genetic influence for stuttering was studied based on adult self...

  18. Genetic and environmental influences on emotion-modulated startle reflex: a twin study.

    Science.gov (United States)

    Anokhin, Andrey P; Golosheykin, Simon; Heath, Andrew C

    2007-01-01

    Emotion-modulated startle reflex is an important indicator of traitlike differences in affective processing implicated in the biological basis of personality and psychopathology. This study examined heritability of startle modulation by affective pictures in 66 pairs of monozygotic and 57 pairs of dizygotic female twins. Consistent with previous studies, startle magnitude was significantly influenced by emotional valence of the picture (positive < neutral < negative). Absolute response magnitude showed high heritability in all three valence conditions (59-61%); however, there were no significant genetic influences on the amount of startle modulation. Thus, our data do not support the hypothesis that emotion-modulated startle can serve as an indicator of genetically transmitted individual differences in affective processing.

  19. A twin study of posttraumatic stress disorder symptoms and chronic widespread pain.

    Science.gov (United States)

    Arguelles, Lester M; Afari, Niloofar; Buchwald, Dedra S; Clauw, Daniel J; Furner, Sylvia; Goldberg, Jack

    2006-09-01

    Previous studies of the association between posttraumatic stress disorder (PTSD) and chronic widespread pain (CWP) or fibromyalgia have not examined the role of familial or genetic factors. The goals of this study were to determine if symptoms of PTSD are related to CWP in a genetically informative community-based sample of twin pairs, and if so, to ascertain if the association is due to familial or genetic factors. Data were obtained from the University of Washington Twin Registry, which contains 1042 monozygotic and 828 dizygotic twin pairs. To assess the symptoms of PTSD, we used questions from the Impact of Events Scale (IES). IES scores were partitioned into terciles. CWP was defined as pain located in 3 body regions lasting at least 1 week during the past 3 months. Random-effects regression models, adjusted for demographic features and depression, examined the relationship between IES and CWP. IES scores were strongly associated with CWP (P<0.0001). Compared to those in the lowest IES tercile, twins in the highest tercile were 3.5 times more likely to report CWP. Although IES scores were associated with CWP more strongly among dizygotic than among monozygotic twins, this difference was not significant. Our findings suggest that PTSD symptoms, as measured by IES, are strongly linked to CWP, but this association is not explained by a common familial or genetic vulnerability to both conditions. Future research is needed to understand the temporal association of PTSD and CWP, as well as the physiological underpinnings of this relationship.

  20. Relationships between state and trait anxiety inventory and alcohol use disorder identification test scores among Korean twins and families: the healthy twin study.

    Science.gov (United States)

    Sung, Joohon; Lee, Kayoung; Song, Yun-Mi; Kim, Ji-Hae

    2011-02-01

    We explored heritabilities of the State and Trait Anxiety Inventory (STAI) and the Alcohol Use Disorders Identification Test (AUDIT), and associations including genetic and environmental correlations between the phenotypes among Korean twins and their families. We analyzed the data of 1,748 participants (835 men, 913 women, 656 individuals of monozygotic twins, 173 individuals of same-sexed dizygotic twins, 919 non-twin family members, age 30-79 years) from the Healthy Twin study. Heritabilities and bivariate analyses were assessed using the SOLAR package software. In the methods of generalized estimation equations, women in the 4th quartile of state and trait scores were 17% and 15%, respectively more likely to be hazardous alcohol users compared to women in the lower three quartiles (P genetic correlation between the trait score and the AUDIT score, and a significant non-genetic correlation between the state score and the AUDIT score in women, while there were no significant genetic or non-genetic correlations between these phenotypes in men. The STAI and AUDIT scores are heritable in Koreans and the relationships between these phenotypes may be inconsistent by sex.

  1. The Heritability of Prostate Cancer in the Nordic Twin Study of Cancer

    DEFF Research Database (Denmark)

    Hjelmborg, Jacob B; Scheike, Thomas; Holst, Klaus

    2014-01-01

    Background: Prostate cancer is thought to be the most heritable cancer, although little is known about how this genetic contribution varies across age. Methods: To address this question, we undertook the world's largest prospective study in the Nordic Twin Study of Cancer cohort, including 18......,680 monozygotic and 30,054 dizygotic same sex male twin pairs. We incorporated time-to-event analyses to estimate the risk concordance and heritability while accounting for censoring and competing risks of death, essential sources of biases that have not been accounted for in previous twin studies modeling cancer...... diagnoses was significantly shorter for MZ than DZ pairs (median 3.8 versus 6.5 years, respectively). Genetic differences contributed substantially to variation in both the risk and the liability (heritability=58% (95% CI 52%-63%) of developing prostate cancer. The relative contribution of genetic factors...

  2. Genetic and Environmental Influences on Pulmonary Function and Muscle Strength: The Chinese Twin Study of Aging

    DEFF Research Database (Denmark)

    Tian, Xiaocao; Xu, Chunsheng; Wu, Yili

    2017-01-01

    Genetic and environmental influences on predictors of decline in daily functioning, including forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), handgrip, and five-times-sit-to-stand test (FTSST), have not been addressed in the aging Chinese population. We performed classical twin...... modeling on FEV1, FVC, handgrip, and FTSST in 379 twin pairs (240 MZ and 139 DZ) with median age of 50 years (40-80 years). Data were analyzed by fitting univariate and bivariate twin models to estimate the genetic and environmental influences on these measures of physical function. Heritability...... environment (40-50%). Bivariate analysis showed highly positive genetic correlations between FEV1 and FVC (r G = 1.00), and moderately negative genetic correlations between FTSST and FEV1 (r G = -0.33) and FVC (r G = -0.42). FEV1 and FVC, as well as FEV1 and handgrip, displayed high common environmental...

  3. Conjoined Twins

    Science.gov (United States)

    ... sites of conjoined twins. Abdomen. Omphalopagus (om-fuh-LOP-uh-gus) twins are joined near the bellybutton. ... brain tissue. Head and chest. Cephalopagus (sef-uh-LOP-uh-gus) twins are joined at the face ...

  4. Passive-aggressive (negativistic) personality disorder: a population-based twin study.

    Science.gov (United States)

    Czajkowski, Nikolai; Kendler, Kenneth S; Jacobson, Kristen C; Tambs, Kristian; Røysamb, Espen; Reichborn-Kjennerud, Ted

    2008-02-01

    The objective of this study was to investigate the familial aggregation of passive aggressive personality disorder (PAPD), and explore issues regarding PAPD raised by the DSM-IV Personality Disorder Work Group. Two thousand seven hundred and ninety-four Norwegian twins from the population-based Norwegian Institute of Public Health Twin Panel were interviewed with the Structured Interview for DSM-IV Personality (SIDP-IV). Because of the rarity of the twins meeting full diagnostic criteria for PAPD a dimensional representation of the disorder was used for the analyses. Overlap with other axis II disorders was assessed by polychoric correlations, while familial aggregation was explored by structural equation twin models. Overlap was highest with paranoid (r = 0.52) and borderline personality disorder (r = 0.53), and lowest with schizoid (r = 0.26). Significant familial aggregation was found for PAPD. The twin correlations and parameter estimates in the full model indicated genetic and shared environmental effects for females, and only shared environmental effects for males, but the prevalence of endorsed PAPD criteria in this community sample was too low to permit us to conclude with confidence regarding the relative influence of genetic and shared environmental factors on the familial aggregation of PAPD.

  5. Can prematurity risk in twin pregnancies after in vitro fertilization be predicted? A retrospective study

    Directory of Open Access Journals (Sweden)

    Barad David

    2009-01-01

    Full Text Available Abstract Background Assisted reproduction (ART contributes to world-wide increases of twin pregnancies, in turn raising prematurity risks. Whether characteristics of ART cycles, resulting in twin gestations, can predict prematurity risks was the subject of this study. Methods One-hundred-and-six women, ages 20 to 39 years, with consecutive dichorionic-diamniotic (DC/DA twin gestations were retrospectively investigated. All pregnancies investigated followed fresh ART cycles, with use of autologous gamets, and were delivered at a university-based high-risk, maternal-fetal medicine unit. Only premature deliveries (i.e., <37.0 weeks gestational age, with viable neonate(s of ≥ 500 grams, were considered for analysis. Results After 1.8 +/- 1.2 ART cycles, 11.0 +/- 5.4 oocytes were retrieved and 2.4 +/- 0.9 embryos transferred in 106 women aged 31.6 +/- 4.2 years. Indications for ART treatment were male factor in 51.9%, female infertility in 27.4% and combined infertility in 20.8%. Though maternal age significantly influenced prematurity risk (p < 0.05, paternal age, maternal body mass index, indications for fertility treatment, number of previous ART attempts, oocytes retrieved or embryos transferred, as well as stimulation protocols and previous ART pregnancies, were not associated with gestational duration in twin pregnancies. Summary Except for female age, baseline and ART cycle characteristics do not allow for prediction of prematurity risk in dichorionic twin gestations after assisted reproduction.

  6. A Swedish Population-Based Multivariate Twin Study of Externalizing Disorders.

    Science.gov (United States)

    Kendler, Kenneth S; Lönn, Sara Larsson; Maes, Hermine H; Lichtenstein, Paul; Sundquist, Jan; Sundquist, Kristina

    2016-03-01

    In epidemiological and twin populations, prior interview studies have identified an externalizing spectrum of disorders. Could this be detected utilizing objective registry data? In 20,603 twin pairs from the Swedish Twin Registry, we obtained information from national medical, criminal and pharmacy records on drug abuse (DA), criminal behavior (CB) and alcohol use disorders (AUD). Multivariate twin modeling was performed with the OpenMx package. A common pathway model with quantitative but not qualitative sex effects fit best with twin resemblance for the latent liability to externalizing syndromes due to both genetic and shared environmental factors. Heritability of the liability was higher in females (76 vs. 62%) while shared environmental influences were considerably stronger in males (23 vs. 3%). In both sexes, this latent liability was most strongly indexed by DA and least by CB. All three syndromes had specific genetic influences (especially CB and AUD in males, and CB in females) and specific shared environmental effects (especially DA and CB in males, and AUD in females). For DA, CB and AUD in men, and DA and AUD in women, at least 75% of the genetic risk arose through the common factor. The best fit model assumed that genetic and environmental influences on these externalizing syndromes in males and females were the same. We identified, in registry data, a highly heritable externalizing spectrum. DA, CB and AUD share substantial genetic and modest to moderate shared environmental influences. The nature of the externalizing spectrum differed meaningfully between the sexes.

  7. A biomechanical study on fixation stability with twin hook or lag screw in artificial cancellous bone.

    Science.gov (United States)

    Olsson, O; Tanner, K E; Ceder, L; Ryd, L

    2002-01-01

    The twin hook has been developed as an alternative to the conventional lag screw to be combined with a barrelled side-plate in the treatment of trochanteric hip fractures. With two oppositely directed apical hooks introduced into the subchondral bone of the femoral head, the twin hook provides different stabilising properties to the lag screw. The femoral head purchase of the twin hook and the lag screw were compared in a biomechanical study using artificial cancellous bone, and responses to axial and torsional loading was determined. A distinct yield point in load and torque was noted for the lag screw, representing failure of the laminas supporting the threads. For the twin hook, gradual increase of load and torque occurred during impaction of the bone supporting the hooks. The peak loads and torques were higher for the lag screw, but were similar for both devices after 8 mm deformation. The stiffness was higher for the lag screw, but in counter-clockwise rotation the stiffness for the lag screw was negligible. The twin hook appeared to provide fixation stability comparable to that offered by the lag screw, but with conceivable advantages in terms of a deformation response involving bone impaction and gradually increasing stability.

  8. Social activity and healthy aging: a study of aging Danish twins.

    Science.gov (United States)

    McGue, Matt; Christensen, Kaare

    2007-04-01

    Although social and intellectual engagement have been consistently associated with late-life functioning, rather than true causation, these associations may reflect the experiential choices of high functioning individuals (i.e., selection effects). We investigated the association of social activity with late-life physical functioning, cognitive functioning, and depression symptomatology using data from 1112 pairs of like-sex twins who participated in the Longitudinal Study of Aging Danish Twins. Consistent with previous research, we found that social activity was significantly correlated with overall level of physical functioning, cognitive functioning, and depression symptomatology. We also found that social activity was significantly and moderately heritable (estimate of .36), raising the possibility that its association with late-life functioning might reflect selection processes. Further, social activity did not predict change in functioning and in monozygotic twin pairs discordant on level of social activity, the more socially active twin was not less susceptible to age decreases in physical and cognitive functioning and increases in depression symptomatology than the less socially active twin. These results are interpreted in the context of the additional finding that nonshared environmental factors, although apparently not social activity, are the predominant determinant of changes in late-life functioning.

  9. Losing one twin in the NICU - A case study of parental experience

    DEFF Research Database (Denmark)

    Aagaard, Hanne; Storm, Ida; Klitgaard, Jeannett

    2016-01-01

    and revealed tree overall themes. These themes indicate that besides struggling with grief related to the loss of one infant, the parents were challenged by the medical discourse, the lack of staff continuity and space to develop parenthood. This case study emphasizes how the loss of a premature twin......The aim of this case study was to generate a deeper understanding of parents’ experiences of losing one twin in the NICU. In an in-depth interview the parents told their story of giving birth to twins born extremely preterm and shortly after losing one of them. A thematic analysis was conducted...... reinforced the parents’ need of an understandable dialogue with a team of nurses. Furthermore the nurses have to offer a close partnership and create the necessary space for parents to develop parenthood while simultaneously dealing with the unexpected and traumatising circumstances related to the loss...

  10. Heritability of pain catastrophizing and associations with experimental pain outcomes: a twin study.

    Science.gov (United States)

    Trost, Zina; Strachan, Eric; Sullivan, Michael; Vervoort, Tine; Avery, Ally R; Afari, Niloofar

    2015-03-01

    This study used a twin paradigm to examine genetic and environmental contributions to pain catastrophizing and the observed association between pain catastrophizing and cold-pressor task (CPT) outcomes. Male and female monozygotic (n = 206) and dizygotic twins (n = 194) from the University of Washington Twin Registry completed a measure of pain catastrophizing and performed a CPT challenge. As expected, pain catastrophizing emerged as a significant predictor of several CPT outcomes, including cold-pressor Immersion Tolerance, Pain Tolerance, and Delayed Pain Rating. The heritability estimate for pain catastrophizing was found to be 37% with the remaining 63% of variance attributable to unique environmental influence. Additionally, the observed associations between pain catastrophizing and CPT outcomes were not found attributable to shared genetics or environmental exposure, which suggests a direct relationship between catastrophizing and experimental pain outcomes. This study is the first to examine the heritability of pain catastrophizing and potential processes by which pain catastrophizing is related to experimental pain response.

  11. Temperament and character in the Child and Adolescent Twin Study in Sweden (CATSS: comparison to the general population, and genetic structure analysis.

    Directory of Open Access Journals (Sweden)

    Danilo Garcia

    Full Text Available BACKGROUND: The Child and Adolescent Twin Study in Sweden (CATSS is an on-going, large population-based longitudinal twin study. We aimed (1 to investigate the reliability of two different versions (125-items and 238-items of Cloninger's Temperament and Character Inventory (TCI used in the CATSS and the validity of extracting the short version from the long version, (2 to compare these personality dimensions between twins and adolescents from the general population, and (3 to investigate the genetic structure of Cloninger's model. METHOD: Reliability and correlation analyses were conducted for both TCI versions, 2,714 CATSS-twins were compared to 631 adolescents from the general population, and the genetic structure was investigated through univariate genetic analyses, using a model-fitting approach with structural equation-modeling techniques based on same-sex twin pairs from the CATSS (423 monozygotic and 408 dizygotic pairs. RESULTS: The TCI scores from the short and long versions showed comparable reliability coefficients and were strongly correlated. Twins scored about half a standard deviation higher in the character scales. Three of the four temperament dimensions (Novelty Seeking, Harm Avoidance, and Persistence had strong genetic and non-shared environmental effects, while Reward Dependence and the three character dimensions had moderate genetic effects, and both shared and non-shared environmental effects. CONCLUSIONS: Twins showed higher scores in character dimensions compared to adolescents from the general population. At least among adolescents there is a shared environmental influence for all of the character dimensions, but only for one of the temperament dimensions (i.e., Reward Dependence. This specific finding regarding the existence of shared environmental factors behind the character dimensions in adolescence, together with earlier findings showing a small shared environmental effects on character among young adults and no

  12. Temperament and character in the Child and Adolescent Twin Study in Sweden (CATSS): comparison to the general population, and genetic structure analysis.

    Science.gov (United States)

    Garcia, Danilo; Lundström, Sebastian; Brändström, Sven; Råstam, Maria; Cloninger, C Robert; Kerekes, Nóra; Nilsson, Thomas; Anckarsäter, Henrik

    2013-01-01

    The Child and Adolescent Twin Study in Sweden (CATSS) is an on-going, large population-based longitudinal twin study. We aimed (1) to investigate the reliability of two different versions (125-items and 238-items) of Cloninger's Temperament and Character Inventory (TCI) used in the CATSS and the validity of extracting the short version from the long version, (2) to compare these personality dimensions between twins and adolescents from the general population, and (3) to investigate the genetic structure of Cloninger's model. Reliability and correlation analyses were conducted for both TCI versions, 2,714 CATSS-twins were compared to 631 adolescents from the general population, and the genetic structure was investigated through univariate genetic analyses, using a model-fitting approach with structural equation-modeling techniques based on same-sex twin pairs from the CATSS (423 monozygotic and 408 dizygotic pairs). The TCI scores from the short and long versions showed comparable reliability coefficients and were strongly correlated. Twins scored about half a standard deviation higher in the character scales. Three of the four temperament dimensions (Novelty Seeking, Harm Avoidance, and Persistence) had strong genetic and non-shared environmental effects, while Reward Dependence and the three character dimensions had moderate genetic effects, and both shared and non-shared environmental effects. Twins showed higher scores in character dimensions compared to adolescents from the general population. At least among adolescents there is a shared environmental influence for all of the character dimensions, but only for one of the temperament dimensions (i.e., Reward Dependence). This specific finding regarding the existence of shared environmental factors behind the character dimensions in adolescence, together with earlier findings showing a small shared environmental effects on character among young adults and no shared environmental effects on character among adults

  13. Heredity and Environment in Etiology of Eating Disorders. I. Review of Twin Studies

    Directory of Open Access Journals (Sweden)

    Meshkova T.A.

    2015-06-01

    Full Text Available Twin studies of eating disorders (anorexia nervosa, bulimia nervosa, and binge eating are reviewed. Historically, eating disorders (ED was viewed as a disorders primarily influenced by sociocultural factors, however, over the past decade, this perception has been challenged. Twin studies demonstrate that genetic factors significantly influence the risk for ED and substantially contribute to the observed association between ED and other disorders and personal traits (major depression, anxiety disorders, substance use disorders, perfectionism. Among environmental factors nonshared (unique environment plays the main role, except of early puberty.

  14. Heritability of Gestational Weight Gain-A Swedish Register-Based Twin Study

    DEFF Research Database (Denmark)

    Andersson, Elina Scheers; Silventoinen, Karri; Tynelius, Per;

    2015-01-01

    on the variation in GWG in the first and second pregnancy in monozygotic (MZ) and dizygotic (DZ) twin mother-pairs. Further, we explored if any co-variance existed between factors influencing the variation in GWG of the mothers' first and second pregnancies. By using Swedish nationwide record-linkage data, we...... modeling (SEM) to assess the contribution of genetic, shared, and unique environmental factors to the variation in GWG. A bivariate Cholesky decomposition model was used for the subanalysis. We found that genetic factors explained 43% (95% CI: 36-51%) of the variation in GWG in the first pregnancy and 26......% (95% CI: 16-36%) in the second pregnancy. The remaining variance was explained by unique environmental factors. Both overlapping and distinct genetic and unique environmental factors influenced GWG in the first and the second pregnancy. This study showed that GWG has a moderate heritability...

  15. The genetic and environmental basis of the relationship between schizotypy and personality: a twin study.

    Science.gov (United States)

    Jang, Kerry L; Woodward, Todd S; Lang, Donna; Honer, William G; Livesley, W John

    2005-03-01

    The clinical phenotype commonly referred to as schizotypy is used in two different ways in psychiatric practice. One usage emphasizes psychosis-proneness where schizotypy is considered part of the schizophrenia spectrum. The other emphasizes personality aberrations and is classed as a personality disorder. The present study provides evidence that schizotypy is a unitary construct and that features like schizophrenia and personality share a common genetic basis. A sample of 102 monozygotic and 90 dizygotic general population twin pairs completed measures of psychosis-proneness and traits delineating personality disorder. Multivariate genetic analyses showed that the observed relationship between psychotic and personality features is caused almost entirely by common genetic factors. Environmental factors appear to be unique to each measure. On the basis of these findings, it is suggested that the environment mediates change in personality function to psychosis as proposed by Meehl's original concept of schizotaxia.

  16. Cognitive function in unaffected twins discordant for affective disorder

    DEFF Research Database (Denmark)

    Christensen, Maj Vinberg; Kyvik, Kirsten Ohm; Kessing, Lars Vedel

    2006-01-01

    is associated with cognitive impairment. METHOD: In a cross-sectional high-risk case-control study, healthy monozygotic (MZ) and dizygotic (DZ) twins with (High-Risk twins) and without (the control group/Low-Risk twins) a co-twin history of affective disorder were identified through nationwide registers....... Cognitive performance of 203 High-Risk and Low-Risk twins was compared. RESULTS: Healthy twins discordant for unipolar disorder showed lower performance on almost all measures of cognitive function: selective and sustained attention, executive function, language processing and working and declarative memory......, and also after adjustment for demographic variables, subclinical symptoms and minor psychopathology. Healthy twins discordant for bipolar disorder showed lower performance on tests measuring episodic and working memory, also after adjustment for the above-mentioned covariables. The discrete cognitive...

  17. Sex differences and heritability of two indices of heart rate dynamics : A twin study

    NARCIS (Netherlands)

    Snieder, Harold; van Doornen, Lorenz J. P.; Boomsma, Dorret I.; Thayer, Julian F.

    2007-01-01

    We investigated whether women show larger heart rate variability (HRV) than men after controlling for a large number of health-related covariates, using two indices of HRV, namely respiratory sinus arrhythmia (RSA) and approximate entropy (ApEn). In a twin design, the heritability of both indices wa

  18. Longitudinal Twin Study of Early Literacy Development: Preschool through Grade 1

    Science.gov (United States)

    Byrne, Brian; Samuelsson, Stefan; Wadsworth, Sally; Hulslander, Jacqueline; Corley, Robin; DeFries, John C.; Quain, Peter; Willcutt, Erik G.; Olson, Richard K.

    2007-01-01

    Grade 1 literacy skills of twin children in Australia (New South Wales) and the United States (Colorado) were explored in a genetically sensitive design (N = 319 pairs). Analyses indicated strong genetic influence on word and nonword identification, reading comprehension, and spelling. Rapid naming showed more modest, though reliable, genetic…

  19. Genetic and Environmental Parent-Child Transmission of Value Orientations: An Extended Twin Family Study

    Science.gov (United States)

    Kandler, Christian; Gottschling, Juliana; Spinath, Frank M.

    2016-01-01

    Despite cross-cultural universality of core human values, individuals differ substantially in value priorities, whereas family members show similar priorities to some degree. The latter has often been attributed to intrafamilial socialization. The analysis of self-ratings on eight core values from 399 twin pairs (ages 7-11) and their biological…

  20. Genetic and Environmental Parent-Child Transmission of Value Orientations: An Extended Twin Family Study

    Science.gov (United States)

    Kandler, Christian; Gottschling, Juliana; Spinath, Frank M.

    2016-01-01

    Despite cross-cultural universality of core human values, individuals differ substantially in value priorities, whereas family members show similar priorities to some degree. The latter has often been attributed to intrafamilial socialization. The analysis of self-ratings on eight core values from 399 twin pairs (ages 7-11) and their biological…

  1. A twin study of the genetics of high cognitive ability selected from 11,000 twin pairs in six studies from four countries.

    Science.gov (United States)

    Haworth, Claire M A; Wright, Margaret J; Martin, Nicolas W; Martin, Nicholas G; Boomsma, Dorret I; Bartels, Meike; Posthuma, Danielle; Davis, Oliver S P; Brant, Angela M; Corley, Robin P; Hewitt, John K; Iacono, William G; McGue, Matthew; Thompson, Lee A; Hart, Sara A; Petrill, Stephen A; Lubinski, David; Plomin, Robert

    2009-07-01

    Although much genetic research has addressed normal variation in intelligence, little is known about the etiology of high cognitive abilities. Using data from 11,000 twin pairs (age range = 6-71 years) from the genetics of high cognitive abilities consortium, we investigated the genetic and environmental etiologies of high general cognitive ability (g). Age-appropriate psychometric cognitive tests were administered to the twins and used to create g scores standardized within each study. Liability-threshold model fitting was used to estimate genetic and environmental parameters for the top 15% of the distribution of g. Genetic influence for high g was substantial (0.50, with a 95% confidence interval of 0.41-0.60). Shared environmental influences were moderate (0.28, 0.19-0.37). We conclude that genetic variation contributes substantially to high g in Australia, the Netherlands, the United Kingdom and the United States.

  2. The heritability and genetic correlates of mobile phone use: a twin study of consumer behavior.

    Science.gov (United States)

    Miller, Geoffrey; Zhu, Gu; Wright, Margaret J; Hansell, Narelle K; Martin, Nicholas G

    2012-02-01

    There has been almost no overlap between behavior genetics and consumer behavior research, despite each field's importance in understanding society. In particular, both have neglected to study genetic influences on consumer adoption and usage of new technologies -- even technologies as important as the mobile phone, now used by 5.8 out of 7.0 billion people on earth. To start filling this gap, we analyzed self-reported mobile phone use, intelligence, and personality traits in two samples of Australian teenaged twins (mean ages 14.2 and 15.6 years), totaling 1,036 individuals. ACE modeling using Mx software showed substantial heritabilities for how often teens make voice calls (.60 and .34 in samples 1 and 2, respectively) and for how often they send text messages (.53 and. 50). Shared family environment - including neighborhood, social class, parental education, and parental income (i.e., the generosity of calling plans that parents can afford for their teens) -- had much weaker effects. Multivariate modeling based on cross-twin, cross-trait correlations showed negative genetic correlations between talking/texting frequency and intelligence (around -.17), and positive genetic correlations between talking/texting frequency and extraversion (about .20 to .40). Our results have implications for assessing the risks of mobile phone use such as radiofrequency field (RF) exposure and driving accidents, for studying adoption and use of other emerging technologies, for understanding the genetic architecture of the cognitive and personality traits that predict consumer behavior, and for challenging the common assumption that consumer behavior is shaped entirely by culture, media, and family environment.

  3. Twin study of heritability of eating bread in Danish and Finnish men and women

    DEFF Research Database (Denmark)

    Hasselbalch, Ann Louise; Silventoinen, Karri; Keskitalo, Kaisu;

    2010-01-01

    Bread is an elementary part of the western diet, and especially rye bread is regarded as an important source of fibre. We investigated the heritability of eating bread in terms of choice of white and rye bread and use-frequency of bread in female and male twins in Denmark and Finland. The study...... cohorts included 575 Danish (age range 18-67 years) and 2009 Finnish (age range 22-27 years) adult twin pairs. Self-reported frequency of eating bread was obtained by food frequency questionnaires. Univariate models based on linear structural equations for twin data were used to estimate the relative...... magnitude of the additive genetic, shared environmental and individual environmental effects on bread eating frequency and choice of bread. The analysis of bread intake frequency demonstrated moderate heritability ranging from 37-40% in the Finnish cohort and 23-26% in the Danish cohort. The genetic...

  4. Predicting individual differences in reading comprehension: a twin study

    Science.gov (United States)

    Cutting, Laurie; Deater-Deckard, Kirby; DeThorne, Laura S.; Justice, Laura M.; Schatschneider, Chris; Thompson, Lee A.; Petrill, Stephen A.

    2010-01-01

    We examined the Simple View of reading from a behavioral genetic perspective. Two aspects of word decoding (phonological decoding and word recognition), two aspects of oral language skill (listening comprehension and vocabulary), and reading comprehension were assessed in a twin sample at age 9. Using latent factor models, we found that overlap among phonological decoding, word recognition, listening comprehension, vocabulary, and reading comprehension was primarily due to genetic influences. Shared environmental influences accounted for associations among word recognition, listening comprehension, vocabulary, and reading comprehension. Independent of phonological decoding and word recognition, there was a separate genetic link between listening comprehension, vocabulary, and reading comprehension and a specific shared environmental link between vocabulary and reading comprehension. There were no residual genetic or environmental influences on reading comprehension. The findings provide evidence for a genetic basis to the “Simple View” of reading. PMID:20814768

  5. Predicting individual differences in reading comprehension: a twin study.

    Science.gov (United States)

    Harlaar, Nicole; Cutting, Laurie; Deater-Deckard, Kirby; Dethorne, Laura S; Justice, Laura M; Schatschneider, Chris; Thompson, Lee A; Petrill, Stephen A

    2010-12-01

    We examined the Simple View of reading from a behavioral genetic perspective. Two aspects of word decoding (phonological decoding and word recognition), two aspects of oral language skill (listening comprehension and vocabulary), and reading comprehension were assessed in a twin sample at age 9. Using latent factor models, we found that overlap among phonological decoding, word recognition, listening comprehension, vocabulary, and reading comprehension was primarily due to genetic influences. Shared environmental influences accounted for associations among word recognition, listening comprehension, vocabulary, and reading comprehension. Independent of phonological decoding and word recognition, there was a separate genetic link between listening comprehension, vocabulary, and reading comprehension and a specific shared environmental link between vocabulary and reading comprehension. There were no residual genetic or environmental influences on reading comprehension. The findings provide evidence for a genetic basis to the "Simple View" of reading.

  6. Twin-singleton differences in intelligence: a register-based birth cohort study of Norwegian males.

    Science.gov (United States)

    Eriksen, Willy; Sundet, Jon M; Tambs, Kristian

    2012-10-01

    The aim was to determine the difference in intelligence between singletons and twins in young adulthood. Data from the Medical Birth Register of Norway were linked with register data from the Norwegian National Conscript Service. The study base consisted of data on the 445,463 males who were born alive in either single or twin births in Norway during 1967-1984 and who were examined at the time of the mandatory military conscription (age 18-20). Within this study base, there were data on 1,653 sibships of full brothers that included at least one man born in single birth and at least one man born in twin birth (4,307 persons, including 2,378 twins and 1,929 singletons). The intelligence scores of the singletons were 11% (95% confidence interval [CI]: 9-14%) of a standard deviation higher than those of the twins, after adjustment for birth year, birth order, parental ages at delivery, parental education levels, and other factors. The adjusted within-family difference was also 11% (95 % CI: 6-16%) of a standard deviation, indicating that unmeasured factors shared by siblings (e.g., maternal body height) have not influenced the estimate in important ways. When gestational age at birth was added to the model, the estimate for the difference in intelligence score was approximately the same. Including birth weight in the model strongly reduced the estimate. In conclusion, twins born in Norway during 1967-1984 had slightly lower intelligence in early adulthood compared with the singletons.

  7. A Longitudinal Twin Study of General Cognitive Ability over Four Decades

    Science.gov (United States)

    Lyons, Michael J.; Panizzon, Matthew S.; Liu, Weijian; McKenzie, Ruth; Bluestone, Noah J.; Grant, Michael D.; Franz, Carol E.; Vuoksimaa, Eero P.; Toomey, Rosemary; Jacobson, Kristen C.; Reynolds, Chandra A.; Kremen, William S.; Xian, Hong

    2017-01-01

    In this longitudinal study we examined the stability of general cognitive ability (GCA), as well as heterogeneity and genetic and environmental influences underlying individual differences in change. We investigated GCA from young adulthood through late midlife in 1,288 Vietnam Era Twin Study of Aging participants at ages ~20, ~56, and ~62 years.…

  8. Perinatal risk factors and neonatal complications in discordant twins admitted to the neonatal intensive care unit

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiao-rui; LIU Jie; ZENG Chao-mei

    2013-01-01

    Background Many studies have shown a relationship between birth weight discordance and adverse perinatal outcomes.This study aimed to investigate the perinatal risk factors and neonatal complications of discordant twins who are admitted to the neonatal intensive care unit.Methods A total of 87 sets of twins were enrolled in this retrospective study,of which 22 sets were discordant twins and 65 sets were concordant twins.Binary Logistic regression analysis was used to identify the risk factors associated with the occurrence of discordant twins.The common neonatal complications of discordant twins were also investigated.Results Multivariate analysis showed that the use of assisted reproductive techniques,pregnancy-induced hypertension,and unequal placental sharing were risk factors for the occurrence of discordant twins.The incidence of small for gestational age infants and very low birth weight infants of discordant twins was significantly higher,while the birth weight of discordant twins was significantly lower than those of concordant twins.The duration of hospitalization of discordant twins was longer than that of concordant twins.The incidence of several neonatal complications,such as neonatal respiratory distress syndrome and intracranial hemorrhage,was higher in discordant twins than that in concordant twins.The percentage of those requiring pulmonary surfactant and mechanical ventilation was significantly higher in discordant twins than that in concordant twins.Conclusions Use of assisted reproductive techniques,pregnancy-induced hypertension,and unequal placental sharing are perinatal risk factors of discordant twins who are admitted to the neonatal intensive care unit.These infants are also much more likely to suffer from various neonatal complications,especially respiratory and central nervous system diseases.It is important to prevent the occurrence of discordant twins by decreasing these risk factors and timely treatment should be given to discordant

  9. Twinning in shear and uniaxial loading in five layered martensite Ni-Mn-Ga single crystals

    Science.gov (United States)

    Aaltio, Ilkka; Ge, Yanling; Hannula, Simo-Pekka

    2013-02-01

    Five-layered martensite Ni-Mn-Ga single crystals are known for their exceptionally mobile twin boundaries allowing a shape change under mechanical stress and by magnetic field. The mechanically measured twinning stress has usually been studied in uniaxial mode, however the twinning and detwinning is generally accepted to be resulted by the shear component. We have studied the twinning behavior at uniaxial and shear stress. In addition we have applied the shear stress at different angles in relation to the expected twinning direction [ {10bar 1} ]. The results show that the onset of twinning lays at similar stress levels in both uniaxial and shear modes.

  10. Exploring Anxiety Symptoms in a Large-Scale Twin Study of Children with Autism Spectrum Disorders, Their Co-Twins and Controls

    Science.gov (United States)

    Hallett, Victoria; Ronald, Angelica; Colvert, Emma; Ames, Catherine; Woodhouse, Emma; Lietz, Stephanie; Garnett, Tracy; Gillan, Nicola; Rijsdijk, Fruhling; Scahill, Lawrence; Bolton, Patrick; Happé, Francesca

    2013-01-01

    Background: Although many children with autism spectrum disorders (ASDs) experience difficulties with anxiety, the manifestation of these difficulties remains unresolved. The current study assessed anxiety in a large population-based twin sample, aged 10-15 years. Phenotypic analyses were used to explore anxiety symptoms in children with ASDs,…

  11. Conjoined Twins : A Worldwide Collaborative Epidemiological Study of the International Clearinghouse for Birth Defects Surveillance and Research

    NARCIS (Netherlands)

    Mutchinick, Osvaldo M.; Luna-Munoz, Leonora; Amar, Emmanuelle; Bakker, Marian K.; Clementi, Maurizio; Cocchi, Guido; Dutra, Maria da Graca; Feldkamp, Marcia L.; Landau, Danielle; Leoncini, Emanuele; Li, Zhu; Lowry, Brian; Marengo, Lisa K.; Martinez-Frias, Maria-Luisa; Mastroiacovo, Pierpaolo; Metneki, Julia; Morgan, Margery; Pierini, Anna; Rissman, Anke; Ritvanen, Annukka; Scarano, Gioacchino; Siffel, Csaba; Szabova, Elena; Arteaga-Vazquez, Jazmin

    2011-01-01

    Conjoined twins (CT) are a very rare developmental accident of uncertain etiology. Prevalence has been previously estimated to be 1 in 50,000 to 1 in 100,000 births. The process by which monozygotic twins do not fully separate but form CT is not well understood. The purpose of the present study was

  12. A Twin Study of Heritable and Shared Environmental Contributions to Autism

    Science.gov (United States)

    Frazier, Thomas W.; Thompson, Lee; Youngstrom, Eric A.; Law, Paul; Hardan, Antonio Y.; Eng, Charis; Morris, Nathan

    2014-01-01

    The present study examined genetic and shared environment contributions to quantitatively-measured autism symptoms and categorically-defined autism spectrum disorders (ASD). Participants included 568 twins from the Interactive Autism Network. Autism symptoms were obtained using the Social Communication Questionnaire and Social Responsiveness…

  13. Prevalence, concordance, and heritability of Scheuermann kyphosis based on a study of twins

    DEFF Research Database (Denmark)

    Damborg, Frank; Engell, Vilhelm; Andersen, Mikkel;

    2006-01-01

    BACKGROUND: The purpose of this study was to establish a cohort of symptomatic twins with Scheuermann kyphosis to provide estimates of prevalence, concordance, odds ratio, and heritability. These estimates indicate to what extent genetic factors contribute to the etiology of this disease. METHODS...

  14. Losing one twin in the NICU - A case study of parental experience

    DEFF Research Database (Denmark)

    Aagaard, Hanne; Storm, Ida; Klitgaard, Jeannett

    2016-01-01

    and revealed tree overall themes. These themes indicate that besides struggling with grief related to the loss of one infant, the parents were challenged by the medical discourse, the lack of staff continuity and space to develop parenthood. This case study emphasizes how the loss of a premature twin...

  15. Twin study of genetic and environmental influences on adult body size, shape, and composition

    DEFF Research Database (Denmark)

    Schousboe, K; Visscher, P M; Erbas, B;

    2004-01-01

    OBJECTIVE: To investigate the genetic and environmental influences on adult body size, shape, and composition in women and men, and to assess the impact of age. MATERIALS AND METHODS: In this cross-sectional study of 325 female and 299 male like-sex healthy twin pairs, on average 38 y old (18-67 ...

  16. Genetic amniocentesis in twin pregnancies: results of a multicenter study of 529 cases

    NARCIS (Netherlands)

    Pruggmayer, M.R.K.; M.G. Jahoda (M.); Van der Pol, J.G.; Baumann, P.; Holzgreve, W.; Karkut, G.; Lettau, R.; Eiben, B.; Osmers, R.; Gola, H.W.; Duda, V.; Polak, P.; Körner, H.; Schulte‐Valentin, M.; Schütte, H.

    1992-01-01

    textabstractTo evaluate the risk of abortion after genetic amniocentesis in twin pregnancies, a retrospective study of 15 centers was performed. The spontaneous abortion rate up to 20 completed weeks of gestation was 2.3%; the abortion rate up to 28 completed weeks, as defined by WHO, was 3.7%. The

  17. Measuring adolescents’ exposure to victimization: The Environmental Risk (E-Risk) Longitudinal Twin Study

    Science.gov (United States)

    Fisher, Helen L.; Caspi, Avshalom; Moffitt, Terrie E.; Wertz, Jasmin; Gray, Rebecca; Newbury, Joanne; Ambler, Antony; Zavos, Helena; Danese, Andrea; Mill, Jonathan; Odgers, Candice L.; Pariante, Carmine; Wong, Chloe C.; Arseneault, Louise

    2016-01-01

    This paper presents mutlilevel findings on adolescents’ victimization exposure from a large longitudinal cohort of twins. Data were obtained from the Environmental Risk (E-Risk) Longitudinal Twin Study, an epidemiological study of 2,232 children (1,116 twin pairs) followed to 18 years of age (with 93% retention). To assess adolescent victimization we combined best practices in survey research on victimization with optimal approaches to measuring life stress and traumatic experiences, and introduce a reliable system for coding severe victimization. One in three children experienced at least one type of severe victimization during adolescence (crime victimization, peer/sibling victimization, internet/mobile phone victimization, sexual victimization, family violence, maltreatment, or neglect), and most types of victimization were more prevalent amongst children from low socioeconomic backgrounds. Exposure to multiple victimization types was common, as was re-victimization; over half of those physically maltreated in childhood were also exposed to severe physical violence in adolescence. Biometric twin analyses revealed that environmental factors had the greatest influence on most types of victimization, while severe physical maltreatment from caregivers during adolescence was predominantly influenced by heritable factors. The findings from this study showcase how distinct levels of victimization measurement can be harmonized in large-scale studies of health and development. PMID:26535933

  18. Aging Trajectories in Different Body Systems Share Common Environmental Etiology : The Healthy Aging Twin Study (HATS)

    NARCIS (Netherlands)

    Moayyeri, Alireza; Hart, Deborah J.; Snieder, Harold; Hammond, Christopher J.; Spector, Timothy D.; Steves, Claire J.

    Little is known about the extent to which aging trajectories of different body systems share common sources of variance. We here present a large twin study investigating the trajectories of change in five systems: cardiovascular, respiratory, skeletal, morphometric, and metabolic. Longitudinal

  19. Examining Genetic and Environmental Effects on Social Aggression: A Study of 6-Year-Old Twins

    Science.gov (United States)

    Brendgen, Mara; Dionne, Ginette; Girard, Alain; Boivin, Michel; Vitaro, Frank; Prusse, Daniel

    2005-01-01

    Using a genetic design of 234 six-year-old twins, this study examined (a) the contribution of genes and environment to social versus physical aggression, and (b) whether the correlation between social and physical aggression can be explained by similar genetic or environmental factors or by a directional link between the phenotypes. For social…

  20. Twin studies as a model for exploring the aetiology of autoimmune thyroid disease

    DEFF Research Database (Denmark)

    Brix, Thomas Heiberg; Hegedüs, Laszlo

    2012-01-01

    triggers such as cigarette smoking, birth characteristics, infection with Yersinia enterocolitica, microchimerism and degree of X chromosome inactivation (XCI) has been evaluated by investigating AITD discordant twin pairs. These studies indicate that smoking, Y. enterocolitica infection and skewed XCI may...

  1. Exploring the Co-Development of Reading Fluency and Reading Comprehension: A Twin Study

    Science.gov (United States)

    Little, Callie W.; Hart, Sara A.; Quinn, Jamie M.; Tucker-Drob, Elliot M.; Taylor, Jeanette; Schatschneider, Christopher

    2017-01-01

    This study explores the co-development of two related but separate reading skills, reading fluency and reading comprehension, across Grades 1-4. A bivariate biometric dual change score model was applied to longitudinal data collected from 1,784 twin pairs between the ages of 6 and 10 years. Grade 1 skills were influenced by highly overlapping…

  2. A Twin-Study of Sleep Difficulties in School-Aged Children

    Science.gov (United States)

    Gregory, Alice M.; Rijsdijk, Fruhling V.; Eley, Thalia C.

    2006-01-01

    This study examines frequency, overlap, and genetic and environmental influences on sleep difficulties, which are understudied in school-aged children. The Sleep Self Report and the Children's Sleep Habits Questionnaire were completed by 300 twin pairs (aged 8 years) and their parents. Child report suggested more frequent sleep problems than…

  3. A Twin Study of Heritable and Shared Environmental Contributions to Autism

    Science.gov (United States)

    Frazier, Thomas W.; Thompson, Lee; Youngstrom, Eric A.; Law, Paul; Hardan, Antonio Y.; Eng, Charis; Morris, Nathan

    2014-01-01

    The present study examined genetic and shared environment contributions to quantitatively-measured autism symptoms and categorically-defined autism spectrum disorders (ASD). Participants included 568 twins from the Interactive Autism Network. Autism symptoms were obtained using the Social Communication Questionnaire and Social Responsiveness…

  4. Genetic amniocentesis in twin pregnancies: results of a multicenter study of 529 cases

    NARCIS (Netherlands)

    Pruggmayer, M.R.K.; M.G. Jahoda (M.); Van der Pol, J.G.; Baumann, P.; Holzgreve, W.; Karkut, G.; Lettau, R.; Eiben, B.; Osmers, R.; Gola, H.W.; Duda, V.; Polak, P.; Körner, H.; Schulte‐Valentin, M.; Schütte, H.

    1992-01-01

    textabstractTo evaluate the risk of abortion after genetic amniocentesis in twin pregnancies, a retrospective study of 15 centers was performed. The spontaneous abortion rate up to 20 completed weeks of gestation was 2.3%; the abortion rate up to 28 completed weeks, as defined by WHO, was 3.7%. The

  5. Effect of triple junctions on deformation twinning in a nanostructured Cu–Zn alloy: A statistical study using transmission Kikuchi diffraction

    Directory of Open Access Journals (Sweden)

    Silu Liu

    2016-10-01

    Full Text Available Scanning electron microscopy transmission Kikuchi diffraction is able to identify twins in nanocrystalline material, regardless of their crystallographic orientation. In this study, it was employed to characterize deformation twins in Cu/10 wt % Zn processed by high-pressure torsion. It was found that in 83% of grains containing twins, at least one twin intersects with a triple junction. This suggests that triple junctions could have promoted the nucleation of deformation twins. It should be cautioned that this technique might be unable to detect extremely small nanoscale twins thinner than its step size.

  6. Twin boundary energy and characterization of charge redistribution near the twin boundaries of cupperate superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi, Mahnaz [Faculty of Physics, University of Kashan, Kashan (Iran, Islamic Republic of); Khoshnevisan, Bahram, E-mail: m.mohammadi_2@grad.kashanu.ac.ir [Faculty of Physics, University of Kashan, Kashan (Iran, Islamic Republic of); Javad Hashemifar, S. [Department of Physics, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of)

    2014-12-15

    Highlights: • Ab initio simulation for twin boundary energy in YBCO system for the 1st time. • Study of the twin boundary energy variation versus the inserted strain. • Proportionality of twin lamella width by the inserted strain. • Local charge transfer and charge redistribution on the twin planes. • Total DOSs for the twined system at Fermi level is higher than the untwined one. • This explain the effect of twin boundaries in agreement with experimental data. - Abstract: Ab-initio calculations under general gradient approximation have been employed for the first time to find out twin boundary energy, γ, in twined YBCO systems. Despite a vast discrepancy in reported experimental values, our results show that the γ value falls in the range of 40–85 mJ/m{sup 2}. On the other hand, functional form of γ versus inserted strains shows that the mean value for the twin width lamella would tend to approach zero as the strain goes to zero. We have also investigated the local charge transfer and the modification of the electronic states of the basal and twin planes in YBCO, because the charge redistribution at interfaces can modify transport across the grains considerably and determine the applicability of high-T{sub c} superconductors in the electronic applications. The total density of electronic states at the Fermi level for the twined system is enhanced in comparison with the untwined one. Our results explain the influence of twin boundaries in superconductive properties of YBCO, in experimental situations.

  7. ACARDIAC TWIN

    OpenAIRE

    Vinayachandran; Jyothi,; Bindu; Umadevi

    2014-01-01

    Acardiac twin is a very rare complication occurring in monozygotic twins in which one fetus develops normally (pump twin) and the other (recipient twin) demonstrate cardiac non development and othe r anomalies. This may represent an extreme form of TTTS, also referred to as TRAP sequence. 1,2,

  8. Shared Etiology of Psychotic Experiences and Depressive Symptoms in Adolescence: A Longitudinal Twin Study.

    Science.gov (United States)

    Zavos, Helena M S; Eley, Thalia C; McGuire, Philip; Plomin, Robert; Cardno, Alastair G; Freeman, Daniel; Ronald, Angelica

    2016-09-01

    Psychotic disorders and major depression, both typically adult-onset conditions, often co-occur. At younger ages psychotic experiences and depressive symptoms are often reported in the community. We used a genetically sensitive longitudinal design to investigate the relationship between psychotic experiences and depressive symptoms in adolescence. A representative community sample of twins from England and Wales was employed. Self-rated depressive symptoms, paranoia, hallucinations, cognitive disorganization, grandiosity, anhedonia, and parent-rated negative symptoms were collected when the twins were age 16 (N = 9618) and again on a representative subsample 9 months later (N = 2873). Direction and aetiology of associations were assessed using genetically informative cross-lagged models. Depressive symptoms were moderately correlated with paranoia, hallucinations, and cognitive disorganization. Lower correlations were observed between depression and anhedonia, and depression and parent-rated negative symptoms. Nonsignificant correlations were observed between depression and grandiosity. Largely the same genetic effects influenced depression and paranoia, depression and hallucinations, and depression and cognitive disorganization. Modest overlap in environmental influences also played a role in the associations. Significant bi-directional longitudinal associations were observed between depression and paranoia. Hallucinations and cognitive disorganization during adolescence were found to impact later depression, even after controlling for earlier levels of depression. Our study shows that psychotic experiences and depression, as traits in the community, have a high genetic overlap in mid-adolescence. Future research should test the prediction stemming from our longitudinal results, namely that reducing or ameliorating positive and cognitive psychotic experiences in adolescence would decrease later depressive symptoms. © The Author 2016. Published by Oxford

  9. Heritability of face shape in twins: a preliminary study using 3D stereophotogrammetry and geometric morphometrics

    Directory of Open Access Journals (Sweden)

    Seth M. Weinberg

    2013-11-01

    Full Text Available Introduction: Previous research suggests that aspects of facial surface morphology are heritable.  Traditionally, heritability studies have used a limited set of linear distances to quantify facial morphology and often employ statistical methods poorly designed to deal with biological shape.  In this preliminary report, we use a combination of 3D photogrammetry and landmark-based morphometrics to explore which aspects of face shape show the strongest evidence of heritability in a sample of twins. Methods: 3D surface images were obtained from 21 twin pairs (10 monozygotic, 11 same-sex dizygotic.  Thirteen 3D landmarks were collected from each facial surface and their coordinates subjected to geometric morphometric analysis.  This involved superimposing the individual landmark configurations and then subjecting the resulting shape coordinates to a principal components analysis.  The resulting PC scores were then used to calculate rough narrow-sense heritability estimates. Results: Three principal components displayed evidence of moderate to high heritability and were associated with variation in the breadth of orbital and nasal structures, upper lip height and projection, and the vertical and forward projection of the root of the nose due to variation in the position of nasion. Conclusions: Aspects of facial shape, primarily related to variation in length and breadth of central midfacial structures, were shown to demonstrate evidence of strong heritability. An improved understanding of which facial features are under strong genetic control is an important step in the identification of specific genes that underlie normal facial variation.

  10. A twin and molecular genetics study of sleep paralysis and associated factors.

    Science.gov (United States)

    Denis, Dan; French, Christopher C; Rowe, Richard; Zavos, Helena M S; Nolan, Patrick M; Parsons, Michael J; Gregory, Alice M

    2015-08-01

    Sleep paralysis is a relatively common but under-researched phenomenon. In this paper we examine prevalence in a UK sample and associations with candidate risk factors. This is the first study to investigate the heritability of sleep paralysis in a twin sample and to explore genetic associations between sleep paralysis and a number of circadian expressed single nucleotide polymorphisms. Analyses are based on data from the Genesis1219 twin/sibling study, a community sample of twins/siblings from England and Wales. In total, data from 862 participants aged 22-32 years (34% male) were used in the study. This sample consisted of monozygotic and dizygotic twins and siblings. It was found that self-reports of general sleep quality, anxiety symptoms and exposure to threatening events were all associated independently with sleep paralysis. There was moderate genetic influence on sleep paralysis (53%). Polymorphisms in the PER2 gene were associated with sleep paralysis in additive and dominant models of inheritance-although significance was not reached once a Bonferroni correction was applied. It is concluded that factors associated with disrupted sleep cycles appear to be associated with sleep paralysis. In this sample of young adults, sleep paralysis was moderately heritable. Future work should examine specific polymorphisms associated with differences in circadian rhythms and sleep homeostasis further in association with sleep paralysis.

  11. Promoter methylation of serotonin transporter gene is associated with obesity measures: a monozygotic twin study.

    Science.gov (United States)

    Zhao, J; Goldberg, J; Vaccarino, V

    2013-01-01

    Epigenetic mechanisms are increasingly being recognized as an important factor for obesity. The serotonin transporter gene (SLC6A4) has a critical role in regulating food intake, body weight and energy balance. This study examines the potential association between SLC6A4 promoter methylation and obesity measures in a monozygotic (MZ) twin sample. We studied 84 MZ twin pairs drawn from the Vietnam Era Twin Registry. Obesity measures include body mass index (BMI), body weight, waist circumference (WC) and waist-hip ratio (WHR). The SLC6A4 promoter methylation profile in peripheral blood leukocytes was quantified by bisulfite pyrosequencing. The association between methylation variation and obesity parameters was examined by mixed-model regression and matched pair analysis, adjusting for age, smoking, alcohol consumption, physical activity and total daily energy intake. Multiple testing was controlled using the adjusted false discovery rate (q-value). Mean methylation level was positively correlated with BMI (r=0.29; P=0.0002), body weight (r=0.31; Pobesity within a MZ twin study.

  12. A simulation study on power of epigenome-wide association analysis using disease-discordant twin design

    DEFF Research Database (Denmark)

    Li, Weilong; Baumbach, Jan; Christiansen, Lene

    -control design, its statistical power has not been well investigated. Methods We perform a computer simulation study on the power of the disease discordant twin design assuming that both genetic and environmental factors contribute to the liability of a disease phenotype. Power is assessed under different levels......Background Identical twin pairs discordant for a disease have been widely used in epigenome-wide association studies (EWAS) of complex diseases because the underlying genetic background is cancelled out. Although the twin design is deemed to have enriched power as compared with ordinary case...... with moderate effect and for diseases with heritability>0.3. The power advantage in discordant twin design becomes more obvious with increasing heritability. For diseases with no genetic background, the twin design is slightly underpowered, while for high heritability (0.5), high intrapair methylation...

  13. Variance components models for physical activity with age as modifier: a comparative twin study in seven countries

    DEFF Research Database (Denmark)

    Vink, Jacqueline M; Boomsma, Dorret I; Medland, Sarah E;

    2011-01-01

    Physical activity is influenced by genetic factors whose expression may change with age. We employed an extension to the classical twin model that allows a modifier variable, age, to interact with the effects of the latent genetic and environmental factors. The model was applied to self-reported ......Physical activity is influenced by genetic factors whose expression may change with age. We employed an extension to the classical twin model that allows a modifier variable, age, to interact with the effects of the latent genetic and environmental factors. The model was applied to self......-reported data from twins aged 19 to 50 from seven countries that collaborated in the GenomEUtwin project: Australia, Denmark, Finland, Norway, Netherlands, Sweden and United Kingdom. Results confirmed the importance of genetic influences on physical activity in all countries and showed an age-related decrease...... into account when exploring the genetic and environmental contribution to physical activity. It also suggests that the power of genome-wide association studies to identify the genetic variants contributing to physical activity may be larger in young adult cohorts....

  14. Twin screw wet granulation: the study of a continuous twin screw granulator using Positron Emission Particle Tracking (PEPT) technique.

    Science.gov (United States)

    Lee, Kai T; Ingram, Andy; Rowson, Neil A

    2012-08-01

    In this paper, Positron Emission Particle Tracking (PEPT) techniques are utilised to track the trajectory of single particles through the mixing and conveying zones of a Twin Screw Granulator (TSG). A TSG consisting of conveying zones and mixing zones is used in this study. The mixing zones are arranged with kneading discs at an angle of 30°, 60° or 90°. Experiments were carried out using different mixing configurations with various screw speed and total mass flow rate. The PEPT data obtained were then utilised to obtain the residence time distribution (RTD) and the Peclet number in an attempt to gain some insight into the mixing of the process. The fill level of the granulator was also estimated to study the mechanism of granulation. As might be expected, it was shown that the residence time of the granulation process increases with decreasing screw speed. It also increases with increasing angle of the arrangement of kneading blocks in the mixing zones, but will decreases when powder feed rate is increased. The fill level of the mixing zone in particular increases when the screw speed decreases or when powder feed rate increases. Furthermore, the fill level of the granulator will increase when the mixing zone configuration changes from 30° to 90°. It is shown that the granulator is never fully filled, even using 90° mixer elements implying limited compaction which may explain why the granules produced are porous compared with those from a high shear mixer. Interestingly, the RTD analysis reveals that the extent of axial mixing in the mixing zone of the granulator does not change significantly for different configurations and process conditions. There is evidence of a tail in the RTD which implies some material hold up and channelling.

  15. Effect of birth parameters on retinal vascular caliber: the Twins Eye Study in Tasmania.

    Science.gov (United States)

    Sun, Cong; Ponsonby, Anne-Louise; Wong, Tien Y; Brown, Shayne A; Kearns, Lisa S; Cochrane, Jenny; MacKinnon, Jane R; Ruddle, Jonathan B; Hewitt, Alex W; Liew, Gerald; Dwyer, Terence; Scurrah, Katrina; Mackey, David A

    2009-03-01

    Recent studies reported an association between smaller birth size and narrower retinal vascular caliber, but it remains unclear whether this association is attributed to confounding by shared environment or genetic factors. At a mean age of 9.3 years, 266 twins (49 monozygotic and 84 dizygotic pairs) in the Twins Eye Study in Tasmania underwent an ophthalmic examination including retinal photography. Retinal vascular caliber was measured using a validated protocol. The majority of these twins were also in the Tasmanian Infant Health Study, which prospectively collected data on birth parameters and antenatal maternal factors. We conducted the main analysis using linear mixed models, accounting for birth set clustering. Both the within-pair (-9.73; 95% CI: -14.68 to -4.77 microm per 5-cm decrease in birth length) and between-pair associations (-7.15; 95% CI: -11.54 to -3.01) with retinal arteriolar caliber were significant and of similar magnitude (difference in effect, P=0.61), after adjusting for age, sex, maternal smoking, mean arterial blood pressure, and other confounders. These associations remained within dizygotic and monozygotic pairs. Analyses of head circumference and retinal arteriolar caliber were similar to those of birth length (within-pair regression coefficient: -2.41; 95% CI: -5.09 to 0.28; between-pair regression coefficient: -2.60; 95% CI: -5.00 to -0.19). For birth weight, only a between-pair association was evident (-7.28; 95% CI: -13.07 to -1.48). This study demonstrates a consistent association between smaller birth size and narrower retinal arterioles in twins. The independent effect of shorter birth length on retinal arteriolar caliber supports a role for twin-specific supply line factors affecting fetal growth on vascular structure.

  16. The response to oxidative stress and metallomics analysis in a twin study: The role of the environment.

    Science.gov (United States)

    Medda, Emanuela; Minoprio, Anna; Nisticò, Lorenza; Bocca, Beatrice; Simonelli, Valeria; D'Errico, Mariarosaria; Calcagnile, Angelo; Giuliani, Alessandro; Toccaceli, Virgilia; Minghetti, Luisa; Alimonti, Alessandro; Stazi, Maria Antonietta; Mazzei, Filomena; Dogliotti, Eugenia

    2016-08-01

    Inefficient response to oxidative stress has been associated with ageing and health risk. Metals are known to inhibit DNA repair and may modify the antioxidant response. How genetic variability and lifestyle factors modulate the response to oxidative stress is poorly explored. Our study aims to disentangle the contribution of genetics and environmental exposures to oxidative stress response using data from twin pairs. The non-enzymatic antioxidant capacity (NEAC), the repair capacity of 8-oxo-7,8-dihydroguanine (OGG activity) and the levels of 12 metals were measured in blood of 64 monozygotic and 31 dizygotic twin pairs. The contributions of genetic and environmental effects were assessed using standard univariate twin modelling. NEAC and OGG activity significantly decreased with age. Gender-, age- and body mass index-associated differences were identified for some metals. Principal Component Analysis identified two groups of metals whose levels in blood were highly correlated: As, Hg, Pb, Se, Zn and Al, Co, Cr, Mn, Ni. The environmental influence was predominant on OGG activity and NEAC variance whereas for most metals the best-fitting model incorporated additive genetic and unique environmental sources of variance. NEAC and OGG activity were both inversely correlated with blood levels of various metals. The inhibition of OGG activity by Cd was largely explained by smoking. Our data show a substantial role of environmental factors in NEAC and OGG activity variance that is not explained by twins' age. Exogenous environmental factors such as metals contribute to oxidative stress by decreasing NEAC and inhibiting repair of oxidatively-induced DNA damage.

  17. What Might MZ Twin Research Teach Us about Race, Gender & Class Issues?

    Science.gov (United States)

    Charlemaine, Christiane

    2002-01-01

    Deconstructs mainstream twin studies to show the relationship between twins research and race, gender, and class issues related to intelligence and IQ measures. The paper notes that genetic determinism drawn from twin studies based on the assumption that genetics predominates the environment in the transmission of human intelligence is…

  18. Infant twin mortality and hospitalisations after the perinatal period - a prospective cohort study from Guinea-Bissau

    DEFF Research Database (Denmark)

    Bjerregaard-Andersen, M; Biering-Sørensen, S; Gomes, G M

    2014-01-01

    at the National Hospital. RESULTS: About 495 twins and 333 singletons were alive on day 7 after birth. In total, 36 twins and 12 singletons died during follow-up, the post-perinatal infant mortality rate being 91/1000 person-years for twins and 42/1000 for singletons (HR = 2.11, 95% CI: 1...... was strongly associated with twin mortality [3.16, (1.24-8.05)]. Death occurred at home for 60% of twins and 67% of singletons. During follow-up, 90 first-time hospital admissions were registered, with similar rates observed for twins (139/1000) and singletons (143/1000) [0.97, (0.61-1.52)]. CONCLUSION......OBJECTIVE: To examine mortality and hospitalisations among infant twins and singletons after the perinatal period in Guinea-Bissau. METHODS: The study was conducted from September 2009 to November 2012 by the Bandim Health Project (BHP). Newborn twins and unmatched singleton controls were included...

  19. Does sedentary behavior increase the risk of low back pain? A population-based co-twin study of Spanish twins.

    Science.gov (United States)

    Amorim, Anita B; Levy, Gavin M; Pérez-Riquelme, Francisco; Simic, Milena; Pappas, Evangelos; Dario, Amabile B; Ferreira, Manuela L; Carrillo, Eduvigis; Luque-Suarez, Alejandro; Ordoñana, Juan R; Ferreira, Paulo H

    2017-07-01

    The relationship between sedentary lifestyle and low back pain (LBP) remains unclear and previous research has not accounted for genetic and early environmental factors. Our aim was to investigate if sedentary behavior is associated with the lifetime prevalence of persistent LBP and the risk of developing persistent LBP, care-seeking due to LBP, and activity limiting LBP when genetics and early environmental factors are accounted for. Both cross-sectional and longitudinal designs with a within-pair twin case-control were implemented. There were 2,148 twins included in the cross-sectional analysis whereas 1,098 twins free of persistent LBP at baseline were included in the longitudinal analysis. Sedentary behavior was the explanatory variable. Lifetime prevalence of LBP was the outcome variable in the cross-sectional analysis. The incidence of persistent LBP, care-seeking due to LBP, and activity limiting LBP were the outcome variables for the longitudinal analysis. This observational study was supported by a grant in 2012. No competing interests were declared. In the cross-sectional analysis, sedentary behavior was slightly associated with an increased prevalence of persistent LBP in females but not in males. This association was not apparent when genetics and early environmental factors were accounted for. We acknowledge that the small sample included in the co-twin analyses have yielded wide confidence intervals, and that caution should be exercised when interpreting and an association may not be ruled out. In the longitudinal analysis, sedentary behavior did not significantly increase the risk of persistent LBP, care-seeking due to LBP, or activity limiting LBP. Sedentary behavior is associated with concurrent LBP. However, this association is weak; it only appears in females and decreases when accounting for genetics. Future studies using a twin design with larger samples should be conducted to further test these findings. Copyright © 2017 Elsevier Inc. All

  20. A Study of Sedentary Behaviour in the Older Finnish Twin Cohort: A Cross Sectional Analysis

    Directory of Open Access Journals (Sweden)

    Maarit Piirtola

    2014-01-01

    Full Text Available The aim of the study was to investigate the effects of age, sex, and body mass index (BMI on total sitting time among the Finnish twin cohort. Also, heritability and environmental factors were analysed. The final sample included 6713 twin individuals 53–67 years of age (46% men. Among them there were 1940 complete twin pairs (732 monozygotic [MZ] and 1208 dizygotic [DZ] twin pairs. Sedentary behaviour was queried with a self-reported questionnaire with multiple-choice questions about sitting time at different domains. The mean total sitting time per day was 6 hours 41 minutes (standard deviation: 2 hours 41 minutes. The total sitting time was less in women than in men (P=0.002. Older age was associated with less total sitting time (P<0.001. Those with higher body mass index had higher total sitting time in age and sex adjusted analysis (P<0.001. MZ pairs were more similar for sitting time than DZ pairs, with initial estimates of heritability for the total sitting time of 35%.The influence of shared environmental factors was negligible (1%, while most (64% of the variation could be ascribed to unique environmental factors, the latter including measurement error.

  1. Heritability assessment of cartilage metabolism. A twin study on circulating procollagen IIA N-terminal propeptide (PIIANP)

    DEFF Research Database (Denmark)

    Munk, H L; Svendsen, A J; Hjelmborg, J V B;

    2014-01-01

    OBJECTIVE: The aim of this investigation was to estimate the heritability of circulating collagen IIA N-terminal propeptide (PIIANP) by studying mono- and dizygotic healthy twin pairs at different age and both genders. DESIGN: 598 monozygotic (MZ) and dizygotic (DZ) twin individuals aged 18......-59 years were recruited from the Danish Twin Registry. PIIANP was measured by competitive ELISA. The similarity of circulating PIIANP among MZ and DZ twins was assessed by intraclass correlations according to traits. The heritability was estimated by variance component analysis accounting for additive...... and dominant genetic factors as well as shared and non-shared environment but ignoring epistasis (genetic inter-locus interaction) and gene-environment interaction. RESULTS: The intraclass correlation of PIIANP in MZ and DZ twins was 0.69 (0.60-0.76) and 0.46 (0.34-0.58) respectively indicating a significant...

  2. Co-twin study of the effect of environment and dietary elements on acquisition of Helicobacter pylori infection.

    Science.gov (United States)

    Malaty, H M; Graham, D Y; Isaksson, I; Engstrand, L; Pedersen, N L

    1998-10-15

    The rate of Helicobacter pylori infection is inversely related to socioeconomic status, and childhood is thought to be the major acquisition period. The authors investigated the importance of childhood environment in the acquisition of H. pylori infection. A cross-sectional study was conducted of monozygotic and dizygotic twins who were reared apart or reared together. Three hundred twins from a subregistry of the Swedish Twin Registry were studied. H. pylori status was evaluated by using an enzyme-linked immunosorbent assay for anti-H. pylori immunoglobulin G. Socioeconomic status during childhood was assessed on the basis of the density of the living conditions and the economic situation of the family that reared the twins. Current socioeconomic status was estimated by using a scale that combined income and education. Dietary elements that were studied included fat and fiber intake and ascorbic acid consumption. The density of the childhood home was consistently found to be significantly associated with the acquisition of H. pylori infection (p = 0.04). Among monozygotic twins reared apart and discordant for H. pylori status, affected twins were raised in homes under poorer socioeconomic conditions than those of their unaffected co-twins (p = 0.02). Additionally, infected twins consumed more ascorbic acid than their unaffected co-twins (p = 0.04). The finding of an effect of socioeconomic status during childhood on the acquisition of H. pylori among monozygotic twins who were reared apart and had an identical genetic makeup but not a common environment confirms the hypothesis that childhood acquisition of H. pylori infection is linked to hygiene practices.

  3. Delivery in Twin Gestation

    Directory of Open Access Journals (Sweden)

    Mark T. Peters

    1995-01-01

    Full Text Available Objective: The objective of this study was to determine whether prophylactic treatment with oral broad-spectrum antimicrobial therapy improves pregnancy outcomes in twin gestations.

  4. The Roots of Autism and ADHD Twin Study in Sweden (RATSS).

    Science.gov (United States)

    Bölte, Sven; Willfors, Charlotte; Berggren, Steve; Norberg, Joakim; Poltrago, Lina; Mevel, Katell; Coco, Christina; Fransson, Peter; Borg, Jacqueline; Sitnikov, Rouslan; Toro, Roberto; Tammimies, Kristiina; Anderlid, Britt-Marie; Nordgren, Ann; Falk, Anna; Meyer, Urs; Kere, Juha; Landén, Mikael; Dalman, Christina; Ronald, Angelica; Anckarsäter, Henrik; Lichtenstein, Paul

    2014-06-01

    Neurodevelopmental disorders affect a substantial minority of the general population. Their origins are still largely unknown, but a complex interplay of genetic and environmental factors causing disturbances of the central nervous system's maturation and a variety of higher cognitive skills is presumed. Only limited research of rather small sample size and narrow scope has been conducted in neurodevelopmental disorders using a twin-differences design. The Roots of Autism and ADHD Twin Study in Sweden (RATSS) is an ongoing project targeting monozygotic twins discordant for categorical or dimensional autistic and inattentive/hyperactive-impulsive phenotypes as well as other neurodevelopmental disorders, and typically developing twin controls. Included pairs are 9 years of age or older, and comprehensively assessed for psychopathology, medical history, neuropsychology, and dysmorphology, as well as structural, functional, and molecular brain imaging. Specimens are collected for induced pluripotent (iPS) and neuroepithelial stem cells, genetic, gut bacteria, protein-/monoamine, and electron microscopy analyses. RATSS's objective is to generate a launch pad for novel surveys to understand the complexity of genotype-environment-phenotype interactions in autism spectrum disorder and attention-deficit hyperactivity disorder (ADHD). By October 2013, RATSS had collected data from 55 twin pairs, among them 10 monozygotic pairs discordant for autism spectrum disorder, seven for ADHD, and four for other neurodevelopmental disorders. This article describes the design, recruitment, data collection, measures, collected pairs' characteristics, as well as ongoing and planned analyses in RATSS. Potential gains of the study comprise the identification of environmentally mediated biomarkers, the emergence of candidates for drug development, translational modeling, and new leads for prevention of incapacitating outcomes.

  5. Path analytic, sib-pair linkage and co-twin control studies of asthma and atopy

    Energy Technology Data Exchange (ETDEWEB)

    Duffy, D.L.; Healey, S.C.; Martin, N.G. [Queensland Institute of Medical Research, Brisband (Austria)

    1994-09-01

    Asthma and atopy are complex traits with multifactorial determinants, and require appropriate choice of phenotypes and analyses, including a linkage analysis of the putative 11q atopy locus. Participants in a large registry-based twin study of asthma were invited to take part in clinical testing. A total of 863 individuals including 419 complete twin pairs (where one or both members reported a history of wheeze) underwent histamine inhalation challenge, allergen skin prick testing, and venesection. Total serum immunoglobulin E (IgE) and bronchial responsiveness (BR) to histamine were highest in those who had wheezed most recently, and whose skin tests demonstrated allergy to house dust mite, cockroach, and rye grass. In ascertainment-corrected path analyses (FISHER), the heritability of IgE and BR were both 60%. Monozygotic (MZ) co-twin control analyses suggested house dust mite sensitization was the single strongest environmentally controlled risk factor for wheeze, while path analyses suggested genetic determination. In dizygotic (DZ) co-twin control analyses, sensitization to grasses was also an important predictor, suggesting pollinosis to be genetically correlated with wheezing, rather than causative. Multivariate path analyses suggested separate (correlated) genetic factors for BR, IgE, and allergy to house dust mite. A sib-pair (Haseman-Elston) linkage analysis of 220 DZ twin pairs did not support linkage to the high-affinity IgE receptor beta-subunit gene on 11q13 of atopy or BR. More recent linkage analyses that include parental genotyping will also be discussed. We conclude that the atopic phenotype consists of a number of traits with specific genetic allergens. Exposure to particular allergens can then cause specific outcomes, such as asthma.

  6. Healthy co-twins of patients with affective disorders show reduced risk-related activation of the insula during a monetary gambling task

    DEFF Research Database (Denmark)

    Macoveanu, Julian; Miskowiak, Kamilla; Kessing, Lars V

    2016-01-01

    brain. RESULTS: We included 30 monozygotic and 37 dizygotic twins in our analysis. Neural activity in the anterior insula and ventral striatum increased linearly with the amount of gambling risk in the entire cohort. Individual neuroticism scores were positively correlated with the neural response...

  7. Healthy co-twins of patients with affective disorders show reduced risk-related activation of the insula during a monetary gambling task

    DEFF Research Database (Denmark)

    Macoveanu, Julian; Miskowiak, Kamilla; Kessing, Lars V

    2015-01-01

    brain. RESULTS: We included 30 monozygotic and 37 dizygotic twins in our analysis. Neural activity in the anterior insula and ventral striatum increased linearly with the amount of gambling risk in the entire cohort. Individual neuroticism scores were positively correlated with the neural response...

  8. Twins Early Development Study (TEDS): a genetically sensitive investigation of cognitive and behavioral development from childhood to young adulthood.

    Science.gov (United States)

    Haworth, Claire M A; Davis, Oliver S P; Plomin, Robert

    2013-02-01

    The Twins Early Development Study (TEDS) is a large longitudinal sample of twins born in England and Wales between 1994 and 1996. The focus of TEDS has been on cognitive and behavioral development, including difficulties in the context of normal development. TEDS began when multiple births were identified from birth records and the families were invited to take part in the study; 16,810 pairs of twins were originally enrolled in TEDS. More than 10,000 of these twin pairs remain enrolled in the study to date. DNA has been collected for more than 7,000 pairs, and genome-wide genotyping data for two million DNA markers are available for 3,500 individuals. The TEDS families have taken part in studies when the twins were aged 2, 3, 4, 7, 8, 9, 10, 12, 14, and 16 years of age. Data collection is currently underway to assess the adult destinations of the twins as they move from school to university and the workplace. Between January 2012 and December 2014, all of the TEDS twins will turn 18, and the study will transition to an adult sample. TEDS represents an outstanding resource for investigating the developmental effects of genes and environments on complex quantitative traits from childhood to young adulthood and beyond.

  9. Feature Discretization for Individuality Representation in Twins Handwritten Identification

    Directory of Open Access Journals (Sweden)

    Bayan O. Mohammed

    2011-01-01

    Full Text Available Problem statement: The study on twins is an important form of study in the forensic and biometrics field as twins share similar genetic traits. Handwriting is one of the common types of forensic evidence. Differentiating the similarities of writing of a pair of twins is critical in establishing the reliability of handwriting identification. Writing style can be used as biometric features in authenticating individual uniqueness where these unique features can be used to identify the writer, including between a pair of twins. Existing works in Writer Identification concentrate on feature extraction and the classification task in order to identify authorship. The high similarity in a pair of twins’ handwriting may degrade classification performance. There should be some standards to represent these unique features before entering into the classification task which is with the use of discretization technique. Approach: We proposed a new framework for writer identification in terms of identifying twins' handwriting and showed the effect of discretization process on handwriting samples of a pair of twins in order to obtain individual identification. Results: An experiment has been done at the Sulaimania University in Iraq with fourteen pairs of identical twins where each twin provides 4 samples of handwriting for the purpose of data collecting. These samples were implemented in this research making a comparison between the new proposed framework and classic framework. Conclusion: Our experimental results showed that with new framework identification of handwriting of a pair of twins can be improved through the discretization process.

  10. X Chromosome inactivation pattern is not associated with interindividual variations in thyroid volume: a study of euthyroid danish female twins

    DEFF Research Database (Denmark)

    Brix, Thomas Heiberg; Hansen, Pia Skov; Bennedbak, Finn Noe

    2009-01-01

    Ahigher frequency of skewed X chromosome inactivation (XCI) is found in patients with autoimmune thyroid disease (AITD) than in controls. Although goitre is often present in AITD, a recent study failed to show an association between XCI and clinically overt nontoxic goitre. However, the etiology...... of overt goitre is complex, and the mechanisms influencing thyroid volume may involve fewer factors than the mechanisms underlying overt goitre. In order to examine the impact of XCI on thyroid volume in euthyroid females, we studied whether within cohort (n = 138) and within twin pair (n = 69) differences...

  11. The influence of general anesthesia and surgery on cognition in old age: A twin study

    DEFF Research Database (Denmark)

    Dokkedal, Unni; Hansen, Tom G.; Rasmussen, Lars S;

    Introduction: There is a pronounced variation in level of cognitive function and rate of cognitive decline in late life. Results from smaller human and animal studies suggest that exposure to anesthesia may be a risk factor for cognitive impairment. Using a twin design, the objective of the present...... study was to examine whether exposure to anesthesia and surgery is associated with level of cognitive function in middle and old age. Materials and Methods: The study is based on two population-based surveys comprising 8,503 Danish twins aged 45–102 years at study intake during 1995–2001. Through...... linkage to the Danish National Patient Register, we obtained information on surgeries performed in hospitals in Denmark from 1977 and until study intake. Four exposure groups were defined based on type of surgery (major, minor, knee and hip replacement, other). A cognitive test battery consisting of five...

  12. Infant Reactivity to Redundant Proprioceptive and Auditory Stimulation: A Twin Study.

    Science.gov (United States)

    Van den Daele, Leland D.

    The role of genetic factors in infant response to redundancy was evaluated through observation of the behavior of three sets of same-sex fraternal twins and six sets of same-sex identical twins to combinations of redundant proprioceptive and auditory stimulation. The twins ranged in age from 6 weeks to 24 weeks. One member of each twin set was…

  13. Vascular programming in twins: the effects of chorionicity and fetal therapy for twin-to-twin transfusion syndrome.

    Science.gov (United States)

    Gardiner, H M; Barlas, A; Matsui, H; Diemert, A; Taylor, M J O; Preece, J; Gordon, F; Greenwald, S E; Hecher, K

    2012-06-01

    We assessed vascular programming in genetically identical monochorionic twin pairs with twin-to-twin transfusion syndrome (TTTS) treated differently in utero by serial amnioreduction or fetal laser arterial photocoagulation. This case-control study re-assessed four twin groups at median 11 years comprising 20 pairs of monochorionic diamniotic twins: nine treated by amnioreduction (TTTS-amnio) and eleven by laser (TTTS-laser) with seven monochorionic and six dichorionic control pairs. Outcome measures were current blood pressure (BP), brachio-radial arterial stiffness derived from pulse wave velocity (PWV), resting microcirculation (Flux) and response to heating and post-occlusive reactive hyperaemia measured using laser Doppler. Potential confounders [PWV and BP at first study, current height, weight, heart rate and twin type (ex-recipient, ex-donor or heavier/lighter of pair)] were accounted for by Mixed Linear Models statistical methodology. PWV dichorionic > monochorionic (P = 0.024); systolic and diastolic BP dichorionic > TTTS-amnio and TTTS-laser (P = 0.004, P = 0.02 and P = 0.005, P = 0.02, respectively). Within-twin pair pattern of PWV discordance was similar in laser treated and dichorionic controls (heavier-born > lighter), opposite to TTTS-amnio and monochorionic controls. Flux monochorionic > dichorionic (P = 0.044) and heavier > lighter-born (P = 0.024). TTTS-laser and dichorionic diamniotic showed greatest hyperaemic responses (dichorionic > TTTS-amnio or monochorionic controls (P = 0.007, P = 0.025). Hyperaemic responses were slower in heavier-born twins (P = 0.005). In summary, monochorionic twins had lower BP, arterial stiffness and increased resting vasodilatation than dichorionic twins implying shared fetal circulation affects vascular development. Vascular responses in laser-TTTS were similar to dichorionic and opposite to TTTS-amnio suggesting a lasting effect of fetal therapy on vascular health.

  14. Heritability of refractive astigmatism: a population-based twin study among 63- to 75-year-old female twins.

    Science.gov (United States)

    Pärssinen, Olavi; Kauppinen, Markku; Kaprio, Jaakko; Koskenvuo, Markku; Rantanen, Taina

    2013-09-09

    To examine the heritability of refractive astigmatism in older women. Astigmatism was measured with an autorefractor in 88 monozygotic and 82 dizygotic female twin pairs aged 63 to 75 years. The prevalence and distribution of astigmatism and polar values J0 and J45 were estimated by standard statistical methods. Bivariate maximum likelihood model fitting was used to estimate genetic and environmental variance components using information from both eyes. Mean astigmatism of the more astigmatic eye was 0.93 diopters (D; SD ±0.58). Astigmatism of at least 0.25 D, 0.5 D, 0.75 D, or 1.0 D in either eye was present in 99.7%, 88.5%, 66.5%, and 46.2% of cases, respectively. The main direction of astigmatism was against the rule. The age-adjusted quantitative genetic modeling revealed that additive genetic effects accounted for 33.3% (95% confidence interval [CI], 21.9%-43.8%) of the total variance of astigmatism and for 18% (95% CI, 4%-31%) of the total variance of polar value J45 of both eyes (bivariate model), with the remaining variances due to nongenetic effects. There were no significant correlations between the twin pairs for polar value J0. In elderly female twins, additive genetic effects accounted for one-third of the variance of the amount of astigmatism and only a small fraction of the total variance of polar value J45.

  15. Genetics of dietary habits and obesity - a twin study

    DEFF Research Database (Denmark)

    Hasselbalch, Ann Louise

    2010-01-01

    influences on dietary intake in adults and the interplay between diet, genes and obesity. The focus of the thesis was to investigate the genetic and environmental influence on habitual diet and obesity as well as the association between habitual diet and anthropometry. The thesis is based on structural....... The study showed, however, consistent positive associations between intake of sugar-sweetened soft drink and BMI, FMI and waist circumference in men. Gene-environment interaction models showed that while high physical activity is associated with a down-regulation of genes predisposing to obesity......Obesity has become a major health concern due to the increased risk of co-morbidities, resulting in decreased quality of life, stigmatization, reduced working ability and early death. This causes a great challenge for the health care systems and results in increased direct costs related...

  16. Education in Twins and Their Parents Across Birth Cohorts Over 100 years: An Individual-Level Pooled Analysis of 42-Twin Cohorts.

    Science.gov (United States)

    Silventoinen, Karri; Jelenkovic, Aline; Latvala, Antti; Sund, Reijo; Yokoyama, Yoshie; Ullemar, Vilhelmina; Almqvist, Catarina; Derom, Catherine A; Vlietinck, Robert F; Loos, Ruth J F; Kandler, Christian; Honda, Chika; Inui, Fujio; Iwatani, Yoshinori; Watanabe, Mikio; Rebato, Esther; Stazi, Maria A; Fagnani, Corrado; Brescianini, Sonia; Hur, Yoon-Mi; Jeong, Hoe-Uk; Cutler, Tessa L; Hopper, John L; Busjahn, Andreas; Saudino, Kimberly J; Ji, Fuling; Ning, Feng; Pang, Zengchang; Rose, Richard J; Koskenvuo, Markku; Heikkilä, Kauko; Cozen, Wendy; Hwang, Amie E; Mack, Thomas M; Siribaddana, Sisira H; Hotopf, Matthew; Sumathipala, Athula; Rijsdijk, Fruhling; Sung, Joohon; Kim, Jina; Lee, Jooyeon; Lee, Sooji; Nelson, Tracy L; Whitfield, Keith E; Tan, Qihua; Zhang, Dongfeng; Llewellyn, Clare H; Fisher, Abigail; Burt, S Alexandra; Klump, Kelly L; Knafo-Noam, Ariel; Mankuta, David; Abramson, Lior; Medland, Sarah E; Martin, Nicholas G; Montgomery, Grant W; Magnusson, Patrik K E; Pedersen, Nancy L; Dahl Aslan, Anna K; Corley, Robin P; Huibregtse, Brooke M; Öncel, Sevgi Y; Aliev, Fazil; Krueger, Robert F; McGue, Matt; Pahlen, Shandell; Willemsen, Gonneke; Bartels, Meike; van Beijsterveldt, Catharina E M; Silberg, Judy L; Eaves, Lindon J; Maes, Hermine H; Harris, Jennifer R; Brandt, Ingunn; Nilsen, Thomas S; Rasmussen, Finn; Tynelius, Per; Baker, Laura A; Tuvblad, Catherine; Ordoñana, Juan R; Sánchez-Romera, Juan F; Colodro-Conde, Lucia; Gatz, Margaret; Butler, David A; Lichtenstein, Paul; Goldberg, Jack H; Harden, K Paige; Tucker-Drob, Elliot M; Duncan, Glen E; Buchwald, Dedra; Tarnoki, Adam D; Tarnoki, David L; Franz, Carol E; Kremen, William S; Lyons, Michael J; Maia, José A; Freitas, Duarte L; Turkheimer, Eric; Sørensen, Thorkild I A; Boomsma, Dorret I; Kaprio, Jaakko

    2017-10-01

    Whether monozygotic (MZ) and dizygotic (DZ) twins differ from each other in a variety of phenotypes is important for genetic twin modeling and for inferences made from twin studies in general. We analyzed whether there were differences in individual, maternal and paternal education between MZ and DZ twins in a large pooled dataset. Information was gathered on individual education for 218,362 adult twins from 27 twin cohorts (53% females; 39% MZ twins), and on maternal and paternal education for 147,315 and 143,056 twins respectively, from 28 twin cohorts (52% females; 38% MZ twins). Together, we had information on individual or parental education from 42 twin cohorts representing 19 countries. The original education classifications were transformed to education years and analyzed using linear regression models. Overall, MZ males had 0.26 (95% CI [0.21, 0.31]) years and MZ females 0.17 (95% CI [0.12, 0.21]) years longer education than DZ twins. The zygosity difference became smaller in more recent birth cohorts for both males and females. Parental education was somewhat longer for fathers of DZ twins in cohorts born in 1990-1999 (0.16 years, 95% CI [0.08, 0.25]) and 2000 or later (0.11 years, 95% CI [0.00, 0.22]), compared with fathers of MZ twins. The results show that the years of both individual and parental education are largely similar in MZ and DZ twins. We suggest that the socio-economic differences between MZ and DZ twins are so small that inferences based upon genetic modeling of twin data are not affected.

  17. What monozygotic twins discordant for phenotype illustrate about mechanisms influencing genetic forms of neurodegeneration

    NARCIS (Netherlands)

    Ketelaar, M. E.; Hofstra, R. M. W.; Hayden, M. R.

    2012-01-01

    As monozygotic (MZ) twins are believed to be genetically identical, discordance for disease phenotype between MZ twins has been used in genetic research to understand the contribution of genetic vs environmental factors in disease development. However, recent studies show that MZ twins can differ bo

  18. Cancer risk in opposite-sex and same-sex twins

    DEFF Research Database (Denmark)

    Juel Ahrenfeldt, Linda

    2015-01-01

    Twin pregnancies are characterized by simultaneous development of two fetuses that share the womb. An interest in opposite-sex (OS) twins, twin pairs consisting of one male and one female, comes from animal studies that showed that exposure to sex hormones is influenced by the position of the fetus...

  19. Genetic and environmental influences on individual differences in attitudes toward homosexuality: an Australian twin study.

    Science.gov (United States)

    Verweij, Karin J H; Shekar, Sri N; Zietsch, Brendan P; Eaves, Lindon J; Bailey, J Michael; Boomsma, Dorret I; Martin, Nicholas G

    2008-05-01

    Previous research has shown that many heterosexuals hold negative attitudes toward homosexuals and homosexuality (homophobia). Although a great deal of research has focused on the profile of homophobic individuals, this research provides little theoretical insight into the aetiology of homophobia. To examine genetic and environmental influences on variation in attitudes toward homophobia, we analysed data from 4,688 twins who completed a questionnaire concerning sexual behaviour and attitudes, including attitudes toward homosexuality. Results show that, in accordance with literature, males have significantly more negative attitudes toward homosexuality than females and non-heterosexuals are less homophobic than heterosexuals. In contrast with some earlier findings, age had no significant effect on the homophobia scores in this study. Genetic modelling showed that variation in homophobia scores could be explained by additive genetic (36%), shared environmental (18%) and unique environmental factors (46%). However, corrections based on previous findings show that the shared environmental estimate may be almost entirely accounted for as extra additive genetic variance arising from assortative mating for homophobic attitudes. The results suggest that variation in attitudes toward homosexuality is substantially inherited, and that social environmental influences are relatively minor.

  20. Malaysian Twin Registry.

    Science.gov (United States)

    Jahanfar, Shayesteh; Jaffar, Sharifah Halimah

    2013-02-01

    The National Malaysian Twin Registry was established in Royal College of Medicine, Perak, University Kuala Lumpur (UniKL) in June 2008 through a grant provided by UniKL. The general objective is to facilitate scientific research involving participation of twins and their family members in order to answer questions of health and wellbeing relevant to Malaysians. Recruitment is done via mass media, poster, and pamphlets. We now have 266 adult and 204 children twins registered. Several research projects including reproductive health study of twins and the role of co-bedding on growth and development of children are carried out. Registry holds annual activities for twins and seeks to provide health-related information for twins. We seek international collaboration.

  1. [A 20-year follow-up study of a sample of 50 pairs of twins with neurotic-psychosomatic disorders].

    Science.gov (United States)

    Muhs, A; Schepank, H; Manz, R

    1990-01-01

    As part of a research project, examination was made of a sample of 50 pairs of twins (21 pairs of identical twins, 16 pairs of non-identical twins of the same sex, and 13 pairs of male-female twins [n = 100 test persons]) between 1963 and 1969 and again recently after a period of 20 years. The index twins were drawn from among the patients who made use of the services of an out-patient psychotherapeutic clinic, and they were determined to be either psychoneurotic, character neurotic, or psychosomatically ill. The question examined was again one of nature vs. nurture. Identical twins showed a significantly higher similarity with regard to the seriousness of their neuroses and the manifestation of neurotic symptoms than did non-identical twins. Noticeable similarities existed in cases of depressive disturbances, disturbances of oral and aggressive behavior, and disturbances of interpersonal contact. With regard to the influence of variables in the environment, we examined the effect of factors in early childhood on neurotic development. Lack of a reference person, a negative attitude on the part of parents toward the child, etc., frustration within and outside the family have an effect on the manifestation of neuroses and on the course of their development. The influence of early childhood factors on the degree of neurotic disorder is still to be noted in the current point prevalence.

  2. Induction of twin pregnancy and the risk of caesarean delivery: a cohort study.

    Science.gov (United States)

    Jonsson, Maria

    2015-06-16

    Complications are common in twin pregnancies and induction of labour is often indicated. Most methods for induction are used but data on risks related to induction methods are sparse. The aim of this study was to investigate the association between induction of labour and caesarean delivery in twin pregnancies, and to assess the influence of induction method. Cohort study of twin pregnancies ≥ 34 weeks, planned for vaginal delivery, from two University Hospitals in Sweden. Data were collected from medical records during the periods 1994 (Örebro) and 2004 (Uppsala) to 2013. During the study period there were 78,180 live born births and 1,282 were twin births. Women with previous caesarean section were excluded. Induction methods were categorized into amniotomy, oxytocin and cervical ripening (intra cervical Foley catheter or prostaglandin). Adjusted odds ratios (AOR) with 95 % confidence interval (CI) for caesarean section were calculated by logistic regression and were adjusted for parity, maternal age, gestational length, complications to the pregnancy, infant birth weight and year of birth. Spontaneous labour onsets were used as the reference group. The main outcome measure was caesarean section. In 462 twin pregnancies, 220 (48 %) had induction of labour and 242 (52 %) a spontaneous labour onset. Amniotomy was performed in 149 (68 %) of these inductions, oxytocin was administered in 11 (5 %) and cervical ripening was used in 60 (27 %). The rate of caesarean sections was 21 % in induced and 12 % in spontaneous labours (p 0.01). The absolute risk of caesarean section following induction was: 15 % with amniotomy; 36 % with oxytocin and 37 % with Foley/prostaglandin. Induction of labour increased the risk of caesarean section by 90 % compared with spontaneous labour onset (AOR 1.9, 95 % CI 1.1-3.5) and, when cervical ripening was used, the risk increased more than two fold (AOR 2.5, 95 % CI 1.2-5.3). Induction of labour in twin pregnancies increases the risk of

  3. Secular change in 13 metabolic phenotypes: A Chinese longitudinal twin study

    DEFF Research Database (Denmark)

    Li, Shuxia; Pang, Zengchang; Zhang, Dongfeng

    in prospective investigations. Based on Chinese twin data collected from Danish-Chinese collaboration research, we perform twin modeling on 13 metabolic phenotypes (total cholesterol; triglyceride; high density lipoprotein (HDL); low density lipoprotein (LDL); urine acid (UA); glucose; weight; body mass index...... fitted to the secular changes in each of the 13 phenotypes with best fitting model selected based on model performance. Age and sex were included as covariates in the models to adjust for their effects on secular trend. Results: Variations in secular change in 3 lipids (total cholesterol; triglyceride...... environmental factors. Secular changes in all phenotypes are under moderate to high (e2: 0.45 - 0.79) control by unique environmental factors. Conclusions: Variations in secular change in the 13 metabolic phenotypes show limited genetic control. Our results emphasize the special importance of unique environment...

  4. The Brazilian Twin Registry.

    Science.gov (United States)

    Ferreira, Paulo H; Oliveira, Vinicius C; Junqueira, Daniela R; Cisneros, Lígia C; Ferreira, Lucas C; Murphy, Kate; Ordoñana, Juan R; Hopper, John L; Teixeira-Salmela, Luci F

    2016-12-01

    The Brazilian Twin Registry (BTR) was established in 2013 and has impelled twin research in South America. The main aim of the initiative was to create a resource that would be accessible to the Brazilian scientific community as well as international researchers interested in the investigation of the contribution of genetic and environmental factors in the development of common diseases, phenotypes, and human behavior traits. The BTR is a joint effort between academic and governmental institutions from Brazil and Australia. The collaboration includes the Federal University of Minas Gerais (UFMG) in Brazil, the University of Sydney and University of Melbourne in Australia, the Australian Twin Registry, as well as the research foundations CNPq and CAPES in Brazil. The BTR is a member of the International Network of Twin Registries. Recruitment strategies used to register twins have been through participation in a longitudinal study investigating genetic and environmental factors for low back pain occurrence, and from a variety of sources including media campaigns and social networking. Currently, 291 twins are registered in the BTR, with data on demographics, zygosity, anthropometrics, and health history having been collected from 151 twins using a standardized self-reported questionnaire. Future BTR plans include the registration of thousands of Brazilian twins identified from different sources and collaborate nationally and internationally with other research groups interested on twin studies.

  5. Twin births

    DEFF Research Database (Denmark)

    Hoffmann, Elise; Oldenburg, Anna; Rode, Line;

    2012-01-01

    To assess morbidity and mortality in twin pregnancy deliveries, according to chorionicity and mode of delivery.......To assess morbidity and mortality in twin pregnancy deliveries, according to chorionicity and mode of delivery....

  6. Tribute to dr louis keith: twin and physician extraordinaire/twin research reports: influences on asthma severity; chimerism revisited; DNA strand break repair/media reports: twins born apart; elevated twin frequencies; celebrity father of twins; conjoined twinning.

    Science.gov (United States)

    Segal, Nancy L

    2014-10-01

    The International Society for Twin Studies has lost a valued friend and colleague. Dr Louis Keith, Emeritus Professor of Obstetrics and Gynecology at Northwestern University, in Chicago, passed away on Sunday, July 6, 2014. His life and work with twins will be acknowledged at the November 2014 International Twin Congress in Budapest, Hungary. Next, twin research reports on the severity of asthma symptoms, a case of chimerism, and factors affecting DNA breakage and repair mechanisms are reviewed. Media reports cover twins born apart, elevated twin frequencies, a celebrity father of twins, and a family's decision to keep conjoined twins together.

  7. Genetic and environmental influence on DNA strand break repair: a twin study

    DEFF Research Database (Denmark)

    Garm, Christian; Moreno-Villanueva, Maria; Bürkle, Alexander

    2013-01-01

    factors are likely to influence DNA repair capacity. In order to gain more insight into the genetic and environmental contribution to the molecular basis of DNA repair, we have performed a human twin study, where we focused on the consequences of some of the most abundant types of DNA damage (single......Accumulation of DNA damage deriving from exogenous and endogenous sources has significant consequences for cellular survival, and is implicated in aging, cancer, and neurological diseases. Different DNA repair pathways have evolved in order to maintain genomic stability. Genetic and environmental......-strand breaks), and some of the most hazardous lesions (DNA double-strand breaks). DNA damage signaling response (Gamma-H2AX signaling), relative amount of endogenous damage, and DNA-strand break repair capacities were studied in peripheral blood mononuclear cells from 198 twins (94 monozygotic and 104...

  8. The contribution of diet and genotype to iron status in women: a classical twin study.

    Directory of Open Access Journals (Sweden)

    Susan J Fairweather-Tait

    Full Text Available This is the first published report examining the combined effect of diet and genotype on body iron content using a classical twin study design. The aim of this study was to determine the relative contribution of genetic and environmental factors in determining iron status. The population was comprised of 200 BMI- and age-matched pairs of MZ and DZ healthy twins, characterised for habitual diet and 15 iron-related candidate genetic markers. Variance components analysis demonstrated that the heritability of serum ferritin (SF and soluble transferrin receptor was 44% and 54% respectively. Measured single nucleotide polymorphisms explained 5% and selected dietary factors 6% of the variance in iron status; there was a negative association between calcium intake and body iron (p = 0.02 and SF (p = 0.04.

  9. Attachment to the Romantic Partner and Sibling: Attachment Hierarchies of Twins and Non-Twin Siblings

    Directory of Open Access Journals (Sweden)

    Sascha Schwarz

    2015-12-01

    Full Text Available Previous studies have shown that romantic partners and siblings are important attachment figures. This study compares the attachment to the romantic partner with the attachment to the sibling as a function of the participant’s sibling type among monozygotic (MZ twins, dizygotic (DZ twins, and non-twin (NT siblings. The results show that MZ twins prefer their sibling to their romantic partner whereas DZ twins are equally attached to their sibling and romantic partner. In contrast, NT siblings are more attached to their romantic partner compared to their sibling. These results indicate that genetic relatedness has profound impact on a person’s attachment hierarchy and the relative rank of the romantic partner and the sibling.

  10. Methylation matters? Decreased methylation status of genomic DNA in the blood of schizophrenic twins.

    Science.gov (United States)

    Bönsch, Dominikus; Wunschel, Michael; Lenz, Bernd; Janssen, Gesa; Weisbrod, Matthias; Sauer, Heinrich

    2012-08-15

    Studies of schizophrenia inheritance in identical twins show a concordance of about 50%, which supports an epigenetic model. In our present study we investigated methylation of genomic DNA and promoter methylation of Reelin and SOX10 genes in peripheral blood of twins suffering from schizophrenia. Global DNA methylation was reduced (52.3%) in schizophrenic twins if compared with healthy control twins (65.7%). The reduced methylation was significant in males only. We also found a similar hypomethylation in the non-affected twins of discordant pairs and a mixed group of psychiatric controls. In discordant twins there was a relative hypermethylation of the SOX10 promoter. Within-pair-difference of methylation of Reelin promoter was significantly lower in monozygotic twins than in dizygotic twins.

  11. Genetic Factors Explain Variation in the Age at Onset of Psoriasis: A Population-based Twin Study.

    Science.gov (United States)

    Lønnberg, Ann Sophie; Skov, Lone; Duffy, David Lorenzo; Skytthe, Axel; Kyvik, Kirsten Ohm; Pedersen, Ole Birger; Thomsen, Simon Francis

    2016-01-01

    The aim of this study was to determine the age at onset of psoriasis in a population-based twin sample. Questionnaire-data in 10,725 twin pairs, 20-71 years of age, from the Danish Twin Registry, was collected, and analysed using survival regression analysis. Median age at onset was 25 and 28 years among women and men, respectively. The correlation between the ages was 0.84 (bootstrap standard error?=?0.044) in monozygotic twin pairs and 0.60 (0.051) in dizygotic twin pairs, permutation p?=?0.001. Age at onset of psoriasis in the index twin did not predict risk of psoriasis in the co-twin, hazard ratio (per year of later onset =?1.01 (0.99-1.03), p?=?0.434. In conclusion, these data support that the age at onset of psoriasis is, in part, an inherited property. Our results do not support that early-onset psoriasis is more genetically determined.

  12. In situ study of defect migration kinetics and self-healing of twin boundaries in heavy ion irradiated nanotwinned metals.

    Science.gov (United States)

    Li, J; Yu, K Y; Chen, Y; Song, M; Wang, H; Kirk, M A; Li, M; Zhang, X

    2015-05-13

    High energy particles introduce severe radiation damage in metallic materials, such as Ag. Here we report on the study on twin boundary (TB) affected zone in irradiated nanotwinned Ag wherein time accumulative defect density and defect diffusivity are substantially different from those in twin interior. In situ studies also reveal surprising resilience and self-healing of TBs in response to radiation. This study provides further support for the design of radiation-tolerant nanotwinned metallic materials.

  13. Associations Between Fast-Food Consumption and Body Mass Index: A Cross-Sectional Study in Adult Twins.

    Science.gov (United States)

    Cohen-Cline, Hannah; Lau, Richard; Moudon, Anne V; Turkheimer, Eric; Duncan, Glen E

    2015-08-01

    Obesity is a substantial health problem in the United States, and is associated with many chronic diseases. Previous studies have linked poor dietary habits to obesity. This cross-sectional study aimed to identify the association between body mass index (BMI) and fast-food consumption among 669 same-sex adult twin pairs residing in the Puget Sound region around Seattle, Washington. We calculated twin-pair correlations for BMI and fast-food consumption. We next regressed BMI on fast-food consumption using generalized estimating equations (GEE), and finally estimated the within-pair difference in BMI associated with a difference in fast-food consumption, which controls for all potential genetic and environment characteristics shared between twins within a pair. Twin-pair correlations for fast-food consumption were similar for identical (monozygotic; MZ) and fraternal (dizygotic; DZ) twins, but were substantially higher in MZ than DZ twins for BMI. In the unadjusted GEE model, greater fast-food consumption was associated with larger BMI. For twin pairs overall, and for MZ twins, there was no association between within-pair differences in fast-food consumption and BMI in any model. In contrast, there was a significant association between within-pair differences in fast-food consumption and BMI among DZ twins, suggesting that genetic factors play a role in the observed association. Thus, although variance in fast-food consumption itself is largely driven by environmental factors, the overall association between this specific eating behavior and BMI is largely due to genetic factors.

  14. Not all risks are created equal: A twin study and meta-analyses of risk taking across seven domains.

    Science.gov (United States)

    Wang, X T Xiao-Tian; Zheng, Rui; Xuan, Yan-Hua; Chen, Jie; Li, Shu

    2016-11-01

    Humans routinely deal with both traditional and novel risks. Different kinds of risks have been a driving force for both evolutionary adaptations and personal development. This study explored the genetic and environmental influences on human risk taking in different task domains. Our approach was threefold. First, we integrated several scales of domain-specific risk-taking propensity and developed a synthetic scale, including both evolutionarily typical and modern risks in the following 7 domains: cooperation/competition, safety, reproduction, natural/physical risk, moral risk, financial risk, and gambling. Second, we conducted a twin study using the scale to estimate the contributions of genes and environment to risk taking in each of these 7 domains. Third, we conducted a series of meta-analyses of extant twin studies across the 7 risk domains. The results showed that individual differences in risk-taking propensity and its consistency across domains were mainly regulated by additive genetic influences and individually unique environmental experiences. The heritability estimates from the meta-analyses ranged from 29% in financial risk taking to 55% in safety. Supporting the notion of risk-domain specificity, both the behavioral and genetic correlations among the 7 domains were generally low. Among the relatively few correlations between pairs of risk domains, our analysis revealed a common genetic factor that regulates moral, financial, and natural/physical risk taking. This is the first effort to separate genetic and environmental influences on risk taking across multiple domains in a single study and integrate the findings of extant twin studies via a series of meta-analyses conducted in different task domains. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  15. 3D Evaluation of Palatal Rugae in Identical Twins

    Directory of Open Access Journals (Sweden)

    Emiliya Taneva

    2017-01-01

    Full Text Available The study of identical twins can point out potential limitations in biometrics and forensic odontology. This case report presents three-dimensional (3D palatal rugae analysis in monozygotic twins utilizing digital models obtained directly by scanning the maxillary dental arch with the iTero® intraoral digital scanner. The results show that the rugae patterns contain related but not identical features between the pair of identical twins. Dental study models taken on a regular basis for diagnosis and treatment planning in dentistry include the palatal rugae, which could be valuable to forensics in identical twin identification cases.

  16. 3D Evaluation of Palatal Rugae in Identical Twins.

    Science.gov (United States)

    Taneva, Emiliya; Evans, Carla; Viana, Grace

    2017-01-01

    The study of identical twins can point out potential limitations in biometrics and forensic odontology. This case report presents three-dimensional (3D) palatal rugae analysis in monozygotic twins utilizing digital models obtained directly by scanning the maxillary dental arch with the iTero® intraoral digital scanner. The results show that the rugae patterns contain related but not identical features between the pair of identical twins. Dental study models taken on a regular basis for diagnosis and treatment planning in dentistry include the palatal rugae, which could be valuable to forensics in identical twin identification cases.

  17. Twin Interactions in Pure Ti Under High Strain Rate Compression

    Science.gov (United States)

    Zhou, Ping; Xiao, Dawu; Jiang, Chunli; Sang, Ge; Zou, Dongli

    2017-01-01

    Twin interactions associated with {11 overline{2} 1} (E2) twins in titanium deformed by high strain rate ( 2600 s-1) compression were studied using electron backscatter diffraction technique. Three types of twins, {10 overline{1} 2} (E1), {11 overline{2} 2} (C1), and {11 overline{2} 4} (C3), were observed to interact with the preformed E2 twins in four parent grains. The E1 variants nucleated at twin boundaries of some E2 variants. And the C3 twins were originated from the intersection of C1 and E2. The selection of twin variant was investigated by the Schmid factors (SFs) and the twinning shear displacement gradient tensors (DGTs) calculations. The results show that twin variants that did not follow the Schmid law were more frequently observed under high strain rate deformation than quasi-static deformation. Among these low-SF active variants, 73 pct (8 out of 11) can be interpreted by DGT. Besides, 26 variants that have SF values close to or higher than their active counterparts were absent. Factors that may affect the twin variant selections were discussed.

  18. Heritability of Tpeak-Tend Interval and T-wave Amplitude: A Twin Study

    DEFF Research Database (Denmark)

    Haarmark, Christian; Kyvik, Kirsten O; Vedel-Larsen, Esben;

    2011-01-01

    BACKGROUND: -Tpeak-Tend interval (TpTe) and T-wave amplitude (Tamp) carry diagnostic and prognostic information regarding cardiac morbidity and mortality. Heart rate and QT interval are known to be heritable traits. The heritability of T-wave morphology parameters such as TpTe and Tamp is unknown....... TpTe and Tamp were evaluated in a large sample of twins. METHODS AND RESULTS: -Twins from the GEMINAKAR study (611 pairs, 246 monozygotic, 365 dizygotic, aged 38±11 years, 49 % men) who had an ECG performed during 1997-2000 were included. Tamp was measured in leads V1 and V5. Duration variables (RR...... are heritable ECG parameters....

  19. Importance of genetic factors in the occurrence of epilepsy syndrome type: a twin study

    DEFF Research Database (Denmark)

    Corey, Linda A; Pellock, John M; Kjeldsen, Marianne J

    2011-01-01

    Although there is strong evidence that genetic factors contribute to risk for epilepsy, their role in the determination of syndrome type is less clear. This study was undertaken to address this question. Information related to epilepsy was obtained from twins included in 455 monozygotic and 868...... dizygotic pairs ascertained from population-based twin registries in Denmark, Norway and the United States. Syndrome type was determined based on medical record information and detailed clinical interviews and classified using the International Classification Systems for the Epilepsies and Epileptic...... Syndromes. Concordance rates were significantly increased in monozygotic versus dizygotic pairs for all major syndrome groups except localization-related cryptogenic epilepsy. Among generalized epilepsies, genetic factors were found to play an important role in the determination of childhood absence...

  20. Complications arising in twin pregnancy: findings of prenatal ultrasonography

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jeong Ah; Cho, Jeong Yeon; Lee, Young Ho; Song, Mi Jin; Min, Jee Yeon; Lee, Hak Jong; Han, Byoung Hee; Lee, Kyung Sang; Cho, Byung Jae; Chun, Yi Kyeong [Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2003-03-01

    Multifetal gestations are high-risk pregnancies involving higher perinatal morbidity and mortality, and are subject to unique complications including twin oligohydramnios- polyhydramnios sequence, twin-to-twin transfusion syndrome, acardiac twins, conjoined twins, co-twin demise, and heterotopic pregnancies. The purpose of this study is to describe the prenatal ultrasonographic and pathologic findings of these complications.

  1. Association of β3 Adrenergic Receptor and Peroxisome Proliferator-activated Receptor Gamma 2 Polymorphisms With Insulin Sensitivity: A Twin Study

    Institute of Scientific and Technical Information of China (English)

    TIAN-JIAO CHEN; CHENG-YE JI; XIAO-YING ZHENG; YONG-HUA HU

    2007-01-01

    Objective To study the effect of β3 adrenergic receptor (β3AR) Trp64Arg and peroxisome proliferator activated receptor gamma 2 (PPARγ2) Pro12Ala polymorphisms on insulin resistance. Methods One hundred and eight dizygotic twin pairs were enrolled in this study. Microsatellite polymorphism was used to diagnose zygosity of twins. Insulin sensitivity was estimated with logarithm transformed homeostasis model assessment (HOMA). PCR-RFLP analysis was performed to detect the variants. As a supplement to the sib-pair method, identity by state (IBS) was used to analyze the association of polymorphisms with insulin sensitivity. Results The genotype frequencies of Trp64Trg, Trp64Arg, and Arg64Arg were 72.3%, 23.8%, and 3.9%, respectively, while the genotype frequencies of Pro12Pro, Pro12Ala, and Ala12Ala were 89.9%, 9.6%,and 0.5%, respectively. For β3AR Trp64Arg the interclass co-twin correlations of Waist-to-hip ratio (WHR), blood glucose (GLU), and insulin (INS), homeostasis model assessment insulin resistance index (HOMA-IR) of the twin pairs sharing 2alleles of IBS were greater than those sharing 0-1 allele of IBS, and HOMA-IR had statistic significance. For PPARγ2 Pro12Ala most traits of twin pairs sharing 2 alleles of IBS had greater correlations and statistic significance in body mass index (BMI),WHR, percent of body fat (PBF) and GLU, but there were low correlations of either insulin or HOMA-IR of twin pairs sharing 1 or 2 alleles of IBS. The combined effects of the two variations showed less squared significant twin-pair differences of INS and HOMA-IR among twins sharing 4 alleles of IBS. Conclusions β3AR Trp64Arg and PPARγ2 Pro12Ala polymorphisms might be associated with insulin resistance and obesity, and there might be slight synergistic effects between this two gene loci,and further studies are necessary to confirm this finding.

  2. Dental anxiety in relation to neuroticism and pain sensitivity. A twin study.

    Science.gov (United States)

    Vassend, Olav; Røysamb, Espen; Nielsen, Christopher S

    2011-03-01

    Predisposing personality traits as well as heightened pain sensitivity and fear of pain have been hypothesized as central factors in the development of dental anxiety. The aim of the study was to estimate the heritability of dental anxiety, and to investigate the genetic and environmental sources of covariance between dental anxiety on one hand, and pain sensitivity and the neuroticism trait on the other. A sample comprising 188 twins, aged 23-35 years (53 monozygotic and 39 dizygotic twin pairs, and 4 single twins whose co-twin did not participate), was included in the study. Measures of dental anxiety and personality were obtained using Corah's Dental Anxiety Scale and the NEO Personality Inventory Revised, respectively. Heat pain and cold pressor pain sensitivity were assessed using standard pain testing procedures. Bivariate Cholesky models were employed to decompose the correlations between phenotypes into genetic and environmental factors. Using models with common additive genetic (A) and individual-specific environmental (E) factors, moderate heritability (i.e., .41) for dental anxiety was demonstrated. Virtually all of the phenotypic correlation between neuroticism and dental anxiety could be accounted for by A. Furthermore, a substantial part of the variance in dental anxiety was due to specific genetic and individual environmental influences unrelated to neuroticism. The phenotypic correlations between dental anxiety and the pain sensitivity indices were close to zero. Thus, while neuroticism and dental anxiety share a sizeable proportion of genetic (but not environmental) risk factors, the results also suggest that these two attributes are distinct entities with overlapping, but not identical, etiologies.

  3. Reproductive factors associated with mammographic density: a Korean co-twin control study.

    Science.gov (United States)

    Sung, Joohon; Song, Yun-Mi; Stone, Jennifer; Lee, Kayoung; Lee, Donghun

    2011-07-01

    To determine the mechanism by which menstrual and reproductive factors are associated with the risk of breast cancer, we examined the relationships between mammographic density and known menstrual and reproductive risk factors for breast cancer. A co-twin control study was conducted with 122 pairs of monozygotic Korean female twins selected from the Healthy Twin study. Mammographic density was measured from digital mammograms using a computer-assisted method. Information on selected menstrual and reproductive factors was collected through a self-administered questionnaire. Within-pair differences for each mammographic measure were regressed against within-pair differences for each menstrual and reproductive risk factor with an adjustment for body mass index and other menstrual and reproductive factors. The percent dense area was inversely associated with the age at the first full-term childbirth (FFTB) and the number of live births, although the associations were marginally significant with an adjustment for BMI and other reproductive factors. The non-dense area was positively associated with the age at the FFTB and the number of live births. The absolute dense area was positively associated with the duration of breast feeding. The age at menarche was not associated with any component of the mammographic measures. This finding suggests that mammographic density can mediate the protective effect of greater parity against breast cancer, at least in part while age at menarche, age at the FFTB, and breast feeding do not exert their effects through mammographic density.

  4. Etiology of the stability of reading difficulties: the longitudinal twin study of reading disabilities.

    Science.gov (United States)

    Astrom, Raven L; Wadsworth, Sally J; DeFries, John C

    2007-06-01

    Results obtained from previous longitudinal studies of reading difficulties indicate that reading deficits are generally stable. However, little is known about the etiology of this stability. Thus, the primary objective of this first longitudinal twin study of reading difficulties is to provide an initial assessment of genetic and environmental influences on the stability of reading deficits. Data were analyzed from a sample of 56 twin pairs, 18 identical (monozygotic, MZ) and 38 fraternal (dizygotic, DZ), in which at least one member of each pair was classified as reading-disabled in the Colorado Learning Disabilities Research Center, and on whom follow-up data were available. The twins were tested at two time points (average age of 10.3 years at initial assessment and 16.1 years at follow-up). A composite measure of reading performance (PIAT Reading Recognition, Reading Comprehension and Spelling) was highly stable, with a stability correlation of .84. Data from the initial time point were first subjected to univariate DeFries-Fulker multiple regression analysis and the resulting estimate of the heritability of the group deficit (h2g) was .84 (+/-.26). When the initial and follow-up data were then fitted to a bivariate extension of the basic DF model, bivariate heritability was estimated at .65, indicating that common genetic influences account for approximately 75% of the stability between reading measures at the two time points.

  5. Longitudinal relationships of metabolic syndrome and obesity with kidney function: Healthy Twin Study.

    Science.gov (United States)

    Song, Yun-Mi; Sung, Joohon; Lee, Kayoung

    2015-10-01

    To examine cross-sectional and longitudinal relationships, including genetic and environmental correlations, of metabolic syndrome (MetS) and obesity with kidney function. Subjects were 3,437 Korean adults of the Healthy Twin Study for cross-sectional relationships and 1,881 participants for longitudinal relationships (follow-up interval 3.7 ± 1.4 years). Obesity (body mass index ≥ 25 vs. obesity and MetS, prevalent CKD was associated with MetS regardless of weight status [adjusted odds ratio (AOR) 4.19 for those with MetS but without obesity; AOR 4.63 for those with MetS and obesity]. Incident CKD was associated with obesity regardless of baseline metabolic status (AOR 2.03 for those with obesity but without MetS; AOR 2.85 for those with obesity and MetS). MetS at follow-up was associated with incident CKD regardless of baseline MetS (AOR 2.42-2.52). Sex-adjusted bivariate analyses show inverse environmental correlations of the number of MetS components and BMI at baseline, with eGFR at baseline and follow-up (ρ E, -0.26 to -0.42, P obesity, and obesity predicts incident CKD regardless of baseline MetS. Incident CKD is also associated with MetS at follow-up regardless of baseline MetS. These associations appear to be explained by shared environmental factors.

  6. The heritability of the skin conductance orienting response: a longitudinal twin study.

    Science.gov (United States)

    Tuvblad, Catherine; Gao, Yu; Isen, Joshua; Botwick, Theodore; Raine, Adrian; Baker, Laura A

    2012-01-01

    The orienting response is a widely used experimental paradigm that reflects the association between electrodermal activity and psychological processes. The present study examined the genetic and environmental etiology of skin conductance orienting response (SCOR) magnitude in a sample of twins assessed at ages 9-10, 11-13 and 14-16 years. Structural equation modeling at each visit showed that genetic influences explained 56%, 83%, and 48% of the total variance in SCOR at visits 1, 2, and 3, respectively, with the remaining variance explained by non-shared environmental factors. SCOR was moderately stable across ages, with phenotypic correlations between time points ranging from .35 to .45. A common genetic factor explained 36%, 45% and 49% of the variance in SCOR magnitude across development. Additional age-specific genetic effects were found at ages 9-10 and 11-13 years, explaining 18% and 35% of the variance, respectively. The genetic correlations among the three time points were high, ranging from .55 to .73, indicating a substantial continuity in genetic influences from ages 9 to 16. These findings suggest that genetic factors are important influences in SCOR magnitude during late childhood and adolescence.

  7. Molecular Dynamics Study on the Distributed Plasticity of Penta-twinned Silver Nanowires

    Directory of Open Access Journals (Sweden)

    Sangryun eLee

    2015-08-01

    Full Text Available The distributed plasticity of pentatwinned silver nanowires has been revealed in recent computational and experimental studies. However, the molecular dynamics (MD simulations have not considered the imperfections seen in experiments, such as irregular surface undulations, the high aspect ratio of nanowires, and the stiffness of loading devices. In this work, we report the effect of such inherent imperfections on the distributed plasticity of penta-twinned silver nanowires in MD simulations. We find that the distributed plasticity occurs for nanowires having undulations that are less than 5% of the nanowire diameter. The elastic stress field induced by a stacking fault promotes the nucleation of successive stacking fault decahedrons (SFDs at long distance, making it hard for necking to occur. By comparing the tensile simulation using the steered molecular dynamics (SMD method with the tensile simulation with periodic boundary condition (PBC, we show that a sufficiently long nanowire must be used in the constant strain rate simulations with PBC, because the plastic displacement burst caused by the SFD formation induces compressive stress, promoting the removal of other SFDs. Our finding can serve as a guidance for the molecular dynamics simulation of crystalline materials with large plastic deformation, and in the design of mechanically reliable devices based on silver nanowires.

  8. Mechanical twinning in small quartz crystals

    Science.gov (United States)

    Laughner, J. W.; Newnham, R. E.; Cross, L. E.

    1982-02-01

    Quartz is known to be ferrobielastic; that is, quartz crystals have domain states (Dauphiné twins) which differ in their elastic compliance values and which can be switched by an appropriately oriented stress. Polycrystalline quartz has also been reported (Tullis 1970) to show preferential orientation of these domains following application of large uniaxial stresses. These experiments were designed to study twinning of synthetic quartz “grains” (minimum size 0.07×0.07×0.02 cm) in specially-constructed composites and of grains in three natural quartz aggregates — a quartzite, a novaculite, and a jasper. Backreflection X-ray techniques were used to verify twinning in the composite grains, while special electroding and electrical detection allowed the twinning processes to be examined in “real time.” Small synthetic quartz crystals were found to behave identically to the massive samples previously studied. Electrical pulses due to the reversal of piezoelectric coefficient d 11 in twinned quartz were detected from quartzite and from the man-made composites. Novaculite also gave electrical pulses which were probably from twinning (evidenced by the correlation of expected and observed pulse sizes and shapes), while no pulses from the jaspers indicative of twinning were detected. Grain size distribution differences are considered the main structural reason for the different behaviors.

  9. Hypoalbuminemia in Donors with Twin-Twin Transfusion Syndrome

    NARCIS (Netherlands)

    Verbeek, L.; Middeldorp, J. M.; Hulzebos, C. V.; Oepkes, D.; Walther, F. J.; Lopriore, E.

    2013-01-01

    Objective: To estimate the differences in albumin levels between donors and recipients with twin-twin transfusion syndrome (TTTS). Methods: We performed a matched case-control study including twin pairs with TTTS treated conservatively (conservative group) or with fetoscopic laser surgery (laser gro

  10. Brain SCALE: brain structure and cognition: an adolescent longitudinal twin study into the genetic etiology of individual differences.

    Science.gov (United States)

    van Soelen, Inge L C; Brouwer, Rachel M; Peper, Jiska S; van Leeuwen, Marieke; Koenis, Marinka M G; van Beijsterveldt, Toos C E M; Swagerman, Suzanne C; Kahn, René S; Hulshoff Pol, Hilleke E; Boomsma, Dorret I

    2012-06-01

    From childhood into adolescence, the child's brain undergoes considerable changes in both structure and function. Twin studies are of great value to explore to what extent genetic and environmental factors explain individual differences in brain development and cognition. In The Netherlands, we initiated a longitudinal study in which twins, their siblings and their parents are assessed at three year intervals. The participants were recruited from The Netherlands Twin Register (NTR) and at baseline consisted of 112 families, with 9-year-old twins and an older sibling. Three years later, 89 families returned for follow-up assessment. Data collection included psychometric IQ tests, a comprehensive neuropsychological testing protocol, and parental and self-ratings of behavioral and emotional problems. Physical maturation was measured through assessment of Tanner stages. Hormonal levels (cortisol, luteinizing hormone, follicle-stimulating hormone, testosterone, and estrogens) were assessed in urine and saliva. Brain scans were acquired using 1.5 Tesla Magnetic Resonance Imaging (MRI), which provided volumetric measures and measures of cortical thickness. Buccal swabs were collected for DNA isolation for future candidate gene and genome-wide analysis studies. This article gives an overview of the study and the main findings. Participants will return for a third assessment when the twins are around 16 years old. Longitudinal twin-sibling studies that map brain development and cognitive function at well-defined ages aid in the understanding of genetic influences on normative brain development.

  11. DISTINCT ETIOLOGICAL INFLUENCES ON OBSESSIVE-COMPULSIVE SYMPTOM DIMENSIONS: A MULTIVARIATE TWIN STUDY

    Science.gov (United States)

    López-Solà, Clara; Fontenelle, Leonardo F.; Verhulst, Brad; Neale, Michael C.; Menchón, José M.; Alonso, Pino; Harrison, Ben J.

    2016-01-01

    Background Obsessive-compulsive disorder (OCD) is characterized by five major dimensions, including contamination/washing, harm/checking, symmetry/ordering, hoarding, and forbidden thoughts. How these dimensions may relate etiologically to the symptoms of other obsessive-compulsive related disorders (OCRDs) and anxiety disorders (ADs) is not well known. The aim of this study was to examine the genetic and environmental overlap between each major obsessive-compulsive dimension with the symptoms of other OCRDs and ADs. Methods Two thousand four hundred ninety-five twins of both sexes, aged between 18 and 45 years, were recruited from the Australian Twin Registry. Measures used scores on four dimensions (obsessing (forbidden thoughts), washing, checking, and ordering) of the Obsessive-Compulsive Inventory-Revised, Dysmorphic Concerns Questionnaire, Hoarding Rating Scale, Anxiety Sensitivity Index, Social Phobia Inventory, and Stress subscale of the Depression, Anxiety, and Stress Scale. Multivariate twin modeling methods using continuous and categorized variables were performed, also controlling for age and gender. Results Our findings suggested that forbidden thoughts and washing demonstrated the strongest genetic overlap with other AD symptoms, while ordering was genetically related to OCRD symptoms. Common genetic influences on checking symptoms were best estimated when modeling OCRDs together with AD symptoms. Common environmental factors of ordering and checking were shared with AD symptoms. Conclusions Important shared genetic and environmental risk factors exist between OCD, OCRDs, and ADs, but which vary alongside the expression of its major dimensions. PMID:26630089

  12. The Danish Twin Registry

    DEFF Research Database (Denmark)

    Skytthe, Axel; Ohm Kyvik, Kirsten; Vilstrup Holm, Niels

    2011-01-01

    Introduction: The Danish Twin Registry is a unique source for studies of genetic, familial and environmental factors on life events, health conditions and diseases. Content: More than 85,000 twin pairs born 1870-2008 in Denmark. Validity and coverage: Four main ascertainment methods have been emp...

  13. Unilateral primary pulmonary agenesis and hypoplasia in monozygotic twins.

    Science.gov (United States)

    Alsaadi, Muslim; Al Muqhem, Badr; Boukai, A; Iqbal, Shaikh M

    2012-01-01

    We describe 10-month-old identical female twin infants, one with primary left-sided pulmonary agenesis and the other with primary left-sided pulmonary hypoplasia. They came to our outpatient clinic complaining of persistent dry cough. The clinical examination revealed decreased air entry over the left hemithorax. Chest x-rays showed complete left-sided radio-opacity in both the twins. The chest computed tomography scan with contrast confirmed the diagnoses of left-sided pulmonary agenesis (twin A) and left-sided hypoplasia (twin B). No other associated congenital anomaly was noted in either of the twins. To our knowledge, such a condition in live monozygotic twins has not been previously reported in published studies.

  14. Academic performance of opposite-sex and same-sex twins in adolescence: A Danish national cohort study.

    Science.gov (United States)

    Ahrenfeldt, Linda; Petersen, Inge; Johnson, Wendy; Christensen, Kaare

    2015-03-01

    Testosterone is an important hormone in the sexual differentiation of the brain, contributing to differences in cognitive abilities between males and females. For instance, studies in clinical populations such as females with congenital adrenal hyperplasia (CAH) who are exposed to high levels of androgens in utero support arguments for prenatal testosterone effects on characteristics such as visuospatial cognition and behaviour. The comparison of opposite-sex (OS) and same-sex (SS) twin pairs can be used to help establish the role of prenatal testosterone. However, although some twin studies confirm a masculinizing effect of a male co-twin regarding for instance perception and cognition it remains unclear whether intra-uterine hormone transfer exists in humans. Our aim was to test the potential influences of testosterone on academic performance in OS twins. We compared ninth-grade test scores and teacher ratings of OS (n=1812) and SS (n=4054) twins as well as of twins and singletons (n=13,900) in mathematics, physics/chemistry, Danish, and English. We found that males had significantly higher test scores in mathematics than females (.06-.15 SD), whereas females performed better in Danish (.33-.49 SD), English (.20 SD), and neatness (.45-.64 SD). However, we did not find that OS females performed better in mathematics than SS and singleton females, nor did they perform worse either in Danish or English. Scores for OS and SS males were similar in all topics. In conclusion, this study did not provide evidence for a masculinization of female twins with male co-twins with regard to academic performance in adolescence.

  15. Twin Studies and Their Implications for Molecular Genetic Studies: Endophenotypes Integrate Quantitative and Molecular Genetics in ADHD Research

    Science.gov (United States)

    Wood, Alexis C.; Neale, Michael C.

    2010-01-01

    Objective: To describe the utility of twin studies for attention-deficit/hyperactivity disorder (ADHD) research and demonstrate their potential for the identification of alternative phenotypes suitable for genomewide association, developmental risk assessment, treatment response, and intervention targets. Method: Brief descriptions of the classic…

  16. Genetic and Environmental Influences on Traits of Gender Identity Disorder: A Study of Japanese Twins Across Developmental Stages.

    Science.gov (United States)

    Sasaki, Shoko; Ozaki, Koken; Yamagata, Shinji; Takahashi, Yusuke; Shikishima, Chizuru; Kornacki, Tamara; Nonaka, Koichi; Ando, Juko

    2016-10-01

    The present study examined: (1) gender and age differences of mean gender identity disorder (GID) trait scores in Japanese twins; (2) the validity of the prenatal hormone transfer theory, which predicts that, in dizygotic (DZ) twin pairs, twins with an opposite-gender co-twin more frequently exhibit GID traits than twins with a same-gender co-twin; and (3) the magnitude of genetic and environmental influences on GID traits as a function of age and gender. Data from 1450 male twin pairs, 1882 female twin pairs, and 1022 DZ male-female pairs ranging from 3 to 26 years of age were analyzed. To quantify individual variances in GID traits, each participant completed four questionnaire items based on criteria for GID from the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR). Our most important findings were: (1) Japanese females exhibited GID traits more frequently than males and Japanese children exhibited GID traits less frequently than adolescents and adults (among females, the prevalence was 1.6 % in children, 10 % in adolescents, and 12 % in adults; among males, the prevalence was 0.5, 2, and 3 %, respectively); (2) the data did not support the prenatal hormone transfer theory for GID traits; and (3) a large part of the variance for GID traits in children was accounted for by familial factors; however, the magnitude was found to be greater in children than in adolescents or adults, particularly among females. This study suggests that although the prevalence is likely to increase, familial effects are likely to decrease as individuals age.

  17. Etiological influences on the stability of autistic traits from childhood to early adulthood: evidence from a twin study.

    Science.gov (United States)

    Taylor, Mark J; Gillberg, Christopher; Lichtenstein, Paul; Lundström, Sebastian

    2017-01-01

    Autism spectrum disorders (ASD) are persistent and lifelong conditions. Despite this, almost all twin studies focus on childhood. This twin study investigated the stability of autistic traits from childhood to early adulthood and explored the degree to which any stability could be explained by genetic or environmental factors. Parents of over 2500 twin pairs completed questionnaires assessing autistic traits when twins were aged either 9 or 12 years and again when twins were aged 18. Bivariate twin analysis assessed the degree of phenotypic and etiological stability in autistic traits across this period. Genetic overlap in autistic traits across development was also tested in individuals displaying a broad ASD phenotype, defined as scoring within the highest 5% of the sample. Autistic traits displayed moderate phenotypic stability (r = .39). The heritability of autistic traits was 76-77% in childhood and 60-62% in adulthood. A moderate degree of genetic influences on childhood autistic traits were carried across into adulthood (genetic correlation = .49). The majority (85%) of the stability in autistic traits was attributable to genetic factors. Genetic influences on autistic traits were moderately stable from childhood to early adulthood at the extremes (genetic correlation = .64). Broad autistic traits display moderate phenotypic and etiological stability from childhood to early adulthood. Genetic factors accounted for almost all phenotypic stability, although there was some phenotypic and etiological instability in autistic traits. Thus, autistic traits in adulthood are influenced by a combination of enduring and unique genetic factors.

  18. Clinical characteristics of fetal and neonatal outcomes in twin pregnancy with preeclampsia in a retrospective case–control study

    Science.gov (United States)

    Yuan, Ting; Wang, Wei; Li, Xue-Lan; Li, Chun-Fang; Li, Chao; Gou, Wen-Li; Han, Zhen

    2016-01-01

    Abstract The aim of our study was to compare the clinical characteristics of fetal and neonatal outcomes in twin pregnancies between women with preeclampsia (PE) and those with normotension in a Chinese population. There were 143 preeclamptic women and 367 normotensive women with twin pregnancies included in this retrospective case–control study. The baseline characteristics and perinatal outcomes were collected and compared between the groups. Multiple logistic regression and linear regression were used to assess the correlations between PE and the outcomes. Significant increases were observed in the frequencies of preterm delivery (OR = 2.75, P < 0.001), iatrogenic preterm birth (OR = 3.52, P < 0.001), and IUGR (OR = 2.94, P = 0.001) in the PE group, and the PE group had more than a 2-fold risk of adverse neonatal outcomes. Preeclamptic twin neonates had lower birth weights (β = −147.34, P = 0.005; β = −169.47, P = 0.001). The comparison on the discordance of intertwin weight was not significantly different. Twin pregnancies with PE are associated with worse perinatal outcomes. The adverse outcomes of preeclamptic twin pregnancies may be associated with lower birth weights rather than the discordance of the intertwin weight, which requires further confirmation. The results may provide helpful references for better clinical assessments, evaluations of prognosis, and a deeper understanding of preeclamptic twin pregnancies. PMID:27787375

  19. The Relationship Between Neuroticism and Inflammatory Markers : A Twin Study

    NARCIS (Netherlands)

    Sas, Arthur A.; Rijsdijk, Fruehling V.; Ormel, Johan; Snieder, Harold; Riese, Harriette

    2014-01-01

    Introduction: Neuroticism is an important marker of vulnerability for both mental and physical disorders. Its link with multiple etiological pathways has been studied before. Inflammatory markers have been demonstrated to predict similar mental and physical disorders as neuroticism. However, current

  20. Etiological overlap between obsessive-compulsive disorder and anorexia nervosa: a longitudinal cohort, multigenerational family and twin study

    Science.gov (United States)

    Cederlöf, Martin; Thornton, Laura M; Baker, Jessica; Lichtenstein, Paul; Larsson, Henrik; Rück, Christian; Bulik, Cynthia M; Mataix-Cols, David

    2015-01-01

    Obsessive-compulsive disorder (OCD) often co-occurs with anorexia nervosa (AN), a comorbid profile that complicates the clinical management of both conditions. This population-based study aimed to examine patterns of comorbidity, longitudinal risks, shared familial risks and shared genetic factors between OCD and AN at the population level. Participants were individuals with a diagnosis of OCD (N=19,814) or AN (N=8,462) in the Swedish National Patient Register between January 1992 and December 2009; their first-, second- and third-degree relatives; and population-matched (1:10 ratio) unaffected comparison individuals and their relatives. Female twins from the population-based Swedish Twin Register (N=8,550) were also included. Females with OCD had a 16-fold increased risk of having a comorbid diagnosis of AN, whereas males with OCD had a 37-fold increased risk. Longitudinal analyses showed that individuals first diagnosed with OCD had an increased risk for a later diagnosis of AN (risk ratio, RR=3.6), whereas individuals first diagnosed with AN had an even greater risk for a later diagnosis of OCD (RR=9.6). These longitudinal risks were about twice as high for males than for females. First- and second-degree relatives of probands with OCD had an increased risk for AN, and the magnitude of this risk tended to increase with the degree of genetic relatedness. Bivariate twin models revealed a moderate but significant degree of genetic overlap between self-reported OCD and AN diagnoses (ra=0.52, 95% CI: 0.26-0.81), but most of the genetic variance was disorder-specific. The moderately high genetic correlation supports the idea that this frequently observed comorbid pattern is at least in part due to shared genetic factors, though disorder-specific factors are more important. These results have implications for current gene-searching efforts and for clinical practice. PMID:26407789

  1. Etiological overlap between obsessive-compulsive disorder and anorexia nervosa: a longitudinal cohort, multigenerational family and twin study.

    Science.gov (United States)

    Cederlöf, Martin; Thornton, Laura M; Baker, Jessica; Lichtenstein, Paul; Larsson, Henrik; Rück, Christian; Bulik, Cynthia M; Mataix-Cols, David

    2015-10-01

    Obsessive-compulsive disorder (OCD) often co-occurs with anorexia nervosa (AN), a comorbid profile that complicates the clinical management of both conditions. This population-based study aimed to examine patterns of comorbidity, longitudinal risks, shared familial risks and shared genetic factors between OCD and AN at the population level. Participants were individuals with a diagnosis of OCD (N=19,814) or AN (N=8,462) in the Swedish National Patient Register between January 1992 and December 2009; their first-, second- and third-degree relatives; and population-matched (1:10 ratio) unaffected comparison individuals and their relatives. Female twins from the population-based Swedish Twin Register (N=8,550) were also included. Females with OCD had a 16-fold increased risk of having a comorbid diagnosis of AN, whereas males with OCD had a 37-fold increased risk. Longitudinal analyses showed that individuals first diagnosed with OCD had an increased risk for a later diagnosis of AN (risk ratio, RR=3.6), whereas individuals first diagnosed with AN had an even greater risk for a later diagnosis of OCD (RR=9.6). These longitudinal risks were about twice as high for males than for females. First- and second-degree relatives of probands with OCD had an increased risk for AN, and the magnitude of this risk tended to increase with the degree of genetic relatedness. Bivariate twin models revealed a moderate but significant degree of genetic overlap between self-reported OCD and AN diagnoses (ra =0.52, 95% CI: 0.26-0.81), but most of the genetic variance was disorder-specific. The moderately high genetic correlation supports the idea that this frequently observed comorbid pattern is at least in part due to shared genetic factors, though disorder-specific factors are more important. These results have implications for current gene-searching efforts and for clinical practice.

  2. Subjective wellbeing and longevity: a co-twin control study

    DEFF Research Database (Denmark)

    Sadler, Michael E; Miller, Christopher J; Christensen, Kaare

    2011-01-01

    Mental health is increasingly defined not only by the absence of illness but by the presence of subjective well-being (SWB). Previous cohort studies have consistently shown that indicators of SWB predict favorable life outcomes, including better mental and somatic health, and longevity. The favor......Mental health is increasingly defined not only by the absence of illness but by the presence of subjective well-being (SWB). Previous cohort studies have consistently shown that indicators of SWB predict favorable life outcomes, including better mental and somatic health, and longevity....... The favorable effects associated with SWB have prompted new research aimed at raising happiness and wellbeing through individual interventions and public health initiatives. Standard observational studies of individual-level associations, however, are subject to potential confounding of exposure and outcome...

  3. Hypoalbuminemia in Donors with Twin Anemia-Polycythemia Sequence : A Matched Case-Control Study

    NARCIS (Netherlands)

    Verbeek, L.; Slaghekke, F.; Hulzebos, C. V.; Oepkes, D.; Walther, F. J.; Lopriore, E.

    2013-01-01

    Objective: To determine the differences in albumin levels between donors and recipients with twin anemia-polycythemia sequence (TAPS). Methods: We included all consecutive monochorionic twins with TAPS with double survivors. Each twin pair was matched for gestational age at birth with 2 control nnon

  4. Hypoalbuminemia in Donors with Twin Anemia-Polycythemia Sequence : A Matched Case-Control Study

    NARCIS (Netherlands)

    Verbeek, L.; Slaghekke, F.; Hulzebos, C. V.; Oepkes, D.; Walther, F. J.; Lopriore, E.

    2013-01-01

    Objective: To determine the differences in albumin levels between donors and recipients with twin anemia-polycythemia sequence (TAPS). Methods: We included all consecutive monochorionic twins with TAPS with double survivors. Each twin pair was matched for gestational age at birth with 2 control

  5. Epidemiology of Anorexia Nervosa in Men : A Nationwide Study of Finnish Twins

    NARCIS (Netherlands)

    Raevuori, Anu; Hoek, Hans W.; Susser, Ezra; Kaprio, Jaakko; Rissanen, Aila; Keski-Rahkonen, Anna

    2009-01-01

    Background: To examine the epidemiology of anorexia nervosa in men, we screened Finnish male twins born in 1975-79. Methods and Findings: Men (N = 2122) from FinnTwin16 birth cohorts were screened for lifetime eating disorders by a questionnaire. The screen positives (N = 18), their male co-twins (N

  6. Aortic root dimensions are predominantly determined by genetic factors: a classical twin study

    Energy Technology Data Exchange (ETDEWEB)

    Celeng, Csilla; Kolossvary, Marton; Kovacs, Attila; Molnar, Andrea Agnes; Szilveszter, Balint; Karolyi, Mihaly; Jermendy, Adam L.; Karady, Julia; Merkely, Bela; Maurovich-Horvat, Pal [Semmelweis University, MTA-SE Cardiovascular Imaging Research Group, Heart and Vascular Center, Budapest (Hungary); Horvath, Tamas [Budapest University of Technology and Economics, Department of Hydrodynamic Systems, Budapest (Hungary); Tarnoki, Adam D.; Tarnoki, David L. [Semmelweis University, Department of Radiology and Oncotherapy, Budapest (Hungary); Voros, Szilard [Global Genomics Group, Atlanta, GA (United States); Jermendy, Gyoergy [Bajcsy-Zsilinszky Hospital, Medical Department, Budapest (Hungary)

    2017-06-15

    Previous studies using transthoracic echocardiography (TTE) observed moderate heritability of aortic root dimensions. Computed tomography angiography (CTA) might provide more accurate heritability estimates. Our primary aim was to assess the heritability of the aortic root with CTA. Our secondary aim was to derive TTE-based heritability and compare this with the CTA-based results. In the BUDAPEST-GLOBAL study 198 twin subjects (118 monozygotic, 80 dizygotic; age 56.1 ± 9.4 years; 126 female) underwent CTA and TTE. We assessed the diameter of the left ventricular outflow tract (LVOT), annulus, sinus of Valsalva, sinotubular junction and ascending aorta. Heritability was assessed using ACDE model (A additive genetic, C common environmental, D dominant genetic, E unique environmental factors). Based on CTA, additive genetic effects were dominant (LVOT: A = 0.67, E = 0.33; annulus: A = 0.76, E = 0.24; sinus of Valsalva: A = 0.83, E = 0.17; sinotubular junction: A = 0.82, E = 0.18; ascending aorta: A = 0.75, E = 0.25). TTE-derived measurements showed moderate to no genetic influence (LVOT: A = 0.38, E = 0.62; annulus: C = 0.47, E = 0.53; sinus of Valsalva: C = 0.63, E = 0.37; sinotubular junction: C = 0.45, E = 0.55; ascending aorta: A = 0.67, E = 0.33). CTA-based assessment suggests that aortic root dimensions are predominantly determined by genetic factors. TTE-based measurements showed moderate to no genetic influence. The choice of measurement method has substantial impact on heritability estimates. (orig.)

  7. A Computational Discriminability Analysis on Twin Fingerprints

    Science.gov (United States)

    Liu, Yu; Srihari, Sargur N.

    Sharing similar genetic traits makes the investigation of twins an important study in forensics and biometrics. Fingerprints are one of the most commonly found types of forensic evidence. The similarity between twins’ prints is critical establish to the reliability of fingerprint identification. We present a quantitative analysis of the discriminability of twin fingerprints on a new data set (227 pairs of identical twins and fraternal twins) recently collected from a twin population using both level 1 and level 2 features. Although the patterns of minutiae among twins are more similar than in the general population, the similarity of fingerprints of twins is significantly different from that between genuine prints of the same finger. Twins fingerprints are discriminable with a 1.5%~1.7% higher EER than non-twins. And identical twins can be distinguished by examine fingerprint with a slightly higher error rate than fraternal twins.

  8. Generalised Anxiety Disorder--A Twin Study of Genetic Architecture, Genome-Wide Association and Differential Gene Expression.

    Directory of Open Access Journals (Sweden)

    Matthew N Davies

    Full Text Available Generalised Anxiety Disorder (GAD is a common anxiety-related diagnosis, affecting approximately 5% of the adult population. One characteristic of GAD is a high degree of anxiety sensitivity (AS, a personality trait which describes the fear of arousal-related sensations. Here we present a genome-wide association study of AS using a cohort of 730 MZ and DZ female twins. The GWAS showed a significant association for a variant within the RBFOX1 gene. A heritability analysis of the same cohort also confirmed a significant genetic component with h2 of 0.42. Additionally, a subset of the cohort (25 MZ twins discordant for AS was studied for evidence of differential expression using RNA-seq data. Significant differential expression of two exons with the ITM2B gene within the discordant MZ subset was observed, a finding that was replicated in an independent cohort. While previous research has shown that anxiety has a high comorbidity with a variety of psychiatric and neurodegenerative disorders, our analysis suggests a novel etiology specific to AS.

  9. Generalised Anxiety Disorder--A Twin Study of Genetic Architecture, Genome-Wide Association and Differential Gene Expression.

    Science.gov (United States)

    Davies, Matthew N; Verdi, Serena; Burri, Andrea; Trzaskowski, Maciej; Lee, Minyoung; Hettema, John M; Jansen, Rick; Boomsma, Dorret I; Spector, Tim D

    2015-01-01

    Generalised Anxiety Disorder (GAD) is a common anxiety-related diagnosis, affecting approximately 5% of the adult population. One characteristic of GAD is a high degree of anxiety sensitivity (AS), a personality trait which describes the fear of arousal-related sensations. Here we present a genome-wide association study of AS using a cohort of 730 MZ and DZ female twins. The GWAS showed a significant association for a variant within the RBFOX1 gene. A heritability analysis of the same cohort also confirmed a significant genetic component with h2 of 0.42. Additionally, a subset of the cohort (25 MZ twins discordant for AS) was studied for evidence of differential expression using RNA-seq data. Significant differential expression of two exons with the ITM2B gene within the discordant MZ subset was observed, a finding that was replicated in an independent cohort. While previous research has shown that anxiety has a high comorbidity with a variety of psychiatric and neurodegenerative disorders, our analysis suggests a novel etiology specific to AS.

  10. Genetic and environmental determinants on bone loss in postmenopausal Caucasian women: a 14-year longitudinal twin study.

    Science.gov (United States)

    Zhai, G; Andrew, T; Kato, B S; Blake, G M; Spector, T D

    2009-06-01

    This longitudinal twin study documented that genetic factors explain 44-56% of the between-individual variance in bone loss at femoral neck, lumbar spine, and forearm in postmenopausal Caucasian women, providing a rationale for identifying the specific genes involved. Although there is a significant genetic effect on peak BMD, until recently, no substantive studies on heritability of bone loss in human were available. The aim of the study was to estimate the heritability of the bone loss at multiple sites in postmenopausal Caucasian women. Postmenopausal female monozygotic (MZ) and dizygotic (DZ) twins aged 40 or above at baseline were selected from the TwinsUK registry and followed up for an average of 8 years (range 5-14 years). All twins were noncurrent hormone replacement therapy users and not on any osteoporosis treatment. They had dual-energy X-ray absorptiometry (DXA) scans of their hip, lumbar spine, and forearm several times (range 2-9) during the follow-up period. Individual bone losses at femoral neck, lumbar spine, and forearm were estimated by linear regression modeling. Structural equation modeling was utilized to estimate the heritability of the bone loss. A total of 712 postmenopausal Caucasian female twins (152 MZ and 204 DZ pairs) were included. MZ twins were older and had slightly lower BMD at all sites than DZ twins. DZ twins had slightly higher bone loss at lumbar spine, but similar at femoral neck and forearm compared to MZ twins. Intraclass correlation coefficients (ICC) for the bone loss at all sites were significantly higher in MZ than DZ twin pairs (p = 0.0045, 0.0003, and 0.0007 for femoral neck, lumbar spine, and forearm, respectively), indicating a significant genetic influence on bone loss at these sites. After adjustment for age at baseline and weight change during the follow-up, the heritability estimate was 47% (95% CI 27-63%) for bone loss at femoral neck, 44% (95% CI 27-58%) for lumbar spine, and 56% (95% CI 44-65%) for forearm

  11. Heritability of brain activity related to response inhibition: A longitudinal genetic study in adolescent twins.

    Science.gov (United States)

    Anokhin, Andrey P; Golosheykin, Simon; Grant, Julia D; Heath, Andrew C

    2017-05-01

    The ability to inhibit prepotent but context- or goal-inappropriate responses is essential for adaptive self-regulation of behavior. Deficits in response inhibition, a key component of impulsivity, have been implicated as a core dysfunction in a range of neuropsychiatric disorders such as ADHD and addictions. Identification of genetically transmitted variation in the neural underpinnings of response inhibition can help to elucidate etiological pathways to these disorders and establish the links between genes, brain, and behavior. However, little is known about genetic influences on the neural mechanisms of response inhibition during adolescence, a developmental period characterized by weak self-regulation of behavior. Here we investigated heritability of ERPs elicited in a Go/No-Go task in a large sample of adolescent twins assessed longitudinally at ages 12, 14, and 16. Genetic analyses showed significant heritability of inhibition-related frontal N2 and P3 components at all three ages, with 50 to 60% of inter-individual variability being attributable to genetic factors. These genetic influences included both common genetic factors active at different ages and novel genetic influences emerging during development. Finally, individual differences in the rate of developmental changes from age 12 to age 16 were significantly influenced by genetic factors. In conclusion, the present study provides the first evidence for genetic influences on neural correlates of response inhibition during adolescence and suggests that ERPs elicited in the Go/No-Go task can serve as intermediate neurophysiological phenotypes (endophenotypes) for the study of disinhibition and impulse control disorders. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Dramatically different dizygotic twins: will we include them in Research? Twin research reviews: congenital anomalies, mirror-image effects in conjoined twins, older mothers of twins; Twin statistics: 'Massachusetts, land of twins'; Tribute: Dr Victor A. McKusick.

    Science.gov (United States)

    Segal, Nancy L

    2008-10-01

    The increased frequency of interracial marriage is a likely source of unusual-looking dizygotic (DZ) twins. Some members of DZ twin pairs born to mixed-race couples inherit very different physical features from their parents. This raises several questions, such as: Will researchers wish to include such twins in their ongoing studies? Next, new twin research concerned with congenital anomalies, mirror-image effects in conjoined twins and older mothers of twins will be reviewed. New statistics on twinning rates in Massachusetts will also be summarized, followed by a tribute to the late medical geneticist Dr. Victor A. McKusick.

  13. Genetic and environmental contributions to the overlap between psychological, fatigue and somatic symptoms: a twin study in Sri Lanka

    Science.gov (United States)

    Ball, Harriet A.; Siribaddana, Sisira H.; Sumathipala, Athula; Kovas, Yulia; Glozier, Nick; Rijsdijk, Frühling; McGuffin, Peter; Hotopf, Matthew

    2011-01-01

    Background Somatic symptoms often co-occur with psychological symptoms but this overlap is poorly understood. Some aspects of this overlap differ in the South Asian context, but it is not clear whether this is a reporting effect or an underlying difference in experienced illness. Methods Home interviews were administered to 4,024 twins randomly selected from a population-based twin register in the Colombo district of Sri Lanka (the CoTASS study). These included assessments of psychological, somatic and fatigue symptoms. The data were analysed using factor analytic and quantitative genetic approaches. Results Confirmatory factor analysis showed that the symptoms from the three scales represented three separate dimensions, rather than all tapping into a single dimension. However, familial correlations among the data were most consistent with a common pathway model. This implies that a portion of the underlying vulnerability is common across psychological, fatigue and somatic symptoms. There were sex differences in the aetiology of this model, with shared environmental and genetic influences playing different roles in men and women. Conclusions There is a complex aetiological relationship between psychological, fatigue and somatic symptoms. This is similar in Sri Lanka to Western countries, but there may be a greater influence from the family environment, suggesting that care needs to be taken when generalising research findings between countries. People who complain of certain fatigue or somatic symptoms may well also have psychologicial symptoms, or may have genetic or environmental vulnerabilities to such problems. PMID:21314256

  14. Heritability and Genome-Wide Association Studies for Hair Color in a Dutch Twin Family Based Sample

    Directory of Open Access Journals (Sweden)

    Bochao Danae Lin

    2015-07-01

    Full Text Available Hair color is one of the most visible and heritable traits in humans. Here, we estimated heritability by structural equation modeling (N = 20,142, and performed a genome wide association (GWA analysis (N = 7091 and a GCTA study (N = 3340 on hair color within a large cohort of twins, their parents and siblings from the Netherlands Twin Register (NTR. Self-reported hair color was analyzed as five binary phenotypes, namely “blond versus non-blond”, “red versus non-red”, “brown versus non-brown”, “black versus non-black”, and “light versus dark”. The broad-sense heritability of hair color was estimated between 73% and 99% and the genetic component included non-additive genetic variance. Assortative mating for hair color was significant, except for red and black hair color. From GCTA analyses, at most 24.6% of the additive genetic variance in hair color was explained by 1000G well-imputed SNPs. Genome-wide association analysis for each hair color showed that SNPs in the MC1R region were significantly associated with red, brown and black hair, and also with light versus dark hair color. Five other known genes (HERC2, TPCN2, SLC24A4, IRF4, and KITLG gave genome-wide significant hits for blond, brown and light versus dark hair color. We did not find and replicate any new loci for hair color.

  15. Heritability and Genome-Wide Association Studies for Hair Color in a Dutch Twin Family Based Sample

    Science.gov (United States)

    Lin, Bochao Danae; Mbarek, Hamdi; Willemsen, Gonneke; Dolan, Conor V.; Fedko, Iryna O.; Abdellaoui, Abdel; de Geus, Eco J.; Boomsma, Dorret I.; Hottenga, Jouke-Jan

    2015-01-01

    Hair color is one of the most visible and heritable traits in humans. Here, we estimated heritability by structural equation modeling (N = 20,142), and performed a genome wide association (GWA) analysis (N = 7091) and a GCTA study (N = 3340) on hair color within a large cohort of twins, their parents and siblings from the Netherlands Twin Register (NTR). Self-reported hair color was analyzed as five binary phenotypes, namely “blond versus non-blond”, “red versus non-red”, “brown versus non-brown”, “black versus non-black”, and “light versus dark”. The broad-sense heritability of hair color was estimated between 73% and 99% and the genetic component included non-additive genetic variance. Assortative mating for hair color was significant, except for red and black hair color. From GCTA analyses, at most 24.6% of the additive genetic variance in hair color was explained by 1000G well-imputed SNPs. Genome-wide association analysis for each hair color showed that SNPs in the MC1R region were significantly associated with red, brown and black hair, and also with light versus dark hair color. Five other known genes (HERC2, TPCN2, SLC24A4, IRF4, and KITLG) gave genome-wide significant hits for blond, brown and light versus dark hair color. We did not find and replicate any new loci for hair color. PMID:26184321

  16. A Twin Protection Effect? Explaining Twin Survival Advantages with a Two-Process Mortality Model.

    Science.gov (United States)

    Sharrow, David J; Anderson, James J

    2016-01-01

    Twin studies that focus on the correlation in age-at-death between twin pairs have yielded important insights into the heritability and role of genetic factors in determining lifespan, but less attention is paid to the biological and social role of zygosity itself in determining survival across the entire life course. Using data from the Danish Twin Registry and the Human Mortality Database, we show that monozygotic twins have greater cumulative survival proportions at nearly every age compared to dizygotic twins and the Danish general population. We examine this survival advantage by fitting these data with a two-process mortality model that partitions survivorship patterns into extrinsic and intrinsic mortality processes roughly corresponding to acute, environmental and chronic, biological origins. We find intrinsic processes confer a survival advantage at older ages for males, while at younger ages, all monozygotic twins show a health protection effect against extrinsic death akin to a marriage protection effect. While existing research suggests an increasingly important role for genetic factors at very advanced ages, we conclude that the social closeness of monozygotic twins is a plausible driver of the survival advantage at ages <65.

  17. Exploring the Co-Development of Reading Fluency and Reading Comprehension: A Twin Study.

    Science.gov (United States)

    Little, Callie W; Hart, Sara A; Quinn, Jamie M; Tucker-Drob, Elliot M; Taylor, Jeanette; Schatschneider, Christopher

    2016-11-10

    This study explores the co-development of two related but separate reading skills, reading fluency and reading comprehension, across Grades 1-4. A bivariate biometric dual change score model was applied to longitudinal data collected from 1,784 twin pairs between the ages of 6 and 10 years. Grade 1 skills were influenced by highly overlapping genetic and environmental factors. Growth in both skills was influenced by highly overlapping shared environmental factors. Cross-lagged parameters indicated bidirectional effects, with stronger effects from fluency to comprehension change than from comprehension to fluency change.

  18. Effect of street connectivity and density on adult BMI: results from the Twin Cities Walking Study.

    Science.gov (United States)

    McDonald, Kelsey N; Oakes, J Michael; Forsyth, Ann

    2012-07-01

    The prevalence of overweight and obesity in the US population has risen dramatically in recent years. To try to explain this, some studies have examined the association between the built environment and obesity (measured using the body mass index (BMI)). Most of these studies have not sought to identify causal effects, but rather correlations. Data from the Twin Cities Walking Study were used to examine the effect of population density and block size on BMI. Although the Twin Cities Walking Study is a cross-sectional observational study, the matched-sampling design is novel in that it maximises environmental variance while minimising person variance to enhance exchangeability of subjects and more closely mimic an experimental study. Contrary to expectations, the hypothesised most walkable neighbourhood (high density, small block stratum) had the greatest mean and median BMI. After adjusting for demographic covariates, physical activity and clustering due to neighbourhood, no conclusive effect of population density by block size on BMI was found (β=-1.024, 95% CI -2.408 to 0.359). There is no evidence of an effect of population density by block size on BMI.

  19. SUSY Meets Her Twin

    CERN Document Server

    Katz, Andrey; Pokorski, Stefan; Redigolo, Diego; Ziegler, Robert

    2016-01-01

    We investigate the general structure of mirror symmetry breaking in the Twin Higgs scenario. We show, using the IR effective theory, that a significant gain in fine tuning can be achieved if the symmetry is broken hardly. We emphasize that weakly coupled UV completions can naturally accommodate this scenario. We analyze SUSY UV completions and present a simple Twin SUSY model with a tuning of around 10% and colored superpartners as heavy as 2 TeV. The collider signatures of general Twin SUSY models are discussed with a focus on the extended Higgs sectors.

  20. SUSY Meets Her Twin

    CERN Document Server

    Katz, Andrey; Pokorski, Stefan; Redigolo, Diego; Ziegler, Robert

    2017-01-01

    We investigate the general structure of mirror symmetry breaking in the Twin Higgs scenario. We show, using the IR effective theory, that a significant gain in fine tuning can be achieved if the symmetry is broken hardly. We emphasize that weakly coupled UV completions can naturally accommodate this scenario. We analyze SUSY UV completions and present a simple Twin SUSY model with a tuning of around 10% and colored superpartners as heavy as 2 TeV. The collider signatures of general Twin SUSY models are discussed with a focus on the extended Higgs sectors.

  1. SUSY Meets Her Twin

    CERN Document Server

    Katz, Andrey; Pokorski, Stefan; Redigolo, Diego; Ziegler, Robert

    2017-01-31

    We investigate the general structure of mirror symmetry breaking in the Twin Higgs scenario. We show, using the IR effective theory, that a significant gain in fine tuning can be achieved if the symmetry is broken hardly. We emphasize that weakly coupled UV completions can naturally accommodate this scenario. We analyze SUSY UV completions and present a simple Twin SUSY model with a tuning of around 10% and colored superpartners as heavy as 2 TeV. The collider signatures of general Twin SUSY models are discussed with a focus on the extended Higgs sectors.

  2. The impact of laser surgery on angiogenic and anti-angiogenic factors in twin-twin transfusion syndrome: a prospective study().

    Science.gov (United States)

    Chon, Andrew H; Chavira, Emiliano R; Wilson, Melissa L; Ingles, Sue A; Llanes, Arlyn; Chmait, Ramen H

    2017-04-03

    To examine the effect of laser surgery on angiogenic and anti-angiogenic factors in patients with twin-twin transfusion syndrome (TTTS). Cases of TTTS and uncomplicated monochorionic diamniotic twin pregnancies between 16 and 26 weeks' gestation were prospectively enrolled into the study. Maternal blood samples were obtained to measure angiogenic factors (vascular endothelial growth factor-A [VEGF], placental-derived growth factor [PlGF], and endothelin) and anti-angiogenic factors (soluble fms-like tyrosine kinase (sFlt-1), soluble endoglin (sEng), and sFlt-1/PlGF ratio). For cases, these factors were measured at visit 1 (pre-operatively), visit 2 (postoperative day one), and visit 3 (at least 3 weeks after surgery). In controls, the factors were measured at visit 1 (enrollment) and visit 2 (at least 3 weeks later). Levels of angiogenic and anti-angiogenic factors between cases and controls were compared. At enrollment, the TTTS cases demonstrated an anti-angiogenic state with significantly higher sFlt-1, sEng, sFlt-1/PlGF ratio, and lower PlGF. Laser surgery, comparing visit 1-3, had a partial corrective effect on TTTS cases. sFlt-1 significantly decreased several weeks after surgery. The other factors (PlGF, endothelin, sFlt-1, sEng, and sFlt-1/PlGF ratio) were not statistically significantly different by visit 3. Laser surgery partially corrected the angiogenic profile in patients with TTTS.

  3. Rate and Outcomes of Pulmonary Stenosis and Functional Pulmonary Atresia in Recipient Twins with Twin-Twin Transfusion Syndrome.

    Science.gov (United States)

    Ortiz, Javier U; Masoller, Narcís; Gómez, Olga; Bennasar, Mar; Eixarch, Elisenda; Lobmaier, Silvia M; Crispi, Fàtima; Gratacos, Eduard; Martinez, Josep María

    2017-01-01

    To evaluate the rate of pulmonary stenosis and functional pulmonary atresia (PS/PA) in recipient twins prior to fetal surgery for twin-twin transfusion syndrome (TTTS) and their pre- and postnatal outcomes. We carried out a prospective study including 260 cases of TTTS. Echocardiography was performed before laser surgery to detect the presence of PS/PA. The outcomes of recipients with and without PS/PA were compared. The need of postnatal cardiac interventions and the survival rate at 6 months of age were also evaluated. PS was observed in 16/260 (6.2%) of recipient twins and PA in 12/260 (4.6%). After fetal surgery, 10/28 (35.7%) recipients died, 9/28 (32.1%) showed in utero regression, and 9/28 (32.1%) had persistence of PS/PA. Postnatally, seven recipients underwent percutaneous balloon pulmonary valvuloplasty, one required surgical valvotomy and one palliative surgery. Pregnancies with recipient twins with PS/PA had lower survival of at least one twin (67.9 vs. 83.6%, p = 0.045) and lower overall survival (57.1 vs. 72.8%, p = 0.015) at 6 months of age. PS and PA were observed in 10.8% of recipients. Among these, about one third showed persistence of pulmonary valve pathology after delivery, which stresses the need for strict follow-up. © 2016 S. Karger AG, Basel.

  4. Fetal Environment Is a Major Determinant of the Neonatal Blood Thyroxine Level: Results of a Large Dutch Twin Study.

    Science.gov (United States)

    Zwaveling-Soonawala, Nitash; van Beijsterveldt, Catharina E M; Mesfum, Ertirea T; Wiedijk, Brenda; Oomen, Petra; Finken, Martijn J J; Boomsma, Dorret I; van Trotsenburg, A S Paul

    2015-06-01

    The interindividual variability in thyroid hormone function parameters is much larger than the intraindividual variability, suggesting an individual set point for these parameters. There is evidence to suggest that environmental factors are more important than genetic factors in the determination of this individual set point. This study aimed to quantify the effect of genetic factors and (fetal) environment on the early postnatal blood T4 concentration. This was a classical twin study comparing the resemblance of neonatal screening blood T4 concentrations in 1264 mono- and 2566 dizygotic twin pairs retrieved from the population-based Netherlands Twin Register. Maximum-likelihood estimates of variance explained by genetic and environmental influences were obtained by structural equation modeling in data from full-term and preterm twin pairs. In full-term infants, genetic factors explained 40%/31% of the variance in standardized T4 scores in boys/girls, and shared environment, 27%/22%. The remaining variance of 33%/47% was due to environmental factors not shared by twins. For preterm infants, genetic factors explained 34%/0% of the variance in boys/girls, shared environment 31%/57%, and unique environment 35%/43%. In very preterm twins, no significant contribution of genetic factors was observed. Environment explains a large proportion of the resemblance of the postnatal blood T4 concentration in twin pairs. Because we analyzed neonatal screening results, the fetal environment is the most likely candidate for these environmental influences. Genetic influences on the T4 set point diminished with declining gestational age, especially in girls. This may be due to major environmental influences such as immaturity and nonthyroidal illness in very preterm infants.

  5. Genetic overlap between impulsivity and alcohol dependence: a large-scale national twin study.

    Science.gov (United States)

    Khemiri, L; Kuja-Halkola, R; Larsson, H; Jayaram-Lindström, N

    2016-04-01

    Alcohol dependence is associated with increased levels of impulsivity, but the genetic and environmental underpinnings of this overlap remain unclear. The purpose of the current study was to investigate the degree to which genetic and environmental factors contribute to the overlap between alcohol dependence and impulsivity. Univariate and bivariate twin model fitting was conducted for alcohol dependence and impulsivity in a national sample of 16 819 twins born in Sweden from 1959 to 1985. The heritability estimate for alcohol dependence was 44% [95% confidence interval (CI) 31-57%] for males and 62% (95% CI 52-72%) for females. For impulsivity, the heritability was 33% (95% CI 30-36%) in males and females. The bivariate twin analysis indicated a statistically significant genetic correlation between alcohol dependence and impulsivity of 0.40 (95% CI 0.23-0.58) in males and 0.20 (95% CI 0.07-0.33) in females. The phenotypic correlation between alcohol dependence and impulsivity was 0.20 and 0.17 for males and females, respectively, and the bivariate heritability was 80% (95% CI 47-117%) for males and 53% (95% CI 19-86%) for females. The remaining variance in all models was accounted for by non-shared environmental factors. The association between alcohol dependence and impulsivity can be partially accounted for by shared genetic factors. The genetic correlation was greater in men compared with women, which may indicate different pathways to the development of alcohol dependence between sexes. The observed genetic overlap has clinical implications regarding treatment and prevention, and partially explains the substantial co-morbidity between alcohol dependence and psychiatric disorders characterized by impulsive behaviour.

  6. Genetic influences on brain asymmetry: a DTI study of 374 twins and siblings.

    Science.gov (United States)

    Jahanshad, Neda; Lee, Agatha D; Barysheva, Marina; McMahon, Katie L; de Zubicaray, Greig I; Martin, Nicholas G; Wright, Margaret J; Toga, Arthur W; Thompson, Paul M

    2010-08-15

    Brain asymmetry, or the structural and functional specialization of each brain hemisphere, has fascinated neuroscientists for over a century. Even so, genetic and environmental factors that influence brain asymmetry are largely unknown. Diffusion tensor imaging (DTI) now allows asymmetry to be studied at a microscopic scale by examining differences in fiber characteristics across hemispheres rather than differences in structure shapes and volumes. Here we analyzed 4Tesla DTI scans from 374 healthy adults, including 60 monozygotic twin pairs, 45 same-sex dizygotic pairs, and 164 mixed-sex DZ twins and their siblings; mean age: 24.4years+/-1.9 SD). All DTI scans were nonlinearly aligned to a geometrically-symmetric, population-based image template. We computed voxel-wise maps of significant asymmetries (left/right differences) for common diffusion measures that reflect fiber integrity (fractional and geodesic anisotropy; FA, GA and mean diffusivity, MD). In quantitative genetic models computed from all same-sex twin pairs (N=210 subjects), genetic factors accounted for 33% of the variance in asymmetry for the inferior fronto-occipital fasciculus, 37% for the anterior thalamic radiation, and 20% for the forceps major and uncinate fasciculus (all L>R). Shared environmental factors accounted for around 15% of the variance in asymmetry for the cortico-spinal tract (R>L) and about 10% for the forceps minor (L>R). Sex differences in asymmetry (men>women) were significant, and were greatest in regions with prominent FA asymmetries. These maps identify heritable DTI-derived features, and may empower genome-wide searches for genetic polymorphisms that influence brain asymmetry.

  7. Genetic and environmental influences on impulsivity: A meta-analysis of twin, family and adoption studies

    Science.gov (United States)

    Bezdjian, Serena; Baker, Laura A.; Tuvblad, Catherine

    2011-01-01

    A meta-analysis of twin, family and adoption studies was conducted to estimate the magnitude of genetic and environmental influences on impulsivity. The best fitting model for 41 key studies (58 independent samples from 14 month old infants to adults; N = 27,147) included equal proportions of variance due to genetic (0.50) and non-shared environmental (0.50) influences, with genetic effects being both additive (0.38) and non-additive (0.12). Shared environmental effects were unimportant in explaining individual differences in impulsivity. Age, sex, and study design (twin vs. adoption) were all significant moderators of the magnitude of genetic and environmental influences on impulsivity. The relative contribution of genetic effects (broad sense heritability) and unique environmental effects were also found to be important throughout development from childhood to adulthood. Total genetic effects were found to be important for all ages, but appeared to be strongest in children. Analyses also demonstrated that genetic effects appeared to be stronger in males than in females. Method of assessment (laboratory tasks vs. questionnaires), however, was not a significant moderator of the genetic and environmental influences on impulsivity. These results provide a structured synthesis of existing behavior genetic studies on impulsivity by providing a clearer understanding of the relative genetic and environmental contributions in impulsive traits through various stages of development. PMID:21889436

  8. Twin studies of schizophrenia: from bow-and-arrow concordances to star wars Mx and functional genomics.

    Science.gov (United States)

    Cardno, A G; Gottesman, I I

    2000-01-01

    Twin studies have been vital for establishing an important genetic contribution to the etiology of schizophrenia. The five newest studies since 1995 from Europe and Japan have confirmed earlier findings. They yielded probandwise concordance rates of 41-65% in monozygotic (MZ) pairs and 0-28% in dizygotic (DZ) pairs, and heritability estimates of approximately 80-85%. Twin studies are also valuable for investigating the etiological relationships between schizophrenia and other disorders, and the genetic basis of clinical heterogeneity within schizophrenia. Studies of discordant MZ pairs provide further insights into non-inherited factors that contribute to the multifactorial etiology of this disorder. More recently, twin studies have begun to be used to directly investigate molecular genetic and epigenetic processes underlying schizophrenia.

  9. Twin pregnancy

    DEFF Research Database (Denmark)

    Sperling, Lene; Tabor, A

    2001-01-01

    Determination of chorionicity is one of the most important issues in the management of twin pregnancy. Modern ultrasound equipment has made it possible to accurately assess placentation already in the first trimester with the lambda sign. With regard to prenatal diagnosis, it is important to know...... for clinicians caring for twin pregnancies....

  10. Application of hierarchical genetic models to Raven and WAIS subtests: a Dutch twin study.

    Science.gov (United States)

    Rijsdijk, Frühling V; Vernon, P A; Boomsma, Dorret I

    2002-05-01

    Hierarchical models of intelligence are highly informative and widely accepted. Application of these models to twin data, however, is sparse. This paper addresses the question of how a genetic hierarchical model fits the Wechsler Adult Intelligence Scale (WAIS) subtests and the Raven Standard Progressive test score, collected in 194 18-year-old Dutch twin pairs. We investigated whether first-order group factors possess genetic and environmental variance independent of the higher-order general factor and whether the hierarchical structure is significant for all sources of variance. A hierarchical model with the 3 Cohen group-factors (verbal comprehension, perceptual organisation and freedom-from-distractibility) and a higher-order g factor showed the best fit to the phenotypic data and to additive genetic influences (A), whereas the unique environmental source of variance (E) could be modeled by a single general factor and specifics. There was no evidence for common environmental influences. The covariation among the WAIS group factors and the covariation between the group factors and the Raven is predominantly influenced by a second-order genetic factor and strongly support the notion of a biological basis of g.

  11. Mechanistic studies on the release of lysozyme from twin-screw extruded lipid implants.

    Science.gov (United States)

    Sax, Gerhard; Winter, Gerhard

    2012-10-28

    The influence of lipid melting on the in-vitro release of lysozyme from twin-screw extruded lipid implants was investigated. Triglyceride based implants were prepared by admixing of glycerol tristearin and various low melting lipids and subsequent twin-screw extrusion (tsc-extrusion) of these mixtures at moderate temperatures. Lysozyme was embedded as model protein and PEG 4000 or PEG 6000 was used as pore-forming excipient. By decreasing the amount of pore-forming agent from 40% to 0% lysozyme release became more sustained and the release kinetics changed from a matrix-type release profile to a linear release profile. Differential scanning calorimetry, X-ray diffraction and scanning electron microscopy measurements showed a change in implant structure upon long-term release (240 days) at 37 °C which was explained by partial matrix melting. In addition, partial melting of the implants was found to facilitate complete drug release at 37 °C whereas at 20 °C without partial melting 20% to 90% of the incorporated protein remained trapped in the implant matrix. In conclusion, partial melting of the implants during in-vitro release was found to be a major factor for the control of protein release from extruded implants and can be useful to trigger release, achieve in-vivo biodegradability and complete long-term protein release.

  12. Mitral valve regurgitation in twins

    DEFF Research Database (Denmark)

    Bakkestrøm, Rine; Larsen, Lisbeth Aagaard; Møller, Jacob Eifer

    2016-01-01

    BACKGROUND: Smaller observational studies have suggested familial clustering of mitral regurgitation (MR). Using a large twin cohort, the aims were to assess MR concordance rates and assess mortality in MR twins and unaffected cotwins. METHODS: Through the Danish Twin Registry, twins...... with an International Classification of Diseases, Eighth Revision and Tenth Revision diagnosis code of MR born 1880-1989 were identified and proband-wise concordance rates were calculated. To assess whether having a cotwin with MR affected survival, 10 matched twins without MR (n = 5,575) were selected for each MR twin...... (n = 562), and all-cause mortality rates were assessed. RESULTS: Among the 87,432 twins alive January 1, 1977, or later, 494 (0.57%) MR individuals were identified. Six MR concordant pairs were found, of which 3 were monozygotic. Proband-wise concordance rate when accounting for right censoring...

  13. Neonatal status of twins

    Directory of Open Access Journals (Sweden)

    Božinović Dragica

    2012-01-01

    Full Text Available Multiple pregnancy is a pregnancy where more than one fetus develops simultaneously in the womb, as a result of the ovulation and fertilization of more than one egg. It is relatively rare in humans and represents the rest of the phylogenetic stages. The most common are twins and they indicate the development of two fetuses in the womb. The frequency of twin pregnancies is about 1%. Multiple pregnancies belong to a group of high-risk pregnancies because of the many complications that occur during the pregnancy: higher number of premature deliveries, bleeding, early neonatal complications and higher perinatal morbidity and mortality. Such pregnancies and infants require greater supervision and monitoring. The aim of this study was to determine the percentage of baby twins born at the maternity ward of the General Hospital in Prokuplje and their morbidity and mortality. Data on the total number of deliveries, number of twins, parity and maternal age, gestational age, body weight of twins, method of delivery, Apgar score and perinatal mortality were collected and statistically analyzed by means of retrospective analysis of operative birth and neonatal protocol for 6 years (2005 of 2010. Out of 4527 mothers who gave birth 43 were pairs of twins, or 0.95% of women gave birth to twins. These babies are more likely born by Caesarean section, but delivered with slightly lower birth weight.

  14. Plasticity and ultra-low stress induced twin boundary migration in nanotwinned Cu by in situ nanoindentation studies

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y.; Chen, Y. [Department of Materials Science and Engineering, Texas A and M University, College Station, Texas 77843 (United States); Jian, J. [Department of Electrical Engineering, Texas A and M University, College Station, Texas 77843 (United States); Wang, H. [Department of Materials Science and Engineering, Texas A and M University, College Station, Texas 77843 (United States); Department of Electrical Engineering, Texas A and M University, College Station, Texas 77843 (United States); Zhang, X., E-mail: zhangx@tamu.edu [Department of Materials Science and Engineering, Texas A and M University, College Station, Texas 77843 (United States); Department of Mechanical Engineering, Texas A and M University, College Station, Texas 77843 (United States)

    2014-06-09

    Nanotwinned metals have rare combinations of mechanical strength and ductility. Previous studies have shown that detwinning occurs in plastically deformed nanotwinned metals. Although molecular dynamics simulations have predicted that fine nanotwins can migrate at low stress, there is little in situ evidence to validate such predictions. Also it is unclear if detwinning occurs prior to or succeeding plastic yielding. Here, by using in situ nanoindentation in a transmission electron microscope, we show that a non-elastic detwinning process in nanotwinned Cu occurred at ultra-low indentation stress (0.1 GPa), well before the stress necessary for plastic yielding. Furthermore, the in situ nanoindentation technique allows us to differentiate dislocation-nucleation dominated microscopic yielding preceding macroscopic yielding manifested by dislocation-transmission through twin boundaries. This study thus provides further insights for understanding plasticity in nanotwinned metals at microscopic levels.

  15. The Genetic and Environmental Contributions to Internet Use and Associations With Psychopathology: A Twin Study.

    Science.gov (United States)

    Long, Elizabeth C; Verhulst, Brad; Neale, Michael C; Lind, Penelope A; Hickie, Ian B; Martin, Nicholas G; Gillespie, Nathan A

    2016-02-01

    Excessive internet use has been linked to psychopathology. Therefore, understanding the genetic and environmental risks underpinning internet use and their relation to psychopathology is important. This study aims to explore the genetic and environmental etiology of internet use measures and their associations with internalizing disorders and substance use disorders. The sample included 2,059 monozygotic (MZ) and dizygotic (DZ) young adult twins from the Brisbane Longitudinal Twin Study (BLTS). Younger participants reported more frequent internet use, while women were more likely to use the internet for interpersonal communication. Familial aggregation in 'frequency of internet use' was entirely explained by additive genetic factors accounting for 41% of the variance. Familial aggregation in 'frequency of use after 11 pm', 'using the internet to contact peers', and 'using the internet primarily to access social networking sites' was attributable to varying combinations of additive genetic and shared environmental factors. In terms of psychopathology, there were no significant associations between internet use measures and major depression (MD), but there were positive significant associations between 'frequency of internet use' and 'frequency of use after 11 pm' with social phobia (SP). 'Using the internet to contact peers' was positively associated with alcohol abuse, whereas 'using the internet to contact peers' and 'using the internet primarily to access social networking sites' were negatively associated with cannabis use disorders and nicotine symptoms. Individual differences in internet use can be attributable to varying degrees of genetic and environmental risks. Despite some significant associations of small effect, variation in internet use appears mostly unrelated to psychopathology.

  16. Coordination difficulty and internalizing symptoms in adults: A twin/sibling study.

    Science.gov (United States)

    Waszczuk, Monika A; Leonard, Hayley C; Hill, Elisabeth L; Rowe, Richard; Gregory, Alice M

    2016-05-30

    Increased anxiety and depression symptoms have been reported in individuals with neurodevelopmental disorders, and have been found to be associated with motor coordination difficulties, but little is known about the etiology of these associations. This study aimed to assess genetic, shared (making twins/siblings alike) and non-shared (individual-specific) environmental influences on the association between poor coordination and symptoms of anxiety and depressed mood using a sample of adult twin and sibling pairs. Participants were asked about their coordination skill and anxiety and depression symptoms. About half of the variance in coordination difficulty was explained by familial (combined genetic and shared environmental) influences, with the remaining variance explained by non-shared environmental influences. Phenotypic associations between coordination and anxiety (r=.46) and depression symptoms (r=.44) were largely underpinned by shared familial liability for the three traits. Non-shared environment accounted for about a third of the phenotypic association. Results suggest that both familial and non-shared environmental influences play a role in the etiology of coordination difficulty and its association with internalizing symptoms. The current study highlights that both biological and environmental pathways shared between these symptoms should be examined in future research to inform prevention and treatment approaches in clinical settings.

  17. Chaotic homes and children's disruptive behavior: a longitudinal cross-lagged twin study.

    Science.gov (United States)

    Jaffee, Sara R; Hanscombe, Ken B; Haworth, Claire M A; Davis, Oliver S P; Plomin, Robert

    2012-06-01

    Chaotic home lives are correlated with behavior problems in children. In the study reported here, we tested whether there was a cross-lagged relation between children's experience of chaos and their disruptive behaviors (conduct problems and hyperactivity-inattention). Using genetically informative models, we then tested for the first time whether the influence of household chaos on disruptive behavior was environmentally mediated and whether genetic influences on children's disruptive behaviors accounted for the heritability of household chaos. We measured children's perceptions of household chaos and parents' ratings of children's disruptive behavior at ages 9 and 12 in a sample of 6,286 twin pairs from the Twins Early Development Study (TEDS). There was a phenotypic cross-lagged relation between children's experiences of household chaos and their disruptive behavior. In genetically informative models, we found that the effect of household chaos on subsequent disruptive behavior was environmentally mediated. However, genetic influences on disruptive behavior did not explain why household chaos was heritable.

  18. Measuring early or late dependence for bivariate lifetimes of twins

    DEFF Research Database (Denmark)

    Scheike, Thomas; Holst, Klaus K; Hjelmborg, Jacob B

    2015-01-01

    We consider data from the Danish twin registry and aim to study in detail how lifetimes for twin-pairs are correlated. We consider models where we specify the marginals using a regression structure, here Cox's regression model or the additive hazards model. The best known such model is the Clayton...... procedures are applied to Danish twin data to describe dependence in the lifetimes of the twins. Here we show that the early deaths are more correlated than the later deaths, and by comparing MZ and DZ associations we suggest that early deaths might be more driven by genetic factors. This conclusion requires...... models that are able to look at more local dependence measures. We further show that the dependence differs for MZ and DZ twins and appears to be the same for males and females, and that there are indications that the dependence increases over calendar time....

  19. Twinning Phenomena along and beyond the Bain Path

    Directory of Open Access Journals (Sweden)

    Sebastian Fähler

    2013-10-01

    Full Text Available Twinning is a phenomenon that occurs, e.g., during deformation, martensitic transformation and film growth. The present study shows that the crystallography of twinning can be described by two twinning modes along the complete Bain transformation path and beyond connecting body-centered and face-centered cubic structures. To probe this concept, we used strained epitaxial films of the Fe-Pd magnetic shape memory system. As the substrate acts as an absolute reference frame, we could show by pole figure measurements that all observed twinning can be a body-centered and face-centered cubic twinning mode. This continuously transforms towards identity when approaching the complementary structure.

  20. Symptoms of autism and ADHD: a Swedish twin study examining their overlap.

    Science.gov (United States)

    Ronald, Angelica; Larsson, Henrik; Anckarsäter, Henrik; Lichtenstein, Paul

    2014-05-01

    Autism spectrum disorders (ASD) and attention deficit hyperactivity disorder (ADHD) show high comorbidity. The following questions were addressed regarding their specific symptoms: What is the factor structure of ASD and ADHD symptoms, to what degree do different symptom domains cluster together, to what extent are these domains caused by the same genetic and environmental influences, and what is the best model of their co-occurrence? A population-based twin cohort of over 17,000 9- and 12-year-olds were assessed using the Autism-Tics, AD/HD, and other Comorbidities parental interview inventory. Principal component analyses were conducted, and symptom domain clustering was assessed. Four multivariate twin models were compared. Factors split into three ASD (social impairments, communication impairments, and restricted repetitive behaviors and interests), and three ADHD (inattention, hyperactivity, and impulsivity) symptom domains. Some ASD-ADHD symptom domain combinations clustered together often, although others not at all. A two-factor common pathway model fit the data, suggesting that ASD and ADHD symptom domains tap into separate "ASD" and "ADHD" latent factors that showed high genetic overlap. All subdomains also showed significant specific genetic and environmental influences, reflecting the etiological heterogeneity both within and between ASD and ADHD. These findings support the conceptual distinction of ASD and ADHD, and demonstrate the considerable natural co-occurrence of particular ASD/ADHD symptom domains. The results imply that more children with 1 condition show features of the other condition than show complete comorbidity. Emphasis on symptom co-occurrence, rather than complete comorbidity between disorders, may help focus clinical approaches and advance molecular genetic research.

  1. Brain Activation during Memory Encoding in Type 2 Diabetes Mellitus: A Discordant Twin Pair Study

    Directory of Open Access Journals (Sweden)

    Amanda G. Wood

    2016-01-01

    Full Text Available Type 2 diabetes mellitus increases the risk of dementia and neuronal dysfunction may occur years before perceptible cognitive decline. We aimed to study the impact of type 2 diabetes on brain activation during memory encoding in middle-aged people, controlling for age, sex, genes, and early-shared environment. Twenty-two twin pairs discordant for type 2 diabetes mellitus (mean age 60.9 years without neurological disease were recruited from the Australian Twin Registry (ATR and underwent functional magnetic resonance imaging (fMRI during a memory encoding task, cognitive tests, and structural MRI. Type 2 diabetes was associated with significantly reduced activation in left hemisphere temporoparietal regions including angular gyrus, supramarginal gyrus, and middle temporal gyrus and significantly increased activation in bilateral posteriorly distributed regions. These findings were present in the absence of within-pair differences in standard cognitive test scores, brain volumes, or vascular lesion load. Differences in activation were more pronounced among monozygotic (MZ pairs, with MZ individuals with diabetes also displaying greater frontal activation. These results provide evidence for preclinical memory-related neuronal dysfunction in type 2 diabetes. They support the search for modifiable later-life environmental factors or epigenetic mechanisms linking type 2 diabetes and cognitive decline.

  2. The contribution of endogenous and exogenous factors to male alopecia: a study of identical twins.

    Science.gov (United States)

    Gatherwright, James; Liu, Mengyuan T; Amirlak, Bardia; Gliniak, Christy; Totonchi, Ali; Guyuron, Bahman

    2013-05-01

    The purpose of this study was to investigate the potential contribution of environmental factors and testosterone on male alopecia. Ninety-two identical male twins were recruited from 2009 to 2011. A comprehensive questionnaire was completed followed by the acquisition of sputum samples for testosterone analysis and standardized digital photography. Frontal, temporal, and vertex hair loss was assessed from these photographs. Hair loss was then correlated with survey responses and testosterone levels between twin pairs. Two independent, blinded observers also rated the photographs for hair thinning. Increased smoking duration (p money spent on hair loss products (p = 0.050) were all associated with increased temporal hair loss. Daily hat use (p = 0.050), higher body mass index (p = 0.012), and higher testosterone levels (p = 0.040) were associated with decreased temporal hair loss. Factors that were significantly associated with increased vertex hair loss included abstinence from alcohol consumption (p = 0.030), consumption of more than four alcoholic drinks per week (p = 0.004), increased smoking duration (p = 0.047), increased exercise duration (p = 0.050), and increased stress duration (p = 0.010). Lower body mass index, more children, increased caffeine consumption, history of skin disease, and abstinence from alcohol were significantly associated with increased hair thinning scores (p exogenous factors may have a clinically significant impact on hair loss. Risk, III.

  3. Genetic and Environmental Influences on Pulmonary Function and Muscle Strength: The Chinese Twin Study of Aging

    DEFF Research Database (Denmark)

    Tian, Xiaocao; Xu, Chunsheng; Wu, Yili;

    2017-01-01

    Genetic and environmental influences on predictors of decline in daily functioning, including forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), handgrip, and five-times-sit-to-stand test (FTSST), have not been addressed in the aging Chinese population. We performed classical twin...... was moderate for FEV1, handgrip, and FTSST (55-60%) but insignificant for FVC. Only FVC showed moderate control, with shared environmental factors accounting for about 50% of the total variance. In contrast, all measures of pulmonary function and muscle strength showed modest influences from the unique...... direction. We conclude that genetic factors contribute significantly to the individual differences in common indicators of daily functioning (FEV1, handgrip, and FTSST). FEV1 and FVC were genetically and environmentally correlated. Pulmonary function and FTSST may share similar sets of genes...

  4. Zika May Persist for Months in Newborns, Study Shows

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_160594.html Zika May Persist for Months in Newborns, Study Shows ... There's more bad news when it comes to Zika's effect on infants: A case study suggests the ...

  5. Genetic, maternal and placental factors in the association between birth weight and physical fitness: a longitudinal twin study.

    Directory of Open Access Journals (Sweden)

    Robbert N H Touwslager

    Full Text Available BACKGROUND: Adult cardiorespiratory fitness and muscle strength are related to all-cause and cardiovascular mortality. Both are possibly related to birth weight, but it is unclear what the importance is of genetic, maternal and placental factors in these associations. DESIGN: Peak oxygen uptake and measures of strength, flexibility and balance were obtained yearly during adolescence (10-18 years in 114 twin pairs in the Leuven Longitudinal Twin Study. Their birth weights had been collected prospectively within the East Flanders Prospective Twin Survey. RESULTS: We identified linear associations between birth weight and adolescent vertical jump (b = 1.96 cm per kg birth weight, P = 0.02, arm pull (b = 1.85 kg per kg birth weight P = 0.03 and flamingo balance (b = -1.82 attempts to stand one minute per kg birth weight, P = 0.03. Maximum oxygen uptake appeared to have a U-shaped association with birth weight (the smallest and largest children had the lowest uptake, P = 0.01, but this association was no longer significant after adjustment for parental BMI. Using the individual twin's deviation from his own twin pair's average birth weight, we found positive associations between birth weight and adolescent vertical jump (b = 3.49, P = 0.0007 and arm pull (b = 3.44, P = 0.02. Δ scores were calculated within the twin pairs as first born twin minus second born twin. Δ birth weight was associated with Δ vertical jump within MZ twin pairs only (b = 2.63, P = 0.009, which indicates importance of placental factors. CONCLUSIONS: We found evidence for an association between adolescent physical performance (strength, balance and possibly peak oxygen uptake and birth weight. The associations with vertical jump and arm pull were likely based on individual, more specifically placental (in the case of vertical jump factors. Our results should be viewed as hypothesis-generating and need confirmation, but potentially support preventive strategies to optimize

  6. A study of concentrated acid hydrolysis conversion of lignocellulosic materials to sugars using a co-rotating twin-screw reactor extruder and plug flow reactor

    Science.gov (United States)

    Miller, William Scott

    Concerns about the ability of petroleum to continue supplying ever increasing global energy demands, at a price capable of generating continued economic growth, have spurred innovative research in the field of alternative energy. One alternative energy option that has the ability to provide long-term sustainable energy supplies for the global energy market is the conversion of lignocellulosic materials, via acid hydrolysis, to fermentable sugars for the production of fuel grade ethanol. This research demonstrates the ability of a co-rotating twin-screw reactor extruder and plug flow reactor to continuously convert lignocellulosic materials to fermentable sugars using high temperature concentrated acid hydrolysis. In addition to demonstrating continuous operation of the two-stage concentrated acid hydrolysis system, a number of design of experiments were conducted to model the twin-screw performance and maximize its ability to effectively solubilize lignocellulosic feedstocks in the high shear, elevated temperature, concentrated acid environment. These studies produced a base case twin-screw operating condition used to generate a standard extrudate composition for an extensive high temperature acid hydrolysis batch reactor kinetic modeling study. In this study a number of nonlinear and linear regression analyses were undertaken so that the concentration of less resistant cellulose, or the amount of solublilized extrudate cellulose, resistant cellulose, or non-solubilized extrudate cellulose, glucose, and decomposition products could be obtained as a function of time, temperature, and acid concentration. This study demonstrated that the theoretical cellulose conversion of 51% was limited by the amount of solubilized polysaccharides that could be produced in the twin-screw pretreatment. Further experimentation, showing twin-screw pretreatment lignocellulosic versatility, produced nearly identical results as the southern yellow pine sawdust experiments that were

  7. Skewed X inactivation and survival: a 13-year follow-up study of elderly twins and singletons

    DEFF Research Database (Denmark)

    Mengel-From, Jonas; Thinggaard, Mikael; Christiansen, Lene;

    2012-01-01

    . In populations of women past 55-60 years of age, an increased degree of skewing (DS) is found. Here the association between age-related skewing and mortality is analyzed in a 13-year follow-up study of 500 women from three cohorts (73-100 years of age at intake). Women with low DS had significantly higher...... mortality than the majority of women who had a more skewed DS (hazard ratio: 1.30; 95% CI: 1.04-1.64). The association between X inactivation and mortality was replicated in dizygotic twin pairs for which the co-twin with the lowest DS also had a statistically significant tendency to die first in the twin...

  8. A Chaotic Home Environment Accounts for the Association between Respect for Rules Disposition and Reading Comprehension: A Twin Study.

    Science.gov (United States)

    Taylor, Jeanette; Hart, Sara A

    2014-10-01

    This study examined the association between socioemotional dispositions from the developmental propensity model and reading comprehension and whether those associations could be accounted for by level of chaos in the home. Data from 342 monozygotic and 333 same-sex dizygotic twin pairs age 7-13 years were used. A parent rated the twins on sympathy, respect for rules, negative emotionality, and daring and level of chaos in the twins' home. Reading comprehension was measured using a state-wide school assessment. Only respect for rules significantly and uniquely predicted reading comprehension. Biometric models indicated that respect for rules was positively associated with reading comprehension via the shared environment and home chaos accounted for a significant amount of that shared environmental variance even after controlling for family income. Children with higher respect for rules have better reading comprehension scores in school and this relationship owes partly to the level of chaos in the family home.

  9. TEM study of pseudo-twin in an off-stoichiometric Ni{sub 2}MnGa

    Energy Technology Data Exchange (ETDEWEB)

    Maeda, Hidefumi [Department of Materials Science and Engineering, Graduate School of Engineering, Osaka University, 2-1, Yamada-oka, Suita, Osaka 565-0871 (Japan); Department of Mechanical and Systems Engineering, Faculty of Science and Technology, Ryukoku University, Yokotani 1-5, Seta Oe-cyo, Otsu, Shiga 520-2194 (Japan); Taguchi, Eiji [Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, 7-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Fukuda, Takashi; Kakeshita, Tomoyuki [Department of Materials Science and Engineering, Graduate School of Engineering, Osaka University, 2-1, Yamada-oka, Suita, Osaka 565-0871 (Japan)

    2013-11-15

    Highlights: ► In Ni–Mn–Ga alloy which has transformation temperature around room temperature, it is difficult to observe in static by using transmission electron microscope. ► In a condition that the magnetic field in TEM hardly influences to the sample transformation, the TEM bright field micrograph of uniform texture in Ni{sub 55.5}Mn{sub 20.0}Ga{sub 24.5} (T{sub M} at 360 K) was captured along [0 1 0] and [1 1 1] direction. ► This texture was revealed that a twin-like banded structure composed of two orthorhombic lattice. ► The precisely measuring of angles subtended by diffraction spots on the [1 1 1] diffraction pattern revealed that two crystals which constructed a twin-like structure have different crystal structure in a microscopic region. -- Abstract: We have investigated twin-like microstructure of the martensite phase in a Ni{sub 55.5}Mn{sub 20.0}Ga{sub 24.5} (at.%) alloy by using transmission electron microscope (TEM). The bright field image of the martensite phase showed striped microstructure composed of two crystals. Assuming that both crystals have orthorhombic structures, we calculated the axial ratios c/a and b/a from the 1 1 1 diffraction patterns by using angles between reflections. As a result, we found that the axial ratios of one crystal are slightly different from those of the other crystal. This result implies that the twin-like (striped) microstructure of Ni{sub 55.5}Mn{sub 20.0}Ga{sub 24.5} is not true twin but is pseudo-twin.

  10. A Study on Person Deixis Used in TV Talk Show

    Institute of Scientific and Technical Information of China (English)

    肖晓

    2014-01-01

    Deixis means“pointing” via language. There are many scholars who study person deixis in different discourses. However, few of them have analyzed person deixis used in TV talk show, which is more popular in our daily life. TV talk show is an important face-to-face conversation in which the participants use some person deixis to reach certain goal. This thesis studies the person deixis used in TV talk show especial y three types of unconventional usage of person deixis in the TV talk show discourse.

  11. The relationship between obesity, low back pain, and lumbar disc degeneration when genetics and the environment are considered: a systematic review of twin studies.

    Science.gov (United States)

    Dario, Amabile B; Ferreira, Manuela L; Refshauge, Kathryn M; Lima, Thais S; Ordoñana, Juan R; Ferreira, Paulo H

    2015-05-01

    The relationships between obesity and low back pain (LBP) and lumbar disc degeneration (LDD) remain unclear. It is possible that familial factors, including genetics and early environment, affect these relationships. To investigate the relationship between obesity-related measures (eg, weight, body mass index [BMI]) and LBP and LDD using twin studies, where the effect of genetics and early environment can be controlled. A systematic review with meta-analysis. MEDLINE, CINAHL, Scopus, Web of Science, and EMBASE databases were searched from the earliest records to August 2014. All cross-sectional and longitudinal observational twin studies identified by the search strategy were considered for inclusion. Two investigators independently assessed the eligibility, conducted the quality assessment, and extracted the data. Metaanalyses (fixed or random effects, as appropriate) were used to pool studies' estimates of association. In total, 11 articles met the inclusion criteria. Five studies were included in the LBP analysis and seven in the LDD analysis. For the LBP analysis, pooling of the five studies showed that the risk of having LBP for individuals with the highest levels of BMI or weight was almost twice that of people with a lower BMI (odds ratio [OR] 1.8; 95% confidence interval [CI] 1.6-2.0; I(2)=0%). A dose-response relationship was also identified. When genetics and the effects of a shared early environment were adjusted for using a within-pair twin case-control analysis, pooling of three studies showed a reduced but statistically positive association between obesity and prevalence of LBP (OR 1.5; 95% CI 1.1-2.1; I(2)=0%). However, the association was further diminished and not significant (OR 1.4; 95% CI 0.8-2.3; I(2)=0%) when pooling included two studies on monozygotic twin pairs only. Seven studies met the inclusion criteria for LDD. When familial factors were not controlled for, body weight was positively associated with LDD in all five cross

  12. Are lifestyle-factors in adolescence predictors for adult low back pain? A cross-sectional and prospective study of young twins

    Directory of Open Access Journals (Sweden)

    Leboeuf-Yde Charlotte

    2006-03-01

    Full Text Available Abstract Introduction With more than half of the population experiencing low back pain (LBP before the age of 20, research must focus on young populations. Lifestyle-factors might be important elements of prevention, since they are modifiable in nature. Therefore, the objective of the present study is to investigate the association between smoking, alcohol consumption and overweight in adolescence and 1 present LBP (cross-sectionally and 2 the risk of future LBP (longitudinally. Methods Data from 9,600 twins, aged 12–22, were analysed cross-sectionally with respect to associations between the above-mentioned lifestyle-factors and LBP. Eight years later, a follow-up survey (n = 6,554 was conducted and LBP at follow-up was correlated to the lifestyle-factors at baseline. Finally, the associations found to be significant were tested in a twin-control study design. Results Our cross-sectional study demonstrated small, but statistically significant, positive associations between all three investigated life-style factors and LBP. In the longitudinal study, smoking at baseline showed a monotonic dose-response relationship with LBP at follow-up (OR up to 4.0 for those smoking >20 cig./day. There was also evidence of temporality (smoking preceding LBP. Adult LBP was negatively associated with adolescent alcohol consumption. We found no evidence of a dose-response relationship or temporality. There were no associations detected between adolescent overweight and adult LBP. In the twin-control study, the directions of associations were the same, but none of these associations attained statistical significance. Conclusion Several of the Bradford Hill criteria for causality were fulfilled for smoking whereas the crucial aspect of temporality was missing for alcohol consumption and overweight. The twin-control study failed to confirm a statistically significant link between smoking and LBP.

  13. The Spread of Substance Use and Delinquency between Adolescent Twins

    Science.gov (United States)

    Laursen, Brett; Hartl, Amy C.; Vitaro, Frank; Brendgen, Mara; Dionne, Ginette; Boivin, Michel

    2017-01-01

    This investigation examines the spread of problem behaviors (substance use and delinquency) between twin siblings. A sample of 628 twins (151 male twin pairs and 163 female twin pairs) drawn from the Quebec Newborn Twin Study completed inventories describing delinquency and substance use at ages 13, 14, and 15. A 3-wave longitudinal actor-partner…

  14. Comparative study of social skills observation of twin with and without visual impairment

    Directory of Open Access Journals (Sweden)

    Carolina Severino Lopes da Costa

    2012-03-01

    Full Text Available The general aim was to describe and characterize the social performances of two identical twins aged ten years old: one blind and one sighted. The data were obtained by filming the children during free situations. According to a protocol for observing the free situations, the films were assessed so that the children’s performances enabled to infer the categories of social skills. The results showed that the sighted child presented a wider and more refined repertoire of social skills in relation to her sister. From the data, it is possible to conclude, in this case, that blind and sighted children have distinct social skills repertories, and the existing differences can be related to the blind variable as well as to the differences in the way the environment stimulates the children.

  15. Stability and Change in Executive Function Abilities from Late Adolescence to Early Adulthood: A Longitudinal Twin Study

    Science.gov (United States)

    Friedman, Naomi P.; Miyake, Akira; Altamirano, Lee J.; Corley, Robin P.; Young, Susan E.; Rhea, Sally Ann; Hewitt, John K.

    2016-01-01

    Executive functions (EFs)--the higher level cognitive abilities that enable us to control our own thoughts and actions--continue to develop into early adulthood, yet no longitudinal study has examined their stability during the important life transition from late adolescence to young adulthood. In this twin study (total N = 840 individuals from…

  16. Maternal serum steroid levels are unrelated to fetal sex: a study in twin pregnancies.

    NARCIS (Netherlands)

    Cohen-Bendahan, C.C.; Goozen, S.H. van; Buitelaar, J.K.; Cohen-Kettenis, P.T.

    2005-01-01

    Increased prenatal exposure to testosterone (T) in females of an opposite-sex (OS) twin pair may have an effect on the development of sex-typical cognitive and behavioral patterns. The prenatal exposure to T due to hormone transfer in OS twin females may occur in two ways, one directly via the feto-

  17. Origins of Familial Similarity in Parenting: A Study of Twins and Adoptive Siblings.

    Science.gov (United States)

    Losoya, Sandra H.; Callor, Suzanne; Rowe, David C.; Goldsmith, H. Hill

    1997-01-01

    Parents who were identical twins, fraternal twins, or adopted siblings completed questionnaires assessing attitudes toward parenting and specific parenting practices, the emotional atmosphere of the home, and parental personality. Model-fitting results implicated modest genetic effects on affect-related aspects of parenting, such as parental…

  18. Genetic Influences on Reading Difficulties in Boys and Girls: The Colorado Twin Study

    Science.gov (United States)

    Hawke, Jesse L.; Wadsworth, Sally J.; DeFries, John C.

    2006-01-01

    To test the hypothesis that the genetic etiology for reading disability may differ in males and females, data from identical and fraternal twin pairs were analysed using both concordance and multiple regression methods. The sample included 264 identical (129 male, 135 female) and 214 same-sex fraternal (121 male, 93 female) twin pairs in which at…

  19. Twin Studies in Autism: What Might They Say about Genetic and Environmental Influences

    Science.gov (United States)

    Anderson, George M.

    2012-01-01

    Genetic and epigenetic differences exist within monozygote twin-pairs and might be especially important in the expression of autism. Assuming phenotypic differences between monozygotic twins are due to environmental influences may lead to mistaken conclusions regarding the relative genetic and environmental contribution to autism risk.

  20. Unraveling Genetic and Environmental Components of Early Literacy: A Twin Study

    Science.gov (United States)

    Bus, A. G.; Out, D.

    2009-01-01

    Even though the acquisition of early literacy skills obviously depends on stimuli and incentives in children's environment we may expect that genes define the constraints for acquiring some or all early literacy skills. Therefore behavior genetic analyses were carried out on twin data including 27 identical and 39 same sex dizygotic twins, 4 years…

  1. Study of obstetric and fetal outcome of twin pregnancy in a tertiary care centre

    Directory of Open Access Journals (Sweden)

    Gurpreet Kaur Nandmer

    2015-12-01

    Conclusions: Twin pregnancies are high risk pregnancies with more maternal and fetal complications. The use of antenatal care services, identification and anticipation of complications, intrapartum management and good NICU facilities will help to improve maternal and neonatal outcome in twin pregnancies. [Int J Reprod Contracept Obstet Gynecol 2015; 4(6.000: 1789-1792

  2. Why does parental language input style predict child language development? A twin study of gene–environment correlation

    Science.gov (United States)

    Dale, Philip S.; Tosto, Maria Grazia; Hayiou-Thomas, Marianna E.; Plomin, Robert

    2015-01-01

    There are well-established correlations between parental input style and child language development, which have typically been interpreted as evidence that the input style causes, or influences the rate of, changes in child language. We present evidence from a large twin study (TEDS; 8395 pairs for this report) that there are also likely to be both child-to-parent effects and shared genetic effects on parent and child. Self-reported parental language style at child age 3 and age 4 was aggregated into an ‘informal language stimulation’ factor and a ‘corrective feedback’ factor at each age; the former was positively correlated with child language concurrently and longitudinally at 3, 4, and 4.5 years, whereas the latter was weakly and negatively correlated. Both parental input factors were moderately heritable, as was child language. Longitudinal bivariate analysis showed that the correlation between the language stimulation factor and child language was significantly and moderately due to shared genes. There is some suggestive evidence from longitudinal phenotypic analysis that the prediction from parental language stimulation to child language includes both evocative and passive gene–environment correlation, with the latter playing a larger role. Learning outcomes: The reader will understand why correlations between parental language and rate of child language are by themselves ambiguous, and how twin studies can clarify the relationship. The reader will also understand that, based on the present study, at least two aspects of parental language style – informal language stimulation and corrective feedback – have substantial genetic influence, and that for informal language stimulation, a substantial portion of the prediction to child language represents the effect of shared genes on both parent and child. It will also be appreciated that these basic research findings do not imply that parental language input style is unimportant or that interventions

  3. Why does parental language input style predict child language development? A twin study of gene-environment correlation.

    Science.gov (United States)

    Dale, Philip S; Tosto, Maria Grazia; Hayiou-Thomas, Marianna E; Plomin, Robert

    2015-01-01

    There are well-established correlations between parental input style and child language development, which have typically been interpreted as evidence that the input style causes, or influences the rate of, changes in child language. We present evidence from a large twin study (TEDS; 8395 pairs for this report) that there are also likely to be both child-to-parent effects and shared genetic effects on parent and child. Self-reported parental language style at child age 3 and age 4 was aggregated into an 'informal language stimulation' factor and a 'corrective feedback' factor at each age; the former was positively correlated with child language concurrently and longitudinally at 3, 4, and 4.5 years, whereas the latter was weakly and negatively correlated. Both parental input factors were moderately heritable, as was child language. Longitudinal bivariate analysis showed that the correlation between the language stimulation factor and child language was significantly and moderately due to shared genes. There is some suggestive evidence from longitudinal phenotypic analysis that the prediction from parental language stimulation to child language includes both evocative and passive gene-environment correlation, with the latter playing a larger role. The reader will understand why correlations between parental language and rate of child language are by themselves ambiguous, and how twin studies can clarify the relationship. The reader will also understand that, based on the present study, at least two aspects of parental language style - informal language stimulation and corrective feedback - have substantial genetic influence, and that for informal language stimulation, a substantial portion of the prediction to child language represents the effect of shared genes on both parent and child. It will also be appreciated that these basic research findings do not imply that parental language input style is unimportant or that interventions cannot be effective. Copyright

  4. The Qingdao Twin Registry: a status update.

    Science.gov (United States)

    Duan, Haiping; Ning, Feng; Zhang, Dongfeng; Wang, Shaojie; Zhang, Dong; Tan, Qihua; Tian, Xiaocao; Pang, Zengchang

    2013-02-01

    In 1998, the Qingdao Twin Registry was initiated as the main part of the Chinese National Twin Registry. By 2005, a total of 10,655 twin pairs had been recruited. Since then new twin cohorts have been sampled, with one longitudinal cohort of adolescent twins selected to explore determinants of metabolic disorders and health behaviors during puberty and young adulthood. Adult twins have been sampled for studying heritability of multiple phenotypes associated with metabolic disorders. In addition, an elderly twin cohort has been recruited with a focus on genetic studies of aging-related phenotypes using twin modeling and genome-wide association analysis. Cross-cultural collaborative studies have been carried out between China, Denmark, Finland, and US cohorts. Ongoing data collection and analysis for the Qingdao Twin Registry will be discussed in this article.

  5. Fuzzy Controller Design Using Evolutionary Techniques for Twin Rotor MIMO System: A Comparative Study

    Directory of Open Access Journals (Sweden)

    H. A. Hashim

    2015-01-01

    Full Text Available This paper presents a comparative study of fuzzy controller design for the twin rotor multi-input multioutput (MIMO system (TRMS considering most promising evolutionary techniques. These are gravitational search algorithm (GSA, particle swarm optimization (PSO, artificial bee colony (ABC, and differential evolution (DE. In this study, the gains of four fuzzy proportional derivative (PD controllers for TRMS have been optimized using the considered techniques. The optimization techniques are developed to identify the optimal control parameters for system stability enhancement, to cancel high nonlinearities in the model, to reduce the coupling effect, and to drive TRMS pitch and yaw angles into the desired tracking trajectory efficiently and accurately. The most effective technique in terms of system response due to different disturbances has been investigated. In this work, it is observed that GSA is the most effective technique in terms of solution quality and convergence speed.

  6. Multi-scale modeling and experimental study of twin inception and propagation in hexagonal close-packed materials using a crystal plasticity finite element approach; part II: Local behavior

    Science.gov (United States)

    Abdolvand, Hamidreza; Daymond, Mark R.

    2013-03-01

    In-situ tensile tests are performed on Zircaloy-2 samples with various grain sizes to study twin inception and propagation. Orientation maps of some areas at the surface are measured before and after deformation, using the Electron BackScattered Diffraction (EBSD) technique. Strain fields of the same areas are determined using the digital image correlation technique and are compared with results from Crystal Plasticity Finite Element (CPFE) simulations. Different assumptions are made within the CPFE code to simulate twin propagation. It is observed that the predictions of different models does not really change from one model to another when statistical information on the twins is compared, yet local predictions for each grain, i.e. twin direction, twin variant selection, and twin inception site, do change. Also, it is shown that the twin Schmid factor can vary drastically within grains and that for those grains with a low tendency for twinning this variation may make them susceptible to twinning.

  7. Heritability of corneal refraction and corneal astigmatism: a population-based twin study among 66- to 79-year-old female twins.

    Science.gov (United States)

    Pärssinen, Olavi; Kauppinen, Markku; Kaprio, Jaakko; Koskenvuo, Markku; Rantanen, Taina

    2013-03-01

    To examine the heritability of corneal refraction power (CR) and corneal astigmatism (AST) in older women. Corneal refraction and AST were measured by IOL master in 52 monozygotic (MZ) and 47 dizygotic (DZ) female twin pairs aged 66-79 years. The relative contribution of genetic and environmental factors to individual differences in CR was estimated by applying an independent pathway model to the twin data and AST by intraclass correlations (ICC). For the right eye, mean CR was 44.58 dioptres (D) (standard deviation (SD) ±1.28) When comparing CR of the right and left eye between MZ and DZ, no significant difference was found. Mean AST was 0.77 D (SD ±0.44) with no differences observed either between the MZ and the DZ individuals, or between the left and the right eyes. ICCs between the sisters for CR were, for the right eye, 0.882 and 0.378 for MZ and DZ, respectively, and for the left eye 0.855 and 0.358. For AST of the right eye, the ICCs were 0.533 and 0.096 for the MZ and DZ pairs, respectively, and for the left eye, the MZ and DZ correlations were 0.396 and 0.299. Quantitative genetic modelling showed that 81% of the variance in CR could be explained by genetic factors, additive genetic factors explaining 62% (95% confidence interval [CI] 44% -86%) and dominant genetic effect 19% (95% CI 7-49%) of the variance in CR. Different models were constructed to explain the heredity of AST. None of these models gave meaningful results, although the ICC values for MZ were higher than those for DZ. Most of the variance in CR among older Finnish women could be explained by genetic factors. © 2012 The Authors. Acta Ophthalmologica © 2012 Acta Ophthalmologica Scandinavica Foundation.

  8. Association between intake of dairy products and short-term memory with and without adjustment for genetic and family environmental factors: A twin study.

    Science.gov (United States)

    Ogata, Soshiro; Tanaka, Haruka; Omura, Kayoko; Honda, Chika; Hayakawa, Kazuo

    2016-04-01

    Previous studies have indicated associations between intake of dairy products and better cognitive function and reduced risk of dementia. However, these studies did not adjust for genetic and family environmental factors that may influence food intake, cognitive function, and metabolism of dairy product nutrients. In the present study, we investigated the association between intake of dairy products and short-term memory with and without adjustment for almost all genetic and family environmental factors using a genetically informative sample of twin pairs. A cross-sectional study was conducted among twin pairs aged between 20 and 74. Short-term memory was assessed as primary outcome variable, intake of dairy products was analyzed as the predictive variable, and sex, age, education level, marital status, current smoking status, body mass index, dietary alcohol intake, and medical history of hypertension or diabetes were included as possible covariates. Generalized estimating equations (GEE) were performed by treating twins as individuals and regression analyses were used to identify within-pair differences of a twin pair to adjust for genetic and family environmental factors. Data are reported as standardized coefficients and 95% confidence intervals (CI). Analyses were performed on data from 78 men and 278 women. Among men, high intake of dairy products was significantly associated with better short-term memory after adjustment for the possible covariates (standardized coefficients = 0.22; 95% CI, 0.06-0.38) and almost all genetic and family environmental factors (standardized coefficients = 0.38; 95% CI, 0.07-0.69). Among women, no significant associations were found between intake of dairy products and short-term memory. Subsequent sensitivity analyses were adjusted for small samples and showed similar results. Intake of dairy product may prevent cognitive declines regardless of genetic and family environmental factors in men. Copyright © 2015 Elsevier Ltd

  9. Heritability and confirmation of genetic association studies for childhood asthma in twins.

    Science.gov (United States)

    Ullemar, V; Magnusson, P K E; Lundholm, C; Zettergren, A; Melén, E; Lichtenstein, P; Almqvist, C

    2016-02-01

    Although the genetics of asthma has been extensively studied using both quantitative and molecular genetic analysis methods, both approaches lack studies specific to the childhood phenotype and including other allergic diseases. This study aimed to give specific estimates for the heritability of childhood asthma and other allergic diseases, to attempt to replicate findings from genomewide association studies (GWAS) for childhood asthma and to test the same variants against other allergic diseases. In a cohort of 25 306 Swedish twins aged 9 or 12 years, data on asthma were available from parental interviews and population-based registers. The interviews also inquired about wheeze, hay fever, eczema, and food allergy. Through structural equation modeling, the heritability of all phenotypes was calculated. A subset of 10 075 twins was genotyped for 16 single nucleotide polymorphisms (SNPs) selected from previous GWAS; these were first tested for association with asthma and significant findings also against the other allergic diseases. The heritability of any childhood asthma was 0.82 (95% CI 0.79-0.85). For the other allergic diseases, the range was approximately 0.60-0.80. Associations for six SNPs with asthma were replicated, including rs2305480 in the GSDMB gene (OR 0.80, 95% CI 0.74-0.86, P = 1.5*10(-8) ; other significant associations all below P = 3.5*10(-4) ). Of these, only rs3771180 in IL1RL1 was associated with any other allergic disease (for hay fever, OR 0.64, 95% CI 0.53-0.77, P = 2.5*10(-6) ). Asthma and allergic diseases of childhood are highly heritable, and these high-risk genetic variants associated specifically with childhood asthma, except for one SNP shared with hay fever. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. A New Look at Genetic and Environmental Architecture on Lipids Using Non-Normal Structural Equation Modeling in Male Twins: The NHLBI Twin Study.

    Science.gov (United States)

    Wu, Sheng-Hui; Ozaki, Koken; Reed, Terry; Krasnow, Ruth E; Dai, Jun

    2017-07-01

    This study examined genetic and environmental influences on the lipid concentrations of 1028 male twins using the novel univariate non-normal structural equation modeling (nnSEM) ADCE and ACE models. In the best fitting nnSEM ADCE model that was also better than the nnSEM ACE model, additive genetic factors (A) explained 4%, dominant genetic factors (D) explained 17%, and common (C) and unique (E) environmental factors explained 47% and 33% of the total variance of high-density lipoprotein cholesterol (HDL-C). The percentage of variation explained for other lipids was 0% (A), 30% (D), 34% (C) and 37% (E) for low-density lipoprotein cholesterol (LDL-C); 30, 0, 31 and 39% for total cholesterol; and 0, 31, 12 and 57% for triglycerides. It was concluded that additive and dominant genetic factors simultaneously affected HDL-C concentrations but not other lipids. Common and unique environmental factors influenced concentrations of all lipids.

  11. Ground-based and in-flight simulator studies of flight characteristics of a twin-fuselage passenger transport airplane during approach and landing

    Science.gov (United States)

    Grantham, W. D.; Smith, P. M.; Neely, W. R., Jr.; Deal, P. L.; Yenni, K. R.

    1985-01-01

    Six-degree-of-freedom ground-based and in-flight simulator studies were conducted to evaluate the low-speed flight characteristics of a twin-fuselage passenger transport airplane and to compare these characteristics with those of a large, single-fuselage (reference) transport configuration similar to the Lockheed C-5A airplane. The primary piloting task was the approach and landing task. The results of this study indicated that the twin-fuselage transport concept had acceptable but unsatisfactory longitudinal and lateral-directional low-speed flight characteristics, and that stability and control augmentation would be required in order to improve the handling qualities. Through the use of rate-command/attitude-hold augmentation in the pitch and roll axes, and the use of several turn coordination features, the handling qualities of the simulated transport were improved appreciably. The in-flight test results showed excellent agreement with those of the six-degree-of-freedom ground-based simulator handling qualities tests. As a result of the in-flight simulation study, a roll-control-induced normal-acceleration criterion was developed. The handling qualities of the augmented twin-fuselage passenger transport airplane exhibited an improvement over the handling characteristics of the reference (single-fuselage) transport.

  12. Evidence of a unique and common genetic etiology between the CAR and the remaining part of the diurnal cycle: A study of 14 year-old twins.

    Science.gov (United States)

    Ouellet-Morin, Isabelle; Brendgen, Mara; Girard, Alain; Lupien, Sonia J; Dionne, Ginette; Vitaro, Frank; Boivin, Michel

    2016-04-01

    By and large, studies have reported moderate contributions of genetic factors to cortisol secreted in the early morning and even smaller estimates later in the day. In contrast, the cortisol awakening response (CAR) has shown much stronger heritability estimates, which prompted the hypothesis that the etiology of cortisol secretion may vary according to the time of day. A direct test of this possibility has, however, not yet been performed. To describe the specific and common etiology of the CAR, awakening level and cortisol change from morning to evening in an age-homogenous sample of twin adolescents. A total of 592 participants of the Québec Newborn Twin Study, a population-based 1995-1998 cohort of families with twins in Canada, have collected saliva at awakening, 30 min later, at the end of afternoon and in the evening over four collection days. Multivariate Cholesky models showed both specific and common sources of variance between the CAR, awakening and cortisol diurnal change. The CAR had the strongest heritability estimates, which, for the most part, did not overlap with the other indicators. Conversely, similar magnitudes of genetic and environmental contributions were detected at awakening and for diurnal change, which partially overlapped. Our study unraveled differences between the latent etiologies of the CAR and the rest of the diurnal cycle, which may contribute to identify regulatory genes and environments and detangle how these indicators each relate to physical and mental health. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Associations of Mother's and Father's Parenting Practices with Children's Observed Social Reticence in a Competitive Situation: A Monozygotic Twin Difference Study

    Science.gov (United States)

    Guimond, Fanny-Alexandra; Brendgen, Mara; Forget-Dubois, Nadine; Dionne, Ginette; Vitaro, Frank; Tremblay, Richard E.; Boivin, Michel

    2012-01-01

    This study used the monozygotic (MZ) twin difference method to examine whether the unique environmental effects of maternal and paternal overprotection and hostility at the age of 30 months predict twins' observed social reticence in a competitive situation in kindergarten, while controlling for the effect of family-wide influences, including…

  14. Brain SCALE : Brain Structure and Cognition: an Adolescent Longitudinal Twin Study into the Genetic Etiology of Individual Differences

    NARCIS (Netherlands)

    van Soelen, Inge L. C.; Brouwer, Rachel M.; Peper, Jiska S.; van Leeuwen, Marieke; Koenis, Marinka M. G.; van Beijsterveldt, Toos C. E. M.; Swagerman, Suzanne C.; Kahn, Rene S.; Pol, Hilleke E. Hulshoff; Boomsma, Dorret I.

    2012-01-01

    From childhood into adolescence, the child's brain undergoes considerable changes in both structure and function. Twin studies are of great value to explore to what extent genetic and environmental factors explain individual differences in brain development and cognition. In The Netherlands, we init

  15. The Association between Persistent Disruptive Childhood Behaviour and the Psychopathic Personality Constellation in Adolescence: A Twin Study

    Science.gov (United States)

    Forsman, Mats; Larsson, Henrik; Andershed, Henrik; Lichtenstein, Paul

    2007-01-01

    This study tested if persistent externalizing behaviour and symptoms of Attention Deficit Hyperactivity Disorder (ADHD) in childhood are associated with personality and behavioural aspects of the psychopathic personality constellation in adolescence. The target sample consisted of all 1,480 twin pairs born in Sweden between 1985 and 1986.…

  16. Genetic and environmental influences on cannabis use initiation and problematic use: A meta-analysis of twin studies

    NARCIS (Netherlands)

    Verweij, C.J.H.; Zietsch, B.P.; Lynskey, M.T.; Medland, S.E.; Neale, M.C.; Martin, N.G.; Boomsma, D.I.; Vink, J.M.

    2010-01-01

    Background Because cannabis use is associated with social, physical and psychological problems, it is important to know what causes some individuals to initiate cannabis use and a subset of those to become problematic users. Previous twin studies found evidence for both genetic and environmental inf

  17. Cancer risk in opposite-sex and same-sex twins

    DEFF Research Database (Denmark)

    Juel Ahrenfeldt, Linda

    2015-01-01

    Twin pregnancies are characterized by simultaneous development of two fetuses that share the womb. An interest in opposite-sex (OS) twins, twin pairs consisting of one male and one female, comes from animal studies that showed that exposure to sex hormones is influenced by the position of the fetus...... in the womb. Studies in rodents have shown that female fetuses developing between males are masculinized in several anatomical, physiological and behavioral traits....

  18. Craniofacial anomalies in twins.

    Science.gov (United States)

    Keusch, C F; Mulliken, J B; Kaplan, L C

    1991-01-01

    Studies of twins provide insight into the relative contribution of genetic and environmental factors in the causality of structural anomalies. Thirty-five affected twin pairs were identified from a group of 1114 patients with congenital craniofacial deformities evaluated from 1972 to 1989. Forty-three of these 70 twins exhibited one or more craniofacial anomalies; these were analyzed for dysmorphic characteristics, zygosity, concordance, and family history. The anomalies were categorized into two groups: malformations and deformations. The malformations (n = 36) included hemifacial microsomia (n = 10), cleft lip and palate (n = 8), cleft palate (n = 4), rare facial cleft (n = 2), craniosynostosis (n = 2), Binder syndrome (n = 2), Treacher Collins syndrome (n = 2), craniopagus (n = 2), CHARGE association (n = 1), frontonasal dysplasia (n = 2), and constricted ears (n = 1). The deformations (n = 7) included plagiocephaly (n = 5), hemifacial hypoplasia (n = 1), and micrognathia (n = 1). Twenty-one monozygotic and 14 dizygotic twin pairs were identified. The concordance rate was 33 percent for monozygotic twins and 7 percent for dizygotic twins.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. Effects of magnetic field and twin domains on magnetostructural phase mixture in Mn3O4 : Raman scattering studies of untwinned crystals

    Science.gov (United States)

    Byrum, T.; Gleason, S. L.; Thaler, A.; MacDougall, G. J.; Cooper, S. L.

    2016-05-01

    The ferrimagnetic spinel Mn3O4 exhibits large and anisotropic changes in electronic and structural properties in response to an applied magnetic field. These changes are thought to result from the field-dependent tuning—via strong spin-lattice coupling—between two nearly degenerate magnetostructural phases. Recent variable-magnetic-field studies of Mn3O4 have been performed on melt-grown crystals, which can exhibit twin domains due to a Jahn-Teller structural transition below the melting temperature. Because of the near degeneracy of the magnetostructural phases, however, strain associated with the twin domains likely affects the magnetic responses of Mn3O4 . In this report, we present a variable-magnetic-field Raman scattering study of untwinned Mn3O4 crystals grown out of a flux below the Jahn-Teller structural transition. We measure distinct q =0 magnetic and vibrational excitation spectra for each isolated magnetostructural phase of untwinned Mn3O4 crystals and determine the symmetries of the observed excitations. We determine how the magnetostructural phase mixture changes in response to magnetic fields applied in the magnetic easy plane. Last, by comparing results on flux- and melt-grown Mn3O4 crystals, we show that the intrinsic mixture of the two magnetostructural phases is indeed strongly influenced by the presence of twin domains.

  20. Seasonal genetic influence on serum 25-hydroxyvitamin D levels: a twin study.

    Directory of Open Access Journals (Sweden)

    Greta Snellman

    Full Text Available BACKGROUND: Although environmental factors, mainly nutrition and UV-B radiation, have been considered major determinants of vitamin D status, they have only explained a modest proportion of the variation in serum 25-hydroxyvitamin D. We aimed to study the seasonal impact of genetic factors on serum 25-hydroxyvitamin D concentrations. METHODOLOGY/PRINCIPAL FINDINGS: 204 same-sex twins, aged 39-85 years and living at northern latitude 60 degrees, were recruited from the Swedish Twin Registry. Serum 25-hydroxyvitamin D was analysed by high-pressure liquid chromatography and mass spectrometry. Genetic modelling techniques estimated the relative contributions of genetic, shared and individual-specific environmental factors to the variation in serum vitamin D. The average serum 25-hydroxyvitamin D concentration was 84.8 nmol/l (95% CI 81.0-88.6 but the seasonal variation was substantial, with 24.2 nmol/l (95% CI 16.3-32.2 lower values during the winter as compared to the summer season. Half of the variability in 25-hydroxyvitamin D during the summer season was attributed to genetic factors. In contrast, the winter season variation was largely attributable to shared environmental influences (72%; 95% CI 48-86%, i.e., solar altitude. Individual-specific environmental influences were found to explain one fourth of the variation in serum 25-hydroxyvitamin D independent of season. CONCLUSIONS/SIGNIFICANCE: There exists a moderate genetic impact on serum vitamin D status during the summer season, probably through the skin synthesis of vitamin D. Further studies are warranted to identify the genes impacting on vitamin D status.

  1. Twins' injuries: genetic and environmental risks / twin research reports / human interest stories.

    Science.gov (United States)

    Segal, Nancy L

    2011-04-01

    The relative contributions of genetic and environmental factors to unintentional injuries are of interest to families with young twins. A recent study found that childhood injuries are explained mostly by child-specific environmental factors. Next, twin research reviews of the association between periodontal disease and cancer, secular trends in gestational age and birthweight, and language development in hearing and deaf co-twins are also summarized. Interesting reports of newborn twins, twin-like relationships, twin interactions and missed twin relationships are presented.

  2. Sport disciplines, types of sports, and waist circumference in young adulthood - a population-based twin study.

    Science.gov (United States)

    Rottensteiner, Mirva; Mäkelä, Sara; Bogl, Leonie H; Törmäkangas, Timo; Kaprio, Jaakko; Kujala, Urho M

    2017-10-01

    The benefits of physical activity (PA) in preventing abdominal obesity are well recognized, but the role of different sport disciplines remains open. We aimed, therefore, to investigate how participation in different sport disciplines, and the number and types of sports engaged in are associated with waist circumference (WC) in young adulthood. This population-based cohort study comprised 4027 Finnish twin individuals (1874 men), with a mean age of 34 y (32-37), who answered a survey, including self-measured WC. We extracted the number and identified the types (aerobic, power, and mixed) of the different sport disciplines respondents reported participating in. The number of sport disciplines participated in was inversely associated with WC, the linear decrease averaging 1.38 cm (95% CI 1.10-1.65) per each additional sport discipline. The result persisted after adjustment for the main covariates, such as volume of PA and diet quality. Among dizygotic twin pairs discordant for sports participation (0-2 vs. 5 or more disciplines), the mean within-pair difference in WC was 4.8 cm (95% CI 0.4-9.1) for men and 11.2 cm (95% CI 4.4-18.0) for women; among discordant monozygotic pairs, no differences were observed. In men, all three types of sports were individually associated with smaller WC, while in women, only mixed and power sports showed this association. Participation in several sport disciplines and sport types was associated with smaller WC among young adults in their mid-30s. Shared genetic background may explain some of the associations.

  3. [The Chinese national twin cohort: an update].

    Science.gov (United States)

    Gao, W J; Li, L M

    2017-06-10

    The importance of large cohort studies in China has been increasingly emphasized. As special group in the population, twins provide excellent natural resources since they share the same birthday, maternal intrauterine environment and early family environment. Twin cohorts are unique for and benefit on controlling the confounding factors as age, gender (same-sex twins), genetic background (monozygotic twins) or early environment (being raised together) in the etiological studies on complex diseases. In this review, we briefly introduce the objectives, current situation, challenges and opportunities related to the Chinese national twin cohort, focusing on the characteristics of twins that are different from other groups in the general population.

  4. Twin and family studies reveal strong environmental and weaker genetic cues explaining heritability of eosinophilic esophagitis.

    Science.gov (United States)

    Alexander, Eileen S; Martin, Lisa J; Collins, Margaret H; Kottyan, Leah C; Sucharew, Heidi; He, Hua; Mukkada, Vincent A; Succop, Paul A; Abonia, J Pablo; Foote, Heather; Eby, Michael D; Grotjan, Tommie M; Greenler, Alexandria J; Dellon, Evan S; Demain, Jeffrey G; Furuta, Glenn T; Gurian, Larry E; Harley, John B; Hopp, Russell J; Kagalwalla, Amir; Kaul, Ajay; Nadeau, Kari C; Noel, Richard J; Putnam, Philip E; von Tiehl, Karl F; Rothenberg, Marc E

    2014-11-01

    Eosinophilic esophagitis (EoE) is a chronic antigen-driven allergic inflammatory disease, likely involving the interplay of genetic and environmental factors, yet their respective contributions to heritability are unknown. To quantify the risk associated with genes and environment on familial clustering of EoE. Family history was obtained from a hospital-based cohort of 914 EoE probands (n = 2192 first-degree "Nuclear-Family" relatives) and an international registry of monozygotic and dizygotic twins/triplets (n = 63 EoE "Twins" probands). Frequencies, recurrence risk ratios (RRRs), heritability, and twin concordance were estimated. Environmental exposures were preliminarily examined. Analysis of the Nuclear-Family-based cohort revealed that the rate of EoE, in first-degree relatives of a proband, was 1.8% (unadjusted) and 2.3% (sex-adjusted). RRRs ranged from 10 to 64, depending on the family relationship, and were higher in brothers (64.0; P = .04), fathers (42.9; P = .004), and males (50.7; P Twins cohort, genetic heritability was 14.5% ± 4.0% (P twins was 57.9% ± 9.5% compared with 36.4% ± 9.3% in dizygotic co-twins (P = .11). Greater birth weight difference between twins (P = .01), breast-feeding (P = .15), and fall birth season (P = .02) were associated with twin discordance in disease status. EoE RRRs are increased 10- to 64-fold compared with the general population. EoE in relatives is 1.8% to 2.4%, depending on relationship and sex. Nuclear-Family heritability appeared to be high (72.0%). However, the Twins cohort analysis revealed a powerful role for common environment (81.0%) compared with additive genetic heritability (14.5%). Copyright © 2014 American Academy of Allergy, Asthma & Immunology. All rights reserved.

  5. Do Twin Boundaries Always Strengthen Metal Nanowires?

    OpenAIRE

    Zhang Yongfeng; Huang Hanchen

    2008-01-01

    Abstract It has been widely reported that twin boundaries strengthen nanowires regardless of their morphology—that is, the strength of nanowires goes up as twin spacing goes down. This article shows that twin boundaries do not always strengthen nanowires. Using classical molecular dynamics simulations, the authors show that whether twin boundaries strengthen nanowires depends on the necessary stress for dislocation nucleation, which in turn depends on surface morphologies. When nanowire...

  6. Asthma affects time to pregnancy and fertility: a register-based twin study.

    Science.gov (United States)

    Gade, Elisabeth J; Thomsen, Simon F; Lindenberg, Svend; Kyvik, Kirsten O; Lieberoth, Sofie; Backer, Vibeke

    2014-04-01

    Coexistence of infertility and asthma has been observed clinically. Therefore, we investigated the association between asthma and delayed pregnancy in a nationwide population-based cohort of twins. A cohort of 15 250 twins living in Denmark (aged 12-41 years) participated in a questionnaire study including questions about the presence of asthma and fertility. Differences in time to pregnancy and pregnancy outcome were analysed in subjects with asthma, allergy and in healthy individuals using multiple regression analysis. Asthma was associated with an increased time to pregnancy, the percentage of asthmatics with a time to pregnancy >1 year was 27% versus 21.6% for non-asthmatics (OR (95% CI) 1.31 (1.1-1.6); p=0.009). The association remained significant after adjustment for age, age at menarche, body mass index and socioeconomic status (OR (95% CI) 1.25 (1.0-1.6); p=0.05), and was more pronounced in those >30 years of age (32.2% versus 24.9%, OR (95% CI) 1.44 (1.1-1.9); p=0.04). Untreated asthmatics had a significant increased risk of prolonged time to pregnancy compared to healthy individuals (OR (95% CI) 1.79 (1.20-2.66); p=0.004), while asthmatics receiving any kind of treatment for asthma tended to have a shorter time to pregnancy than untreated asthmatics (OR 1.40; p=0.134). Asthma prolongs time to pregnancy. The negative effect of asthma on fertility increases with age and with disease intensity, indicating that a systemic disease characterised by systemic inflammation also can involve reproductive processes.

  7. Socioeconomic position and twins' health

    DEFF Research Database (Denmark)

    Osler, Merete; McGue, Matt; Christensen, Kaare

    2007-01-01

    of middle-aged Danish twins was conducted in 1998-99. The study population included 1266 like-sex twin pairs [52.5% monozygotic (MZ) and 47.6% dizygotic (DZ)]. Data were obtained on childhood and adult social class and on height, BMI, grip strength, depression symptoms, self-rated health, cognitive function......, prenatal and rearing environmental factors from environmental factor later in life, we compared the health status among male and female twin pairs who lived together during childhood and were discordant or concordant on adult socioeconomic position. METHODS: A cross-sectional survey among a random sample......, physical activity, smoking, alcohol and food intake. RESULTS: The expected associations between the individual twins' adult social class and health measures were observed. Among DZ male twins discordant on adult social class, the higher social class twin was on average significantly taller and had higher...

  8. Testing putative causal associations of risk factors for early intercourse in the study of twin adults: genes and environment (STAGE).

    Science.gov (United States)

    Donahue, Kelly L; D'Onofrio, Brian M; Lichtenstein, Paul; Långström, Niklas

    2013-01-01

    Adverse childhood experiences and substance use have been identified as potential causal risk factors for early-onset sexual intercourse. While it is possible that exposure to these risk factors directly increases the likelihood of engaging in early intercourse, an alternative explanation is that observed associations between these variables are due to shared familial confounds. These unmeasured confounds may increase the likelihood of being exposed to these risk factors and of engaging in early intercourse. Participants drawn from a population-based study of Swedish adult twins (ages 19-47 years; N = 12,126) reported on their history of exposure to early physical and sexual trauma, cigarette use, and cannabis use. We investigated the nature of the association between these risk factors and young age at first intercourse, using a comparison of twins differentially exposed to each risk factor. When compared to non-exposed, unrelated individuals, participants who reported adverse childhood experiences or who engaged in early cigarette use or cannabis use were more likely to engage in early intercourse. However, co-twin comparisons indicated that observed associations between these risk factors and early intercourse may be due to familial factors shared within twin pairs, and risk factor exposure may not lead directly to early intercourse. Our results suggest that preventing trauma exposure or preventing or delaying adolescents' cigarette smoking or cannabis use may not effectively delay intercourse onset; instead, other aspects of the adolescent's environment should be addressed.

  9. Importance of genetic factors in the etiology of atopic dermatitis: a twin study

    DEFF Research Database (Denmark)

    Thomsen, Simon F; Ulrik, Charlotte S; Kyvik, Kirsten O;

    2007-01-01

    ?" Latent factor models of genetic and environmental influences were fitted to the observed data using maximum likelihood methods. The overall lifetime prevalence of atopic dermatitis was 7.3%. A cotwin of an affected identical twin had a sevenfold increased risk of atopic dermatitis compared......The susceptibility to develop atopic dermatitis can be attributed both to genetic and environmental causes. We estimated the relative impact of genetic and environmental factors in the etiology of atopic dermatitis in a population-based sample of twins. From the birth cohorts of 1953-1982 who were...... enrolled in The Danish Twin Registry, a total of 11,515 twin pairs were identified in a nationwide questionnaire survey. Subjects were classified as atopic dermatitis cases when responding affirmatively to the question, "Do you have, or have you ever had, eczema in the folds of your elbows or knees...

  10. Causal direction between respiratory syncytial virus bronchiolitis and asthma studied in monozygotic twins

    DEFF Research Database (Denmark)

    Poorisrisak, Porntiva; Halkjaer, Liselotte Brydensholt; Thomsen, Simon Francis

    2010-01-01

    Respiratory syncytial virus (RSV) bronchiolitis has been associated with later development of asthma, wheezing, abnormal pulmonary function, and sensitization. Our aim was to determine the differential effect within monozygotic (MZ) twin pairs discordant for severe RSV bronchiolitis in infancy...

  11. Genetic and family and community environmental effects on drug abuse in adolescence: a Swedish national twin and sibling study.

    Science.gov (United States)

    Kendler, Kenneth S; Maes, Hermine H; Sundquist, Kristina; Ohlsson, Henrik; Sundquist, Jan

    2014-02-01

    Using Swedish nationwide registry data, the authors investigated genetic and environmental risk factors in the etiology of drug abuse by twin sibling modeling. The authors followed up with epidemiological analyses to identify shared environmental influences on drug abuse. Drug abuse was defined using public medical, legal, or pharmacy records. Twin and sibling pairs were obtained from the national twin and genealogical registers. Information about sibling pair residence within the same household, small residential area, or municipality was obtained from Statistics Sweden. The authors predicted concordance for drug abuse by years of co-residence until the older sibling turned 21 and risk for future drug abuse in adolescents living with parental figures as a function of family-level socioeconomic status and neighborhood social deprivation. The best twin sibling fit model predicted substantial heritability for drug abuse in males (55%) and females (73%), with environmental factors shared by siblings operating only in males and accounting for 23% of the variance in liability. For each year of living in the same household, the probability of sibling concordance for drug abuse increased 2%-5%. When not residing in the same household, concordance was predicted from residence in the same small residential area or municipality. Risk for drug abuse was predicted both by family socioeconomic status and neighborhood social deprivation. Controlling for family socioeconomic status, each year of living in a high social deprivation neighborhood increased the risk for drug abuse by 2%. Using objective registry data, the authors found that drug abuse is highly heritable. A substantial proportion of the shared environmental effect on drug abuse comes from community-wide rather than household-level influences. Genetic effects demonstrated in twin studies have led to molecular analyses to elucidate biological pathways. In a parallel manner, environmental effects can be followed up by

  12. Problem in twin pregnancy: Findings of prenatal sonography and autopsy

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jeong Ah; Cho, Jeong Yeon; Song, Mi Jin; Min, Jee Yeon; Lee, Young Ho; Lee, Hak Jong; Chun, Yi Kyeong; Kim, Yee Jeong; Hong, Sung Ran [Samsung Cheil Hospital, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2001-12-15

    Multifetal gestations are high risk pregnancies with higher perinatal morbidity and mortality. Multifetal gestations are subject to unique complications including conjoined twins, twin-to-twin transfusion syndrome (TTTS), acardiac twins, twin embization of co-twin demise and heterotopic pregnancies. Prenatal sonographic diagnosis of types and complications of multifetal gestations is important for antenatal care and prediction of fetal outcome. This study was performed to present the prenatal ultrasonographic findings and pathologic findings of the unique complications of twin pregnancy. Acardia is a lethal anomaly occurring in 1% of monozygotic twin. The acardiac twin has a parasitic existence and depends on the donor (pump) twin for its blood supply via placental anastomoses and retrograde perfusion of umbilical cord. This twin reversed arterial perfusion (TRAP) sequence is a most extreme manifestation on the TTTS. Doppler verification reversed flow in umbilical cord of the acardiac twin confirms the diagnosis.

  13. Angiotensin I-converting enzyme (ACE) gene polymorphism in relation to physical performance, cognition and survival--a follow-up study of elderly Danish twins

    DEFF Research Database (Denmark)

    Frederiksen, Henrik; Gaist, David; Bathum, Lise

    2003-01-01

    Studies of younger individuals have suggested an association between ACE genotype and physical and cognitive performance. Using a longitudinal study of elderly twins we studied the association between ACE genotype and physical and cognitive functioning and survival in old age....

  14. Preterm twin gestation and cystic periventricular leucomalacia

    NARCIS (Netherlands)

    Resch, B; Jammernegg, A; Vollaard, E; Maurer, U; Mueller, WD; Pertl, B

    2004-01-01

    Objective: To identify risk factors for the development of cystic periventricular leucomalacia (PVL) in twin gestation. Design: Retrospective case-control study. Setting: Tertiary care university hospital, Department of Paediatrics, Division of Neonatology, Graz, Austria. Patients: Preterm twin gest

  15. STOPPIT Baby Follow-up Study: the effect of prophylactic progesterone in twin pregnancy on childhood outcome.

    Directory of Open Access Journals (Sweden)

    Helen Christine McNamara

    Full Text Available To determine the long-term effects of in utero progesterone exposure in twin children.This study evaluated the health and developmental outcomes of all surviving children born to mothers who participated in a double-blind, placebo-controlled trial of progesterone given for the prevention of preterm birth in twin pregnancies (STOPPIT, ISRCTN35782581. Follow-up was performed via record linkage and two parent-completed validated questionnaires, the Child Development Inventory and the Health Utilities Index.Record linkage was successfully performed on at least one record in 759/781 (97% children eligible for follow-up. There were no differences between progesterone-exposed and placebo-exposed twins with respect to incidence of death, congenital anomalies and hospitalisation, nor on routine national child health assessments. Questionnaire responses were received for 324/738 (44% children. The mean age at questionnaire follow-up was 55.5 months. Delay in at least one developmental domain on the Child Development Inventory was observed in 107/324 (33% children, with no evidence of difference between progesterone-exposed and placebo-exposed twins. There was no evidence of difference between the progesterone and placebo groups in global health status assessed using the Health Utilities Index: 89% of children were rated as having 'excellent' health and a further 8% as having 'very good' health.In this cohort of twin children there was no evidence of a detrimental or beneficial impact on health and developmental outcomes at three to six years of age due to in utero exposure to progesterone.

  16. Hypertensive disorders in twin pregnancy

    NARCIS (Netherlands)

    J.G. Santema (Job); E. Koppelaar (Elin); H.C.S. Wallenburg (Henk)

    1995-01-01

    textabstractObjective: To compare the incidence and severity of pregnancy-induced hypertensive disorders in twin pregnancy and in singleton gestation. Study design: Case-control study in the setting of a University Hospital. Each pregnancy of a consecutive series of 187 twin pregnancies attending th

  17. A comparative study of ground tire rubber devulcanization using twin screw extruder and internal mixer

    Science.gov (United States)

    Ujianto, O.; Putri, D. B.; Jayatin; AWinarto, D.

    2017-07-01

    Devulcanization of ground tire rubber (GTR) was done using twin screw extruder (TSE) and internal mixer (IM). Processing parameters were varied to analyze its effect on gel content. Fourier Transform Infrared Spectroscopy (FTIR) analysis was performed as qualitative technique to confirm structural change. The devulcanized rubbers with the least gel content percentage produced in both TSE and IM were then used as filler in natural rubber (NR)/coconut coir (CC) composite preparation. Effects of gel content percentage on NR/CC composite tensile strength and elongation at break were analyzed. The results show that the gel content decreased by 41% for sample processed in TSE and 50% in IM compared to control sample. Overall, the devulcanization is influenced by high energy generated by thermal or thermo-mechanical process. FTIR spectra show chemically structural changes of GTR as C=C, CH2, CH3 with higher intensity for IM sample than its counterpart indicated devulcanization. The replacement of GTR to DGTR on NR/CC/GTR composites provided less network structures and resulted better tensile strength and elongation at break.

  18. White matter development in early puberty: a longitudinal volumetric and diffusion tensor imaging twin study.

    Science.gov (United States)

    Brouwer, Rachel M; Mandl, René C W; Schnack, Hugo G; van Soelen, Inge L C; van Baal, G Caroline; Peper, Jiska S; Kahn, René S; Boomsma, Dorret I; Hulshoff Pol, H E

    2012-01-01

    White matter microstructure and volume show synchronous developmental patterns in children. White matter volume increases considerably during development. Fractional anisotropy, a measure for white matter microstructural directionality, also increases with age. Development of white matter volume and development of white matter microstructure seem to go hand in hand. The extent to which the same or different genetic and/or environmental factors drive these two aspects of white matter maturation is currently unknown. We mapped changes in white matter volume, surface area and diffusion parameters in mono- and dizygotic twins who were scanned at age 9 (203 individuals) and again at age 12 (126 individuals). Over the three-year interval, white matter volume (+6.0%) and surface area (+1.7%) increased, fiber bundles expanded (most pronounced in the left arcuate fasciculus and splenium), and fractional anisotropy increased (+3.0%). Genes influenced white matter volume (heritability ~85%), surface area (~85%), and fractional anisotropy (locally 7% to 50%) at both ages. Finally, volumetric white matter growth was negatively correlated with fractional anisotropy increase (r = -0.62) and this relationship was driven by environmental factors. In children who showed the most pronounced white matter growth, fractional anisotropy increased the least and vice-versa. Thus, white matter development in childhood may reflect a process of both expansion and fiber optimization.

  19. White matter development in early puberty: a longitudinal volumetric and diffusion tensor imaging twin study.

    Directory of Open Access Journals (Sweden)

    Rachel M Brouwer

    Full Text Available White matter microstructure and volume show synchronous developmental patterns in children. White matter volume increases considerably during development. Fractional anisotropy, a measure for white matter microstructural directionality, also increases with age. Development of white matter volume and development of white matter microstructure seem to go hand in hand. The extent to which the same or different genetic and/or environmental factors drive these two aspects of white matter maturation is currently unknown. We mapped changes in white matter volume, surface area and diffusion parameters in mono- and dizygotic twins who were scanned at age 9 (203 individuals and again at age 12 (126 individuals. Over the three-year interval, white matter volume (+6.0% and surface area (+1.7% increased, fiber bundles expanded (most pronounced in the left arcuate fasciculus and splenium, and fractional anisotropy increased (+3.0%. Genes influenced white matter volume (heritability ~85%, surface area (~85%, and fractional anisotropy (locally 7% to 50% at both ages. Finally, volumetric white matter growth was negatively correlated with fractional anisotropy increase (r = -0.62 and this relationship was driven by environmental factors. In children who showed the most pronounced white matter growth, fractional anisotropy increased the least and vice-versa. Thus, white matter development in childhood may reflect a process of both expansion and fiber optimization.

  20. Quality of life in unaffected twins discordant for affective disorder

    DEFF Research Database (Denmark)

    Vinberg, Maj; Bech, Per; Kyvik, Kirsten Ohm

    2006-01-01

    BACKGROUND: The disability and hardship associated with affective disorder is shared by the family members of affective patients and might affect the family member's quality of life. METHOD: In a cross-sectional, high-risk, case-control study, monozygotic (MZ) and dizygotic (DZ) twins with (High...... of life. RESULTS: Univariate analyses showed that quality of life in all domains was impaired for the 121 High-Risk twins compared to the 84 Low-Risk twins. In multiple regression analyses, the differences remained significant after adjustment for sex, age, marital status and years of education. Adjusted...

  1. The Texas Twin Project.

    Science.gov (United States)

    Harden, K Paige; Tucker-Drob, Elliot M; Tackett, Jennifer L

    2013-02-01

    Socioeconomic position, racial/ethnic minority status, and other characteristics of the macro-environment may be important moderators of genetic influence on a wide array of psychosocial outcomes. Designed to maximize representation of low socioeconomic status families and racial/ethnic minorities, the Texas Twin Project is an ongoing study of school-age twins (preschool through 12th grade) enrolled in public schools in the Austin, Texas and Houston, Texas metropolitan areas. School rosters are used to identify twin families from a target population with sizable populations of African American (18%), Hispanic/Latino (48%), and non-Hispanic White (27%) children and adolescents, over half of whom meet US guidelines for classification as economically disadvantaged. Initial efforts have focused on a large-scale, family-based survey study involving both parent and child reports of personality, psychopathology, physical health, academic interests, parent-child relationships, and aspects of the home environment. In addition, the Texas Twin Project is the basis for an in-laboratory study of adolescent decision-making, delinquency, and substance use. Future directions include geographic expansion of the sample to the entire state of Texas (with a population of over 25 million) and genotyping of participating twins.

  2. Genetic and environmental dissections of sub-phenotypes of metabolic syndrome in the chinese population: a twin-based heritability study

    DEFF Research Database (Denmark)

    Duan, Haiping; Pang, Zengchang; Zhang, Dongfeng

    2011-01-01

    Objective: We perform a comprehensive heritability study on multiple phenotypes related to metabolic syndrome using Chinese twins to assess the genetic and environmental effects in determining the variation and covariation of the phenotypes in the Chinese population. Methods: The studied sample...... of the phenotypes. Conclusions: Our results showed significant genetic contributions to the sub-phenotypes of metabolic syndrome. Although pleiotropic genetic control may exist for some physiologically similar phenotypes, our results do not support a common genetic mechanism among the phenotypes covered in our...

  3. Genetic liability to disability pension in women and men: a prospective population-based twin study.

    Directory of Open Access Journals (Sweden)

    Jurgita Narusyte

    Full Text Available BACKGROUND: Previous studies of risk factors for disability pension (DP have mainly focused on psychosocial, or environmental, factors, while the relative importance of genetic effects has been less studied. Sex differences in biological mechanisms have not been investigated at all. METHODS: The study sample included 46,454 Swedish twins, consisting of 23,227 complete twin pairs, born 1928-1958, who were followed during 1993-2008. Data on DP, including diagnoses, were obtained from the National Social Insurance Agency. Within-pair similarity in liability to DP was assessed by calculating intraclass correlations. Genetic and environmental influences on liability to DP were estimated by applying discrete-time frailty modeling. RESULTS: During follow-up, 7,669 individuals were granted DP (18.8% women and 14.1% men. Intraclass correlations were generally higher in MZ pairs than DZ pairs, while DZ same-sexed pairs were more similar than opposite-sexed pairs. The best-fitting model indicated that genetic factors contributed 49% (95% CI: 39-59 to the variance in DP due to mental diagnoses, 35% (95% CI: 29-41 due to musculoskeletal diagnoses, and 27% (95% CI: 20-33 due to all other diagnoses. In both sexes, genetic effects common to all ages explained one-third, whereas age-specific factors almost two-thirds, of the total variance in liability to DP irrespective of diagnosis. Sex differences in liability to DP were indicated, in that partly different sets of genes were found to operate in women and men, even though the magnitude of genetic variance explained was equal for both sexes. CONCLUSIONS: The findings of the study suggest that genetic effects are important for liability to DP due to different diagnoses. Moreover, genetic contributions to liability to DP tend to differ between women and men, even though the overall relative contribution of genetic influences does not differ by sex. Hence, the pathways leading to DP might differ between women and

  4. Postpartum Mental State of Mothers of Twins

    Science.gov (United States)

    Brantmüller, Éva; Gyúró, Mónika; Galgán, Kitti; Pakai, Annamária

    2016-01-01

    Twin birth is a relevant risk factor for postnatal depression (PND). The primary objective of our study is to reveal the prevalence of suspected cases of depression and to identify some background factors among mothers of twins. We applied convenience sampling method within a retrospective, quantitative study among mothers given birth to twins for…

  5. Epigenetic Epidemiology of Complex Diseases Using Twins

    DEFF Research Database (Denmark)

    Tan, Qihua

    2013-01-01

    through multiple epigenetic mechanisms. This paper reviews the new developments in using twins to study disease-related epigenetic alterations, links them to lifetime environmental exposure with a focus on the discordant twin design and proposes novel data-analytical approaches with the aim of promoting...... a more efficient use of twins in epigenetic studies of complex human diseases....

  6. Twin and genetic effects on life events

    NARCIS (Netherlands)

    Middeldorp, C.M.; Cath, D.C.; Vink, J.M.; Boomsma, D.I.

    2005-01-01

    Twin studies that examine the effect of specific environmental risk factors on psychiatric disorders assume that there are no differences in prevalences of these risk factors between twins and singletons. Violation of this assumption signifies that the results from twin studies might not generalize

  7. Concordance for multiple sclerosis in Danish twins

    DEFF Research Database (Denmark)

    Hansen, T; Skytthe, Axel; Stenager, Egon

    2005-01-01

    The occurrence of multiple sclerosis (MS) in twins has not previously been studied in complete nationwide data sets. The existence of almost complete MS and twin registries in Denmark ensures that essentially unbiased samples of MS cases among twins can be obtained. In this population-based study...

  8. Estimating twin concordance for bivariate competing risks twin data

    DEFF Research Database (Denmark)

    Scheike, Thomas Harder; Holst, Klaus Kähler; von Bornemann Hjelmborg, Jacob

    2014-01-01

    For twin time-to-event data, we consider different concordance probabilities, such as the casewise concordance that are routinely computed as a measure of the lifetime dependence/correlation for specific diseases. The concordance probability here is the probability that both twins have experienced...... over time, and covariates may be further influential on the marginal risk and dependence structure. We establish the estimators large sample properties and suggest various tests, for example, for inferring familial influence. The method is demonstrated and motivated by specific twin data on cancer...... the event of interest. Under the assumption that both twins are censored at the same time, we show how to estimate this probability in the presence of right censoring, and as a consequence, we can then estimate the casewise twin concordance. In addition, we can model the magnitude of within pair dependence...

  9. Risk of Oral Clefts in Twins

    DEFF Research Database (Denmark)

    Grosen, Dorthe; Bille, Camilla; Petersen, Inge

    2011-01-01

    BACKGROUND:: Small studies have indicated that twinning increases the risk of oral cleft. METHODS:: We used data from a Danish national population-based cohort study to investigate whether twinning was associated with isolated oral cleft, and to estimate the twin probandwise concordance rate...... and heritability. Twins (207 affected/130,710) and singletons (7766 affected/4,798,526) born from 1936 through 2004 in Denmark were ascertained by linkage among the Danish Facial Cleft Database, the Danish Twin Registry, and the Civil Registration System. We computed oral cleft prevalence and prevalence proportion...... ratio for twins versus singletons, stratified for 3 subphenotypes. Probandwise concordance rates and heritability for twins were estimated for 2 phenotypes-cleft lip with or without cleft palate (CL/P) and cleft palate (CP). RESULTS:: The prevalence of oral cleft was 15.8 per 10,000 twins and 16.6 per...

  10. Longitudinal Relationship between Axial Length and Height in Chinese Children:Guangzhou Twin Eye Study

    Institute of Scientific and Technical Information of China (English)

    Decai Wang; Chen Zhao; Shengsong Huang; Wenyong Huang; Mingguang He

    2015-01-01

    Purpose:.To understand the growth model of axial length (AL) and height, and to explore the relationship between the two with the passage of time. Methods:.We followed twins in the Guangzhou Twin Eye Study for five years..The AL of both eyes was measured by partial coherence interferometry, and height was measured by a standard scale during each visit..A multivariate multilevel mixed model was adopted for data analysis. Results:.A total of 1217 children were included in the study. Both AL and height increased, but the rate of growth slowed down with age..The mitigation rate of height growth was -0.34 cm/year;.while that of AL growth was -0.01 mm/year. AL was positively related to height,.with a relevant coefficient of R=0.22 (Cov [height intercept, AL intercept] =1.56, 95%CI=1.14 to 1.99). The growth rates of AL and height were al-so positively related, with a relevant coefficient of R=0.18 (Cov [height slope, AL slope] =0.03, 95%CI=0.01 to 0.05). However, taller children had slower rates of height increases, with a relevant coefficient of R=-0.12 (Cov[height intercept, height slope]=-1.33,95%CI=-2.25 to-0.42); but had faster AL growth,.with a relevant coefficient of R=(Cov [height intercept, AL slope] =0.02, 95%CI=-0.05 to 0.08, R=0.02). AL and its growth rate were positively related to each other, with a relevant coefficient of R=(Cov [AL intercept,.AL slope]=0.04, 95%CI=0.03 to 0.05, R=0.3); while the growth rates of AL and height were negatively related to each other, with a relevant coefficient of R=(Cov[AL intercept, height slope]=--0.03 95%CI=-0.16 to 0.1, R=-0.02). Conclusion:.The increase in children's AL is relevant to their height increases..The faster their height increases,.the faster their AL increases.

  11. Twinning during hot compression of ZK30 + 0.3Yb magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    YE Cheng-wu; LIU Zhi-yi; ZHANG Kun; ZHENG Qing-chun

    2005-01-01

    The twinning process of ZK30 +0.3Yb magnesium alloy was studied. The results show that twinning occurs at the initial stage of deformation, and decreases during further deformation. The original grain is fragmented after small straining. It is investigated that the twinning boundary activates the occurrence of the non-basal slip system due to the stress concentration at the vicinity of twin boundary introduced by the dislocation pile-ups at the vicinity of twinning boundary. The rearrangement of dislocation after dislocation climb introduces new grain boundary.Simultaneously, twinning occurs to form "polygonization" due to the stress concentration relaxation, and the "polygonization" will transform into low angle boundary to refine the original grain under the shear stress with further straining.

  12. An advanced perspective on twin growth in Nickel-Titanium

    Science.gov (United States)

    Ezaz, Tawhid

    2011-12-01

    This work presents an energetic approach to investigate the attributes of twinning in Nickel-Titanium (NiTi) shape memory alloy. In particular, atomistic mechanisms of twin growth in two different phases of NiTi are characterized with barrier energy in this thesis. In addition, energetics of dislocation twin boundary interactions in a face centered cubic (fcc) metal (Copper) that contributes to strengthening is investigated. Density Functional Theory based ab initio calculation and Molecular dynamics (MD) correspond to the right length and time scale for these events, and utilized in this study. The first part of the work elucidates the details of twinning in martensite (B19') and austenite (B2) as the major deformation mode in NiTi undergoing thermoelastic phase transformation. Combined shears, shuffles and interface shifts are operative in a complicated way to generate different twin modes in these two phases. Along with the growth mechanism, we report on generalized planar fault energy and generalized stacking fault energy barriers in NiTi shape memory alloys in the monoclinic martensite state and cubic austenitic state. Specifically, in martensitic regime, we report energy barriers for (001), (100) and (201) type twin nucleation and growth with atomistic details of combined shear and shuffle. Our energetic approach successfully predicts the evolution of deformation twins in martensite that are observed in experimental studies. In addition, we investigate the (112) and (114) deformation twin formation mechanism in austenitic NiTi that provides enhanced ductility in this intermetallic compound. The entire potential energy surface (PES) and mean energy path (MEP) during twinning is an outcome of our simulations, providing the needed insight to the atomistic processes. We suggest that the results provide a quantitative methodology in development of new shape memory alloys where twinning can occur at stress levels far below that corresponding to plastic deformation

  13. Heritable influence of DBH on adrenergic and renal function: twin and disease studies.

    Directory of Open Access Journals (Sweden)

    Dalal N Pasha

    Full Text Available BACKGROUND: Elevated sympathetic activity is associated with kidney dysfunction. Here we used twin pairs to probe heritability of GFR and its genetic covariance with other traits. METHODS: We evaluated renal and adrenergic phenotypes in twins. GFR was estimated by CKD-EPI algorithm. Heritability and genetic covariance of eGFR and associated risk traits were estimated by variance-components. Meta-analysis probed reproducibility of DBH genetic effects. Effect of DBH genetic variation on renal disease was tested in the NIDDK-AASK cohort. RESULTS: Norepinephrine secretion rose across eGFR tertiles while eGFR fell (p<0.0001. eGFR was heritable, at h(2 = 67.3±4.7% (p = 3.0E-18, as were secretion of norepinephrine (h(2 = 66.5±5.0%, p = 3.2E-16 and dopamine (h(2 = 56.5±5.6%, p = 1.8E-13, and eGFR displayed genetic co-determination (covariance with norepinephrine (ρG = -0.557±0.088, p = 1.11E-08 as well as dopamine (ρG = -0.223±0.101, p = 2.3E-02. Since dopamine β-hydroxylase (DBH catalyzes conversion of dopamine to norepinephrine, we studied functional variation at DBH; DBH promoter haplotypes predicted transcriptional activity (p<0.001, plasma DBH (p<0.0001 and norepinephrine (p = 0.0297 secretion; transcriptional activity was inversely (p<0.0001 associated with basal eGFR. Meta-analysis validated DBH haplotype effects on eGFR across 3 samples. In NIDDK-AASK, we established a role for DBH promoter variation in long-term renal decline rate (GFR slope, p = 0.003. CONCLUSIONS: The heritable GFR trait shares genetic determination with catecholamines, suggesting new pathophysiologic, diagnostic and therapeutic approaches towards disorders of GFR as well as CKD. Adrenergic activity may play a role in progressive renal decline, and genetic variation at DBH may assist in profiling subjects for rational preventive treatment.

  14. Five-factor personality traits and pain sensitivity: a twin study.

    Science.gov (United States)

    Vassend, Olav; Røysamb, Espen; Nielsen, Christopher S

    2013-05-01

    Factors underlying individual differences in pain responding are incompletely understood, but are likely to include genetic influences on basal pain sensitivity in addition to demographic characteristics such as age, sex, and ethnicity, and psychological factors including personality. This study sought to explore the relationship between personality traits and experimental pain sensitivity, and to determine to what extent the covariances between these phenotypes are mediated by common genetic and environmental factors. A sample composed of 188 twins, aged 23 to 35years, was included in the study. Heat pain intensity (HPI) and cold-pressor pain intensity (CPI) ratings were obtained using standardized pain testing procedures, and personality traits were assessed with the NEO Personality Inventory, Revised. Associations between personality and the pain sensitivity indices were examined using zero-order correlations and generalized estimating equations. Bivariate Cholesky models were used in the biometric analyses. The most robust finding was a significant phenotypic association between CPI and the personality facets Impulsiveness (a facet of Neuroticism) and Excitement-Seeking (a facet of Extraversion), and estimates of the genetic correlation were .37 (Ppersonality seemed weak and unstable, but a significant effect of Angry Hostility (a facet of Neuroticism) emerged in generalized estimating equations analysis. Although the genetic correlation between these phenotypes was essentially zero, a weak but significant individual-specific environmental correlation emerged (re=.21, Ppersonality dispositions than HPI, both phenotypically and genetically.

  15. Probing interactions of neurotransmitters with twin tailed anionic surfactant: A detailed physicochemical study.

    Science.gov (United States)

    Kaur, Rajwinder; Sanan, Reshu; Mahajan, Rakesh Kumar

    2016-05-01

    Keeping in view the role of neurotransmitters (NTs) in central nervous system diseases and in controlling various physiological processes, present study is aimed to study the binding of neurotransmitters (NTs) such as norepinephrine hydrochloride (NE) and serotonin hydrochloride (5-HT) with twin tailed surfactant sodium bis(2-ethylhexyl)sulfosuccinate (AOT). Spectroscopic and electrochemical measurements combined with microcalorimetric measurements were used to characterize the interactions between AOT and NTs. Meteoric modifications to emission profile and absorption spectra of NTs upon addition of AOT are indicative of the binding of NTs with AOT. Distinct interactional states such as formation of ion-pairs, induced and regular micelles with adsorbed NTs molecules have been observed in different concentration regimes of AOT. The formation of ion-pairs from oppositely charged NTs and AOT is confirmed by the reduced absorbance, quenched fluorescence intensity and decrease in peak current (ipa) as well as shifts in peak potential (Epa) values. The stoichiometry and formation of the NTs-AOT complexes has been judged and the extent of interactions is quantitatively discussed in terms of binding constant (K) and free energy of binding (ΔG°). The enthalpy (ΔH°mic) and free energy of micellization (ΔG°mic) for AOT in presence and absence of NTs are determined from the enthalpy curves.

  16. Application of Twin Screw Extrusion in the Manufacture of Cocrystals, Part I: Four Case Studies

    Directory of Open Access Journals (Sweden)

    Karthik Nagapudi

    2011-08-01

    Full Text Available The application of twin screw extrusion (TSE as a scalable and green process for the manufacture of cocrystals was investigated. Four model cocrystal forming systems, Caffeine-Oxalic acid, Nicotinamide-trans cinnamic acid, Carbamazepine-Saccharin, and Theophylline-Citric acid, were selected for the study. The parameters of the extrusion process that influenced cocrystal formation were examined. TSE was found to be an effective method to make cocrystals for all four systems studied. It was demonstrated that temperature and extent of mixing in the extruder were the primary process parameters that influenced extent of conversion to the cocrystal in neat TSE experiments. In addition to neat extrusion, liquid-assisted TSE was also demonstrated for the first time as a viable process for making cocrystals. Notably, the use of catalytic amount of benign solvents led to a lowering of processing temperatures required to form the cocrystal in the extruder. TSE should be considered as an efficient, scalable, and environmentally friendly process for the manufacture of cocrystals with little to no solvent requirements.

  17. Study on Hardware-in-loop Simulation of Twin-screw Extruder Experiment System

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>In order to facilitate the teaching of industrial processes and experiments on the twin-screw extruder control debugging,and be closer to the actual testing,to reduce the debugging costs and the risk of debugging process,the paper designs a hardware-in-loop simulation of twin-screw extruder experiment system which is closer to scene,low cost and high safety.The system through the establishment of twin-screw extruder’s mathematical model on computer to simulate the realistic system and there is hardware practicality in the computer simulation loop.The hardware based on C8051F020 can operate in the simulation loop in real time.In computer software design, we desigh man-machine interface that is intuitive and easy to operate,can reflect twin-screw extruder main operation information vividly.Finally,twin-screw extruder’s 3 heater temperature mathematical model and PID incremental control algorithm are presented.

  18. Lung cancer, genetic predisposition and smoking: the Nordic Twin Study of Cancer

    DEFF Research Database (Denmark)

    Hjelmborg, Jacob v. B.; Korhonen, Tellervo; Holst, Klaus;

    2016-01-01

    Background: We aimed to disentangle genetic and environmental causes in lung cancer while considering smoking status. Methods: Four Nordic twin cohorts (43 512 monozygotic (MZ) and 71 895 same sex dizygotic (DZ) twin individuals) had smoking data before cancer diagnosis. We used time...... for lung cancer, nearly all were current smokers at baseline and only one concordant pair was seen among never smokers. Among ever smokers, the case-wise concordance of lung cancer, that is the risk before a certain age conditional on lung cancer in the co-twin before that age, was significantly increased...... pairs. Among smoking discordant pairs, the pairwise HR for lung cancer of the ever smoker twin compared to the never smoker co-twin was 5.4 (95% CI 2.1 to 14.0) in MZ pairs and 5.0 (95% CI 3.2 to 7.9) in DZ pairs. Conclusions: The contribution of familial effects appears to decrease by age...

  19. Lung cancer, genetic predisposition and smoking: the Nordic Twin Study of Cancer

    DEFF Research Database (Denmark)

    Hjelmborg, Jacob v. B.; Korhonen, Tellervo; Holst, Klaus

    2016-01-01

    Background: We aimed to disentangle genetic and environmental causes in lung cancer while considering smoking status. Methods: Four Nordic twin cohorts (43 512 monozygotic (MZ) and 71 895 same sex dizygotic (DZ) twin individuals) had smoking data before cancer diagnosis. We used time...... for lung cancer, nearly all were current smokers at baseline and only one concordant pair was seen among never smokers. Among ever smokers, the case-wise concordance of lung cancer, that is the risk before a certain age conditional on lung cancer in the co-twin before that age, was significantly increased...... pairs. Among smoking discordant pairs, the pairwise HR for lung cancer of the ever smoker twin compared to the never smoker co-twin was 5.4 (95% CI 2.1 to 14.0) in MZ pairs and 5.0 (95% CI 3.2 to 7.9) in DZ pairs. Conclusions: The contribution of familial effects appears to decrease by age...

  20. Epidemiology of anorexia nervosa in men: a nationwide study of Finnish twins.

    Directory of Open Access Journals (Sweden)

    Anu Raevuori

    Full Text Available BACKGROUND: To examine the epidemiology of anorexia nervosa in men, we screened Finnish male twins born in 1975-79. METHODS AND FINDINGS: Men (N = 2122 from FinnTwin16 birth cohorts were screened for lifetime eating disorders by a questionnaire. The screen positives (N = 18, their male co-twins (N = 10 and those with lifetime minimum BMI< or =17.5 (N = 21 were administered the Structured Clinical Interview for DSM-IV anorexia nervosa. The incidence rate of anorexia nervosa for the presumed peak age of risk (10-24y was 15.7 per 100,000 person-years; its lifetime prevalence was 0.24%. All probands had recovered from eating disorders, but suffered from substantial psychiatric comorbidity, which also manifested in their co-twins. Additionally, male co-twins displayed significant dissatisfaction with body musculature, a male-specific feature of body dysmorphic disorder. CONCLUSIONS: Anorexia nervosa in males in the community is more common, transient and accompanied by more substantial comorbidity than previously thought.

  1. Twinning across the Developing World.

    Directory of Open Access Journals (Sweden)

    Jeroen Smits

    Full Text Available BACKGROUND: Until now, little was known about the variation in incidence of twin births across developing countries, because national representative data was lacking. This study provides the first comprehensive overview of national twinning rates across the developing world on the basis of reliable survey data. METHODS: Data on incidence of twinning was extracted from birth histories of women aged 15-49 interviewed in 150 Demographic and Health Surveys, held between 1987 and 2010 in 75 low and middle income countries. During the interview, information on all live births experienced by the women was recorded, including whether it was a singleton or multiple birth. Information was available for 2.47 million births experienced by 1.38 million women in a period of ten years before the interview. Twinning incidence was measured as the number of twin births per thousand births. Data for China were computed on the basis of published figures from the 1990 census. Both natural and age-standardized twinning rates are presented. RESULTS/CONCLUSIONS: The very low natural twinning rates of 6-9 per thousand births previously observed in some East Asian countries turn out to be the dominant pattern in the whole South and South-East Asian region. Very high twinning rates of above 18 per thousand are not restricted to Nigeria (until now seen as the world's twinning champion but found in most Central-African countries. Twinning rates in Latin America turn out to be as low as those in Asia. Changes over time are small and not in a specific direction. SIGNIFICANCE: We provide the most complete and comparable overview of twinning rates across the developing world currently possible.

  2. The role of cognitive reserve on terminal decline: a cross-cohort analysis from two European studies: OCTO-Twin, Sweden, and Newcastle 85+, UK.

    Science.gov (United States)

    Cadar, Dorina; Stephan, Blossom C M; Jagger, Carol; Johansson, Boo; Hofer, Scott M; Piccinin, Andrea M; Muniz-Terrera, Graciela

    2016-06-01

    Cognitive performance shows a marked deterioration in close proximity to death, as postulated by the terminal decline hypothesis. The effect of education on the rate of terminal decline in the oldest people (i.e. persons 85+ years) has been controversial and not entirely understood. In the current study, we investigated the rate of decline prior to death with a special focus on the role of education and socioeconomic position, in two European longitudinal studies of ageing: the Origins of Variance in the Old-Old: Octogenarian Twins (OCTO-Twin) and the Newcastle 85+ study. A process-based approach was used in which individuals' cognitive scores were aligned according to distance to death. In a coordinated analysis, multilevel models were employed to examine associations between different markers of cognitive reserve (education and socioeconomic position) and terminal decline using the mini-mental state examination (MMSE), controlling for age at baseline, sex, dementia incidence and time to death from the study entry to the time of death within each cohort. The current findings suggest that education was positively associated with higher MMSE scores prior to death in the OCTO-Twin, but not in the Newcastle 85+ study, independent of socioeconomic position and other factors such as baseline age, sex and time to death from the study entry. However, education was not associated with the rate of terminal decline in both of these studies. Our results offer only partial support to the cognitive reserve hypothesis and cognitive performance prior to death. © 2015 The Authors International Journal of Geriatric Psychiatry Published by John Wiley & Sons Ltd.

  3. Is Chronic Low Back Pain Associated with the Prevalence of Coronary Heart Disease when Genetic Susceptibility Is Considered? A Co-Twin Control Study of Spanish Twins.

    Science.gov (United States)

    Fernandez, Matt; Ordoñana, Juan R; Hartvigsen, Jan; Ferreira, Manuela L; Refshauge, Kathryn M; Sánchez-Romera, Juan F; Pinheiro, Marina B; Simpson, Stephen J; Hopper, John L; Ferreira, Paulo H

    2016-01-01

    To investigate the chronic low back pain and coronary heart disease relationship, after adjusting for relevant confounders, including genetics. In a cross-sectional design, 2148 twins were recruited from the Murcia Twin Registry, Spain. The exposure was chronic LBP and the outcomes were myocardial infarction and other coronary heart diseases-lifetime and in the last 2 years-based on standardized health-related questionnaires. First, logistic regression analysis investigated associations of the total sample followed by a matched co-twin control analyses, with all complete twin pairs discordant for chronic LBP utilised, separated for zygosity-dizygotic (DZ) and monozygotic (MZ) pairs, which adjusted for shared familial factors, including genetics. Chronic LBP pain is associated with lifetime myocardial infarction [odds ratio (OR) = 2.69, 95% confidence interval (CI) = 1.35-5.36], other coronary heart diseases over a lifetime (OR = 2.58, 95% CI: 1.69-3.93) and in the last two years (OR = 2.19, 95% CI: 1.33-3.60), while there was a borderline association with myocardial infarction in the last 2 years (OR = 2.64, 95% CI: 0.98-7.12). Although the magnitude of the association remained or increased in the co-twin control analyses, none reached statistical significance. Chronic LBP is associated with a higher prevalence of myocardial infarction and coronary heart disease. It is possible that this association remains even when controlling for genetics and early shared environment, although this should be investigated with larger samples of twins discordant for LBP.

  4. Genetics and the environment affect the relationship between depression and low back pain: a co-twin control study of Spanish twins.

    Science.gov (United States)

    Pinheiro, Marina B; Ferreira, Manuela L; Refshauge, Kathryn; Colodro-Conde, Lucía; Carrillo, Eduvigis; Hopper, John L; Ordoñana, Juan R; Ferreira, Paulo H

    2015-03-01

    Although the co-occurrence of low back pain (LBP) and depression is common, the nature of this association remains unclear. We aimed to investigate whether symptoms of depression are associated with LBP after adjusting for various confounders, including genetics. We used cross-sectional data from 2148 twins from the Murcia Twin Registry, Spain. All twins answered questions about lifetime prevalence of LBP (outcome variable) and symptoms of depression, collected through two instruments, deriving 3 measures: (1) self-report feelings of depression and anxiety; (2) state depression, and (3) trait depression. First, associations were investigated using logistic regression analysis of the total sample. We performed subsequent matched within-pair twin case-control analyses with all complete twin pairs discordant for LBP regardless of zygosity, and separately for dizygotic and monozygotic pairs. This sequential analysis allows for more precise estimates of the relationship between variables, as in each step, the impact of early shared environment and genetics is further considered. Symptoms of depression and anxiety were associated with higher prevalence of LBP in the total sample analysis (odds ratio [OR], 1.64; 95% confidence interval [CI], 1.31-2.05), and this relationship was stronger in the subsequent case-control analysis (OR, 1.74; 95% CI, 1.13-2.69) and dizygotic case-control analysis (OR, 2.39; 95% CI, 1.39-4.08) but disappeared when the analysis was conducted for monozygotic twins (OR, 0.92; 95% CI, 0.42-2.05). A similar pattern was found for state and trait depression. The depression-LBP relationship disappears when high levels of control for confounding factors are applied and seems to be driven by genetic or environmental factors that influence both conditions.

  5. Is Chronic Low Back Pain Associated with the Prevalence of Coronary Heart Disease when Genetic Susceptibility Is Considered? A Co-Twin Control Study of Spanish Twins

    Science.gov (United States)

    Fernandez, Matt; Ordoñana, Juan R.; Hartvigsen, Jan; Ferreira, Manuela L.; Refshauge, Kathryn M.; Sánchez-Romera, Juan F.; Pinheiro, Marina B.; Simpson, Stephen J.; Hopper, John L.; Ferreira, Paulo H.

    2016-01-01

    Objective To investigate the chronic low back pain and coronary heart disease relationship, after adjusting for relevant confounders, including genetics. Methods In a cross-sectional design, 2148 twins were recruited from the Murcia Twin Registry, Spain. The exposure was chronic LBP and the outcomes were myocardial infarction and other coronary heart diseases—lifetime and in the last 2 years–based on standardized health-related questionnaires. First, logistic regression analysis investigated associations of the total sample followed by a matched co-twin control analyses, with all complete twin pairs discordant for chronic LBP utilised, separated for zygosity—dizygotic (DZ) and monozygotic (MZ) pairs, which adjusted for shared familial factors, including genetics. Results Chronic LBP pain is associated with lifetime myocardial infarction [odds ratio (OR) = 2.69, 95% confidence interval (CI) = 1.35–5.36], other coronary heart diseases over a lifetime (OR = 2.58, 95% CI: 1.69–3.93) and in the last two years (OR = 2.19, 95% CI: 1.33–3.60), while there was a borderline association with myocardial infarction in the last 2 years (OR = 2.64, 95% CI: 0.98–7.12). Although the magnitude of the association remained or increased in the co-twin control analyses, none reached statistical significance. Conclusion Chronic LBP is associated with a higher prevalence of myocardial infarction and coronary heart disease. It is possible that this association remains even when controlling for genetics and early shared environment, although this should be investigated with larger samples of twins discordant for LBP. PMID:27171210

  6. Natal Influences and Twin Differences: Draft.

    Science.gov (United States)

    Van den Daele, Leland D.

    1972-01-01

    A classification of natal influences is proposed with a model of their operation. Natal influences affect maternal capacity, maternal load, and maternal efficiency. Since maternal load is increased in twin pregnancy, results of twin studies must be generalized with caution. The method of co-twin control is exemplified by examination of a small…

  7. Age moderates non-genetic influences on the initiation of cannabis use: a twin-sibling study in Dutch adolescents and young adults.

    Science.gov (United States)

    Distel, Marijn A; Vink, Jacqueline M; Bartels, Meike; van Beijsterveldt, Catharina E M; Neale, Michael C; Boomsma, Dorret I

    2011-09-01

    To examine the heritability of cannabis initiation, the influence of a possible twin-specific environment and the influence of age on the effects of genes and environment in Dutch adolescents and young adults. Genetic structural equation modelling was used to partition the variance in the liability to cannabis initiation into genetic and environmental components. All participants were registered with the Netherlands Twin Register. A total of 6,208 twins (age 13-20) and 1,545 siblings (age 11-25) from 3,503 families participated in this study. Self-reported cannabis use was assessed prospectively with the Dutch Health Behavior Questionnaire. At the median age of the sample (16.5), genetic factors explained 40% of the individual differences in liability to cannabis initiation. Twins resembled each other more than non-twin siblings, which could not be attributed to the age difference between non-twin siblings. Environmental influences increased with age. This increase applied to environmental factors shared by twins (47% of the variance), environmental factors shared by twins and siblings (24%) and environmental factors unique to an individual (13%). The heritability of the liability for cannabis initiation is higher in adolescents than in young adults due to a larger contribution of environmental factors in young adults. This is due mainly to environmental factors only shared by twins and those shared by all offspring growing up in the same family, but the contribution of environmental factors specific to individuals is also larger in young adults. © 2011 The Authors, Addiction © 2011 Society for the Study of Addiction.

  8. Behavioral and Environmental Modification of the Genetic Influence on Body Mass Index: A Twin Study.

    Science.gov (United States)

    Horn, Erin E; Turkheimer, Eric; Strachan, Eric; Duncan, Glen E

    2015-07-01

    Body mass index (BMI) has a strong genetic basis, with a heritability around 0.75, but is also influenced by numerous behavioral and environmental factors. Aspects of the built environment (e.g., environmental walkability) are hypothesized to influence obesity by directly affecting BMI, by facilitating or inhibiting behaviors such as physical activity that are related to BMI, or by suppressing genetic tendencies toward higher BMI. The present study investigated relative influences of physical activity and walkability on variance in BMI using 5079 same-sex adult twin pairs (70 % monozygotic, 65 % female). High activity and walkability levels independently suppressed genetic variance in BMI. Estimating their effects simultaneously, however, suggested that the walkability effect was mediated by activity. The suppressive effect of activity on variance in BMI was present even with a tendency for low-BMI individuals to select into environments that require higher activity levels. Overall, our results point to community- or macro-level interventions that facilitate individual-level behaviors as a plausible approach to addressing the obesity epidemic among US adults.

  9. Retrospective reports of parental physical affection and parenting style: a study of Finnish twins.

    Science.gov (United States)

    Harlaar, Nicole; Santtila, Pekka; Björklund, Johanna; Alanko, Katarina; Jern, Patrick; Varjonen, Markus; von der Pahlen, Bettina; Sandnabba, Kenneth

    2008-08-01

    Individual differences in parenting behaviors are due, in part, to genetic factors. In the present study, the authors sought to determine whether the degree of genetic influence varied according to the type of parental behavior under consideration. A population-based sample of 2,334 pairs of Finnish twins provided ratings on the physical affection, control, abusiveness, and indifference shown by their father and mother during childhood. Genetic influences, shared environmental influences, and nonshared environmental influences accounted for a small-to-medium proportion (17%-30%), a small-to-large proportion (22%-44%), and a medium-to-large proportion (37%-55%) of the variance in each parenting measure, respectively. There were no significant differences in effect sizes for mothers and fathers or across the 4 types of parental behavior. The genetic results may reflect characteristic styles with which parents respond to genetically influenced behaviors of individuals (gene-environment correlations) or individual perceptions of this relationship (gene-person correlation processes). The findings have implications for intervention and prevention work with families and for interpretation of evidence for interactions between genes and parenting behaviors.

  10. The Danish Twin Registry

    DEFF Research Database (Denmark)

    Skytthe, Axel; Christiansen, Lene; Kyvik, Kirsten Ohm;

    2013-01-01

    decade of combining questionnaire and survey data with national demographic, social, and health registers in Statistics Denmark. Second, we describe our most recent data collection effort, which was conducted during the period 2008-2011 and included both in-person assessments of 14,000+ twins born 1931......Over the last 60 years, the resources and the research in the Danish Twin Registry (DTR) have periodically been summarized. Here, we give a short overview of the DTR and a more comprehensive description of new developments in the twenty-first century. First, we outline our experience over the last......-1969 and sampling of biological material, hereby expanding and consolidating the DTR biobank. Third, two examples of intensively studied twin cohorts are given. The new developments in the DTR in the last decade have facilitated the ongoing research and laid the groundwork for new research directions....

  11. Genetic and environmental influences on plasma homocysteine: results from a Danish twin study

    DEFF Research Database (Denmark)

    Bathum, Lise; Petersen, Inge; Christiansen, Lene;

    2007-01-01

    BACKGROUND: Increased plasma homocysteine has been linked to many clinical conditions including atherosclerosis and ischemic stroke. We assessed the genetic and environmental influences on homocysteine in adult twins and tested the influence of 3 candidate polymorphisms. METHODS: Homocysteine...... was analyzed in 1206 healthy twins, who were genotyped for 3 polymorphisms: MTHFR 677C>T, MTR 2756A>G, and NNMT (dbSNP: rs694539). To perform quantitative trait linkage analysis of the MTHFR locus, the genotyping was supplemented with 2 genetic markers localized on each site of the MTHFR locus. The twin data...... of the MTHFR locus is estimated to explain 53% (95% CI, 0.07-0.67) of the total phenotypic variation in persons 18-39 years old and 24% (95% CI, 0.00-0.39) in persons 40-65 years old, i.e., almost all additive genetic variance. CONCLUSIONS: Homocysteine concentrations have a high heritability that decreases...

  12. Genetic factors account for most of the variation in serum tryptase-a twin study

    DEFF Research Database (Denmark)

    Sverrild, A.; van der Sluis, S.; Kyvik, K. O.;

    2013-01-01

    Background: Mast cells are involved in a number of diseases, including inflammatory diseases such as asthma. Tryptase is a known marker of mast cell burden and activity. However, little is known about the genetic influence on serum tryptase variation. Also, only few and conflicting data exist......) in a sample of Danish twins. Methods: A total of 575 twins underwent a skin prick test and had lung function, AHR to methacholine, exhaled nitric oxide and serum tryptase measured. Multiple regression and variance components models (using the statistical package SOLAR) were computed. Results: Serum tryptase...... values were available in 569 subjects. Intraclass correlations of serum tryptase in monozygotic and dizygotic twin pairs were 0.84 and 0.42 (P

  13. Effects of early-life environment and epigenetics on cardiovascular disease risk in children: highlighting the role of twin studies.

    Science.gov (United States)

    Sun, Cong; Burgner, David P; Ponsonby, Anne-Louise; Saffery, Richard; Huang, Rae-Chi; Vuillermin, Peter J; Cheung, Michael; Craig, Jeffrey M

    2013-04-01

    Cardiovascular disease (CVD) is the leading cause of death worldwide and originates in early life. The exact mechanisms of this early-life origin are unclear, but a likely mediator at the molecular level is epigenetic dysregulation of gene expression. Epigenetic factors have thus been posited as the likely drivers of early-life programming of adult-onset diseases. This review summarizes recent advances in epidemiology and epigenetic research of CVD risk in children, with a particular focus on twin studies. Classic twin studies enable partitioning of phenotypic variance within a population into additive genetic, shared, and nonshared environmental variances, and are invaluable in research in this area. Longitudinal cohort twin studies, in particular, may provide important insights into the role of epigenetics in the pathogenesis of CVD. We describe candidate gene and epigenome-wide association studies (EWASs) and transgenerational epigenetic inheritance of CVD, and discuss the potential for evidence-based interventions. Identifying epigenetic changes associated with CVD-risk biomarkers in children will provide new opportunities to unravel the underlying biological mechanism of the origins of CVD and enable identification of those at risk for early-life interventions to alter the risk trajectory and potentially reduce CVD incidence later in life.

  14. Metabolism of sex steroids is influenced by acquired adiposity-A study of young adult male monozygotic twin pairs.

    Science.gov (United States)

    Vihma, Veera; Naukkarinen, Jussi; Turpeinen, Ursula; Hämäläinen, Esa; Kaprio, Jaakko; Rissanen, Aila; Heinonen, Sini; Hakkarainen, Antti; Lundbom, Jesper; Lundbom, Nina; Mikkola, Tomi S; Tikkanen, Matti J; Pietiläinen, Kirsi H

    2017-09-01

    Obesity and ageing are associated with lower serum testosterone levels in men. How fat distribution or adipose tissue metabolism, independent of genetic factors and age, are related to sex steroid metabolism is less clear. We studied the associations between adiposity and serum sex hormone concentrations, and mRNA expression of genes regulating sex hormone metabolism in adipose tissue in young adult male monozygotic (MZ) twin pairs. The subjects [n=18 pairs; mean age, 32 years; individual body mass indexes (BMIs) 22-36kg/m(2)] included 9 male MZ twin pairs discordant for BMI [intra-pair difference (Δ) in BMI ≥3kg/m(2)]. Sex steroid concentrations were determined by liquid chromatography-tandem mass spectrometry, body composition by dual-energy X-ray absorptiometry and magnetic resonance imaging, and mRNA expressions from subcutaneous adipose tissue by Affymetrix. In BMI-discordant pairs (mean ΔBMI=5.9kg/m(2)), serum dihydrotestosterone (DHT) was lower [mean 1.9 (SD 0.7) vs. 2.4 (1.0) nmol/l, P=0.040] and mRNA expressions of DHT-inactivating AKR1C2 (P=0.021) and cortisol-producing HSD11B1 (P=0.008) higher in the heavier compared to the leaner co-twins. Serum free 17β-estradiol (E2) was higher [2.3 (0.5) vs. 1.9 (0.5) pmol/l, P=0.028], and in all twin pairs, serum E2 and estrone concentrations were higher in the heavier than in the leaner co-twins [107 (28) vs. 90 (22) pmol/l, P=0.006; and 123 (43) vs. 105 (27) pmol/l, P=0.025]. Within all twin pairs, i.e. independent of genetic effects and age, 1) the amount of subcutaneous fat inversely correlated with serum total and free testosterone, DHT, and sex hormone-binding globulin (SHBG) concentrations (Padiposity correlated positively with mRNA expressions of AKR1C2, HSD11B1, and aromatase in adipose tissue (Padiposity was associated with decreased serum DHT and increased estrogen concentrations, independent of genetic factors and age. The reduction of DHT could be linked to its increased degradation (by AKR1C2 and

  15. Are children's activity levels determined by their genes or environment? A systematic review of twin studies

    OpenAIRE

    Abigail Fisher; Lee Smith; van Jaarsveld, Cornelia H. M.; Alexia Sawyer; Jane Wardle

    2015-01-01

    Context: The importance of physical activity to paediatric health warrants investigation into its determinants. Objective measurement allows a robust examination of genetic and environmental influences on physical activity. Objective: To systematically review the evidence on the extent of genetic and environmental influence on children's objectively-measured activity levels from twin studies. Data sources and search terms: Medline, EMBASE, PsycINFO, Health and Psychosocial Instruments a...

  16. Skeletal Class II correction and neuromuscular adaptation with twin-block: A cephalometric and electromyography study in adults

    OpenAIRE

    Sandeep Kumar; Tulika Tripathi; Maninder Singh Sidhu; Puneet Yadav; Ashish Dabas

    2016-01-01

    Introduction: It is believed that significant changes in electromyography (EMG) activity are observed at the end of the treatment, which are concomitant with a clinical improvement seen in sagittal jaw relationship during skeletal Class II correction by functional appliances. It is thought that similar interaction occurs between bone shape and muscle activity in the maxillofacial complex this study aims at evaluating the effects of twin-block on correction of skeletal Class II by lateral ceph...

  17. Life events as environmental States and genetic traits and the role of personality: a longitudinal twin study.

    Science.gov (United States)

    Kandler, Christian; Bleidorn, Wiebke; Riemann, Rainer; Angleitner, Alois; Spinath, Frank M

    2012-01-01

    The occurrence of many life events is not entirely random but genetically influenced. The current study examined the sources underlying the stability or recurrence of life events and the developmental interplay between personality traits and life events. In a longitudinal study of 338 adult twin pairs we estimated (1) the genetic and environmental sources of continuity in aggregates of life events, (2) the sources through which personality influences the experience of life events, and (3) the sources through which life events influence personality. Unlike personality which showed both genetic and environmental influences on substantial continuity over time, stability of life events was moderate and mainly influenced by genetic factors. Significant associations between personality and life events were specific to certain personality traits and qualitative aspects of life events (controllable positive, controllable negative, and less controllable negative), primarily directional from personality to life events, and basically genetically mediated. Controlled for these genetic associations, we also found some small and basically environmentally mediated effects of life events on personality traits. The results support the concept of genotype-environment correlation as a propulsive mechanism of development.

  18. Epigenome-wide association study on identical twins discordant for birth weight

    DEFF Research Database (Denmark)

    Tan, Qihua; Nielsen, Morten Frost Munk; Christiansen, Lene

    induces persistent epigenetic modification detectable at adult ages, we performed a genome-wide DNA methylation profiling in peripheral blood of 150 pairs of identical Danish twins discordant for birth weight using the Illumina Infinium HumanMethylation450 BeadChip featuring 485,000 CpG sites across...... the genome. After quality control and data preprocessing using free R package minfi, data were analysed by a mixed effects model including fixed effect variables such as birth weight difference, age and sex of twin pairs; random effect variables such as batch, well, and sample position on the array, etc....... Statistical analysis revealed 12 probes with p valuetwins is not associated...

  19. The Charles Perkins Centre's Twins Research Node.

    Science.gov (United States)

    Ferreira, Lucas C; Craig, Jeffrey M; Hopper, John L; Carrick, Susan E

    2016-08-01

    Twins can help researchers disentangle the roles of genes from those of the environment on human traits, health, and diseases. To realize this potential, the Australian Twin Registry (ATR), University of Melbourne, and the Charles Perkins Centre (CPC), University of Sydney, established a collaboration to form the Twins Research Node, a highly interconnected research facility dedicated specifically to research involving twins. This collaboration aims to foster the adoption of twin designs as important tools for research in a range of health-related domains. The CPC hosted their Twins Research Node's launch seminar entitled 'Double the power of your research with twin studies', in which experienced twin researchers described how twin studies are supporting scientific discoveries and careers. The launch also featured twin pairs who have actively participated in research through the ATR. Researchers at the CPC were surveyed before the event to gauge their level of understanding and interest in utilizing twin research. This article describes the new Twins Research Node, discusses the survey's main results and reports on the launch seminar.

  20. Epigenetic Epidemiology of Complex Diseases Using Twins

    DEFF Research Database (Denmark)

    Tan, Qihua

    2013-01-01

    In the past decades, studies on twins have had a great impact on dissecting the genetic and environmental contributions to human diseases and complex traits. In the era of functional genomics, the valuable samples of twins help to bridge the gap between gene activity and environmental conditions...... through multiple epigenetic mechanisms. This paper reviews the new developments in using twins to study disease-related epigenetic alterations, links them to lifetime environmental exposure with a focus on the discordant twin design and proposes novel data-analytical approaches with the aim of promoting...... a more efficient use of twins in epigenetic studies of complex human diseases....