[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.

Non-random X chromosome inactivation in an affected twin in a monozygotic twin pair discordant for Wiedemann-Beckwith syndrome

Energy Technology Data Exchange (ETDEWEB)

Oestavik, R.E.; Eiklid, K.; Oerstavik, K.H. [Ulleval Univ. Hospital, Oslo (Norway)] [and others

1995-03-27

Wiedemann-Beckwith syndrome (WBS) is a syndrome including exomphalos, macroglossia, and generalized overgrowth. The locus has been assigned to 11p15, and genomic imprinting may play a part in the expression of one or more genes involved. Most cases are sporadic. An excess of female monozygotic twins discordant for WBS have been reported, and it has been proposed that this excess could be related to the process of X chromosome inactivation. We have therefore studied X chromosome inactivation in 13-year-old monozygotic twin girls who were discordant for WBS. In addition, both twins had Tourette syndrome. The twins were monochorionic and therefore the result of a late twinning process. This has also been the case in previously reported discordant twin pairs with information on placentation. X chromosome inactivation was determined in DNA from peripheral blood cells by PCR analysis at the androgen receptor locus. The affected twin had a completely skewed X inactivation, where the paternal allele was on the active X chromosome in all cells. The unaffected twin had a moderately skewed X inactivation in the same direction, whereas the mother had a random pattern. Further studies are necessary to establish a possible association between the expression of WBS and X chromosome inactivation. 18 refs., 2 figs., 1 tab.

Heredity In Sarcoidosis - A Registry-Based Twin Study

DEFF Research Database (Denmark)

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

2008-01-01

BACKGROUND: Sarcoidosis is a multiorgan, granulomatous, inflammatory disease with unknown aetiology. Familial clustering of cases and ethnic variation in the epidemiology suggests a genetic influence on the disease susceptibility. AIM: This paper reports twin concordance and heritability estimates...... 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.......012. Compared to the general population we found an 80-fold increased risk of developing sarcoidosis in co-twins of affected monozygotic brothers or sisters. The increased risk in dizygotic twins was on the other hand only 7-fold. Aetiological model fitting gave a heritability of sarcoidosis of 0.66 (95% CI 0...

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.

A population-based study of gastroesophageal reflux disease and sleep problems in elderly twins.

Directory of Open Access Journals (Sweden)

Anna Lindam

Full Text Available BACKGROUND & AIMS: Previous studies indicate an association between sleep problems and gastroesophageal reflux disease (GERD. Although both these conditions separately have moderate heritabilities, confounding by genetic factors has not previously been taken into account. This study aimed to reveal the association between sleep problems and GERD, while adjusting for heredity and other potential confounding factors. METHODS: This cross-sectional population-based study included all 8,014 same-sexed twins of at least 65 years of age and born in Sweden between 1886 and 1958, who participated in telephone interviews in 1998-2002. Three logistic regression models were used 1 external control analysis, 2 within-pair co-twin analysis with dizygotic (DZ twin pairs discordant for GERD, and 3 within-pair co-twin analysis with monozygotic (MZ twin pairs discordant for GERD. Odds ratios (ORs with 95% confidence intervals (CIs were calculated and adjusted for established risk factors for GERD, i.e. sex, age, body mass index (BMI, tobacco smoking, and educational level. RESULTS: A dose-response association was identified between increasing levels of sleep problems and GERD in the external control analysis. Individuals who often experienced sleep problems had a two-fold increased occurrence of GERD compared to those who seldom had sleep problems (OR 2.0, 95% CI 1.8-2.4. The corresponding association was of similar strength in the co-twin analysis including 356 DZ pairs (OR 2.2, 95% CI 1.6-3.4, and in the co-twin analysis including 210 MZ pairs (OR 1.5, 95% CI 0.9-2.7. CONCLUSION: A dose-dependent association between sleep problems and GERD remains after taking heredity and other known risk factors for GERD into account.

The utility of twins in developmental cognitive neuroscience research: How twins strengthen the ABCD research design.

Science.gov (United States)

Iacono, William G; Heath, Andrew C; Hewitt, John K; Neale, Michael C; Banich, Marie T; Luciana, Monica M; Madden, Pamela A; Barch, Deanna M; Bjork, James M

2018-08-01

The ABCD twin study will elucidate the genetic and environmental contributions to a wide range of mental and physical health outcomes in children, including substance use, brain and behavioral development, and their interrelationship. Comparisons within and between monozygotic and dizygotic twin pairs, further powered by multiple assessments, provide information about genetic and environmental contributions to developmental associations, and enable stronger tests of causal hypotheses, than do comparisons involving unrelated children. Thus a sub-study of 800 pairs of same-sex twins was embedded within the overall Adolescent Brain and Cognitive Development (ABCD) design. The ABCD Twin Hub comprises four leading centers for twin research in Minnesota, Colorado, Virginia, and Missouri. Each site is enrolling 200 twin pairs, as well as singletons. The twins are recruited from registries of all twin births in each State during 2006-2008. Singletons at each site are recruited following the same school-based procedures as the rest of the ABCD study. This paper describes the background and rationale for the ABCD twin study, the ascertainment of twin pairs and implementation strategy at each site, and the details of the proposed analytic strategies to quantify genetic and environmental influences and test hypotheses critical to the aims of the ABCD study. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

'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.

Musical Interests and Talent: Twin Jazz Musicians and Twin Studies/Twin Research: Loss of a Preterm Multiple; Conjoined Twin Conception; Depression in Fathers of Twins; Twin-to-Twin Transfusion Syndrome/Twin News: High-Achieving Twins; Twin Children of a Tennis Star; Conjoined Twin Separation; Twin Delivery to a Giant Panda.

Science.gov (United States)

Segal, Nancy L

2017-12-01

Findings from twin studies of musical interests and talent are reviewed as a backdrop to the lives and careers of twin jazz musicians, Peter and Will Anderson. The Anderson twins exemplify many aspects of twin research, namely their matched musical abilities, shared musical interests, and common career. This overview is followed by reviews of studies and case reports of bereavement in families who have lost a preterm multiple birth infant, the conception of conjoined twins following in vitro fertilization (IVF), depression in fathers of twins, and twin-to-twin transfusion incidence in monochorionic-diamniotic IVF twin pairs. Twins highlighted in the media include high-achieving identical female twins with nearly identical academic standing, tennis star Roger Federer's two sets of identical twin children, surgical separation of craniopagus conjoined twins, and the rare delivery of twins to a 23-year-old giant panda.

A Possible Twin: The 1960s Twin Study Revisited/Twin Research: Twin-to-Twin Heart Transplantation; Distinguishing Monozygotic Twins; Twin Conceptions via Oocyte Donation; Factors Affecting Craniofacial Traits/In the Media: Triplet Delivery in the UK; Conjoined Twins and the Concept of Self; Colombian Twin Trainers; Skin Grafting to Save an Identical Co-Twin; Lack of Physical Flaws in Dolly the Cloned Sheep; Possible Conjoined Twins of Opposite-Sex; Passing of the Remaining Twin From the World's Longest Separated Pair.

Science.gov (United States)

Segal, Nancy L

2018-04-01

This article begins with the story of a 51-year-old Los Angeles, California man, Justin Goldberg, whose daughter caught a glimpse of his striking look-alike at a popular market. Many people have so-called doppelgängers, but this occurrence is especially intriguing - the individual in question, born in New York City in the mid-1960s to an unwed mother, was an adoptee placed by the Louise Wise Adoption Agency. This agency, under the guidance of a prominent psychiatrist, decided to place twins in separate homes. Some of these twin children were part of a controversial child development study that was hidden from them and their parents. Next, recent and current twin research on heart transplantation, distinguishing monozygotic co-twins, twin conceptions via oocyte donation and factors affecting craniofacial traits are summarized. The article concludes with highlights on twins in the media, specifically, a triplet delivery in the United Kingdom, self-concept and consciousness in conjoined twins, Colombian twin trainers, skin grafting to save an identical co-twin, lack of physical flaws in Dolly the cloned sheep, possible opposite-sex conjoined twins, and the passing of the remaining twin from the world's longest separated pair.

Cervical column morphology and craniofacial profiles in monozygotic twins.

Science.gov (United States)

Sonnesen, Liselotte; Pallisgaard, Carsten; Kjaer, Inger

2008-02-01

Previous studies have described the relationships between cervical column morphology and craniofacial morphology. The aims of the present study were to describe cervical column morphology in 38 pairs of adult monozygotic (MZ) twins, and compare craniofacial morphology in twins with fusions with craniofacial morphology in twins without fusion. Visual assessment of cervical column morphology and cephalometric measurements of craniofacial morphology were performed on profile radiographs. In the cervical column, fusion between corpora of the second and third vertebrae was registered as fusion. In the twin group, 8 twin pairs had fusion of the cervical column in both individuals within the pair (sub-group A), 25 pairs had no fusions (subgroup B), and in 5 pairs, cervical column morphology was different within the pair (subgroup C), as one twin had fusion and the other did not. Comparison of craniofacial profiles showed a tendency to increased jaw retrognathia, larger cranial base angle, and larger mandibular inclination in subgroup A than in subgroup B. The same tendency was observed within subgroup C between the individual twins with fusion compared with those without fusion. These results confirm that cervical fusions and craniofacial morphology may be interrelated in twins when analysed on profile radiographs. The study also documents that differences in cervical column morphology can occur in individuals within a pair of MZ twins. It illustrates that differences in craniofacial morphology between individuals within a pair of MZ twins can be associated with cervical fusion.

Metabolome and fecal microbiota in monozygotic twin pairs discordant for weight: a Big Mac challenge

OpenAIRE

Bondia-Pons, Isabel; Maukonen, Johanna; Mattila, Ismo; Rissanen, Aila; Saarela, Maria; Kaprio, Jaakko; Hakkarainen, Antti; Lundbom, Jesper; Lundbom, Nina; Hy?tyl?inen, Tuulia; Pietil?inen, Kirsi H.; Ore?i?, Matej

2014-01-01

Postprandial responses to food are complex, involving both genetic and environmental factors. We studied postprandial responses to a Big Mac meal challenge in monozygotic co-twins highly discordant for body weight. This unique design allows assessment of the contribution of obesity, independent of genetic liability. Comprehensive metabolic profiling using 3 analytical platforms was applied to fasting and postprandial serum samples from 16 healthy monozygotic twin pairs discordant for weight (...

Birth size and gestational age in opposite-sex twins as compared to same-sex twins

DEFF Research Database (Denmark)

Jelenkovic, Aline; Sund, Reijo; Yokoyama, Yoshie

2018-01-01

It is well established that boys are born heavier and longer than girls, but it remains unclear whether birth size in twins is affected by the sex of their co-twin. We conducted an individual-based pooled analysis of 21 twin cohorts in 15 countries derived from the COllaborative project of Develo......It is well established that boys are born heavier and longer than girls, but it remains unclear whether birth size in twins is affected by the sex of their co-twin. We conducted an individual-based pooled analysis of 21 twin cohorts in 15 countries derived from the COllaborative project....... In girls, birth size was not associated (5 g birth weight; 95% CI -8 to -18 and -0.089 cm birth length; 95% CI -0.202 to 0.025) with the sex of the co-twin. Gestational age was slightly shorter in boy-boy pairs than in boy-girl and girl-girl pairs. When birth size was standardized by gestational age......, the magnitude of the associations was attenuated in boys, particularly for birth weight. In conclusion, boys with a co-twin sister are heavier and longer at birth than those with a co-twin brother. However, these differences are modest and partly explained by a longer gestation in the presence of a co...

Factors that affect skin aging: a cohort-based survey on twins.

Science.gov (United States)

Martires, Kathryn J; Fu, Pingfu; Polster, Amy M; Cooper, Kevin D; Baron, Elma D

2009-12-01

To identify environmental factors that correlate with skin photoaging, controlling for genetic susceptibility by using a questionnaire administered to twins. The survey collected information about each participant's Fitzpatrick type, history of skin cancer, smoking and drinking habits, and weight from a cohort of twins. Clinicians then assigned a clinical photodamage score to each participant. The annual Twins Days Festival in Twinsburg, Ohio. A voluntary cohort of twins from the general community, mostly from Ohio, Pennsylvania, and the northeastern United States. The survey was completed on a voluntary basis by sets of monozygotic (MZ) and dizygotic (DZ) twins. A total of 130 surveys taken by 65 complete twin pairs were analyzed. Skin aging was assessed using a validated photographic scale of photodamage, graded by such characteristics as wrinkling and pigmentation change. Photodamage scores among twins of a pair, whether MZ or DZ, were highly correlated (P = .92). Factors found to predict higher photodamage include history of skin cancer (P < .001), zygosity status (MZ vs DZ) (P = .001), weight (P = .02), and cigarette smoking (P = .046). Alcohol consumption was significantly associated with lower photodamage scores (P = .003). The study of twins provides a unique opportunity to control for genetic susceptibility in order to elucidate environmental influences on skin aging. The relationships found between smoking, weight, sunscreen use, skin cancer, and photodamage in these twin pairs may help to motivate the reduction of risky behaviors.

Genetic and Environmental Etiologies of Reading Difficulties: DeFries-Fulker Analysis of Reading Performance Data from Twin Pairs and Their Non-Twin Siblings

Science.gov (United States)

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

2012-01-01

Reading performance data from 254 pairs of identical (MZ) and 420 pairs of fraternal (DZ) twins, 8.0 to 20.0 years of age, were subjected to multiple regression analyses. An extension of the DeFries-Fulker (DF) analysis (DeFries & Fulker, 1985, 1988) that facilitated inclusion of data from 303 of their nontwin siblings was employed. In addition to…

Oliver Sacks: Our Correspondence About Twins/Twin Research: Vanishing Twins Syndrome; Discordant Sex in MZ Twins; Pregnancy Outcomes in IVF and ICSI Conceived Twins/Print and Media: Superfetated Twins; Twins Discordant for Smoking; Twins in Fashion; Yale University Twin Hockey Players; Conjoined Twin-Visiting Professor.

Science.gov (United States)

Segal, Nancy L

2017-08-01

The late neurologist and author, Oliver Sacks, published an insightful 1986 review of Marjorie Wallace's book, The Silent Twins, in the New York Times. Taking exception to his assertion about Sir Francis Galton, I wrote a letter to the Times' editor. The letter was unpublished, but it brought a wonderful response from Sacks himself that is reproduced and examined. Next, brief reviews of twin research concerning the vanishing twin syndrome (VTS), discordant sex in a monozygotic (MZ) twin pair, and multiple pregnancy outcomes from assisted reproductive technology (ART) are presented. This section is followed by popular coverage of superfetated twins, smoking-discordant co-twins, twins in fashion, Yale University twin hockey players, and a visiting professor who was a conjoined twin.

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.

Basic Research on A-bomb exposed and nonexposed pair of twins and the pilot case study from socio-psycho-historical viewpoint

International Nuclear Information System (INIS)

Watanabe, Shoji; Satow, Yukio; Okamoto, Naomasa

1980-01-01

A-bomb exposed and nonexposed pair monozygotic twins were investigated. In all the cases, a pair of twins had great similarity in appearance and were connected firmly each other from their childhood. In family relations, each of them was required to take a role as the younger or the elder. Interview and psychological test suggested some psychological trauma in the exposed one compared with the other nonexposed. The mental state of the exposed is little understood even by the other half of twins who are in close relation. (Ueda, J.)

Attractiveness Differences Between Twins Predicts Evaluations of Self and Co-Twin

Science.gov (United States)

Principe, Connor P.; Rosen, Lisa H.; Taylor-Partridge, Teresa; Langlois, Judith H.

2012-01-01

One of the most consistent findings in psychology shows that people prefer and make positive attributions about attractive compared with unattractive people. The goal of the current study was to determine the power of attractiveness effects by testing whether these social judgments are made where attractiveness differences are smallest: between twins. Differences in facial attractiveness predicted twins’ evaluations of self and their co-twin (n = 158; 54 male). In twin pairs, the more attractive twin judged their less attractive sibling as less physically attractive, athletic, socially competent, and emotionally stable. The less attractive twin did the reverse. Given that even negligible differences in facial attractiveness predicted self and co-twin attitudes, these results provide the strongest test yet of appearance-based stereotypes. PMID:23467329

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.

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...... illustrate how the co-twin control method in a register setting can be used to control for the effect of rearing environment and genetic factors in studies of the association between exposures and health. CONCLUSION: The spectrum of register-based twin studies is very wide and have changed in accordance...

Sports pairs: insights on athletic talent; research reviews: twins with leukemia; parents and twins.

Science.gov (United States)

Segal, Nancy L

2007-06-01

Twin research exploring genetic and environmental influences on athletic interests and talents is reviewed. Illustrative examples of twin athletes representing a variety of sports activities are presented. This is followed by an overview of twin studies offering critical insights into the onset and progress of leukemia. In the last section, timely events involving twins and parents of twins will be described--each case provides a new look at an old question.

Differences in frontal and limbic brain activation in a small sample of monozygotic twin pairs discordant for severe stressful life events

Directory of Open Access Journals (Sweden)

Detre A. Godinez

2016-12-01

Full Text Available Monozygotic twin pairs provide a valuable opportunity to control for genetic and shared environmental influences while studying the effects of nonshared environmental influences. The question we address with this design is whether monozygotic twins selected for discordance in exposure to severe stressful life events during development (before age 18 demonstrate differences in brain activation during performance of an emotional word-face Stroop task. In this study, functional magnetic resonance imaging was used to assess brain activation in eighteen young adult twins who were discordant in exposure to severe stress such that one twin had two or more severe events compared to their control co-twin who had no severe events. Twins who experienced higher levels of stress during development, compared to their control co-twins with lower stress, exhibited significant clusters of greater activation in the ventrolateral and medial prefrontal cortex, basal ganglia, and limbic regions. The control co-twins showed only the more typical recruitment of frontoparietal regions thought to be important for executive control of attention and maintenance of task goals. Behavioral performance was not significantly different between twins within pairs, suggesting the twins with stress recruited additional neural resources associated with affective processing and updating working memory when performing at the same level. This study provides a powerful glimpse at the potential effects of stress during development while accounting for shared genetic and environmental influences.

Birth weight and gestational age on retinopathy of prematurity in discordant twins in China

Directory of Open Access Journals (Sweden)

Zong-Hua Wang

2014-08-01

Full Text Available AIM:To assess the relative effect of birth weight and gestational age on retinopathy of prematurity (ROP using preterm twin pairs discordant for birth weigh in a tertiary neonatal intensive care unit in China.METHODS: Fifty-six discordant twin pairs of 112 preterm infants were retrospectively analyzed. The twin pairs were divided into two subgroups based on birth weight in each pair. The occurrence of ROP and severe ROP requiring treatment were compared between the lower birth weight infants and their co-twins with the higher birth weight. Some neonatal morbidities related to prematurity and neonatal characteristics were also compared between the twin pairs.RESULTS: Based on the univariate analysis, gestational age and birth weight were significantly associated with the occurrence and progression of ROP. But no significant differences in ROP between larger and smaller infants were observed in the twin-paired analysis. The incidence of neonatal morbidities regarding respiratory distress syndrome (RDS, patent ductus arteriosus (PDA, intraventricular hemorrhage (IVH, sepsis and neonatal characteristics regarding gender distribution, one- and five-minute Apgar score, postnatal steroid treatment, blood transfusion, supplemental oxygen therapy, and mechanical ventilation were not different between the twins. However, gestational age of ≤28wk was significantly associated with significantly higher rates of ROP and severe ROP.CONCLUSION: Gestational age is a better predictor of ROP than birth weight in the twin-paired study.

Heritability of psoriasis in a large twin sample

DEFF Research Database (Denmark)

Lønnberg, Ann Sophie; Skov, Liselotte; Skytthe, A

2013-01-01

AIM: To study the concordance of psoriasis in a population-based twin sample. METHODS: Data on psoriasis in 10,725 twin pairs, 20-71 years of age, from the Danish Twin Registry was collected via a questionnaire survey. The concordance and heritability of psoriasis were estimated. RESULTS: In total...

Twins with omphalocele in Denmark (1970-1989)

DEFF Research Database (Denmark)

Bugge, Merete

2010-01-01

Seven pairs of twins, two monozygotic (MZ), two dizygotic (DZ), and three like-sex pairs of unknown zygosity are described. The twin pairs were all discordant for omphalocele except for one pair of conjoined twins. The 8 infants with omphalocele represent 3.1% of the 253 infants with omphalocele......, ascertained in an almost complete nationwide data set of live- and stillborn infants with abdominal wall defects in two decades in Denmark (1970-1989). The occurrence of twins with omphalocele was not significantly different from the occurrence of twins in the Danish population in the same period. To our...... knowledge this is the first report of the occurrence of twins with omphalocele in a systematic nationwide epidemiological study....

Kinetics of 3H-serotonin uptake by platelets in infantile autism and developmental language disorder (including five pairs of twins)

International Nuclear Information System (INIS)

Katsui, T.; Okuda, M.; Usuda, S.; Koizumi, T.

1986-01-01

The kinetics of 5-HT uptake by platelets was studied in cases of infantile autism and developmental language disorder (DLD) and normal subjects. Two patients of the autism group were twins, and the seven patients of the DLD group were members of four pairs of twins. The Vmax values (means +/- SD) for autism and DLD were 6.46 +/- .90 pmol 5-HT/10(7) cells/min and 4.85 +/- 1.50 pmol 5-HT/10(7) cells/min, respectively. These values were both significantly higher than that of 2.25 +/- .97 pmole 5-HT/10(7) cells/min for normal children. The Km values of the three groups were not significantly different. Data on the five pairs of twins examined suggested that the elevated Vmax of 5-HT uptake by platelets was determined genetically

Kinetics of 3H-serotonin uptake by platelets in infantile autism and developmental language disorder (including five pairs of twins)

Energy Technology Data Exchange (ETDEWEB)

Katsui, T.; Okuda, M.; Usuda, S.; Koizumi, T.

1986-03-01

The kinetics of 5-HT uptake by platelets was studied in cases of infantile autism and developmental language disorder (DLD) and normal subjects. Two patients of the autism group were twins, and the seven patients of the DLD group were members of four pairs of twins. The Vmax values (means +/- SD) for autism and DLD were 6.46 +/- .90 pmol 5-HT/10(7) cells/min and 4.85 +/- 1.50 pmol 5-HT/10(7) cells/min, respectively. These values were both significantly higher than that of 2.25 +/- .97 pmole 5-HT/10(7) cells/min for normal children. The Km values of the three groups were not significantly different. Data on the five pairs of twins examined suggested that the elevated Vmax of 5-HT uptake by platelets was determined genetically.

Evidence of genetic susceptibility to infectious mononucleosis: a twin study.

Science.gov (United States)

Hwang, A E; Hamilton, A S; Cockburn, M G; Ambinder, R; Zadnick, J; Brown, E E; Mack, T M; Cozen, W

2012-11-01

Infectious mononucleosis is a clinical manifestation of primary Epstein-Barr virus infection. It is unknown whether genetic factors contribute to risk. To assess heritability, we compared disease concordance in monozygotic to dizygotic twin pairs from the population-based California Twin Program and assessed the risk to initially unaffected co-twins. One member of 611 and both members of 58 twin pairs reported a history of infectious mononucleosis. Pairwise concordance in monozygotic and dizygotic pairs was respectively 12·1% [standard error (s.e.)=1·9%] and 6·1% (s.e.=1·2%). The relative risk (hazard ratio) of monozygotic compared to dizygotic unaffected co-twins of cases was 1·9 [95% confidence interval (CI) 1·1-3·4, P=0·03], over the follow-up period. When the analysis was restricted to same-sex twin pairs, that estimate was 2·5 (95% CI 1·2-5·3, P=0·02). The results are compatible with a heritable contribution to the risk of infectious mononucleosis.

Disease-Concordant Twins Empower Genetic Association Studies

DEFF Research Database (Denmark)

Tan, Qihua; Li, Weilong; Vandin, Fabio

2017-01-01

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...... 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...... 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...

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 me...

Fingerprint recognition with identical twin fingerprints.

Science.gov (United States)

Tao, Xunqiang; Chen, Xinjian; Yang, Xin; Tian, Jie

2012-01-01

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.

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.

Twin RSA

OpenAIRE

Lenstra, Arjen K.; Weger, De; Benjamin, M. M.

2005-01-01

We introduce Twin RSA, pairs of RSA moduli (n, n+ 2), and formulate several questions related to it. Our main questions are: is Twin RSA secure, and what is it good for? © Springer-Verlag Berlin Heidelberg 2005.

Genetic and environmental etiologies of reading difficulties: DeFries-Fulker analysis of reading performance data from twin pairs and their nontwin siblings

OpenAIRE

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

2012-01-01

Reading performance data from 254 pairs of identical (MZ) and 420 pairs of fraternal (DZ) twins, 8.0 to 20.0 years of age, were subjected to multiple regression analyses. An extension of the DeFries-Fulker (DF) analysis (DeFries & Fulker, 1985, 1988) that facilitated inclusion of data from 303 of their nontwin siblings was employed. In addition to providing estimates of heritability, this analysis yields a test of the difference between shared environmental influences for twins versus sibling...

Playing a Musical Instrument as a Protective Factor against Dementia and Cognitive Impairment: A Population-Based Twin Study.

Science.gov (United States)

Balbag, M Alison; Pedersen, Nancy L; Gatz, Margaret

2014-01-01

Increasing evidence supports that playing a musical instrument may benefit cognitive development and health at young ages. Whether playing an instrument provides protection against dementia has not been established. In a population-based cotwin control study, we examined the association between playing a musical instrument and whether or not the twins developed dementia or cognitive impairment. Participation in playing an instrument was taken from informant-based reports of twins' leisure activities. Dementia diagnoses were based on a complete clinical workup using standard diagnostic criteria. Among 157 twin pairs discordant for dementia and cognitive impairment, 27 pairs were discordant for playing an instrument. Controlling for sex, education, and physical activity, playing a musical instrument was significantly associated with less likelihood of dementia and cognitive impairment (odds ratio [OR] = 0.36 [95% confidence interval 0.13-0.99]). These findings support further consideration of music as a modifiable protective factor against dementia and cognitive impairment.

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.

Socio-psycho-historical observation on the twin. Sampling methods and case study of the atomic bomb exposed twins

Energy Technology Data Exchange (ETDEWEB)

Watanabe, S; Satow, Y; Ueoka, Hiroshi; Munaka, M; Kurihara, M [Hiroshima Univ. (Japan). Research Inst. for Nuclear Medicine and Biology

1980-07-01

The so-called ''twin control study'', mainly on the monozygotic twins one of which was A-bomb exposed and the other was non-exposed were carried out. Sampling was conducted utilizing the materials as follows: 1) The survey on casualities of A-bomb exposed families in Hiroshima which was undertaken in 1946. 2) The survey of A-bomb survivors in 1965. 3) A-bomb exposed family survey conducted between 1973 to 1975. 4) Investigations of A-bomb victims exposed in the proximal areas from the hypocenter. From the above mentioned materials 470 pairs were selected, of which 220 were exposed. Among them 172 pairs were twins of the same sex. Female and male pair were also employed. In one case they were exposed, while the others were nonexposed. Two pairs were examined under the following methods: 1) Depth interview to ascertain familial casualities with reference to the family life cycle. 2) Socio-historical research. 3) Motoaki's Jinkaku Shindan Kensa (Modified Rorschach test by H. Motoaki), and T.A.T. test. Results obtained were summarized as follows: 1) Both pairs of twins were of similar appearance and personality traits, and had a strong feeling of companionship for each other. 2) In family relationships, the persons studied were very conscious of the role expectations of elder and younger siblings in the twin pairs. 3) Through depth interviews and projective tests, A-bomb exposed pairs still showed deep psychological stresses, resulting from the A-bomb disaster. 4) Both among the exposed twins and within the nonexposed control group twin siblings had a close feeling of companionship for each other. However, nonexposed twins could not understand the psychological experience of twins who had been subjected to the atomic disaster.

Aggregation of thyroid autoantibodies in twins from opposite-sex pairs suggests that microchimerism may play a role in the early stages of thyroid autoimmunity

DEFF Research Database (Denmark)

Brix, Thomas Heiberg; Hansen, Pia Skov; Kyvik, Kirsten Ohm

2009-01-01

to play a role in the pathogenesis of thyroid autoimmunity. In that case, twins from opposite-sex pairs (OS) should have an increased risk of thyroid autoantibodies (TA). AIM: The aim of the study was to compare the frequency of TA in twin individuals from OS and monozygotic (MZ) twin pairs. Design...... positive if greater than 60 U/ml, greater than 60 U/ml, and greater than 1.0 U/liter, respectively. RESULTS: The frequency of TPOAb, TgAb, and TSHRAb among female cases was 15.0, 5.0, and 4.2%, respectively, which was higher than the corresponding prevalences in the female control population: 7.4% (P = 0...

Gray and white matter density changes in monozygotic and same-sex dizygotic twins discordant for schizophrenia using voxel-based morphometry

DEFF Research Database (Denmark)

Hulshoff Pol, HE; Schnack, HG; Mandl, RC

2006-01-01

Global gray matter brain tissue volume decreases in schizophrenia have been associated to disease-related (possibly nongenetic) factors. Global white matter brain tissue volume decreases were related to genetic risk factors for the disease. However, which focal gray and white matter brain regions...... best reflect the genetic and environmental risk factors in the brains of patients with schizophrenia remains unresolved. 1.5-T MRI brain scans of 11 monozygotic and 11 same-sex dizygotic twin-pairs discordant for schizophrenia were compared to 11 monozygotic and 11 same-sex dizygotic healthy control...... twin-pairs using voxel-based morphometry. Linear regression analysis was done in each voxel for the average and difference in gray and white matter density separately, in each twin-pair, with group (discordant, healthy) and zygosity (monozygotic, dizygotic) as between subject variables, and age, sex...

The morphology of the sella turcica in monozygotic twins

DEFF Research Database (Denmark)

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

2009-01-01

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...... 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...

Socio-psycho-historical observation on the twin

International Nuclear Information System (INIS)

Watanabe, Shoji; Satow, Yukio; Ueoka, Hiroshi; Munaka, Masaki; Kurihara, Minoru

1980-01-01

The so-called ''twin control study'', mainly on the monozygotic twins one of which was A-bomb exposed and the other was non-exposed were carried out. Sampling was conducted utilizing the materials as follows: 1) The survey on casualities of A-bomb exposed families in Hiroshima which was undertaken in 1946. 2) The survey of A-bomb survivors in 1965. 3) A-bomb exposed family survey conducted between 1973 to 1975. 4) Investigations of A-bomb victims exposed in the proximal areas from the hypocenter. From the above mentioned materials 470 pairs were selected, of which 220 were exposed. Among them 172 pairs were twins of the same sex. Female and male pair were also employed. In one case they were exposed, while the others were nonexposed. Two pairs were examined under the following methods: 1) Depth interview to ascertain familial casualities with reference to the family life cycle. 2) Socio-historical research. 3) Motoaki's Jinkaku Shindan Kensa (Modified Rorschach test by H. Motoaki), and T.A.T. test. Results obtained were summarized as follows: 1) Both pairs of twins were similar appearance, and also personality traits, and had a strong feeling of companionship for each other. 2) In family relationships, the persons studied were very conscious of the role expectations of elder and younger siblings in the twin pairs. 3) Through depth interview and projective test, A-bomb exposed pairs still showed deep psychological stresses, resulting from the A-bomb disaster. 4) Both among the exposed twins and within the nonexposed control group twin siblings had a close feeling of companionship for each other. However, nonexposed twins could not understand the psychological experience of twins who had been subjected to the atomic disaster. (author)

Migraine and risk of stroke: a national population-based twin study.

Science.gov (United States)

Lantz, Maria; Sieurin, Johanna; Sjölander, Arvid; Waldenlind, Elisabet; Sjöstrand, Christina; Wirdefeldt, Karin

2017-10-01

Numerous studies have indicated an increased risk for stroke in patients with migraine, especially migraine with aura; however, many studies used self-reported migraine and only a few controlled for familial factors. We aimed to investigate migraine as a risk factor for stroke in a Swedish population-based twin cohort, and whether familial factors contribute to an increased risk. The study population included twins without prior cerebrovascular disease who answered a headache questionnaire during 1998 and 2002 for twins born 1935-58 and during 2005-06 for twins born between 1959 and 1985. Migraine with and without aura and probable migraine was defined by an algorithm mapping on to clinical diagnostic criteria according to the International Classification of Headache Disorders. Stroke diagnoses were obtained from the national patient and cause of death registers. Twins were followed longitudinally, by linkage of national registers, from date of interview until date of first stroke, death, or end of study on 31 Dec 2014. In total, 8635 twins had any migraineous headache, whereof 3553 had migraine with aura and 5082 had non-aura migraineous headache (including migraine without aura and probable migraine), and 44 769 twins had no migraine. During a mean follow-up time of 11.9 years we observed 1297 incident cases of stroke. The Cox proportional hazards model with attained age as underlying time scale was used to estimate hazard ratios with 95% confidence intervals for stroke including ischaemic and haemorrhagic subtypes related to migraine with aura, non-aura migraineous headache, and any migraineous headache. Analyses were adjusted for gender and cardiovascular risk factors. Where appropriate; within-pair analyses were performed to control for confounding by familial factors. The age- and gender-adjusted hazard ratio for stroke related to migraine with aura was 1.27 (95% confidence interval 1.00-1.62), P = 0.05, and 1.07 (95% confidence interval 0.91-1.26), P = 0

Sex differences in the pathways to major depression: a study of opposite-sex twin pairs.

Science.gov (United States)

Kendler, Kenneth S; Gardner, Charles O

2014-04-01

The authors sought to clarify the nature of sex differences in the etiologic pathways to major depression. Retrospective and prospective assessments of 20 developmentally organized risk factors and the occurrence of past-year major depression were conducted at two waves of personal interviews at least 12 months apart in 1,057 opposite-sex dizygotic twin pairs from a population-based register. Analyses were conducted by structural modeling, examining within-pair differences. Sixty percent of all paths in the best-fit model exhibited sex differences. Eleven of the 20 risk factors differed across sexes in their impact on liability to major depression. Five had a greater impact in women: parental warmth, neuroticism, divorce, social support, and marital satisfaction. Six had a greater impact in men: childhood sexual abuse, conduct disorder, drug abuse, prior history of major depression, and distal and dependent proximal stressful life events. The life event categories responsible for the stronger effect in males were financial, occupational, and legal in nature. In a co-twin control design, which matches sisters and brothers on genetic and familial-environmental background, personality and failures in interpersonal relationships played a stronger etiologic role in major depression for women than for men. Externalizing psychopathology, prior depression, and specific "instrumental" classes of acute stressors were more important in the etiologic pathway to major depression for men. The results are consistent with previously proposed typologies of major depression that suggest two subtypes that differ in prevalence in women (deficiencies in caring relationships and interpersonal loss) and men (failures to achieve expected goals, with lowered self-worth).

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

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...

Ventricular strain changes in monochorionic twins with and without twin-to-twin transfusion syndrome.

Science.gov (United States)

Taylor-Clarke, Marisa C; Matsui, Hikoro; Roughton, Michael; Wimalasundera, Ruwan C; Gardiner, Helena M

2013-06-01

The objective of the study was to investigate whether vector velocity imaging (VVI), a non-Doppler speckle tracking ultrasound technology, is feasible in twin pregnancies and can aid management of twin-twin transfusion syndrome (TTTS). Twenty-seven women pregnant with monochorionic diamniotic twins affected by TTTS and 28 monochorionic pregnancies that did not develop TTTS were included in a prospective case-control study at a fetal medicine center. Fetal echocardiograms were recorded with dummy electrocardiography to retain original frame rates when exported for offline speckle tracking analysis using Syngo-VVI software (Siemens Corp, Munich, Germany). Right and left ventricular (LV) free wall Lagrangian strain was measured from the original coordinates. Within-twin pair ventricular strain differences including relationship to Quintero staging and response to laser therapy for TTTS were analyzed by Wilcoxon signed-rank test. The VVI strain measurements could be analyzed in 182 of 200 TTTS and 96 of 112 non-TTTS control ventricles. Within-pair strain was concordant in non-TTTS controls. Recipient LV strain was reduced at all Quintero stages compared with donors (P < .01). Recipient right ventricular strain was reduced only in stages 3 and 4 (P < .01). Strain improved at a median of 2 weeks following successful laser therapy. Intertwin differences in strain were independent of weight discordance. Recipient LV strain is reduced in stages 1 and 2 TTTS. Within-pair strain discordance may distinguish early TTTS from growth discordance and guide timing of and management following treatment. Copyright © 2013 Mosby, Inc. All rights reserved.

Hyperthyroidism is associated with work disability and loss of labour market income. A Danish register-based study in singletons and disease-discordant twin pairs.

Science.gov (United States)

Brandt, Frans; Thvilum, Marianne; Hegedüs, Laszlo; Brix, Thomas Heiberg

2015-11-01

To examine the risk of disability pension and changes in labour market income in patients with hyperthyroidism. From a 5% random sample of the Danish population and twins from the Danish Twin Registry we identified 1942 hyperthyroid singletons and 7768 non-hyperthyroid (matched 1:4) controls as well as 584 same-sex twin pairs discordant for hyperthyroidism. Singletons and twins were followed for a mean of 9 years (range 1-20). Cox regression analysis was used to examine the risk of disability pension and a difference-in-differences model was used to evaluate changes in labour market income. Hyperthyroid individuals had an increased risk of receiving disability pension: hazard ratio (HR) was 1.88, (95% CI: 1.57-2.24). Subdividing as to the cause of hyperthyroidism did not change this finding: Graves' disease (GD) HR was 1.51 (95% CI: 0.87-2.63) and toxic nodular goitre (TNG) HR was 2.10 (95% CI: 1.02-4.36). With respect to labour market income, the income of hyperthyroid individuals increased on average 1189 € less than their controls (Phyperthyroidism. Hyperthyroidism is associated with severe work disability as reflected by an 88% increased risk of receiving disability pension and a significant loss of labour market income. Similar results in monozygotic twins discordant for hyperthyroidism suggest that genetic confounding is unlikely. © 2015 European Society of Endocrinology.

Motives for and barriers to physical activity in twin pairs discordant for leisure time physical activity for 30 years.

Science.gov (United States)

Aaltonen, S; Leskinen, T; Morris, T; Alen, M; Kaprio, J; Liukkonen, J; Kujala, U

2012-02-01

Long-term persistent physical activity is important in the prevention of chronic diseases, but a large number of people do not participate in physical activity to obtain health benefits. The purpose of this study was to examine the motives and perceived barriers to long-term engagement in leisure time physical activity. Same-sex twin pairs (N=16, mean age 60) discordant for physical activity over 30 years were identified from the Finnish Twin Cohort. We evaluated participants' physical activity motivation with the 73-item Recreational Exercise Motivation Measure and assessed barriers to physical activity with a 25-item questionnaire. The characteristics of physical activity motivation and perceived barriers between the active and inactive co-twins were analysed using paired tests. Motives related to the sub-dimensions of enjoyment and physical fitness and psychological state were the most important reasons for participation in physical activity among all the twin individuals analysed. The sub-dimensions mastery (p=0.018, Cohen's d=0.76), physical fitness (p=0.029, Cohen's d=0.69), and psychological state (p=0.039, Cohen's d=0.65) differed significantly between active and inactive co-twins. More than half of the participants reported no reasons for not being physically active. If reasons existed, participation in physical activity was deterred mostly by pain and various health problems. This study found no differences in perceived barriers between active and inactive co-twins. We conclude from our results that the main factors promoting persistent leisure time physical activity were participants' wish to improve or maintain their physical skills or techniques, a feeling that exercise would improve their mental and physical health and that they found the activity enjoyable. This study helps us understand the importance of the role of motives and the minor role of perceived barriers for engagement in persistent physical activity. © Georg Thieme Verlag KG Stuttgart �

The relationship between subjective well-being and mortality within discordant twin pairs from two independent samples

DEFF Research Database (Denmark)

Saunders, Gretchen R B; Elkins, Irene J; Christensen, Kaare

2018-01-01

Prior research has shown robust associations between greater subjective well-being (SWB) and reduced mortality. Whether this observed association is causal in nature or due instead to confounding genetic or environmental factors affecting both SWB and mortality is not well understood. We used a c...... when accounting for demographic factors, physical health, and cognitive functioning. (PsycINFO Database Record...... a combined sample of 6,802 twins drawn from two cohorts: the Longitudinal Study of Middle-Aged Danish Twins (MADT; N = 2,815, baseline age between 45 and 69 years, M = 56.8, SD = 6.4) and the Longitudinal Study of Aging Danish Twins (LSADT; N = 3,987, baseline age between 70 and 97 years, M = 76.6, SD = 4...... of SWB on reduced mortality remained significant within both MZ and DZ pairs, suggesting that the association is independent of genetic and nonshared environmental confounding factors. These findings, which generalized across both younger (MADT) and older (LSADT) cohorts of adults, remained significant...

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…

Cohort Profile : The National Academy of Sciences-National Research Council Twin Registry (NAS-NRC Twin Registry)

NARCIS (Netherlands)

Gatz, Margaret; Harris, Jennifer R.; Kaprio, Jaakko; McGue, Matt; Smith, Nicholas L.; Snieder, Harold; Spiro, Avron; Butler, David A.

The National Academy of Sciences-National Research Council Twin Registry (NAS-NRC Twin Registry) is a comprehensive registry of White male twin pairs born in the USA between 1917 and 1927, both of the twins having served in the military. The purpose was medical research and ultimately improved

Long-term leisure time physical activity and properties of bone: a twin study.

Science.gov (United States)

Ma, Hongqiang; Leskinen, Tuija; Alen, Markku; Cheng, Sulin; Sipilä, Sarianna; Heinonen, Ari; Kaprio, Jaakko; Suominen, Harri; Kujala, Urho M

2009-08-01

Effects of physical activity on bone properties, when controlled for genetic effects, are not fully understood. We aimed to study the association between long-term leisure time physical activity (LTPA) and bone properties using twin pairs known to be discordant for leisure time physical activity for at least 30 yr. Volumetric BMD and geometric properties were measured at the tibia shaft and distal end using pQCT in 16 middle-aged (50-74 yr) same-sex twin pairs (seven monozygotic [MZ] and nine dizygotic [DZ] pairs) selected from a population-based cohort. Paired differences between active and inactive co-twins were studied. Active members of MZ twin pairs had larger cortical bone cross-sectional area (intrapair difference: 8%, p = 0.006), thicker cortex (12%, p = 0.003), and greater moment of inertia (I(max), 20%, p = 0.024) at the tibia shaft than their inactive co-twins. At the distal tibia, trabecular BMD (12%, p = 0.050) and compressive strength index (18%, p = 0.038) were also higher in physically active MZ pair members than their inactive co-twins. The trends were similar, but less consistently so, in DZ pairs as in MZ pairs. Our genetically controlled study design shows that LTPA during adulthood strengthens bones in a site-specific manner, that is, the long bone shaft has a thicker cortex, and thus higher bending strength, whereas the distal bone has higher trabecular density and compressive strength. These results suggest that LTPA has a potential causal role in decreasing the long-term risk of osteoporosis and thus preventing osteoporotic fractures.

Twin birth order, birthweight and birthweight discordance: any relationship

Directory of Open Access Journals (Sweden)

Onyiriuka A.N.

2010-12-01

Full Text Available Background: It is widely believed that in twin pairs, at birth, the first-born weigh more than the second-born but this concept has been challenged. Objective: To assess the truthfulness of this common concept that first-born twins are usually heavier than their second-born siblings at birth. Methods: In a series of 104 sets of live-born twins, the birth weights of first-born twins were compared with those of their second-born siblings, after controlling for gender. Their intra-pair birthweight differences were determined and twin pairs whose birthweight difference was 15% or more were designated as discordant. Results: Twin I was heavier than Twin II in 61.5% of cases while Twin II was heavier than Twin I in 28.9% of cases. Twins I and II had equal birthweights in 9.6% of cases. Comparing the mean birthweight of the first-born-male twin with that of second-born- male twin, it was 2515+427g (95% Confidence Interval, CI=2402-2628 versus 2432 +435g (95% CI=2321-2543 p>0.05. The mean birthweight of first-born-female twin was 2326+445g (95% CI=2214-2439 while that of the second-born-female twin was 2325+501g (95% CI=2197-2453 p>0.05. When the birthweight difference exceeded 750g, the probability that Twin I will be heavier than Twin II was 83.3% (5 of 6. Conclusion: Although the first-born twin was more often heavier than their second-born siblings, either could weigh more or less at birth. The larger the birthweight difference between growth-discordant twin pair, the greater the probability that the heavier twin would be delivered first

A population-based twin study of self-esteem and gender.

Science.gov (United States)

Kendler, K S; Gardner, C O; Prescott, C A

1998-11-01

Self-esteem (SE), a widely used construct in the social sciences, is usually conceptualized as a reflection of socialization and interpersonal experiences that may differ considerably between the genders. The Rosenberg self-esteem scale was assessed at personal interview in both members of 3793 unselected twin pairs (1517 male-male, 856 female-female and 1420 male-female) from the population-based Virginia Twin Registry. Gender effects on SE were assessed by both analysis of variance and biometrical twin modelling. The mean SE score was slightly but significantly lower in women v. men, and in women who grew up with a male v. a female co-twin. Twin modelling suggested that: (i) individual differences in self-esteem in both men and women were best explained by genetic and individual-specific environment factors; (ii) heritability estimates were similar in women (32%) and in men (29%); and (iii) the same genetic factors that influenced SE in women also influenced SE in men. Analyses supported the validity of the equal environment assumption for SE. The heritability of SE cannot be explained by the moderate correlation between SE and symptoms of depression. These results are inconsistent with prominent gender-related aetiological models for SE, which postulate that individual differences arise from socialization experiences both within and outside the home of origin which differ widely for the two genders. Instead, a significant proportion of the population variance in SE is due to genetically-influenced temperamental variables that are the same in men and women.

Monozygotic twins discordant for attention-deficit/hyperactivity disorder: ascertainment and clinical characteristics.

Science.gov (United States)

Sharp, Wendy S; Gottesman, Rebecca F; Greenstein, Deanna K; Ebens, Christen L; Rapoport, Judith L; Castellanos, F Xavier

2003-01-01

Nongenetic factors and phenomenology of attention-deficit/hyperactivity disorder (ADHD) were examined in monozygotic (MZ) twin pairs discordant for ADHD. Recruitment included telephone screening (n = 297 pairs), behavioral ratings obtained from parents and teachers (n = 59 pairs), and, finally, in-person assessment (n = 25 pairs; structured classroom observation, diagnostic interview, psychoeducational evaluation, birth record review, establishment of monozygosity, and anatomic brain imaging). Affected twins were further contrasted with previously studied affected singletons. Of the 25 MZ twin pairs qualifying for in-person evaluation, only 10 proved discordant for ADHD. Affected twins were mostly comparable with affected singletons on clinical measures, although fathers' self-ratings of childhood ADHD status were significantly lower in twins than in singletons. Discordance for ADHD in MZ twins appears to be ascribable to greater environmental discordance and decreased familiality. Despite these differences, affected twins were phenotypically comparable with affected singletons. Thus MZ twins discordant for ADHD, while rare, can inform research on the etiology and pathophysiology of this disorder.

Does the sex of one's co-twin affect height and BMI in adulthood? A study of dizygotic adult twins from 31 cohorts.

Science.gov (United States)

Bogl, Leonie H; Jelenkovic, Aline; Vuoksimaa, Eero; Ahrenfeldt, Linda; Pietiläinen, Kirsi H; Stazi, Maria A; Fagnani, Corrado; D'Ippolito, Cristina; Hur, Yoon-Mi; Jeong, Hoe-Uk; Silberg, Judy L; Eaves, Lindon J; Maes, Hermine H; Bayasgalan, Gombojav; Narandalai, Danshiitsoodol; Cutler, Tessa L; Kandler, Christian; Jang, Kerry L; Christensen, Kaare; Skytthe, Axel; Kyvik, Kirsten O; Cozen, Wendy; Hwang, Amie E; Mack, Thomas M; Derom, Catherine A; Vlietinck, Robert F; Nelson, Tracy L; Whitfield, Keith E; Corley, Robin P; Huibregtse, Brooke M; McAdams, Tom A; Eley, Thalia C; Gregory, Alice M; Krueger, Robert F; McGue, Matt; Pahlen, Shandell; Willemsen, Gonneke; Bartels, Meike; van Beijsterveldt, Toos C E M; Pang, Zengchang; Tan, Qihua; Zhang, Dongfeng; Martin, Nicholas G; Medland, Sarah E; Montgomery, Grant W; Hjelmborg, Jacob V B; Rebato, Esther; Swan, Gary E; Krasnow, Ruth; Busjahn, Andreas; Lichtenstein, Paul; Öncel, Sevgi Y; Aliev, Fazil; Baker, Laura A; Tuvblad, Catherine; Siribaddana, Sisira H; Hotopf, Matthew; Sumathipala, Athula; Rijsdijk, Fruhling; Magnusson, Patrik K E; Pedersen, Nancy L; Aslan, Anna K Dahl; Ordoñana, Juan R; Sánchez-Romera, Juan F; Colodro-Conde, Lucia; Duncan, Glen E; Buchwald, Dedra; Tarnoki, Adam D; Tarnoki, David L; Yokoyama, Yoshie; Hopper, John L; Loos, Ruth J F; Boomsma, Dorret I; Sørensen, Thorkild I A; Silventoinen, Karri; Kaprio, Jaakko

2017-01-01

The comparison of traits in twins from opposite-sex (OS) and same-sex (SS) dizygotic twin pairs is considered a proxy measure of prenatal hormone exposure. To examine possible prenatal hormonal influences on anthropometric traits, we compared mean height, body mass index (BMI), and the prevalence of being overweight or obese between men and women from OS and SS dizygotic twin pairs. The data were derived from the COllaborative project of Development of Anthropometrical measures in Twins (CODATwins) database, and included 68,494 SS and 53,808 OS dizygotic twin individuals above the age of 20 years from 31 twin cohorts representing 19 countries. Zygosity was determined by questionnaires or DNA genotyping depending on the study. Multiple regression and logistic regression models adjusted for cohort, age, and birth year with the twin type as a predictor were carried out to compare height and BMI in twins from OS pairs with those from SS pairs and to calculate the adjusted odds ratios and 95% confidence intervals for being overweight or obese. OS females were, on average, 0.31 cm (95% confidence interval (CI) 0.20, 0.41) taller than SS females. OS males were also, on average, taller than SS males, but this difference was only 0.14 cm (95% CI 0.02, 0.27). Mean BMI and the prevalence of overweight or obesity did not differ between males and females from SS and OS twin pairs. The statistically significant differences between OS and SS twins for height were small and appeared to reflect our large sample size rather than meaningful differences of public health relevance. We found no evidence to support the hypothesis that prenatal hormonal exposure or postnatal socialization (i.e., having grown up with a twin of the opposite sex) has a major impact on height and BMI in adulthood.

Heisenberg-limited interferometry with pair coherent states and parity measurements

International Nuclear Information System (INIS)

Gerry, Christopher C.; Mimih, Jihane

2010-01-01

After reviewing parity-measurement-based interferometry with twin Fock states, which allows for supersensitivity (Heisenberg limited) and super-resolution, we consider interferometry with two different superpositions of twin Fock states, namely, two-mode squeezed vacuum states and pair coherent states. This study is motivated by the experimental challenge of producing twin Fock states on opposite sides of a beam splitter. We find that input two-mode squeezed states, while allowing for Heisenberg-limited sensitivity, do not yield super-resolutions, whereas both are possible with input pair coherent states.

Differentially Methylated DNA Regions in Monozygotic Twin Pairs Discordant for Rheumatoid Arthritis

DEFF Research Database (Denmark)

Svendsen, Anders J; Gervin, Kristina; Lyle, Robert

2016-01-01

: Smoking was significantly associated with hypomethylation of a DMR overlapping the promoter region of the RNF5 and the AGPAT1, which are implicated in inflammation and autoimmunity, whereas DMARD treatment induced hypermethylation of the same region. Additionally, the promotor region of both S100A6......OBJECTIVES: In an explorative epigenome-wide association study (EWAS) to search for gene independent, differentially methylated DNA positions and regions (DMRs) associated with rheumatoid arthritis (RA) by studying monozygotic (MZ) twin pairs discordant for RA. METHODS: Genomic DNA was isolated......: We identified several differentially methylated regions associated with RA, which may represent environmental effects or consequences of the disease and plausible biological pathways pertinent to the pathogenesis of RA....

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 t...

Playing a Musical Instrument as a Protective Factor against Dementia and Cognitive Impairment: A Population-Based Twin Study

Directory of Open Access Journals (Sweden)

M. Alison Balbag

2014-01-01

Full Text Available Increasing evidence supports that playing a musical instrument may benefit cognitive development and health at young ages. Whether playing an instrument provides protection against dementia has not been established. In a population-based cotwin control study, we examined the association between playing a musical instrument and whether or not the twins developed dementia or cognitive impairment. Participation in playing an instrument was taken from informant-based reports of twins’ leisure activities. Dementia diagnoses were based on a complete clinical workup using standard diagnostic criteria. Among 157 twin pairs discordant for dementia and cognitive impairment, 27 pairs were discordant for playing an instrument. Controlling for sex, education, and physical activity, playing a musical instrument was significantly associated with less likelihood of dementia and cognitive impairment (odds ratio [OR] = 0.36 [95% confidence interval 0.13–0.99]. These findings support further consideration of music as a modifiable protective factor against dementia and cognitive impairment.

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...

Twin-tubes: 3D tracking based on the ATLAS muon drift tubes

International Nuclear Information System (INIS)

Woudstra, M.; Bobbink, G.J.; Eldik, N. van; Graaf, H. van der; Kluit, P.; Koutsman, A.; Limper, M.; Linde, F.; Massaro, G.; Snuverink, J.; Vreeswijk, M.; Groenstege, H.; Koopstra, J.; Mos, S.; Rewiersma, P.; Timmermans, C.; Dijkema, J.

2006-01-01

The Monitored Drift Tubes (MDTs) of the ATLAS Muon Spectrometer have been paired to form so-called twin-tubes to measure the coordinate which runs along the wire direction. This modification endows the MDTs with full 3D track reconstruction using specially designed electronic boards. The performance of the twin-tubes has been measured for an equipped MDT chamber at the ATLAS Muon Cosmic Ray Test Stand at NIKHEF. The efficiency of a twin-tube has been determined to be 99.8%, and the measured resolution 17 cm per hit. By equipping one multilayer consisting of three layers and combining the measurements a resolution of 10 cm has been obtained

A study of the occurrence of monochorionic and monozygotic twinning in the pig

DEFF Research Database (Denmark)

Bjerre, Ditte; Thorup, F.; Jørgensen, Claus Bøttcher

2009-01-01

the investigation of porcine monochorionic embryos from 76 sows at days 26-29 post-insemination (p.i.), as well as an examination of 10 whole litters at days 21-22 p.i. In the former group, 29% of the sows carried monochorionic embryos. Based on DNA profiling using microsatellite markers, one monozygotic twin pair...... was found among these embryos. In the latter group, three monozygotic twin pairs were identified. Thus, it can be concluded that although the occurrence of monozygotic twins in pigs is a sporadic event, the fusion of extra-embryonic membranes is relatively common....

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

DEFF Research Database (Denmark)

Thomsen, SF; Ulrik, Charlotte Suppli; Kyvik, KO

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....... 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...... and females = 0.54, 95% CI: 0.36-0.80, P = 0.002), and increasing levels of body mass index (BMI; OR per unit = 1.11, 95% CI: 1.02-1.20, P = 0.009) were significant predictors of asthma. CONCLUSIONS: Hay fever, eczema, female sex, exercise and increasing levels of BMI were risk factors for asthma in young...

Concordance Rates of Adolescent Idiopathic Scoliosis in a Danish Twin Population

DEFF Research Database (Denmark)

Simony, Ane; Carreon, Leah Y; Højmark, Karen

2016-01-01

STUDY DESIGN: Clinical, radiological and genetic determination of zygosity of twin pairs from the Danish Twin Registry who self-reported having Adolescent Idiopathic Scoliosis (AIS). OBJECTIVE: To establish concordance rates of AIS. SUMMARY OF BACKGROUND DATA: The aetiology of and the true mode...... reported. METHODS: All 46,418 twins registered in the Danish Twin Registry born from 1931 to 1982 were sent a survey, which included questions about scoliosis. The survey was returned by 34,944 individuals (75.3%) representing 23,204 pairs. From this study, 548 individuals representing 274 complete twin...... pairs where at least one twin self-reported having scoliosis were invited to a clinical and radiological examination. Zygosity was established by genetic testing. RESULTS: 182 individuals (33.2%) of the original cohort agreed to participate, 128 of whom had scoliosis by self-report. There were 91 twin...

Estimating twin concordance for bivariate competing risks twin data

DEFF Research Database (Denmark)

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

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 experience...... events with the competing risk death. We thus aim to quantify the degree of dependence through the casewise concordance function and show a significant genetic component...... 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...... 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...

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,

Estimating Twin Pair Concordance for Age of Onset

DEFF Research Database (Denmark)

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

2015-01-01

that they will develop the disease. The aim of this contribution is to show that the standard casewise concordance and standard prevalence estimators do not work in general for age-of-onset data. We show how one can in fact do something easy and simple even with censored data. The key is to take age into account when......Twin and family data provide a key source for evaluating inheritance of specific diseases. A standard analysis of such data typically involves the computation of prevalences and different concordance measures such as the casewise concordance, that is the probability that one twin has the disease...

Heritability of myopia and ocular biometrics in Koreans: the healthy twin study.

Science.gov (United States)

Kim, Myung Hun; Zhao, Di; Kim, Woori; Lim, Dong-Hui; Song, Yun-Mi; Guallar, Eliseo; Cho, Juhee; Sung, Joohon; Chung, Eui-Sang; Chung, Tae-Young

2013-05-01

To estimate the heritabilities of myopia and ocular biometrics among different family types among a Korean population. We studied 1508 adults in the Healthy Twin Study. Spherical equivalent, axial length, anterior chamber depth, and corneal astigmatism were measured by refraction, corneal topography, and A-scan ultrasonography. To see the degree of resemblance among different types of family relationships, intraclass correlation coefficients (ICC) were calculated. Variance-component methods were applied to estimate the genetic contributions to eye phenotypes as heritability based on the maximum likelihood estimation. Narrow sense heritability was calculated as the proportion of the total phenotypic variance explained by additive genetic effects, and linear and nonlinear effects of age, sex, and interactions between age and sex were adjusted. A total of 240 monozygotic twin pairs, 45 dizygotic twin pairs, and 938 singleton adult family members who were first-degree relatives of twins in 345 families were included in the study. ICCs for spherical equivalent from monozygotic twins, pooled first-degree pairs, and spouse pairs were 0.83, 0.34, and 0.20, respectively. The ICCs of other ocular biometrics were also significantly higher in monozygotic twins compared with other relative pairs, with greater consistency and conformity. The estimated narrow sense heritability (95% confidence interval) was 0.78 (0.71-0.84) for spherical equivalent; 0.86 (0.82-0.90) for axial length; 0.83 (0.76-0.91) for anterior chamber depth; and 0.70 (0.63-0.77) for corneal astigmatism. The estimated heritability of spherical equivalent and ocular biometrics in the Korean population suggests the compelling evidence that all traits are highly heritable.

Ecosensitivity and genetic polymorphism of somatic traits in the perinatal development of twins.

Science.gov (United States)

Waszak, Małgorzata; Cieślik, Krystyna; Skrzypczak-Zielińska, Marzena; Szalata, Marlena; Wielgus, Karolina; Kempiak, Joanna; Bręborowicz, Grzegorz; Słomski, Ryszard

2016-04-01

In view of criticism regarding the usefulness of heritability coefficients, the aim of this study was to analyze separately the information on genetic and environmental variability. Such an approach, based on the normalization of trait's variability for its value, is determined by the coefficients of genetic polymorphism (Pg) and ecosensitivity (De). The studied material included 1263 twin pairs of both sexes (among them 424 pairs of monozygotic twins and 839 pairs of dizygotic twins) born between the 22nd and 41st week of gestation. Variability of six somatic traits was analyzed. The zygosity of same-sex twins was determined based on the polymorphism of DNA from lymphocytes of the umbilical cord blood, obtained at birth. The coefficients of genetic polymorphism and ecosensitivity for analyzed traits of male and female twins born at various months of gestation were calculated. Our study revealed that a contribution of the genetic component predominated over that of the environmental component in determining the phenotypic variability of somatic traits of newborns from twin pregnancies. The genetically determined phenotypic variability in male twins was greater than in the females. The genetic polymorphism and ecosensitivity of somatic traits were relatively stable during the period of fetal ontogeny analyzed in this study. Only in the case of body weight, a slight increase in the genetic contribution of polygenes to the phenotypic variance could be observed with gestational age, along with a slight decrease in the influence of environmental factors. Copyright © 2015 Elsevier GmbH. All rights reserved.

Pathological findings in dicephalus dipus dibrachius: implications for mechanisms in two pairs of lateral conjoined twins.

Science.gov (United States)

Itoh, K; Imai, Y; Obayashi, C; Hayashi, Y; Hanioka, K; Itoh, H

1993-06-01

The anatomical and pathological features of two pairs of dicephalic conjoined twins (case 1 and 2) are described. Both twins showed duplicitas lateralis representing diprosopus dipus dibrachius. There were two complete heads on two necks, one thorax, one abdomen and externally normal two arms and two legs. Case 1 showed dicephalus with anencephaly, two vertebral columns and two spinal cords, which converged from the thoracic region distally. The esophagus, stomachs and partial small intestines were duplicated, which fused at yolk sac (with Meckel's diverticulum). The heart was incompletely fused. The lungs and trachea were doubled. Two spinal cords were fused from the thoracic region caudally and showed myelomeningocele and Arnold-Chiari malformation in case 2. Two larynxes and two thracheas connected with the incompletely fused three lobes of lungs. The conjoined lungs were hypoplastic. The heart was single, showing ventral septal defect, transposition of great arteries, two cuspid aortic valves and preductal aortic coarctation. The duplicated esophagi were conjoined in Y-shape and single stomach, duodenum, intestine and colon were found. There were pairs of kidneys, adrenal glands and ureters and single female genitalia in both cases. These findings indicate that the craniocaudal paleoaxes were separated in the cranial region and converted or fused under the thoracic region like a Y-shape. Further development defects and deformations might be important factors to form malformations in these case.

A comparison of anthropometric, metabolic and reproductive characteristics of young adult women from opposite-sex and same sex twin pairs

Directory of Open Access Journals (Sweden)

Pirkko eKorsoff

2014-03-01

Full Text Available Background: Prenatal exposure to androgens has been linked to masculinization of several traits. We aimed to determine whether putative female intra-uterine exposure to androgens influences PCOS-related phenotypes, including anthropometric, metabolic and reproductive parameters using a twin design.Methods: Two cohorts of Finnish twins born in 1975-1979 and 1983-1987 formed the basis for the longitudinal FinnTwin16 (FT16 and FinnTwin12 (FT12 studies. Self-reported anthropometric characteristics, disease status and reproductive history were compared between 679 same-sex (SS and 789 opposite-sex (OS female twins (mean age ± SD: 34 ± 1.1 from the wave 5 of data collection in FT16. Serum lipid and lipoprotein subclass concentrations measured by nuclear magnetic resonance spectroscopy were compared in 226 SS and 169 OS female twins (mean age ± SD: 24 ± 2.1 from wave 4 of data collection in FT12 and FT16. Results: Anthropometric measures, the prevalence of hypertension and diabetes mellitus type 2 did not differ significantly between females from SS and OS twin pairs at age 34. Similarly, the prevalence of infertility, age at first pregnancy and number of induced and spontaneous abortions did not differ significantly between these two groups of women. The serum lipid and lipoprotein profile did not differ between females from SS and OS twins at age 24. Conclusion: We found no evidence that androgen overexposure of the female fetus affects obesity, metabolic profile or reproductive health in young adult females. However, these results do not exclude the possibility that prenatal androgen exposure in females could be adversely associated with intermediate phenotypes of PCOS later in life.

Asymmetry and discordance for congenital anomalies in conjoined twins: a report of six cases.

Science.gov (United States)

Ornoy, A; Navot, D; Menashi, M; Laufer, N; Chemke, J

1980-10-01

Six pairs of conjoined twins have been studied. The first case was a pair of 13-week-old omphalopagus fetuses. One was a holoacradius amorphus and the other had rachischisis and anencephaly. The second case was a pair of omphalopagus twins. One of the twins was macerated and corresponded to a developmental age of 13-14 weeks, while the other was developed to 28-30 weeks of gestation and exhibited urogenital and gastrointestinal defects not found in the smaller twin. In the third case, that of a thoracoomphalopagus, one had cleft lip and palate, pulmonic stenosis, and atresia of the ileocecal valve, while the other did not show these anomalies. In the fourth cae, also omphalopagus twins, one had a lumbosacral meningomyelocele and severe gastrointestinal and urogenital anomalies not found in the second twin. The fifth case was a pair of thoracoomphalopagus twins, sharing a common heart with asymmetrical anomalies. The sixth case was a diprosopus anencephalic conjoined twin. The first pairs of conjoined twins were discordant for several abnormalities in nonshared organs, in addition to having abnormalities of the conjoined organs. It seems that discordance in conjoined twins is not a rare finding. The factors that play a role in discordance of anomalies in conjoined twins are probably similar to the factors in monozygotic twins--i.e., environmental, genetic, and abnormal placental and/or fetal circulation.

Birth weight, sex, and celiac disease: a nationwide twin study

Directory of Open Access Journals (Sweden)

Kuja-Halkola R

2017-11-01

=1.11–2.02. However, the association was not significant in within-pair analyses for both dizygotic and monozygotic twins and for both sexes.Conclusion: This population-based study found that in male twins, higher birth weight was associated with higher risk of CD. However, when comparing discordant twin pairs in within-twin pair analyses, there was no statistically significant association between birth weight, intrauterine growth, and future risk of CD. Keywords: autoimmune, gestational age, gluten, registries, risk factors, twins

The identical-twin transfusion syndrome: a source of error in estimating IQ resemblance and heritability.

Science.gov (United States)

Munsinger, H

1977-01-01

Published studies show that among identical twins, lower birthweight is associated with lower adult intelligence. However, no such relation between birthweight and adult IQ exists among fraternal twins. A likely explanation for the association between birthweight and intelligence among identical twins is the identical twin transfusion syndrome which occurs only between some monochorionic identical twin pairs. The IQ scores from separated identical twins were reanalysed to explore the consequences of identical twin transfusion syndrome for IQ resemblance and heritability. Among 129 published cases of identical twin pairs reared apart, 76 pairs contained some birthweight information. The 76 pairs were separated into three classes: 23 pairs in which there was clear evidence of a substantial birthweight differences (indicating the probable existence of the identical twin transfusion syndrome), 27 pairs in which the information on birthweight was ambiguous (?), and 26 pairs in which there was clear evidence that the twins were similar in birthweight. The reanalyses showed: (1) birthweight differences are positively associated with IQ differences in the total sample of separated identical twins; (2) within the group of 23 twin pairs who showed large birthweight differences, there was a positive relation between birthweight differences and IQ differences; (3) when heritability of IQ is estimated for those twins who do not suffer large birthweight differences, the resemblance (and thus, h2/b) of the separated identical twins' IG is 0-95. Given that the average reliability of the individual IQ test is around 0-95, these data suggest that genetic factors and errors of measurement cause the individual differences in IQ among human beings. Because of the identical twin transfusion syndrome, previous studies of MZ twins have underestimated the effect of genetic factors on IQ. An analysis of the IQs for heavier and lighter birthweight twins suggests that the main effect of the

[Association between obesity and DNA methylation among the 7-16 year-old twins].

Science.gov (United States)

Li, C X; Gao, Y; Gao, W J; Yu, C Q; Lyu, J; Lyu, R R; Duan, J L; Sun, Y; Guo, X H; Wang, S F; Zhou, B; Wang, G; Cao, W H; Li, L M

2018-04-10

Objective: On whole-genome scale, we tried to explore the correlation between obesity-related traits and DNA methylation sites, based on discordant monozygotic twin pairs. Methods: A total of 90 pairs of 6-17 year-old twins were recruited in Chaoyang district, Yanqing district and Fangshan district in Beijing in 2016. Information on twins was gathered through a self-designed questionnaire and results: from physical examination, including height, weight and waist circumference of the subjects under study. DNA methylation detection was chosen on the Illumina Human Methylation EPIC BeadChip. R 3.3.1 language was used to read the DNA methylation signal under quality control on samples and probes. Ebayes function of empirical Bayes paired moderated t -test was used to identify the differential methylated CpG sites (DMCs). VarFit function of empirical Bayes paired moderated Levene test was used to identify the differentially variables CpG sits (DVCs) in obese and normal groups. Results According to the obesity discordance criteria, we collected 23 pairs of twins (age range 7 to 16 years), including 12 male pairs. A total of 817 471 qualified CpG loci were included in the genome-wide correlation analysis. According to the significance level of FDR set as obesity traits. After multiple testing corrections, no positive sites were found to have associated with obesity. However, results from the correlation analysis demonstrated sites cg05684382 (chr: 12) and cg26188191 (chr: 16) might have played a role in the development of obesity. This study provides a methodologic reference for the studies on discordance twins related problems.

Study of 3-D stress development in parent and twin pairs of a hexagonal close-packed polycrystal: Part II – crystal plasticity finite element modeling

International Nuclear Information System (INIS)

Abdolvand, Hamidreza; Majkut, Marta; Oddershede, Jette; Wright, Jonathan P.; Daymond, Mark R.

2015-01-01

Stress heterogeneity within each individual grain of polycrystalline Zircaloy-2 is studied using a crystal plasticity finite element (CPFE) model. For this purpose, the weighted Voronoi tessellation method is used to construct 3D geometries of more than 2600 grains based on their center-of-mass positions and volumes as measured by three-dimensional X-ray diffraction (3DXRD) microscopy. The constructed microstructure is meshed with different element densities and for different numbers of grains. Then a selected group of twin and parent pairs are studied. It is shown that the measured average stress for each grain from the 3DXRD experiment is within the stress variation zone of the grain modeled in the CPFE simulation. Also, the CPFE average stress calculation for each grain is in good agreement with the measured average stress values. It is shown that upon considering the stress variations within each grain, stresses in the parent and twin are quite different if they are plotted in the global coordinate system. However, if the stress tensor is rotated into the local coordinate system of the twin habit plane, all the stress components averaged over the presented population are close, except for the shear acting on the twin plane and the transverse stress. This result is significant as it provides information needed to model such parent-twin interactions in crystal plasticity codes

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...

Hallux Valgus, By Nature or Nurture? A Twin Study.

Science.gov (United States)

Munteanu, Shannon E; Menz, Hylton B; Wark, John D; Christie, Jemma J; Scurrah, Katrina J; Bui, Minh; Erbas, Bircan; Hopper, John L; Wluka, Anita E

2017-09-01

To evaluate the contributions of shared but unmeasured genetic and environmental factors to hallux valgus (HV). Between 2011 and 2012, 74 monozygotic (MZ) and 56 dizygotic (DZ) female twin pairs self-reported HV and putative risk factors, including footwear use across their lifespan. Estimates of casewise concordance (P C ), correlation (ρ), and odds ratios (ORs) were calculated, adjusting for age and other risk factors, and compared between MZ and DZ pairs using logistic regression, generalized estimating equations, and a maximum likelihood-based method, respectively. A total of 70 participants (27%) reported HV, with 12 MZ and 7 DZ pairs being concordant. After adjusting for age, twins were correlated (ρ = 0.27 [95% confidence interval (95% CI) 0.08, 0.46]) and concordant (P C  = 0.45 [95% CI 0.29, 0.61]; mean age 58 years), with no difference between MZ and DZ pairs (P = 0.7). HV was associated with regularly wearing footwear with a constrictive toe-box during the fourth decade (adjusted OR 2.73 [95% CI 1.12, 6.67]). This risk factor was correlated in MZ (ρ = 0.38 [95% CI 0.15, 0.60]) but not DZ (ρ = -0.20 [95% CI -0.43, 0.03]) pairs. These correlations were significantly different (P = 0.002). Twins are correlated for HV, but we found no evidence that correlation was due to shared genetic factors. We identified an environmental risk factor, footwear with a constrictive toe-box, that is not shared to the same extent by MZ and DZ pairs, contrary to the assumption of the classic twin model. Footwear, and possibly genetic factors and unknown shared environmental factors, could contribute to developing HV. © 2016, American College of Rheumatology.

Heritability of Addison's disease and prevalence of associated autoimmunity in a cohort of 112,100 Swedish twins.

Science.gov (United States)

Skov, Jakob; Höijer, Jonas; Magnusson, Patrik K E; Ludvigsson, Jonas F; Kämpe, Olle; Bensing, Sophie

2017-12-01

The pathophysiology behind autoimmune Addison's disease (AAD) is poorly understood, and the relative influence of genetic and environmental factors remains unclear. In this study, we examined the heritability of AAD and explored disease-associated autoimmune comorbidity among Swedish twins. A population-based longitudinal cohort of 112,100 Swedish twins was used to calculate the heritability of AAD, and to explore co-occurrence of 10 organ-specific autoimmune disorders in twin pairs with AAD. Diagnoses were collected 1964-2012 through linkage to the Swedish National Patient Register. The Swedish Prescribed Drug Register was used for additional diagnostic precision. When available, biobank serum samples were used to ascertain the AAD diagnosis through identification of 21-hydroxylase autoantibodies. We identified 29 twins with AAD. Five out of nine (5/9) monozygotic pairs and zero out of fifteen (0/15) dizygotic pairs were concordant for AAD. The probandwise concordance for monozygotic twins was 0.71 (95% CI 0.40-0.90) and the heritability 0.97 (95% CI 0.88-99). Autoimmune disease patterns of monozygotic twin pairs affected by AAD displayed a higher degree of similarity than those of dizygotic twins, with an incidence rate ratio of 15 (95% CI 1.8-116) on the number of shared autoimmune diagnoses within pairs. The heritability of AAD appears to be very high, emphasizing the need for further research on the genetic etiology of the disease. Monozygotic twin concordance for multiple autoimmune manifestations suggests strong genetic influence on disease specificity in organ-specific autoimmunity.

Twins and non-twin siblings: different estimates of shared environmental influence in early childhood.

Science.gov (United States)

Koeppen-Schomerus, Gesina; Spinath, Frank M; Plomin, Robert

2003-04-01

Twin studies typically indicate shared environmental influence for cognitive abilities, especially in early childhood. However, across studies, DZ twin correlations tend to be greater than non-twin sibling correlations, suggesting that twin estimates of shared environment are to some extent specific to twins. We tested this hypothesis in a sample of more than 1800 MZ and 1800 same-sex DZ pairs from the Twins Early Development Study (TEDS), a study of twins born in England and Wales in 1994 and 1995. For this analysis, we obtained comparable data from more than 130 same-sex younger siblings of the twins. Twins and their younger siblings were assessed for language, cognitive abilities and behavior problems by their parents at 2 and 3 years of age. For language and cognitive measures at both 2 and 3 years, but not for behavior problems, estimates of shared environment were more than twice as large for twins as compared to non-twin siblings. We conclude that about half of twin study estimates of shared environment for cognitive abilities in early childhood are specific to twins. Although many possibilities exist for explaining the special shared environment effect for twins, we suggest that cognitive-relevant experiences that are not shared by siblings are shared by twins because they are exactly the same age.

Birth weight in opposite sex twins as compared to same sex dizygotic twins

NARCIS (Netherlands)

Orlebeke, J.F.; van Baal, G.C.M.; Boomsma, D.I.; Neeleman, D.

1993-01-01

The question addressed in the present report is whether the large birth weight differences in dizygotic twin pairs of opposite sex (DZos), especially in 'male first' couples - observed by Blickstein and Weissman (Blickstein I, Weissman A. Birth weight discordancy in male-first and female-first pairs

Gray and white matter volume abnormalities in monozygotic and same-gender dizygotic twins discordant for schizophrenia

DEFF Research Database (Denmark)

Hilshoff, Hilleke E.; Brans, Rachel G. H.; van Haren, Neeltje E. M.

2004-01-01

BACKGROUND: Whole brain tissue volume decreases in schizophrenia have been related to both genetic risk factors and disease-related (possibly nongenetic) factors; however, whether genetic and environmental risk factors in the brains of patients with schizophrenia are differentially reflected...... in gray or white matter volume change is not known. METHODS: Magnetic resonance imaging (1.5 T) brain scans of 11 monozygotic and 11 same-gender dizygotic twin pairs discordant for schizophrenia were acquired and compared with 11 monozygotic and 11 same-gender dizygotic healthy control twin pairs. RESULTS......: Repeated-measures volume analysis of covariance revealed decreased whole brain volume in the patients with schizophrenia as compared with their co-twins and with healthy twin pairs. Decreased white matter volume was found in discordant twin pairs compared with healthy twin pairs, particularly...

Longitudinal weight differences, gene expression, and blood biomarkers in BMI discordant identical twins

Science.gov (United States)

van Dongen, Jenny; Willemsen, Gonneke; Heijmans, Bastiaan T.; Neuteboom, Jacoline; Kluft, Cornelis; Jansen, Rick; Penninx, Brenda W.J.; Slagboom, P. Eline; de Geus, Eco J.C.; Boomsma, Dorret I.

2015-01-01

Background BMI discordant monozygotic (MZ) twins allows an examination of the causes and consequences of adiposity in a genetically controlled design. Few studies have examined longitudinal BMI discordance in MZ pairs. Objectives To study the development over time of BMI discordance in adolescent and adult MZ twin pairs, and to examine lifestyle, metabolic, inflammatory, and gene expression differences associated with concurrent and long-term BMI discordance in MZ pairs. Subjects/Methods BMI data from 2775 MZ twin pairs, collected in eight longitudinal surveys and a biobank project between 1991 and 2011, were analyzed to characterize longitudinal discordance. Lifestyle characteristics were compared within discordant pairs (ΔBMI ≥ 3 kg/m2) and biomarkers (lipids, glucose, insulin, CRP, fibrinogen, IL-6, TNF-α and sIL-6R and liver enzymes AST, ALT and GGT) and gene expression were compared in peripheral blood from discordant pairs who participated in the NTR biobank project. Results The prevalence of discordance ranged from 3.2% in 1991 (mean age=17, SD=2.4) to 17.4% (N=202 pairs) in 2009 (mean age=35, SD=15), and was 16.5% (N=174) among pairs participating in the biobank project (mean age=35, SD=12). Of 699 MZ with BMI data from 3-5 time points, 17 pairs (2.4%) were long-term discordant (at all available time points; mean follow-up range=6.4 years). Concurrently discordant pairs showed significant differences in self-ratings of which twin eats most (p=2.3×10−13), but not in leisure time exercise activity (p=0.28) and smoking (p>0.05). Ten out of 14 biomarkers showed significantly more unfavorable levels in the heavier of twin of the discordant pairs (p-values BMI discordance is uncommon in adolescent identical pairs but increases with higher pair-mean of BMI at older ages, although long-term BMI discordance is rare. In discordant pairs, the heavier twin had a more unfavorable blood biomarker profile than the genetically matched leaner twin, in support of

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.

Initiation and strain compatibility of connected extension twins in AZ31 magnesium alloy at high temperature

Energy Technology Data Exchange (ETDEWEB)

Liu, Xiao, E-mail: liuxiao0105@163.com [Key Laboratory of High Temperature Wear Resistant Materials Preparation Technology of Hunan Province, Hunan University of Science and Technology, Xiangtan, Hunan 411201 (China); State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha, Hunan 410082 (China); Zhu, Biwu [Key Laboratory of High Temperature Wear Resistant Materials Preparation Technology of Hunan Province, Hunan University of Science and Technology, Xiangtan, Hunan 411201 (China); Huang, Guangjie [College of Materials Science and Engineering, Chongqing University, Chongqing, Chongqing 400045 (China); Li, Luoxing, E-mail: luoxing_li@yahoo.com [State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha, Hunan 410082 (China); Xie, Chao [Faculty of Mechanical Engineering and Mechanics, Ningbo University, Ningbo 315211 (China); Tang, Changping [Key Laboratory of High Temperature Wear Resistant Materials Preparation Technology of Hunan Province, Hunan University of Science and Technology, Xiangtan, Hunan 411201 (China)

2016-12-15

Uniaxial compression tests were carried out at 350 °C and a strain rate of 0.3 s{sup −1} on as-extruded AZ31 magnesium alloy samples. At a true strain of − 0.1, extension twin pairs in a grain and twin chains across adjacent grains were detected. The orientation of selected twins and their host grains were determined by electron backscattered diffraction (EBSD) techniques. The Schmid factors (SFs), accommodation strains and geometric compatibility factors (m{sup ′}) were calculated. Analysis of the data indicated that the formation of twin pair and twin chain was related to the SF and m{sup ′}. Regarding to twin chain across adjacent grains, accommodation strain was also involved. The selection of twin variants in twin chain was generally determined by m{sup ′}. When the twins required the operation of pyramidal slip or twinning in adjacent grain, the corresponding connected twins with a relative high m{sup ′} were selected in this adjacent grain. - Highlights: •The formation of paired twins is studied during high temperature deformation. •The initiation of twinning in twin pair and twin chain obeys the Schmid law. •The twin variants' selection in twin chain is related to the geometric compatibility factor. •The accommodation strain plays an important role on the formation of twin chain.

Epigenetic signature of birth weight discordance in adult twins

DEFF Research Database (Denmark)

Tan, Qihua; Nielsen, Morten Frost Munk; Heijmans, Bastiaan T

2014-01-01

between birth weight and adult life health while controlling for not only genetics but also postnatal rearing environment. We performed an epigenome-wide profiling on blood samples from 150 pairs of adult monozygotic twins discordant for birth weight to look for molecular evidence of epigenetic signatures...... profiling did not reveal epigenetic signatures of birth weight discordance although some sites displayed age-dependent intra-pair differential methylation in the extremely discordant twin pairs....

Neuroanatomic alterations and social and communication deficits in monozygotic twins discordant for autism disorder.

Science.gov (United States)

Mitchell, Shanti R; Reiss, Allan L; Tatusko, Danielle H; Ikuta, Ichiro; Kazmerski, Dana B; Botti, Jo-Anna C; Burnette, Courtney P; Kates, Wendy R

2009-08-01

Investigating neuroanatomic differences in monozygotic twins who are discordant for autism can help unravel the relative contributions of genetics and environment to this pervasive developmental disorder. The authors used magnetic resonance imaging (MRI) to investigate several brain regions of interest in monozygotic twins who varied in degree of phenotypic discordance for narrowly defined autism. The subjects were 14 pairs of monozygotic twins between the ages of 5 and 14 years old and 14 singleton age- and gender-matched typically developing comparison subjects. The monozygotic twin group was a cohort of children with narrowly defined autistic deficits and their co-twins who presented with varying levels of autistic deficits. High-resolution MRIs were acquired and volumetric/area measurements obtained for the frontal lobe, amygdala, and hippocampus and subregions of the prefrontal cortex, corpus callosum, and cerebellar vermis. No neurovolumetric/area differences were found between twin pairs. Relative to typically developing comparison subjects, dorsolateral prefrontal cortex volumes and anterior areas of the corpus callosum were significantly altered in autistic twins, and volumes of the posterior vermis were altered in both autistic twins and co-twins. Intraclass correlation analysis of brain volumes between children with autism and their co-twins indicated that the degree of within-pair neuroanatomic concordance varied with brain region. In the group of subjects with narrowly defined autism only, dorsolateral prefrontal cortex, amygdala, and posterior vermis volumes were significantly associated with the severity of autism based on scores from the Autism Diagnostic Observation Schedule-Generic. These findings support previous research demonstrating alterations in the prefrontal cortex, corpus callosum, and posterior vermis in children with autism and further suggest that alterations are associated with the severity of the autism phenotype. Continued research

Does educational status impact adult mortality in Denmark? A twin approach.

Science.gov (United States)

Madsen, Mia; Andersen, Anne-Marie Nybo; Christensen, Kaare; Andersen, Per Kragh; Osler, Merete

2010-07-15

To disentangle an independent effect of educational status on mortality risk from direct and indirect selection mechanisms, the authors used a discordant twin pair design, which allowed them to isolate the effect of education by means of adjustment for genetic and environmental confounding per design. The study is based on data from the Danish Twin Registry and Statistics Denmark. Using Cox regression, they estimated hazard ratios for mortality according to the highest attained education among 5,260 monozygotic and 11,088 dizygotic same-sex twin pairs born during 1921-1950 and followed during 1980-2008. Both standard cohort and intrapair analyses were conducted separately for zygosity, gender, and birth cohort. Educational differences in mortality were demonstrated in the standard cohort analyses but attenuated in the intrapair analyses in all subgroups but men born during 1921-1935, and no effect modification by zygosity was observed. Hence, the results are most compatible with an effect of early family environment in explaining the educational inequality in mortality. However, large educational differences were still reflected in mortality risk differences within twin pairs, thus supporting some degree of independent effect of education. In addition, the effect of education may be more pronounced in older cohorts of Danish men.

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.

Traits of ADHD and autism in girls with a twin brother

DEFF Research Database (Denmark)

Attermann, Jørn; 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...... of the co-twin influences the level of prenatal exposure to testosterone. We invited parents of 24,552 3- to 15-year-old twins to answer questionnaires on traits of ADHD and ASD. We analysed the data using a proportional odds model with sex of the co-twin as an instrumental variable for prenatal exposure...... to testosterone of female twins. We received responses for 6,339 girls from dizygotic twin pairs. Odds ratios for male versus female co-twin were 0.71 (95 % confidence interval 0.61-0.81) for ADHD traits and 0.74 (0.66-0.83) for ASD traits, indicating that a twin brother reduces traits of ADHD and ASD in females...

Risk of chronic bronchitis in twin pairs discordant for smoking

DEFF Research Database (Denmark)

Meteran, Howraman; Thomsen, Simon Francis; Harmsen, Lotte

2012-01-01

It is well known that smoking is a major risk factor for lung disease and respiratory symptoms. We examined the association between smoking and the risk of chronic bronchitis in a large twin sample.......It is well known that smoking is a major risk factor for lung disease and respiratory symptoms. We examined the association between smoking and the risk of chronic bronchitis in a large twin sample....

Fetal behavior in normal dichorionic twin pregnancy

NARCIS (Netherlands)

Mulder, E. J. H.; Derks, J. B.; de Laat, M. W. M.; Visser, G. H. A.

2012-01-01

Objectives: A prospective study was performed to compare fetal behavioral development in healthy dichorionic twins and singletons, and identify twin intra-pair associations (synchrony) of fetal movements and rest-activity cycles using different criteria to define synchrony. Subjects and methods:

Higher Rates of DZ Twinning in a Twenty-First Century Birth Cohort.

Science.gov (United States)

Rhea, Sally Ann; Corley, Robin P; Heath, Andrew C; Iacono, William G; Neale, Michael C; Hewitt, John K

2017-09-01

The Colorado Twin Registry is a population based registry initiated in 1984 with the involvement of the Colorado Department of Health, Division of Vital Statistics. Recruitment includes birth cohorts several years prior to 1984 and all subsequent years. As part of a recent evaluation of Colorado birth records for the years 2006 through 2008 we became aware of a shifting trend in the proportion of MZ and DZ twins in the Colorado population. Historically (Bulmer 1970 The biology of twinning in man, Clarendon, Oxford) we have expected a 1/3, 1/3, 1/3 ratio of MZ, same-sex DZ and opposite sex DZ twins in Caucasian populations. An excess of MZ pairs in most studies was assumed to be due to selection bias. Somewhat more recently, Hur et al.(1995 Behav Genet 25, 337-340) provided evidence that the DZ twinning rate was falling and that therefore selection bias was not the reason for higher MZ enrollment in most twin studies. They suggested that twin researchers might consider strategies to over-enroll DZ pairs to maximize statistical power. In contrast, we now find that of the 3217 twin births in Colorado from 2006 to 2008 with identified sex information the MZ rate is estimated at only 22%, and we have corroborating reports from other states of similar estimates. These were calculated applying Weinberg's rule which assumes an equal birth rate for same sex and opposite sex DZ pairs so that the proportion of MZ in a sample is the proportion of same sex (MM + FF) minus the proportion of opposite-sex (MF, FM). We explore factors, such as an increase in the proportion of non-Caucasian parents and an increase in average maternal age, which may contribute to this shift.

Natural history of disease in atomic bomb exposed twins in Hiroshima

International Nuclear Information System (INIS)

Satow, Yukio; Ohmae, Kiyokazu; Okamoto, Naomasa; Abe, Tsutomu; Watanabe, Shoji

1982-01-01

The subjects of this study are mainly pairs of monozygotic twins, one of whom was exposed to the atomic bomb and the other not exposed, and the natural history of the diseases of these twins was analyzed to find out genetic and environmental factors of the diseases and some biological effect of the atomic bomb exposure or other. In this study, 13 pairs of monozygotic and 5 pairs of dizygotic twins and other 34 cases of non-twins were examined by means of heart and lung X-ray films and electrocardiograms. The results suggest that most of the monozygotic twins show the similar findings of chest X-ray films, though their electrocardiograms have a tendency to deviate to the left in the QRS axis. These findings will not be enough to clear up the relation between the atomic bomb exposed and the abnormal electrocardiograms. (author)

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.

Metabolic studies in unaffected co-twins of non-insulin-dependent diabetics.

OpenAIRE

Barnett, A H; Spiliopoulos, A J; Pyke, D A; Stubbs, W A; Burrin, J; Alberti, K G

1981-01-01

Forty-eight out of 53 non-insulin-dependent diabetic identical twin pairs were concordant for diabetes. In the five discordant pairs the diabetic twin had only recently been diagnosed. Oral glucose tolerance tests were carried out on the unaffected twins of the five pairs and on matched controls. Fasting concentrations of blood glucose (5.5 +/- 0.6 v 3.7 +/- 0.3 mmol/l; 99.1 +/- 10.8 v 66.6 +/- 5.4 mg/100 ml), haemoglobin A1 (mean 9.1%, range 8.8-9.2% v mean 7.9%, range 7.4-8.4%), lactate, al...

Co-bedding in neonatal nursery for promoting growth and neurodevelopment in stable preterm twins.

Science.gov (United States)

Lai, Nai Ming; Foong, Siew Cheng; Foong, Wai Cheng; Tan, Kenneth

2016-04-14

The increased birth rate of twins during recent decades and the improved prognosis of preterm infants have resulted in the need to explore measures that could optimize their growth and neurodevelopmental outcomes. It has been postulated that co-bedding simulates twins' intrauterine experiences in which co-regulatory behaviors between them are observed. These behaviors are proposed to benefit twins by reducing their stress, which may promote growth and development. However, in practice, uncertainty surrounds the benefit-risk profile of co-bedding. We aimed to assess the effectiveness of co-bedding compared with separate (individual) care for stable preterm twins in the neonatal nursery in promoting growth and neurodevelopment and reducing short- and long-term morbidities, and to determine whether co-bedding is associated with significant adverse effects.As secondary objectives, we sought to evaluate effects of co-bedding via the following subgroup analyses: twin pairs with different weight ranges (very low birth weight [VLBW] growth discordance at birth, preterm versus borderline preterm twins, twins co-bedded in incubator versus cot at study entry, and twins randomized by twin pair versus neonatal unit. We used the standard search strategy of the Cochrane Neonatal Review Group (CNRG). We used keywords and medical subject headings (MeSH) to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 2), MEDLINE (via PubMed), EMBASE (hosted by EBSCOHOST), the Cumulative Index to Nursing and Allied Health Literature (CINAHL), and references cited in our short-listed articles, up to February 29, 2016. We included randomized controlled trials with randomization by twin pair and/or by neonatal unit. We excluded cross-over studies. We extracted data using standard methods of the CNRG. Two review authors independently assessed the relevance and risk of bias of retrieved records. We contacted the authors of included studies to request important

Post-traumatic stress disorder and incidence of coronary heart disease: a twin study.

Science.gov (United States)

Vaccarino, Viola; Goldberg, Jack; Rooks, Cherie; Shah, Amit J; Veledar, Emir; Faber, Tracy L; Votaw, John R; Forsberg, Christopher W; Bremner, J Douglas

2013-09-10

The aim of this study was to determine whether post-traumatic stress disorder (PTSD) is associated with coronary heart disease (CHD) using a prospective twin study design and objective measures of CHD. It has long been hypothesized that PTSD increases the risk of CHD, but empirical evidence using objective measures is limited. We conducted a prospective study of middle-aged male twins from the Vietnam Era Twin Registry. Among twin pairs without self-reported CHD at baseline, we selected pairs discordant for a lifetime history of PTSD, pairs discordant for a lifetime history of major depression, and pairs without either condition. All underwent a clinic visit after a median follow-up of 13 years. Outcomes included clinical events (myocardial infarction, other hospitalizations for CHD and coronary revascularization) and quantitative measures of myocardial perfusion by [(13)N] ammonia positron emission tomography, including a stress total severity score and coronary flow reserve. A total of 562 twins (281 pairs) with a mean age of 42.6 years at baseline were included in this study. The incidence of CHD was more than double in twins with PTSD (22.6%) than in those without PTSD (8.9%; p Stress total severity score was significantly higher (+95%, p = 0.001) and coronary flow reserve was lower (-0.21, p = 0.02) in twins with PTSD than in those without PTSD, denoting worse myocardial perfusion. Associations were only mildly attenuated in 117 twin pairs discordant for PTSD. Among Vietnam-era veterans, PTSD is a risk factor for CHD. Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

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...

Use of a twin dataset to identify AMD-related visual patterns controlled by genetic factors

Science.gov (United States)

Quellec, Gwénolé; Abràmoff, Michael D.; Russell, Stephen R.

2010-03-01

The mapping of genotype to the phenotype of age-related macular degeneration (AMD) is expected to improve the diagnosis and treatment of the disease in a near future. In this study, we focused on the first step to discover this mapping: we identified visual patterns related to AMD which seem to be controlled by genetic factors, without explicitly relating them to the genes. For this purpose, we used a dataset of eye fundus photographs from 74 twin pairs, either monozygotic twins, who have the same genotype, or dizygotic twins, whose genes responsible for AMD are less likely to be identical. If we are able to differentiate monozygotic twins from dizygotic twins, based on a given visual pattern, then this pattern is likely to be controlled by genetic factors. The main visible consequence of AMD is the apparition of drusen between the retinal pigment epithelium and Bruch's membrane. We developed two automated drusen detectors based on the wavelet transform: a shape-based detector for hard drusen, and a texture- and color- based detector for soft drusen. Forty visual features were evaluated at the location of the automatically detected drusen. These features characterize the texture, the shape, the color, the spatial distribution, or the amount of drusen. A distance measure between twin pairs was defined for each visual feature; a smaller distance should be measured between monozygotic twins for visual features controlled by genetic factors. The predictions of several visual features (75.7% accuracy) are comparable or better than the predictions of human experts.

Late language emergence in 24-month-old twins: heritable and increased risk for late language emergence in twins.

Science.gov (United States)

Rice, Mabel L; Zubrick, Stephen R; Taylor, Catherine L; Gayán, Javier; Bontempo, Daniel E

2014-06-01

This study investigated the etiology of late language emergence (LLE) in 24-month-old twins, considering possible twinning, zygosity, gender, and heritability effects for vocabulary and grammar phenotypes. A population-based sample of 473 twin pairs participated. Multilevel modeling estimated means and variances of vocabulary and grammar phenotypes, controlling for familiality. Heritability was estimated with DeFries-Fulker regression and variance components models to determine effects of heritability, shared environment, and nonshared environment. Twins had lower average language scores than norms for single-born children, with lower average performance for monozygotic than dizygotic twins and for boys than girls, although gender and zygosity did not interact. Gender did not predict LLE. Significant heritability was detected for vocabulary (0.26) and grammar phenotypes (0.52 and 0.43 for boys and girls, respectively) in the full sample and in the sample selected for LLE (0.42 and 0.44). LLE and the appearance of Word Combinations were also significantly heritable (0.22-0.23). The findings revealed an increased likelihood of LLE in twin toddlers compared with single-born children that is modulated by zygosity and gender differences. Heritability estimates are consistent with previous research for vocabulary and add further suggestion of heritable differences in early grammar acquisition.

Physical activity, fitness, glucose homeostasis, and brain morphology in twins.

Science.gov (United States)

Rottensteiner, Mirva; Leskinen, Tuija; Niskanen, Eini; Aaltonen, Sari; Mutikainen, Sara; Wikgren, Jan; Heikkilä, Kauko; Kovanen, Vuokko; Kainulainen, Heikki; Kaprio, Jaakko; Tarkka, Ina M; Kujala, Urho M

2015-03-01

The main aim of the present study (FITFATTWIN) was to investigate how physical activity level is associated with body composition, glucose homeostasis, and brain morphology in young adult male monozygotic twin pairs discordant for physical activity. From a population-based twin cohort, we systematically selected 10 young adult male monozygotic twin pairs (age range, 32-36 yr) discordant for leisure time physical activity during the past 3 yr. On the basis of interviews, we calculated a mean sum index for leisure time and commuting activity during the past 3 yr (3-yr LTMET index expressed as MET-hours per day). We conducted extensive measurements on body composition (including fat percentage measured by dual-energy x-ray absorptiometry), glucose homeostasis including homeostatic model assessment index and insulin sensitivity index (Matsuda index, calculated from glucose and insulin values from an oral glucose tolerance test), and whole brain magnetic resonance imaging for regional volumetric analyses. According to pairwise analysis, the active twins had lower body fat percentage (P = 0.029) and homeostatic model assessment index (P = 0.031) and higher Matsuda index (P = 0.021) compared with their inactive co-twins. Striatal and prefrontal cortex (subgyral and inferior frontal gyrus) brain gray matter volumes were larger in the nondominant hemisphere in active twins compared with those in inactive co-twins, with a statistical threshold of P physical activity is associated with improved glucose homeostasis and modulation of striatum and prefrontal cortex gray matter volume, independent of genetic background. The findings may contribute to later reduced risk of type 2 diabetes and mobility limitations.

Long-term relationships between symptoms of Attention Deficit Hyperactivity Disorder and self-esteem in a prospective longitudinal study of twins.

Science.gov (United States)

Edbom, Tobias; Lichtenstein, Paul; Granlund, Mats; Larsson, Jan-Olov

2006-06-01

To study the long-term relationship between symptoms of Attention Deficit Hyperactivity Disorder and the developing self-esteem in a population-based sample of twins. The cohort is all twin pair families born in Sweden between May 1985 and December 1986 (n = 1.480). Wave 1 took place in 1994 when the twins were 8 years old and wave 2 in 1999 when the children were 13 years old. In wave 1 and 2 the parents completed questionnaires regarding ADHD-symptoms about their children. In wave 2 the twins completed a questionnaire about self-esteem and Youth Self Report (YSR). ADHD-symptoms and self-esteem were analyzed in the total study group. There was a long-term relationship between high scores of parental-reported ADHD-symptoms at 8 and 13 years of age and low scores in measures of self-reported self-esteem at 13 years of age. In the cotwin control method controlling for YSR internalizing problem, paired comparisons within the twin pairs revealed that a high score of ADHD-symptoms at age 8 was related to significantly lower scores at age 13 in the self-esteem. The long-term relationships between ADHD-symptoms and a low self-esteem in a population-based sample were confirmed by the co-twin analyses.

Autopsy Findings on a Pair of Dicephalic Parapagus Twins: A Case ...

African Journals Online (AJOL)

Conjoined twins are a rare occurrence that presents significant challenges to both parents and medical care givers with many theories being advanced to explain this occurrence.“Parapagus” is a fairly recent term, in which the twins lie side by side with ventro-lateral fusion and are extremely rare representing 0.5% of all ...

Genetic susceptibility to bilateral tinnitus in a Swedish twin cohort

DEFF Research Database (Denmark)

Maas, Iris Lianne; Brüggemann, Petra; Requena, Teresa

2017-01-01

PURPOSE: Genetic contributions to tinnitus have been difficult to determine due to the heterogeneity of the condition and its broad etiology. Here, we evaluated the genetic and nongenetic influences on self-reported tinnitus from the Swedish Twin Registry (STR). METHODS: Cross-sectional data from...... the STR was obtained. Casewise concordance rates (the risk of one twin being affected given that his/her twin partner has tinnitus) were compared for monozygotic (MZ) and dizygotic (DZ) twin pairs (N = 10,464 concordant and discordant twin pairs) and heritability coefficients (the proportion of the total...... variance attributable to genetic factors) were calculated using biometrical model fitting procedures. RESULTS: Stratification of tinnitus cases into subtypes according to laterality (unilateral versus bilateral) revealed that heritability of bilateral tinnitus was 0.56; however, it was 0.27 for unilateral...

Midlife Alcohol Consumption and Risk of Dementia Over 43 Years of Follow-Up: A Population-Based Study From the Swedish Twin Registry.

Science.gov (United States)

Handing, Elizabeth P; Andel, Ross; Kadlecova, Pavla; Gatz, Margaret; Pedersen, Nancy L

2015-10-01

Midlife alcohol consumption (beer, wine, and spirits) was examined in relation to dementia incidence over 43 years. Participants were 12,326 members of the population-based Swedish Twin Registry born during 1907-1925 who responded to items about alcohol consumption in 1967/1970, subsequently classified as nondrinking (0 grams of ethanol per day), light (1-5g/d), moderate (5-12g/d), heavy (12-24g/d), and very heavy (>24g/d) drinking. Dementia was identified from the National Patient and Cause of Death Registries. Cox proportional hazard models adjusted for cluster-correlated data were used in cohort analyses. Conditional logistic regression (dementia-discordant pairs) and mixed effects models (dementia-concordant pairs) were used in twin analyses. Overall, nondrinkers did not differ from light drinkers in dementia risk. Heavy drinking (hazard ratio = 1.10, p = .028) and very heavy drinking (hazard ratio = 1.18, p = .033) were associated with increased dementia risk controlling for sociodemographic, lifestyle, and cardiovascular factors. More alcohol from spirits was related to increased risk of dementia, whereas more alcohol from wine with decreased risk, although the association for wine reversed direction at high amounts. Relative to co-twins drinking light amounts, moderate-to-heavy drinking twins had (a) greater risk of dementia by 57% (p = .006, 300% in monozygotic pairs only) and (b) reduced time to dementia by 4.76 years (p = .019, 4.78 years in monozygotic pairs only). Averaging more than 12 grams of alcohol per day may increase risk of dementia. Alcohol from spirits appears particularly important for the increased dementia risk. Genetic and/or familial factors do not explain these associations. Alcohol use reduction may be a useful population-wide intervention strategy. © The Author 2015. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Mitochondrial DNA Copy Number in Sleep Duration Discordant Monozygotic Twins.

Science.gov (United States)

Wrede, Joanna E; Mengel-From, Jonas; Buchwald, Dedra; Vitiello, Michael V; Bamshad, Michael; Noonan, Carolyn; Christiansen, Lene; Christensen, Kaare; Watson, Nathaniel F

2015-10-01

Mitochondrial DNA (mtDNA) copy number is an important component of mitochondrial function and varies with age, disease, and environmental factors. We aimed to determine whether mtDNA copy number varies with habitual differences in sleep duration within pairs of monozygotic twins. Academic clinical research center. 15 sleep duration discordant monozygotic twin pairs (30 twins, 80% female; mean age 42.1 years [SD 15.0]). Sleep duration was phenotyped with wrist actigraphy. Each twin pair included a "normal" (7-9 h/24) and "short" (sleeping twin. Fasting peripheral blood leukocyte DNA was assessed for mtDNA copy number via the n-fold difference between qPCR measured mtDNA and nuclear DNA creating an mtDNA measure without absolute units. We used generalized estimating equation linear regression models accounting for the correlated data structure to assess within-pair effects of sleep duration on mtDNA copy number. Mean within-pair sleep duration difference per 24 hours was 94.3 minutes (SD 62.6 min). We found reduced sleep duration (β = 0.06; 95% CI 0.004, 0.12; P sleep efficiency (β = 0.51; 95% CI 0.06, 0.95; P sleep duration was associated with a decrease in mtDNA copy number of 0.06. Likewise, a 1% decrease in actigraphy-defined sleep efficiency was associated with a decrease in mtDNA copy number of 0.51. Reduced sleep duration and sleep efficiency were associated with reduced mitochondrial DNA copy number in sleep duration discordant monozygotic twins offering a potential mechanism whereby short sleep impairs health and longevity through mitochondrial stress. © 2015 Associated Professional Sleep Societies, LLC.

Placental cord insertion and birthweight discordance in twin pregnancies: results of the national prospective ESPRiT Study.

Science.gov (United States)

Kent, Etaoin M; Breathnach, Fionnuala M; Gillan, John E; McAuliffe, Fionnuala M; Geary, Michael P; Daly, Sean; Higgins, John R; Dornan, James; Morrison, John J; Burke, Gerard; Higgins, Shane; Carroll, Stephen; Dicker, Patrick; Manning, Fiona; Malone, Fergal D

2011-10-01

The purpose of this study was to evaluate the impact of noncentral placental cord insertion on birthweight discordance in twins. We performed a multicenter, prospective trial of twin pregnancies. Placental cord insertion was documented as central, marginal, or velamentous according to a defined protocol. Association of the placental cord insertion site with chorionicity, birthweight discordance, and growth restriction were assessed. Eight hundred sixteen twin pairs were evaluated; 165 pairs were monochorionic, and 651 pairs were dichorionic. Monochorionic twins had higher rates of marginal (P = .0068) and velamentous (P < .0001) placental cord insertion. Noncentral placental cord insertion was more frequent in smaller twins of discordant pairs than control pairs (29.8% vs 19.1%; P = .004). Velamentous placental cord insertion in monochorionic twins was associated significantly with birthweight discordance (odds ratio, 3.5; 95% confidence interval, 1.3-9.4) and growth restriction (odds ratio, 4; 95% confidence interval, 1.1-14.3). Noncentral placental cord insertion contributes to birthweight discordance in monochorionic twin pregnancies. Sonographic delineation of placental cord insertion may be of value in antenatal assessment of twin pregnancies. Copyright © 2011 Mosby, Inc. All rights reserved.

Gestation period and twinning in chimpanzees.

Science.gov (United States)

PEACOCK, L J; ROGERS, C M

1959-04-10

The length of the gestation period in 118 births in a colony of chimpanzees was found to be 226.8 days, with a standard deviation of 13.3 and a range of 196 to 260 days. Six pairs of twins were born in 120 parturitions; thus the apparent twinning rate is higher than that in man.

Conjoined twin piglets with duplicated cranial and caudal axes.

Science.gov (United States)

McManus, C A; Partlow, G D; Fisher, K R

1994-06-01

Twins with doubling of the cranial and caudal poles, yet having a single thorax, are rare. One set of diprosopus, dipygus porcine conjoined twins was studied. In addition to the conjoining anomaly, these twins also exhibited ambiguous internal reproductive features. The twins had two snouts, three eyes, a single thorax, and were duplicated from the umbilicus caudally. Radiography indicated a single vertebral column in the cervical region. The vertebral columns were separate caudally from this point. There was a total of six limbs--one pair of forelimbs and two pairs of hindlimbs. Many medial structures failed to develop in these twins. Medial cranial nerves V-XII were absent or displaced although apparently normal laterally. The medial palates were present but shortened, whereas the medial mandibular rami had folded back on themselves rostrally to form a midline mass between the two chins. Each twin had only one lateral kidney and one lateral testis. Medial scrotal sacs were present but devoid of a testis. There was a midline, "uterine"-like structure which crossed between the twins. However, histological analysis of this structure revealed it to be dysplastic testicular tissue. The relationship between the abnormal reproductive features in these twins and the conjoining is unclear. The anatomy of these twins, in addition to the literature reviewed, illustrates the internal anatomical heterogeneity of grossly similar conjoined twins. A review of the literature also suggests that conjoined twinning may be more common in swine than was previously suspected.

Sleep-EEG in dizygotic twins discordant for Williams syndrome.

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Bódizs, Róbert; Gombos, Ferenc; Szocs, Katalin; Réthelyi, János M; Gerván, Patrícia; Kovács, Ilona

2014-01-30

Reports on twin pairs concordant and discordant for Williams syndrome were published before, but no study unravelled sleep physiology in these cases yet. We aim to fill this gap by analyzing sleep records of a twin pair discordant for Williams syndrome extending our focus on presleep wakefulness and sleep spindling. We performed multiplex ligation-dependent probe amplification of the 7q11.23 region of a 17 years old dizygotic opposite-sex twin pair discordant for Williams syndrome. Polysomnography of laboratory sleep at this age was analyzed and followed-up after 1.5 years by ambulatory polysomnography. Sleep stages scoring, EEG power spectra and sleep spindle analyses were carried out. The twin brother showed reduced levels of amplification for all of the probes in the 7q11.23 region indicating a typical deletion spanning at least 1.038 Mb between FKBP6 and CLIP2. The results of the twin sister showed normal copy numbers in the investigated region. Lower sleep times and efficiencies, as well as higher slow wave sleep percents of the twin brother were evident during both recordings. Roughly equal NREM, Stage 2 and REM sleep percents were found. EEG analyses revealed state and derivation-independent decreases in alpha power, lack of an alpha spectral peak in presleep wakefulness, as well as higher NREM sleep sigma peak frequency in the twin brother. Faster sleep spindles with lower amplitude and shorter duration characterized the records of the twin brother. Spectra show a striking reliability and correspondence between the two situations (laboratory vs. home records). Alterations in sleep and specific neural oscillations including the alpha/sigma waves are inherent aspects of Williams syndrome.

White matter differences in monozygotic twins discordant or concordant for obsessive-compulsive symptoms: a combined diffusion tensor imaging/voxel-based morphometry study.

Science.gov (United States)

den Braber, Anouk; van 't Ent, Dennis; Boomsma, Dorret I; Cath, Danielle C; Veltman, Dick J; Thompson, Paul M; de Geus, Eco J C

2011-11-15

Neuroimaging studies of obsessive-compulsive disorder (OCD) patients point to deficits in cortico-striato-thalamo-cortical circuits that might include changes in white matter. The contribution of environmental and genetic factors to the various OCD-related changes in brain structures remains to be established. White matter structures were analyzed in 140 subjects with both diffusion tensor imaging and voxel-based morphometry. We studied 20 monozygotic twin pairs discordant for obsessive-compulsive symptoms (OCS) to detect the effects of environmental risk factors for obsessive-compulsive (OC) symptomatology. Furthermore, we compared 28 monozygotic twin pairs concordant for low OCS scores with 23 twin pairs concordant for high OCS scores to detect the effects of genetic risk factors for OC symptomatology. Discordant pair analysis showed that the environmental risk was associated with an increase in dorsolateral-prefrontal white matter. Analysis of concordant pairs showed that the genetic risk was associated with a decrease in inferior frontal white matter. Various white matter tracts showed opposite effects of environmental and genetic risk factors (e.g., right medial frontal, left parietal, and right middle temporal), illustrating the need for designs that separate these classes of risk factors. Different white matter regions were affected by environmental and genetic risk factors for OC symptomatology, but both classes of risk factors might, in aggregate, create an imbalance between the indirect loop of the cortico-striato-thalamo-cortical network (to the dorsolateral-prefrontal region)-important for inhibition and switching between behaviors-and the direct loop (involving the inferior frontal region) that contributes to the initiation and continuation of behaviors. Copyright © 2011 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Hormone replacement therapy improves contractile function and myonuclear organization of single muscle fibres from postmenopausal monozygotic female twin pairs.

Science.gov (United States)

Qaisar, Rizwan; Renaud, Guillaume; Hedstrom, Yvette; Pöllänen, Eija; Ronkainen, Paula; Kaprio, Jaakko; Alen, Markku; Sipilä, Sarianna; Artemenko, Konstantin; Bergquist, Jonas; Kovanen, Vuokko; Larsson, Lars

2013-05-01

Ageing is associated with a decline in muscle mass and strength leading to increased physical dependency in old age. Postmenopausal women experience a greater decline than men of similar age in parallel with the decrease in female sex steroid hormone production. We recruited six monozygous female twin pairs (55-59 years old) where only one twin pair was on hormone replacement therapy (HRT use = 7.8 ± 4.3 years) to investigate the association of HRT with the cytoplasmic volume supported by individual myonuclei (myonuclear domain (MND) size,) together with specific force at the single fibre level. HRT use was associated with a significantly smaller (∼27%; P muscle fibres expressing the type I but not the IIa myosin heavy chain (MyHC) isoform. In comparison to non-users, higher specific force was recorded in HRT users both in muscle fibres expressing type I (∼27%; P fibre-type dependent, i.e. the higher specific force in fast-twitch muscle fibres was primarily caused by higher force per cross-bridge while slow-twitch fibres relied on both a higher number and force per cross-bridge. HRT use had no effect on fibre cross-sectional area (CSA), velocity of unloaded shortening (V0) and relative proportion of MyHC isoforms. In conclusion, HRT appears to have significant positive effects on both regulation of muscle contraction and myonuclei organization in postmenopausal women.

Effects of social contact and zygosity on 21-y weight change in male twins.

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McCaffery, Jeanne M; Franz, Carol E; Jacobson, Kristen; Leahey, Tricia M; Xian, Hong; Wing, Rena R; Lyons, Michael J; Kremen, William S

2011-08-01

Recent evidence indicates that social contact is related to similarities in weight gain over time. However, no studies have examined this effect in a twin design, in which genetic and other environmental effects can also be estimated. We determined whether the frequency of social contact is associated with similarity in weight change from young adulthood (mean age: 20 y) to middle age (mean age: 41 y) in twins and quantified the percentage of variance in weight change attributable to social contact, genetic factors, and other environmental influences. Participants were 1966 monozygotic and 1529 dizygotic male twin pairs from the Vietnam-Era Twin Registry. Regression models tested whether frequency of social contact and zygosity predicted twin pair similarity in body mass index (BMI) change and weight change. Twin modeling was used to partition the percentage variance attributable to social contact, genetic, and other environmental effects. Twins gained an average of 3.99 BMI units, or 13.23 kg (29.11 lb), over 21 y. In regression models, both zygosity (P social contact (P change. In twin modeling, social contact between twins contributed 16% of the variance in BMI change (P change. Frequency of social contact significantly predicted twin pair similarity in BMI and weight change over 21 y, independent of zygosity and other shared environmental influences.

Genetic and environmental contributions to pro-social attitudes: a twin study of social responsibility.

Science.gov (United States)

Rushton, J Philippe

2004-12-22

Although 51 twin and adoption studies have been performed on the genetic architecture of antisocial behaviour, only four previous studies have examined a genetic contribution to pro-social behaviour. Earlier work by the author with the University of London Institute of Psychiatry Adult Twin Register found that genes contributed approximately half of the variance to measures of self-report altruism, empathy, nurturance and aggression, including acts of violence. The present study extends those results by using a 22-item Social Responsibility Questionnaire with 174 pairs of monozygotic twins and 148 pairs of dizygotic twins. Forty-two per cent of the reliable variance was due to the twins' genes, 23% to the twins' common environment and the remainder to the twins' non-shared environment.

Fetal growth disorders in twin gestations.

LENUS (Irish Health Repository)

Breathnach, Fionnuala M

2012-06-01

Twin growth is frequently mismatched. This review serves to explore the pathophysiologic mechanisms that underlie growth aberrations in twin gestations, the prenatal recognition of abnormal twin growth, and the critical importance of stratifying management of abnormal twin growth by chorionicity. Although poor in utero growth of both twins may reflect maternal factors resulting in global uteroplacental dysfunction, discordant twin growth may be attributed to differences in genetic potential between co-twins, placental dysfunction confined to one placenta only, or one placental territory within a shared placenta. In addition, twin-twin transfusion syndrome represents a distinct entity of which discordant growth is a common feature. Discordant growth is recognized as an independent risk factor for adverse perinatal outcome. Intertwin birth weight disparity of 18% or more should be considered to represent a discordance threshold, which serves as an independent risk factor for adverse perinatal outcome. At this cutoff, perinatal morbidity is found to increase both for the larger and the smaller twin within a discordant pair. There remains uncertainty surrounding the sonographic parameters that are most predictive of discordance. Although heightening of fetal surveillance in the face of discordant twin growth follows the principles applied to singleton gestations complicated by fetal growth restriction, the timing of intervention is largely influenced by chorionicity.

Differences in Religiousness in Opposite-Sex and Same-Sex Twins in a Secular Society.

Science.gov (United States)

Ahrenfeldt, Linda J; Lindahl-Jacobsen, Rune; Möller, Sören; Christensen, Kaare; Hvidtjørn, Dorte; Hvidt, Niels Christian

2016-02-01

Sex differences in religion are well known, with females generally being more religious than males, and shared environmental factors have been suggested to have a large influence on religiousness. Twins from opposite-sex (OS) and same-sex (SS) pairs may differ because of a dissimilar psycho-social rearing environment and/or because of different exposures to hormones in utero. We hypothesized that OS females may display more masculine patterns of religiousness and, vice versa, that OS males may display more feminine patterns. We used a web-based survey conducted in Denmark, which is a secular society. The survey included 2,997 twins aged 20-40 years, identified through the population-based Danish Twin Registry. We applied la Cour and Hvidt's adaptation of Fishman's three conceptual dimensions of meaning: Cognition, Practice, and Importance, and we used Pargament's measure of religious coping (RCOPE) for the assessment of positive and negative religious coping patterns. Differences between OS and SS twins were investigated using logistic regression for each sex. The analyses were adjusted for dependence within twin pairs. No significant differences in religiousness and religious coping were found for OS and SS twins except that more OS than SS females were members of the Danish National Evangelical Lutheran Church and fewer OS than SS females were Catholic, Muslim, or belonged to other religious denominations. Moreover, OS males at age 12 had higher rates of church attendance than did SS males. This study did not provide evidence for masculinization of female twins with male co-twins with regard to religiousness. Nor did it show any significant differences between OS and SS males except from higher rates of church attendance in childhood among males with female co-twins.

Search for Genomic Alterations in Monozygotic Twins Discordant for Cleft Lip and/or Palate

DEFF Research Database (Denmark)

Kimani, Jane W; Yoshiura, Koh-Ichiro; Shi, Min

2009-01-01

consisting of 1,536 SNPs, to scan for genomic alterations in a sample of monozygotic twin pairs with discordant cleft lip and/or palate phenotypes. Paired analysis for deletions, amplifications and loss of heterozygosity, along with sequence verification of SNPs with discordant genotype calls did not reveal...... any genomic discordance between twin pairs in lymphocyte DNA samples. Our results demonstrate that postzygotic genomic alterations are not a common cause of monozygotic twin discordance for isolated cleft lip and/or palate. However, rare or balanced genomic alterations, tissue-specific events...

Nephrolithiasis in identical twins: the impact of nature vs nurture.

Science.gov (United States)

Haleblian, George E; Cantor, David A; Sur, Roger L; Assimos, Dean G; Preminger, Glenn M

2007-09-01

To assess possible underlying metabolic abnormalities in three sets of monozygotic twins, to evaluate the interplay among the factors of kidney stone formation, a complex multifactorial process influenced by environmental, genetic and anatomical factors. Three sets of identical twins with either cystine or calcium oxalate stones were identified. Demographic data, medical histories and the results of 24-h urine testing, with samples collected on self-selected diets, were reviewed and analysed. The cystinuric twins had very similar cystine excretion rates, while stone activity was significantly more pronounced in one. Metabolic abnormalities were concordant in one set of twins with calcium oxalate stones, both being hypercalciuric and hyperuricosuric. However, metabolic abnormalities were discordant in the other pair, one twin with hypercalciuria and the other with hypocitraturia. Two of the three pairs had low urinary volume. These results support previous observations that environmental, genetic and potentially, anatomical factors play roles in kidney-stone formation. Additional controlled studies of monozygotic stone-forming twins might help to define the interplay between environmental and genetic factors, and allow the identification of susceptibility genes involved in stone generation.

Power Estimation for Gene-Longevity Association Analysis Using Concordant Twins

DEFF Research Database (Denmark)

Tan, Qihua; Zhao, Jing Hua; Kruse, Torben A

2014-01-01

Statistical power is one of the major concerns in genetic association studies. Related individuals such as twins are valuable samples for genetic studies because of their genetic relatedness. Phenotype similarity in twin pairs provides evidence of genetic control over the phenotype variation...... in a population. The genetic association study on human longevity, a complex trait that is under control of both genetic and environmental factors, has been confronted by the small sample sizes of longevity subjects which limit statistical power. Twin pairs concordant for longevity have increased probability...... an approximate of 2- to 3-fold increase in sample sizes needed for longevity cutoff at age 90 as compared with that at age 95. Overall, our results showed high value of twins in genetic association studies on human longevity....

Effect of birth order on neonatal morbidity and mortality among very low birthweight twins: a population based study

Science.gov (United States)

Shinwell, E; Blickstein, I; Lusky, A; Reichman, B

2004-01-01

Objective: To study the effect of birth order on the risk for respiratory distress syndrome (RDS), chronic lung disease (CLD), adverse neurological findings, and death in very low birthweight (VLBW; < 1500 g) twins. Methods: A population based study of VLBW infants from the Israel National VLBW Infant Database. The sample included all complete sets of VLBW twin pairs admitted to all 28 neonatal intensive care units between 1995 and 1999. Outcome variables were compared by birth order and stratified by mode of delivery and gestational age, using General Estimating Equation models, with results expressed as odds ratio (OR) with 95% confidence interval (CI). Results: Second twins were at increased risk for RDS (OR 1.51, 95% CI 1.29 to 1.76), CLD (OR 1.36, 95% CI 1.11 to 1.66), and death (OR 1.24, 95% CI 1.02 to 1.51) but not for adverse neurological findings (OR 1.20, 95% CI 0.91 to 1.60). Mode of delivery did not significantly influence outcome. The odds ratio for RDS in the second twin was inversely related to gestational age, and the increased risk for RDS and CLD was found in both vaginal and caesarean deliveries. Conclusions: VLBW second twins are at increased risk for acute and chronic lung disease and neonatal mortality, irrespective of mode of delivery. PMID:14977899

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.

Risk of Monozygotic Twins After Assisted Reproduction: A Population-Based Approach.

Science.gov (United States)

Parazzini, Fabio; Cipriani, Sonia; Bianchi, Stefano; Bulfoni, Camilla; Bortolus, Renata; Somigliana, Edgardo

2016-02-01

Recent studies have suggested that ovarian stimulation and assisted reproductive techniques (ART) may increase the frequency of monozygotic twins. In this article, we present the analysis of the estimated frequency of twin deliveries following in vitro fertilization (IVF) in Lombardy during the period 2010-2014 for a total of 450,949 pregnancies. This is a population-based study using data from the regional data base of Lombardy, a northern Italian region with a population of about 10 million inhabitants. During the considered period, a total of 461,424 single or multiple births were registered in Lombardy. After exclusion of triplets or more pregnancies, the total number of twin deliveries, in separate strata of like and unlike sex pregnancies twin deliveries, were obtained and the rate of twin deliveries was computed according to spontaneous and non-spontaneous conception and type of ART. Further, estimates of dizygotic or monozygotic twin births were calculated using Weinberg's methods. The frequency of twins deliveries was 1.24/100 deliveries after natural conception and 20.05 after assisted conception. The estimated rates of monozygotic twins was 0.45 and 0.72/100 (95% CI: 0.58-0.91) deliveries after natural and assisted conception, respectively. This difference was statistically significant (p assisted than after natural conception.

Labeling of Chromosomes in Cell Development and the Appearance of Monozygotic Twins.

Science.gov (United States)

Jim, Carol; Berkovich, Simon

2015-01-01

Understanding the mechanism behind the structure of the internal cellular clock can lead to advances in the knowledge of origins of pairs of monozygotic twins and higher order multiples as well as other biological phenomena. To gain insight into this mechanism, we analyze possible cell labeling schemes that model an organism's development. Our findings lead us to predict that monozygotic quadruplets are not quadruplets in the traditional sense but rather two pairs of monozygotic twins where the pairs slightly differ-a situation we coin quadruplet twins. From the considered model, the probability of monozygotic twins is found to be (1/2) (K) , and we discover that the probability of monozygotic quadruplets, or triplets as in the case of the death of an embryo, is (1/8) (K) , where K is a species-specific integer representing the number of pairs of homologous chromosomes. The parameter K may determine cancerization with a probability threshold that is approximately inversely proportional to the Hayflick limit. Exposure to some cancerization factors such as small levels of ionizing radiation and chemical pollution may not produce cancer.

Traces of embryogenesis are the same in monozygotic and dizygotic twins: not compatible with double ovulation.

Science.gov (United States)

Boklage, Charles E

2009-06-01

Common knowledge of over a century has it that monozygotic and dizygotic twinning events occur by unrelated mechanisms: monozygotic twinning 'splits' embryos, producing anomalously re-arranged embryogenic asymmetries; dizygotic twinning begins with independent ovulations yielding undisturbed parallel embryogeneses with no expectation of departures from singleton outcomes. The anomalies statistically associated with twin births are due to the re-arranged embryos of the monozygotics. Common knowledge further requires that dizygotic pairs are dichorionic; monochorionicity is exclusive to monozygotic pairs. These are fundamental certainties in the literature of twin biology. Multiple observations contradict those common knowledge understandings. The double ovulation hypothesis of dizygotic twinning is untenable. Girl-boy twins differ subtly from all other humans of either sex, absolutely not representative of all dizygotics. Embryogenesis of dizygotic twins differs from singleton development at least as much as monozygotic embryogenesis does, and in the same ways, and the differences between singletons and twins of both zygosities represent a coherent system of re-arranged embryogenic asymmetries. Dizygotic twinning and monozygotic twinning have the same list of consequences of anomalous embryogenesis. Those include an unignorable fraction of dizygotic pairs that are in fact monochorionic, plus many more sharing co-twins' cells in tissues other than a common chorion. The idea that monozygotic and dizygotic twinning events arise from the same embryogenic mechanism is the only plausible hypothesis that might explain all of the observations.

Genetic susceptibility to bilateral tinnitus in a Swedish twin cohort.

Science.gov (United States)

Maas, Iris Lianne; Brüggemann, Petra; Requena, Teresa; Bulla, Jan; Edvall, Niklas K; Hjelmborg, Jacob V B; Szczepek, Agnieszka J; Canlon, Barbara; Mazurek, Birgit; Lopez-Escamez, Jose A; Cederroth, Christopher R

2017-09-01

Genetic contributions to tinnitus have been difficult to determine due to the heterogeneity of the condition and its broad etiology. Here, we evaluated the genetic and nongenetic influences on self-reported tinnitus from the Swedish Twin Registry (STR). Cross-sectional data from the STR was obtained. Casewise concordance rates (the risk of one twin being affected given that his/her twin partner has tinnitus) were compared for monozygotic (MZ) and dizygotic (DZ) twin pairs (N = 10,464 concordant and discordant twin pairs) and heritability coefficients (the proportion of the total variance attributable to genetic factors) were calculated using biometrical model fitting procedures. Stratification of tinnitus cases into subtypes according to laterality (unilateral versus bilateral) revealed that heritability of bilateral tinnitus was 0.56; however, it was 0.27 for unilateral tinnitus. Heritability was greater in men (0.68) than in women (0.41). However, when female pairs younger than 40 years of age were selected, heritability of 0.62 was achieved with negligible effects of shared environment. Unlike unilateral tinnitus, bilateral tinnitus is influenced by genetic factors and might constitute a genetic subtype. Overall, our study provides the initial evidence for a tinnitus phenotype with a genetic influence.Genet Med advance online publication 23 March 2017.

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.

Genetic and environmental contributions to body mass index: comparative analysis of monozygotic twins, dizygotic twins and same-age unrelated siblings.

Science.gov (United States)

Segal, N L; Feng, R; McGuire, S A; Allison, D B; Miller, S

2009-01-01

Earlier studies have established that a substantial percentage of variance in obesity-related phenotypes is explained by genetic components. However, only one study has used both virtual twins (VTs) and biological twins and was able to simultaneously estimate additive genetic, non-additive genetic, shared environmental and unshared environmental components in body mass index (BMI). Our current goal was to re-estimate four components of variance in BMI, applying a more rigorous model to biological and virtual multiples with additional data. Virtual multiples share the same family environment, offering unique opportunities to estimate common environmental influence on phenotypes that cannot be separated from the non-additive genetic component using only biological multiples. Data included 929 individuals from 164 monozygotic twin pairs, 156 dizygotic twin pairs, five triplet sets, one quadruplet set, 128 VT pairs, two virtual triplet sets and two virtual quadruplet sets. Virtual multiples consist of one biological child (or twins or triplets) plus one same-aged adoptee who are all raised together since infancy. We estimated the additive genetic, non-additive genetic, shared environmental and unshared random components in BMI using a linear mixed model. The analysis was adjusted for age, age(2), age(3), height, height(2), height(3), gender and race. Both non-additive genetic and common environmental contributions were significant in our model (P-valuesrole in BMI and that common environmental factors such as diet or exercise also affect BMI. This conclusion is consistent with our earlier study using a smaller sample and shows the utility of virtual multiples for separating non-additive genetic variance from common environmental variance.

Does the sex of one's co-twin affect height and BMI in adulthood? : A study of dizygotic adult twins from 31 cohorts

NARCIS (Netherlands)

Bogl, Leonie H; Jelenkovic, Aline; Vuoksimaa, Eero; Ahrenfeldt, Linda; Pietiläinen, Kirsi H; Stazi, Maria A; Fagnani, Corrado; D'Ippolito, Cristina; Hur, Yoon-Mi; Jeong, Hoe-Uk; Silberg, Judy L; Eaves, Lindon J; Maes, Hermine H; Bayasgalan, Gombojav; Narandalai, Danshiitsoodol; Cutler, Tessa L; Kandler, Christian; Jang, Kerry L; Christensen, Kaare; Skytthe, Axel; Kyvik, Kirsten Ohm; Cozen, Wendy; Hwang, Amie E; Mack, Thomas M; Derom, Catherine A; Vlietinck, Robert F; Nelson, Tracy L; Whitfield, Keith E; Corley, Robin P; Huibregtse, Brooke M; McAdams, Tom A; Eley, Thalia C; Gregory, Alice M; Krueger, Robert F; McGue, Matt; Pahlen, Shandell; Willemsen, Gonneke; Bartels, Meike; Pang, Zengchang; Tan, Qihua; Zhang, Dongfeng; Martin, Nicholas G; Medland, Sarah E; Montgomery, Grant W; Hjelmborg, Jacob V B; Rebato, Esther; Swan, Gary E; Krasnow, Ruth; Busjahn, Andreas; Lichtenstein, Paul; Öncel, Sevgi Y; Aliev, Fazil; Baker, Laura A; Tuvblad, Catherine; Siribaddana, Sisira H; Hotopf, Matthew; Sumathipala, Athula; Rijsdijk, Fruhling; Magnusson, Patrik K E; Pedersen, Nancy L; Aslan, Anna K Dahl; Ordoñana, Juan R; Sánchez-Romera, Juan F; Colodro-Conde, Lucia; Duncan, Glen E; Buchwald, Dedra; Tarnoki, Adam D; Tarnoki, David L; Yokoyama, Yoshie; Hopper, John L; Loos, Ruth J F; Boomsma, Dorret I; Sørensen, Thorkild I A; Silventoinen, Karri; Kaprio, Jaakko; van Beijsterveldt, C.E.M.

2017-01-01

BACKGROUND: The comparison of traits in twins from opposite-sex (OS) and same-sex (SS) dizygotic twin pairs is considered a proxy measure of prenatal hormone exposure. To examine possible prenatal hormonal influences on anthropometric traits, we compared mean height, body mass index (BMI), and the

Maternal feeding practices and fussy eating in toddlerhood: a discordant twin analysis.

Science.gov (United States)

Harris, Holly A; Fildes, Alison; Mallan, Kimberley M; Llewellyn, Clare H

2016-07-13

Parental feeding practices are thought to play a causal role in shaping a child's fussiness; however, a child-responsive model suggests that feeding practices may develop in response to a child's emerging appetitive characteristics. We used a novel twin study design to test the hypothesis that mothers vary their feeding practices for twin children who differ in their 'food fussiness', in support of a child-responsive model. Participants were mothers and their 16 month old twin children (n = 2026) from Gemini, a British twin birth cohort of children born in 2007. Standardized psychometric measures of maternal 'pressure to eat', 'restriction' and 'instrumental feeding', as well as child 'food fussiness', were completed by mothers. Within-family analyses examined if twin-pair differences in 'food fussiness' were associated with differences in feeding practices using linear regression models. In a subset of twins (n = 247 pairs) who were the most discordant (highest quartile) on 'food fussiness' (difference score ≥ .50), Paired Samples T-test were used to explore the magnitude of differences in feeding practices between twins. Between-family analyses used Complex Samples General Linear Models to examine associations between feeding practices and 'food fussiness'. Within-pair differences in 'food fussiness' were associated with differential 'pressure to eat' and 'instrumental feeding' (ps feeding' were positively associated with 'food fussiness', while 'restriction' was negatively associated with 'food fussiness' (ps feeding practices according to their perceptions of their toddler's emerging fussy eating behavior. Specifically, the fussier toddler is pressured more than their less fussy co-twin, and is more likely to be offered food rewards. Guiding parents on how to respond to fussy eating may be an important aspect of promoting feeding practices that encourage food acceptance.

Molecular analysis of the gut microbiota of identical twins with Crohn's disease.

Science.gov (United States)

Dicksved, Johan; Halfvarson, Jonas; Rosenquist, Magnus; Järnerot, Gunnar; Tysk, Curt; Apajalahti, Juha; Engstrand, Lars; Jansson, Janet K

2008-07-01

Increasing evidence suggests that a combination of host genetics and the composition of the gut microbiota are important for development of Crohn's disease (CD). Our aim was to study identical twins with CD to determine microbial factors independent of host genetics. Fecal samples were studied from 10 monozygotic twin pairs with CD (discordant n=6 and concordant n=4) and 8 healthy twin pairs. DNA was extracted, 16S rRNA genes were PCR amplified and T-RFLP fingerprints generated using general bacterial and Bacteroides group-specific primers. The microbial communities were also profiled based on their percentage G+C contents. Bacteroides 16S rRNA genes were cloned and sequenced from a subset of the samples. The bacterial diversity in each sample and similarity indices between samples were estimated based on the T-RFLP data using a combination of statistical approaches. Healthy individuals had a significantly higher bacterial diversity compared to individuals with CD. The fecal microbial communities were more similar between healthy twins than between twins with CD, especially when these were discordant for the disease. The microbial community profiles of individuals with ileal CD were significantly different from healthy individuals and those with colonic CD. Also, CD individuals had a lower relative abundance of B. uniformis and higher relative abundances of B. ovatus and B. vulgatus. Our results suggest that genetics and/or environmental exposure during childhood, in part, determine the gut microbial composition. However, CD is associated with dramatic changes in the gut microbiota and this was particularly evident for individuals with ileal CD.

Urticaria in monozygotic and dizygotic twins

DEFF Research Database (Denmark)

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

2012-01-01

Aim. To identify risk factors for urticaria, to determine the relative proportion of the susceptibility to urticaria that is due to genetic factors in an adult clinical twin sample, and to further determine whether the genetic susceptibility to urticaria overlaps with the genetic susceptibility...... to atopic diseases. Methods. A total of 256 complete twin pairs and 63 single twins, who were selected from sibships with self-reported asthma via a questionnaire survey of 21,162 adult twins from the Danish Twin Registry, were clinically interviewed about a history of urticaria and examined for atopic...... diseases. Data were analysed with Cox proportional hazards regression and variance components models. Results. A total of 151 individuals (26%) had a history of urticaria, whereas 24 (4%) had had symptoms within the past year. Female sex, HR = 2.09 (1.46-2.99), P = 0.000; hay fever, HR = 1.92 (1...

The Project TALENT Twin and Sibling Study.

Science.gov (United States)

Prescott, Carol A; Achorn, Deanna Lyter; Kaiser, Ashley; Mitchell, Lindsey; McArdle, John J; Lapham, Susan J

2013-02-01

Project TALENT is a US national longitudinal study of about 377,000 individuals born in 1942-1946, first assessed in 1960. Students in about 1,200 schools participated in a 2-day battery covering aptitudes, abilities, interests, and individual and family characteristics (Flanagan, 1962; www.projectTALENT.org). Follow-up assessments 1, 5, and 11 years later assessed educational and occupational outcomes. The sample includes approximately 92,000 siblings from 40,000 families, including 2,500 twin pairs and 1,200 other siblings of twins. Until recently, almost no behavior genetic research has been conducted with the sample. In the original data collection information was not collected with the intent to link family members. Recently, we developed algorithms using names, addresses, birthdates, and information about family structure to link siblings and identify twins. We are testing several methods to determine zygosity, including use of yearbook photographs. In this paper, we summarize the design and measures in Project TALENT, describe the Twin and Sibling sample, and present our twin-sib-classmate model. In most twin and family designs, the 'shared environment' includes factors specific to the family combined with between-family differences associated with macro-level variables such as socioeconomic status. The school-based sampling design used in Project TALENT provides a unique opportunity to partition the shared environment into variation shared by siblings, specific to twins, and associated with school- and community-level factors. The availability of many measured characteristics on the family, schools, and neighborhoods enhances the ability to study the impact of specific factors on behavioral variation.

ON THE OBSERVATION AND SIMULATION OF SOLAR CORONAL TWIN JETS

Energy Technology Data Exchange (ETDEWEB)

Liu, Jiajia; Wang, Yuming; Zhang, Quanhao [CAS Key Laboratory of Geospace Environment, School of Earth and Space Sciences, University of Science and Technology of China, NO. 96, Jinzhai Road, Hefei, Anhui 230026 (China); Fang, Fang [Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, 1234 Innovation Drive, Boulder, CO 80303 (United States); McIntosh, Scott W.; Fan, Yuhong [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307 (United States)

2016-02-01

We present the first observation, analysis, and modeling of solar coronal twin jets, which occurred after a preceding jet. Detailed analysis on the kinetics of the preceding jet reveals its blowout-jet nature, which resembles the one studied in Liu et al. However, the erupting process and kinetics of the twin jets appear to be different from the preceding one. Lacking detailed information on the magnetic fields in the twin jet region, we instead use a numerical simulation using a three-dimensional (3D) MHD model as described in Fang et al., and find that in the simulation a pair of twin jets form due to reconnection between the ambient open fields and a highly twisted sigmoidal magnetic flux, which is the outcome of the further evolution of the magnetic fields following the preceding blowout jet. Based on the similarity between the synthesized and observed emission, we propose this mechanism as a possible explanation for the observed twin jets. Combining our observation and simulation, we suggest that with continuous energy transport from the subsurface convection zone into the corona, solar coronal twin jets could be generated in the same fashion addressed above.

On the Observation and Simulation of Solar Coronal Twin Jets

Science.gov (United States)

Liu, Jiajia; Fang, Fang; Wang, Yuming; McIntosh, Scott W.; Fan, Yuhong; Zhang, Quanhao

2016-02-01

We present the first observation, analysis, and modeling of solar coronal twin jets, which occurred after a preceding jet. Detailed analysis on the kinetics of the preceding jet reveals its blowout-jet nature, which resembles the one studied in Liu et al. However, the erupting process and kinetics of the twin jets appear to be different from the preceding one. Lacking detailed information on the magnetic fields in the twin jet region, we instead use a numerical simulation using a three-dimensional (3D) MHD model as described in Fang et al., and find that in the simulation a pair of twin jets form due to reconnection between the ambient open fields and a highly twisted sigmoidal magnetic flux, which is the outcome of the further evolution of the magnetic fields following the preceding blowout jet. Based on the similarity between the synthesized and observed emission, we propose this mechanism as a possible explanation for the observed twin jets. Combining our observation and simulation, we suggest that with continuous energy transport from the subsurface convection zone into the corona, solar coronal twin jets could be generated in the same fashion addressed above.

Twin studies advance the understanding of gene-environment interplay in human nutrigenomics.

Science.gov (United States)

Pallister, Tess; Spector, Tim D; Menni, Cristina

2014-12-01

Investigations into the genetic architecture of diet-disease relationships are particularly relevant today with the global epidemic of obesity and chronic disease. Twin studies have demonstrated that genetic makeup plays a significant role in a multitude of dietary phenotypes such as energy and macronutrient intakes, dietary patterns, and specific food group intakes. Besides estimating heritability of dietary assessment, twins provide a naturally unique, case-control experiment. Due to their shared upbringing, matched genes and sex (in the case of monozygotic (MZ) twin pairs), and age, twins provide many advantages over classic epidemiological approaches. Future genetic epidemiological studies could benefit from the twin approach particularly where defining what is 'normal' is problematic due to the high inter-individual variability underlying metabolism. Here, we discuss the use of twins to generate heritability estimates of food intake phenotypes. We then highlight the value of discordant MZ pairs to further nutrition research through discovery and validation of biomarkers of intake and health status in collaboration with cutting-edge omics technologies.

Nuchal translucency measurements are highly correlated in both mono- and dichorionic twin pairs

DEFF Research Database (Denmark)

Wøjdemann, Karen R; Larsen, Severin Olesen; Shalmi, Anne-Cathrine

2006-01-01

OBJECTIVES: To establish the distribution of serological and ultrasound first-trimester Down syndrome markers in twins and identify correlations of significance for risk calculation. METHODS: Nuchal translucency (NT), PAPP-A and betahCG data were extracted from 181 twin pregnancies (31 mono- and ...

Minority stressors, rumination, and psychological distress in monozygotic twins discordant for sexual minority status.

Science.gov (United States)

Timmins, Liam; Rimes, Katharine A; Rahman, Qazi

2017-11-07

Lesbian, gay, and bisexual (LGB) individuals report higher levels of depression and anxiety than heterosexual people. Genetic factors may be a 'common cause' of sexual minority status and psychological distress. Alternatively, these may be correlated because of non-genetic environmental factors (e.g. minority stressors). This study investigated minority stressors and distress in monozygotic twins discordant for sexual minority status. This design provides a test of the role of non-shared environmental factors while minimizing differences due to genetics. Thirty-eight twin pairs in which one was heterosexual and the other was LGB completed a survey. Differences between twin pairs in minority stressors, rumination, psychological distress, and gender non-conformity were examined. Associations between these variables were also tested. Although there were no significant group differences for distress, LGB twins had higher rumination, a vulnerability factor for distress, than heterosexual co-twins. LGB twins also had higher scores than heterosexual co-twins on expectations of rejection, active concealment, self-stigma, prejudice events, childhood gender non-conformity, and lower scores on sexual orientation disclosure. Differences between twin pairs in rumination were positively associated with differences in acceptance concerns and self-stigma. Finally, self-stigma was positively associated with rumination in the full sample of heterosexual co-twins and microaggressions were positively associated with rumination when looking at exclusively heterosexual co-twins. These results support environmental factors as a causal explanation for disparities in rumination between LGB and heterosexual individuals. These factors likely include minority stressors. Rumination may also be associated with minority stressors in heterosexual MZ co-twins of LGB individuals.

Magnetic resonance in multiple sclerose twins

International Nuclear Information System (INIS)

Polman, C.H.; UitdeHaag, B.M.J.; Koetsier, C.J.; Valk, J.; Lucas, C.J.

1989-01-01

Magnetic resonance imaging (MR) examinations were performed in a series of 7 twin sets (4 monozygotic and 3 dizygotic) and one triplet set who were clinically discordant for multiple sclerosis (MS). MRI abnormalities were detected in a number of the unaffected members of the nonzygotic twin pairs. The authors discuss the possible implications of their findings for the present view on the aetiology of MS. (author). 3 refs.; 1 fig.; 1 tab

[Genetic and environmental contributions to body mass index in a Spanish adolescent twin sample].

Science.gov (United States)

Iranzo-Tatay, Carmen; Gimeno-Clemente, Natalia; Livianos-Aldana, Lorenzo; Rojo-Moreno, Luis

2015-08-21

Twin and family studies support large genetic influences on variability in body mass index (BMI), with heritability estimates ranging from 47% to over 90%. Our objective was to study the relative contributions of genetics and environment to BMI, evaluating sex differences, in an adolescent twin sample from Valencia, Spain. Five hundred eighty-four pairs of adolescent twins between 13 and 18 years of age completed the study (82 monozygotic [MZ] and 87 dizygotic [DZ] pairs of male twins, 118 MZ and 102 DZ pairs of female twins, and 195 opposite-sex pairs of DZ twins). To determine zygosity, teachers responded a questionnaire on physical similarity. They also measured the participant's height and weight. BMI was calculated and weight status was determined according to age. We used twin models to assess genetic and environmental (common and unique) factors affecting BMI. There was a 7.1% frequency of overweight and 2.8% of obesity. The estimated heritability of BMI was 88.0% in boys and 72.1% in girls, with the remaining variance attributable to non-shared environment in boys (12.0%) and 8.8% in girls. It was only in girls that common environment had an effect on BMI. Genetics appears to play an important role in explaining the variability in BMI in the adolescence, with slight variations between boys and girls. Common environmental factors exert their influence on BMI only in girls. Copyright © 2014 Elsevier España, S.L.U. All rights reserved.

Does the sex of one’s co-twin affect height and BMI in adulthood? A study of dizygotic adult twins from 31 cohorts

DEFF Research Database (Denmark)

Bogl, Leonie H; Jelenkovic, Aline; Vuoksimaa, Eero

2017-01-01

Background: The comparison of traits in twins from opposite-sex (OS) and same-sex (SS) dizygotic twin pairs is considered a proxy measure of prenatal hormone exposure. To examine possible prenatal hormonal influences on anthropometric traits, we compared mean height, body mass index (BMI), and th...

Aortic distensibility as a surrogate for intertwin pulse pressure differences in monochorionic pregnancies with and without twin-twin transfusion syndrome.

Science.gov (United States)

Wohlmuth, C; Osei, F A; Moise, K J; Johnson, A; Papanna, R; Bebbington, M; Gardiner, H M

2016-08-01

Twin-twin transfusion syndrome (TTTS) complicates 10-15% of monochorionic diamniotic (MCDA) twin pregnancies. The donor response to hypovolemia allows the transfer of vasoactive mediators to the recipient, causing increased recipient afterload and hypertension. Our objective was to apply a novel speckle-tracking technique to measure the aortic fractional area change (AFAC) during the cardiac cycle in MCDA twins with and without TTTS, and identify intertwin differences in AFAC and parameters of cardiac function. High-frame rate four-chamber views of the fetal heart, including the mid-thoracic aorta, were collected prospectively in MCDA twin pairs referred to our center between June 2014 and April 2015. Using speckle-tracking software, the endovascular border of the aorta was traced manually during systole, with guidance on cardiac cycle timing by anatomical M-mode. AFAC, defined as the difference between maximum and minimum area divided by minimum area, expressed as a percentage, was calculated offline and averaged over three cardiac cycles. Tissue Doppler and displacement were used to measure long-axis cardiac function. Intra- and interclass correlation coefficients were used to test observer variability. Fifty-one MCDA twin pregnancies were included, comprising uncomplicated MCDA (n = 14), TTTS Stages 1/2 (n = 21) and TTTS Stages 3/4 (n = 16). Median gestational age was 20.4 (range, 16.2-27.5) weeks. Mean ± SD heart rate was 142.6 ± 7.2 bpm with no significant intertwin pair differences. AFAC was significantly higher in recipients than in donors of TTTS pairs (Stages 1/2: 72.3 ± 29.9% vs 43.7 ± 19.3%, P pregnancies with TTTS. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

The accuracy of self-reported history of seizures in Danish, Norwegian and U.S. twins

DEFF Research Database (Denmark)

Corey, Linda A; Kjeldsen, Marianne J; Solaas, Marit H

2009-01-01

. The accuracy of these reports was assessed. Self-reported epilepsy was verified in 81.9% of twins overall (86.1% (DTR), 75.6% (NTR) and 80.7% (MATR)). However, when both pair members reported a history of epilepsy in the affected pair member, epilepsy was verified in >90% of cases. Among MATR twins...... of this approach in identifying true cases. Information on history of seizures obtained by questionnaire from members of 47,626 twin pairs included in the Mid-Atlantic (MATR), Danish (DTR) and Norwegian (NTR) Twin Registries was verified using medical records and detailed clinical and family interviews...... with a verified history of epilepsy, 21.5% reported other seizures but not epilepsy and 18.5% of verified Norwegian epilepsy cases reported no history of epilepsy themselves and were identified only through their co-twin. The results of this study indicate that the accuracy of self-reported epilepsy and febrile...

Gut resistome development in healthy twin pairs in the first year of life.

Science.gov (United States)

Moore, Aimee M; Ahmadi, Sara; Patel, Sanket; Gibson, Molly K; Wang, Bin; Ndao, Malick I; Deych, Elena; Shannon, William; Tarr, Phillip I; Warner, Barbara B; Dantas, Gautam

2015-01-01

The early life of the human host marks a critically important time for establishment of the gut microbial community, yet the developmental trajectory of gut community-encoded resistance genes (resistome) is unknown. We present a longitudinal study of the fecal antibiotic resistome of healthy amoxicillin-exposed and antibiotic-naive twins and their mothers during the first year of life. We extracted metagenomic DNA (mgDNA) from fecal samples collected from three healthy twin pairs at three timepoints (1 or 2 months, 6 or 7 months, and 11 months) and from their mothers (collected at delivery). The mgDNA was used to construct metagenomic expression libraries in an Escherichia coli host. These libraries were screened for antibiotic resistance, and functionally selected resistance genes were sequenced and annotated. A diverse fecal resistome distinct from the maternal resistome was apparent by 2 months of age, and infants' fecal resistomes included resistance to clinically important broad-spectrum beta-lactam antibiotics (e.g., piperacillin-tazobactam, aztreonam, cefepime) not found in their mothers. Dissemination of resistance genes among members of a given family was positively correlated with sharing of those same resistance genes between unrelated families, potentially identifying within-family sharing as a marker of resistance genes emerging in the human community at large. Finally, we found a distinct developmental trajectory for a community-encoded function: chloramphenicol resistance. All study subjects at all timepoints harbored chloramphenicol resistance determinants, but multidrug efflux pumps (rarely found in mothers) were the primary effectors of chloramphenicol resistance in young infants. Chloramphenicol acetyltransferases were more common in mothers than in infants and were found in nearly all the infants at later timepoints. Our results suggest that healthy 1-2-month-old infants' gut microbes harbor clinically relevant resistance genes distinct from

Labeling of Chromosomes in Cell Development and the Appearance of Monozygotic Twins

Directory of Open Access Journals (Sweden)

Carol Jim

2015-01-01

Full Text Available Understanding the mechanism behind the structure of the internal cellular clock can lead to advances in the knowledge of origins of pairs of monozygotic twins and higher order multiples as well as other biological phenomena. To gain insight into this mechanism, we analyze possible cell labeling schemes that model an organism’s development. Our findings lead us to predict that monozygotic quadruplets are not quadruplets in the traditional sense but rather two pairs of monozygotic twins where the pairs slightly differ—a situation we coin quadruplet twins. From the considered model, the probability of monozygotic twins is found to be 1/2K, and we discover that the probability of monozygotic quadruplets, or triplets as in the case of the death of an embryo, is 1/8K, where K is a species-specific integer representing the number of pairs of homologous chromosomes. The parameter K may determine cancerization with a probability threshold that is approximately inversely proportional to the Hayflick limit. Exposure to some cancerization factors such as small levels of ionizing radiation and chemical pollution may not produce cancer.

Metal-mediated DNA base pairing: alternatives to hydrogen-bonded Watson-Crick base pairs.

Science.gov (United States)

Takezawa, Yusuke; Shionoya, Mitsuhiko

2012-12-18

With its capacity to store and transfer the genetic information within a sequence of monomers, DNA forms its central role in chemical evolution through replication and amplification. This elegant behavior is largely based on highly specific molecular recognition between nucleobases through the specific hydrogen bonds in the Watson-Crick base pairing system. While the native base pairs have been amazingly sophisticated through the long history of evolution, synthetic chemists have devoted considerable efforts to create alternative base pairing systems in recent decades. Most of these new systems were designed based on the shape complementarity of the pairs or the rearrangement of hydrogen-bonding patterns. We wondered whether metal coordination could serve as an alternative driving force for DNA base pairing and why hydrogen bonding was selected on Earth in the course of molecular evolution. Therefore, we envisioned an alternative design strategy: we replaced hydrogen bonding with another important scheme in biological systems, metal-coordination bonding. In this Account, we provide an overview of the chemistry of metal-mediated base pairing including basic concepts, molecular design, characteristic structures and properties, and possible applications of DNA-based molecular systems. We describe several examples of artificial metal-mediated base pairs, such as Cu(2+)-mediated hydroxypyridone base pair, H-Cu(2+)-H (where H denotes a hydroxypyridone-bearing nucleoside), developed by us and other researchers. To design the metallo-base pairs we carefully chose appropriate combinations of ligand-bearing nucleosides and metal ions. As expected from their stronger bonding through metal coordination, DNA duplexes possessing metallo-base pairs exhibited higher thermal stability than natural hydrogen-bonded DNAs. Furthermore, we could also use metal-mediated base pairs to construct or induce other high-order structures. These features could lead to metal-responsive functional

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.

Exploring Subclinical Phenotypic Features in Twin Pairs Discordant for Cleft Lip and Palate

DEFF Research Database (Denmark)

Leslie, Elizabeth J; Carlson, Jenna C; Cooper, Margaret E

2017-01-01

OBJECTIVE: Monozygotic twins of an individual with an orofacial cleft have a significantly elevated risk for orofacial cleft compared with the general population, but still the concordance rate for orofacial cleft in monozygotic twins is about 40% to 50%. The goal of this study was to determine w...

Evidences of extragalactic origin and planet engulfment in the metal-poor twin pair HD 134439/HD 134440

Science.gov (United States)

Reggiani, Henrique; Meléndez, Jorge

2018-04-01

Recent studies of chemical abundances in metal-poor halo stars show the existence of different populations, which is important for studies of Galaxy formation and evolution. Here, we revisit the twin pair of chemically anomalous stars HD 134439 and HD 134440, using high resolution (R ˜ 72 000) and high S/N ratio (S/N ˜ 250) HDS/Subaru spectra. We compare them to the well-studied halo star HD 103095, using the line-by-line differential technique to estimate precise stellar parameters and LTE chemical abundances. We present the abundances of C, O, Na, Mg, Si, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Sr, Y, Ba, La, Ce, Nd, and Sm. We compare our results to the precise abundance patterns of Nissen & Schuster (2010) and data from dwarf Spheroidal galaxies (dSphs). We show that the abundance pattern of these stars appears to be closely linked to that of dSphs with [α/Fe] knee below [Fe/H] < -1.5. We also find a systematic difference of 0.06 ± 0.01 dex between the abundances of these twin binary stars, which could be explained by the engulfment of a planet, thus suggesting that planet formation is possible at low metallicities ([Fe/H] = -1.4).

Epidemiological and clinical analysis of a consecutive series of conjoined twins in Spain.

Science.gov (United States)

Martínez-Frías, María Luisa; Bermejo, Eva; Mendioroz, Jacobo; Rodríguez-Pinilla, Elvira; Blanco, Manuel; Egüés, Javier; Félix, Valentín; García, Angel; Huertas, Héctor; Nieto, Carmen; López, José Antonio; López, Santiago; Paisán, Luis; Rosa, Alejandro; Vázquez, María Socorro

2009-04-01

The aim of the study was to analyze the frequency and certain epidemiological characteristics of a consecutive series of conjoined twins born in Spain. We used data from the Spanish Collaborative Study of Congenital Malformations for the period April 1976 to 2006. Because the Spanish law permitting voluntary termination of pregnancies (TOP) when the fetus presented malformations was effective by the end of 1985, we analyzed the data in 4 periods, 2 before 1986 and 2 after. During the first period (1976-1979) only live births were recorded, whereas both still and live births were included in the other three (1980-1985, 1986-1995, and 1996-2006). In the present study, the cases were classified as symmetrical (16 pairs) and asymmetrical (1 pair) conjoined twins. Each pair of conjoined twins was considered as only one case for calculations, regardless of the type of union. Among a total of 2,281,604 consecutive births between 1980 and 2006, there were a total of 15 cases of symmetrical conjoined twins giving a frequency of 0.70 per 100,000 (1/152,107), whereas there was only 1 stillborn asymmetrical conjoined twin pair (0.04/100,000). Among the 13,418 consecutive stillborns surveyed, 6 cases of conjoined twins were identified (either symmetrical or asymmetrical) giving a frequency of 44.72 per 100,000, and 11 pairs were identified among the 2,425,583 total live births surveyed during the first period 1976 to 1979, a frequency of 0.45 per 100,000. Thus, the frequency among stillborn infants is 99.34 times higher than that observed among live births. However, the frequency for the total births (3 last periods) showed a decreasing trend from 1.47 per 100,000 birth in the first period (1980-1985) when TOP was illegal, to a value of 0.09 per 100,000 in the last period, more than 16-fold lower, probably because of the TOP of affected fetuses. Therefore, we consider that the frequencies observed in the period 1980 to 1985 are the basal values in our population. The most

Risk factors for Staphylococcus aureus nasal colonization in Danish middle-aged and elderly twins

DEFF Research Database (Denmark)

Andersen, P S; Larsen, Lisbeth Aagaard; Fowler, V G

2013-01-01

on S. aureus carriage in Danish middle-aged and elderly twins, which indicated no significant heritability that could account for the observed S. aureus carriage. In the present study, we performed a questionnaire-based study of S. aureus colonization on the same cohort of 2,196 Danish middle......-aged and elderly twins to identify specific risk factors for S. aureus nasal colonization, including analyzing the paired twins (n = 478) that were discordant for S. aureus colonization. We found associations between risk factors and S. aureus nasal colonization among middle-aged and elderly twins, including age......, male gender, psoriasis, and atopic diseases. Also, present living on a farm is clearly associated with S. aureus colonization, while smoking had a borderline statistically significant protective effect....

The Child and Adolescent Twin Study in Sweden (CATSS).

Science.gov (United States)

Anckarsäter, Henrik; Lundström, Sebastian; Kollberg, Linnea; Kerekes, Nora; Palm, Camilla; Carlström, Eva; Långström, Niklas; Magnusson, Patrik K E; Halldner, Linda; Bölte, Sven; Gillberg, Christopher; Gumpert, Clara; Råstam, Maria; Lichtenstein, Paul

2011-12-01

The Child and Adolescent Twin Study in Sweden (CATSS) is an ongoing longitudinal twin study targeting all twins born in Sweden since July 1, 1992. Since 2004, parents of twins are interviewed regarding the children's somatic and mental health and social environment in connection with their 9th or 12th birthdays (CATSS-9/12). By January 2010, 8,610 parental interviews concerning 17,220 twins had been completed, with an overall response rate of 80%. At age 15 (CATSS-15) and 18 (CATSS-18), twins and parents complete questionnaires that, in addition to assessments of somatic and mental health, include measures of personality development and psychosocial adaptation. Twin pairs in CATSS-9/12 with one or both twins screening positive for autism spectrum disorders, attention deficit/hyperactivity disorder, tic disorders, developmental coordination disorder, learning disorders, oppositional defiant disorder, conduct disorder, obsessive-compulsive disorder, and/or eating problems have been followed with in-depth questionnaires on family, social environment and personality, and subsequently by clinical assessments at age 15 together with randomly selected population controls, including 195 clinically assessed twin pairs from the first 2 year cohorts (CATSS-15/DOGSS). This article describes the cohorts and study groups, data collection, and measures used. Prevalences, distributions, heritability estimates, ages at onset, and sex differences of mental health problems in the CATSS-9/12, that were analyzed and found to be overall comparable to those of other clinical and epidemiological studies. The CATSS study has the potential of answering important questions on the etiology of childhood mental health problems and their role in the development of later adjustment problems.

Sleep Terrors in Twins

OpenAIRE

J Gordon Millichap

2008-01-01

In an attempt to clarify the genetic and environmental causes of sleep terrors in childhood, reasearchers in Canada followed 390 pairs of monozygotic and dizygotic twins by assessing the frequency of sleep terrors at 18 and 30 months of age using a questionnaire administered to the biological mothers.

Secular trends in gestational age and birthweight in twins.

Science.gov (United States)

Gielen, M; van Beijsterveldt, C E M; Derom, C; Vlietinck, R; Nijhuis, J G; Zeegers, M P A; Boomsma, D I

2010-09-01

In recent decades, the overall rate of preterm births has increased. The aim of the present study was to examine whether this trend is also seen for multiple gestations. More specifically, we examined if there has been a decrease in gestational age for live born monozygotic (MZ) and dizygotic (DZ) twins and if there has been a simultaneous change in birthweight. The contributions of fertility treatments and Caesarean sections were taken into consideration. All analyses were carried out in two large European twin cohorts. Cross-sectional study of 6310 live born twin pairs, born between 1964-2007, from the Belgian East Flanders Prospective Twin Survey and 14,712 twin pairs, born between 1990-2006, from the Netherlands Twin Register. Multiple regression analyses were performed with gestational age as outcome variable, and multilevel analysis with birthweight as outcome variable. All analyses were performed with and without adjustment for zygosity, parity, maternal age, mode of conception and delivery and, for the analyses of birthweight, gestational age. Gestational age decreased in a linear fashion from 1964 to 2007 with a decrease of 0.25 days per year in a similar way for MZ and DZ twins. Changes in birthweight depended on gestational age: up to 32 weeks, birthweight decreased and after 32 weeks birthweight increased. The frequency of infertility treatment and Caesarean sections, primiparity and advanced maternal age increased over the years, but none of these factors influenced the secular trends in gestational age and birthweight. The decrease in gestational age and change in birthweight in twins are sources of concern, especially for very preterm twins, for whom birthweight decreased. For twins born after 32 weeks, an increase in birthweight was observed and this is very likely the explanation for the decrease in gestational age.

Methylomic analysis of monozygotic twins discordant for autism spectrum disorder and related behavioural traits.

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Wong, C C Y; Meaburn, E L; Ronald, A; Price, T S; Jeffries, A R; Schalkwyk, L C; Plomin, R; Mill, J

2014-04-01

Autism spectrum disorder (ASD) defines a group of common, complex neurodevelopmental disorders. Although the aetiology of ASD has a strong genetic component, there is considerable monozygotic (MZ) twin discordance indicating a role for non-genetic factors. Because MZ twins share an identical DNA sequence, disease-discordant MZ twin pairs provide an ideal model for examining the contribution of environmentally driven epigenetic factors in disease. We performed a genome-wide analysis of DNA methylation in a sample of 50 MZ twin pairs (100 individuals) sampled from a representative population cohort that included twins discordant and concordant for ASD, ASD-associated traits and no autistic phenotype. Within-twin and between-group analyses identified numerous differentially methylated regions associated with ASD. In addition, we report significant correlations between DNA methylation and quantitatively measured autistic trait scores across our sample cohort. This study represents the first systematic epigenomic analyses of MZ twins discordant for ASD and implicates a role for altered DNA methylation in autism.

Excess Mortality in Hyperthyroidism: The Influence of Preexisting Comorbidity and Genetic Confounding: A Danish Nationwide Register-Based Cohort Study of Twins and Singletons

Science.gov (United States)

Brandt, Frans; Almind, Dorthe; Christensen, Kaare; Green, Anders; Brix, Thomas Heiberg

2012-01-01

Context: Hyperthyroidism is associated with severe comorbidity, such as stroke, and seems to confer increased mortality. However, it is unknown whether this increased mortality is explained by hyperthyroidism per se, comorbidity, and/or genetic confounding. Objective: The objective of the study was to investigate whether hyperthyroidism is associated with an increased mortality and, if so, whether the association is influenced by comorbidity and/or genetic confounding. Methods: This was an observational cohort study using record-linkage data from nationwide Danish health registers. We identified 4850 singletons and 926 twins from same-sex pairs diagnosed with hyperthyroidism. Each case was matched with four controls for age and gender. The Charlson score was calculated from discharge diagnoses on an individual level to measure comorbidity. Cases and controls were followed up for a mean of 10 yr (range 0–31 yr), and the hazard ratio (HR) for mortality was calculated using Cox regression analyses. Results: In singletons there was a significantly higher mortality in individuals diagnosed with hyperthyroidism than in controls [HR 1.37; 95% confidence interval (CI) 1.30–1.46]. This persisted after adjustment for preexisting comorbidity (HR 1,28; 95% CI 1.21–1.36). In twin pairs discordant for hyperthyroidism (625 pairs), the twin with hyperthyroidism had an increased mortality compared with the corresponding cotwin (HR 1.43; 95% CI 1.09–1.88). However, this was found only in dizygotic pairs (HR 1.80; 95% CI 1.27–2.55) but not in monozygotic pairs (HR 0.95; 95% CI 0.60–1.50). Conclusions: Hyperthyroidism is associated with an increased mortality independent of preexisting comorbidity. The study of twin pairs discordant for hyperthyroidism suggests that genetic confounding influences the association between hyperthyroidism and mortality. PMID:22930783

Report on Pairing-based Cryptography.

Science.gov (United States)

Moody, Dustin; Peralta, Rene; Perlner, Ray; Regenscheid, Andrew; Roginsky, Allen; Chen, Lily

2015-01-01

This report summarizes study results on pairing-based cryptography. The main purpose of the study is to form NIST's position on standardizing and recommending pairing-based cryptography schemes currently published in research literature and standardized in other standard bodies. The report reviews the mathematical background of pairings. This includes topics such as pairing-friendly elliptic curves and how to compute various pairings. It includes a brief introduction to existing identity-based encryption (IBE) schemes and other cryptographic schemes using pairing technology. The report provides a complete study of the current status of standard activities on pairing-based cryptographic schemes. It explores different application scenarios for pairing-based cryptography schemes. As an important aspect of adopting pairing-based schemes, the report also considers the challenges inherent in validation testing of cryptographic algorithms and modules. Based on the study, the report suggests an approach for including pairing-based cryptography schemes in the NIST cryptographic toolkit. The report also outlines several questions that will require further study if this approach is followed.

Objective assessment of facial skin aging and the associated environmental factors in Japanese monozygotic twins.

Science.gov (United States)

Ichibori, Ryoko; Fujiwara, Takashi; Tanigawa, Tomoko; Kanazawa, Shigeyuki; Shingaki, Kenta; Torii, Kosuke; Tomita, Koichi; Yano, Kenji; Sakai, Yasuo; Hosokawa, Ko

2014-06-01

Twin studies, especially those involving monozygotic (MZ) twins, facilitate the analysis of factors affecting skin aging while controlling for age, gender, and genetic susceptibility. The purpose of this study was to objectively assess various features of facial skin and analyze the effects of environmental factors on these features in MZ twins. At the Osaka Twin Research Center, 67 pairs of MZ twins underwent medical interviews and photographic assessments, using the VISIA(®) Complexion Analysis System. First, the average scores of the right and left cheek skin spots, wrinkles, pores, texture, and erythema were calculated; the differences between the scores were then compared in each pair of twins. Next, using the results of medical interviews and VISIA data, we investigated the effects of environmental factors on skin aging. The data were analyzed using Pearson's correlation coefficient test and the Wilcoxon signed-rank test. The intrapair differences in facial texture scores significantly increased as the age of the twins increased (P = 0.03). Among the twin pairs who provided answers to the questions regarding history differences in medical interviews, the twins who smoked or did not use skin protection showed significantly higher facial texture or wrinkle scores compared with the twins not exposed to cigarettes or protectants (P = 0.04 and 0.03, respectively). The study demonstrated that skin aging among Japanese MZ twins, especially in terms of facial texture, was significantly influenced by environmental factors. In addition, smoking and skin protectant use were important environmental factors influencing skin aging. © 2014 The Authors Journal of Cosmetic Dermatology Published by Wiley Periodicals, Inc.

A critical assessment of the equal environment assumption of the twin method for schizophrenia

Directory of Open Access Journals (Sweden)

Roar eFosse

2015-04-01

Full Text Available The classical twin method (CTM is central to the view that schizophrenia is ~80% heritable. The CTM rests on the equal environments assumption (EEA that identical and fraternal twin pairs experience equivalent trait relevant environmental exposures. The EEA has not been directly tested for schizophrenia with measures of child social adversity, which is particularly etiologically relevant to the disorder. However, if child social adversity is more similar in identical than fraternal pairs in the general twin population, the EEA is unlikely to be valid for schizophrenia, a question which we tested in this study. Using results from prior twin studies, we tested if intraclass correlations for the following five categories of child social adversity are larger in identical than fraternal twins: bullying, sexual abuse, physical maltreatment, emotional neglect and abuse, and general trauma. Eleven relevant studies that encompassed 9119 twin pairs provided 24 comparisons of intraclass correlations, which we grouped into the five social exposure categories. Fisher’s z-test revealed significantly higher correlations in identical than fraternal pairs for each exposure category (z ≥ 3.53, p <.001. The difference remained consistent across gender, study site (country, sample size, whether psychometric instruments were used, whether interviewing was proximate or distant to the exposures, and whether informants were twins or third persons. Combined with other evidence that the differential intraclass correlation for child social adversity cannot be explained by evocative gene-environment covariation, our results indicate that the CTM does not provide any valid indication of genomic effects in schizophrenia.

Fasting plasma total ghrelin concentrations in monozygotic twins discordant for obesity.

Science.gov (United States)

Leskelä, Piia; Ukkola, Olavi; Vartiainen, Johanna; Rönnemaa, Tapani; Kaprio, Jaakko; Bouchard, Claude; Kesäniemi, Y Antero

2009-02-01

Ghrelin is a hormone that is involved in the regulation of food intake. Neuronal, endocrine, and genetic factors have been shown to regulate plasma ghrelin levels; but the determinants of fasting ghrelin concentrations are not yet fully understood. The main aim was to explore the roles of adiposity and genetic differences in determining fasting plasma total ghrelin levels. We measured total ghrelin levels in a population of 23 monozygotic twin pairs discordant for obesity. In addition, 2 variants of ghrelin gene, namely, Arg51Gln and Leu72Met, were genotyped in 3 populations of monozygotic twin pairs: 23 obesity-discordant, 43 lean-concordant, and 46 obesity-concordant twin pairs. In discordant twins, lean co-twins had higher fasting plasma total ghrelin levels (950 pg/mL, SD = 328 pg/mL) than obese twins (720 pg/mL, SD = 143 pg/mL; P = .003). Arg51Gln-polymorphism of the ghrelin gene was equally distributed between the twin groups. However, there were significant differences in genotype frequencies at the Leu72Met polymorphism between the discordant and obese-concordant groups (P = .003) and between the discordant and lean-concordant groups (P = .011), but not between the 2 concordant groups. In the discordant group, there were fewer Met carriers (4%) than among the obese (17%) or the lean-concordant groups (15%). Plasma total ghrelin levels are affected by acquired obesity independent of genetic background. The Leu72 allele is particularly common among monozygotic twins discordant for obesity, suggesting that this ghrelin allele is more permissive in the regulation of energy balance. The ghrelin gene may thus play a role in the regulation of variability of body weight, such that Leu72 allele carriers are more prone to weight variability in response to environmental factors.

Heritability of retinal vascular fractals: a twin study

DEFF Research Database (Denmark)

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

. 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...

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.

Sleep Terrors in Twins

Directory of Open Access Journals (Sweden)

J Gordon Millichap

2008-12-01

Full Text Available In an attempt to clarify the genetic and environmental causes of sleep terrors in childhood, reasearchers in Canada followed 390 pairs of monozygotic and dizygotic twins by assessing the frequency of sleep terrors at 18 and 30 months of age using a questionnaire administered to the biological mothers.

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.

Effects of exercise training and a hypocaloric diet on female monozygotic twins in free-living conditions.

Science.gov (United States)

Koenigstorfer, Joerg; Schmidt, Walter F J

2011-10-24

This paper aims to examine the similarities in effects of exercise training and a hypocaloric diet within overweight female monozygotic twin pairs and to assess differences in twin partners' responses depending on the timing of exercise bouts and main meals. Six previously untrained twin pairs (aged 20-37 years, body fat 35.8±6.3%) performed an identical exercise program (12 bouts endurance and 8 bouts resistance training) and took part in a nutrition counseling program for a period of 28 days. They pursued one identical goal: to lose body weight and fat. Each twin partner was randomly assigned to one of the two intervention groups: "exercise after dinner" (A) and "exercise before dinner" (B). Subjects followed a hypocaloric diet, supervised by a nutritionist, in free-living conditions. Reductions in body weight, waist and hip circumference, glucose tolerance, mean daily %fat intake, changes in morning resting energy rate and resting metabolic rate showed great variation between twin pairs, but only small variation within twin pairs. Thus, the genetic influence on the changes in most of the examined anthropometric and physiological variables was high. There was no influence of the specific timing on the dependent variables. Copyright © 2011 Elsevier Inc. All rights reserved.

Atopic diseases in twins born after assisted reproduction

DEFF Research Database (Denmark)

Jäderberg, Ida; Thomsen, Simon F; Kyvik, Kirsten Ohm

2012-01-01

Jäderberg I, Thomsen SF, Kyvik KO, Skytthe A, Backer V. Atopic diseases in twins born after assisted reproduction. Paediatric and Perinatal Epidemiology 2012; 26: 140-145. We examined the risk of atopic diseases in twins born after assisted reproduction. Data on atopic diseases and assisted...... reproduction in 9694 twin pairs, 3-20 years of age, from the Danish Twin Registry were collected via multidisciplinary questionnaires. The risk of atopic diseases in twins born after assisted reproduction was compared with the risk in twins born after spontaneous conception using logistic regression...... and variance components analysis. Children born after assisted reproduction did not have a different risk of atopic outcomes (adjusted odds ratios [95% confidence intervals] for asthma: 0.95 [0.85, 1.07], P = 0.403; hay fever: 1.01 [0.86, 1.18], P = 0.918; and atopic dermatitis: 1.02 [0.81, 1.11], P = 0...

Screening and Invasive Testing in Twins

Directory of Open Access Journals (Sweden)

Giovanni Monni

2014-07-01

Full Text Available Prenatal screening and testing for trisomy 21 in twin pregnancies poses a number of challenges: the exact estimate of the a priori risk of trisomy 21, the choice of prenatal screening test and/or invasive techniques to employ for the diagnosis and the impact of the result on the options of treatment in case of discordant results within a twin pair or among multiples. These different aspects are discussed below while recognizing that many issues remain unresolved.

Associations between social capital and depression: A study of adult twins.

Science.gov (United States)

Cohen-Cline, Hannah; Beresford, Shirley Aa; Barrington, Wendy; Matsueda, Ross; Wakefield, Jon; Duncan, Glen E

2018-03-01

Social capital is associated with depression independently of individual-level risk factors. We used a sample of 1586 same-sex twin pairs to test the association between seven measures of social capital and two related measures of neighborhood characteristics with depressive symptoms accounting for uncontrolled selection factors (i.e., genetics and shared environment). All measures of cognitive social capital and neighborhood characteristics were associated with less depressive symptoms in between-twin analysis. However, only measures of cognitive social capital were significantly associated with less depressive symptoms within-pairs. These results demonstrate that cognitive social capital is associated with depressive symptoms free of confounding from genetic and environmental factors shared within twins. Copyright © 2018 Elsevier Ltd. All rights reserved.

Genetic and environmental influences on motor function: a magnetoencephalographic study of twins

Directory of Open Access Journals (Sweden)

Toshihiko eAraki

2014-06-01

Full Text Available To investigate the effect of genetic and environmental influences on cerebral motor function, we determined similarities of movement-related cortical fields (MRCFs in middle-aged and elderly monozygotic (MZ twins. MRCFs were measured using a 160-channel MEG system when MZ twins were instructed to repeat lifting of the right index finger. We compared latency, amplitude, dipole location, and dipole intensity of movement-evoked field 1 (MEF1 between 16 MZ twins and 16 pairs of genetically unrelated pairs. Differences in latency and dipole location between MZ twins were significantly less than those between unrelated age-matched pairs. However, amplitude and dipole intensity were not significantly different. These results suggest that the latency and dipole location of MEF1 are determined early in life by genetic and early common environmental factors, whereas amplitude and dipole intensity are influenced by long-term environmental factors. Improved understanding of genetic and environmental factors that influence cerebral motor function may contribute to evaluation and improvement for individual motor function.

Leisure-time physical activity and intra-abdominal fat in young adulthood: A monozygotic co-twin control study.

Science.gov (United States)

Rottensteiner, Mirva; Leskinen, Tuija; Järvelä-Reijonen, Elina; Väisänen, Karoliina; Aaltonen, Sari; Kaprio, Jaakko; Kujala, Urho M

2016-05-01

To investigate differences in abdominal fat compartments between young adult monozygotic twin pairs discordant for leisure-time physical activity. Ten young adult male monozygotic twin pairs (age range 32-36 years) discordant for leisure-time physical activity during the past 3 years were systematically selected from a population-based Finnish twin cohort. Magnetic resonance image at the level of the L2-L3 intervertebral disc was used to predict intra-abdominal and subcutaneous abdominal fat masses. Dietary intake was assessed with a 4-day food diary. Inactive twins had 31% more intra-abdominal fat than their active co-twins (mean difference 0.52 kg, 95% CI 0.12 to 0.91, P = 0.016), whereas the difference in subcutaneous abdominal fat was only 13% (P = 0.21) and 3% in body mass index (P = 0.28). Intraperitoneal fat mass was 41% higher among inactive twins compared to their active co-twins (mean difference 0.41 kg, 95% CI 0.11 to 0.70, P = 0.012). Dietary intake did not differ between co-twins. A lower level of physical activity is related to greater accumulation of intra-abdominal fat among healthy adult males in their mid-30s. The findings highlight the importance of leisure-time physical activity independent of genes and diet in the prevention of intra-abdominal fat accumulation from early adulthood onward. © 2016 The Obesity Society.

Hemoglobin Differences in Uncomplicated Monochorionic Twins in Relation to Birth Order and Mode of Delivery.

Science.gov (United States)

Verbeek, Lianne; Zhao, Depeng P; Te Pas, Arjan B; Middeldorp, Johanna M; Hooper, Stuart B; Oepkes, Dick; Lopriore, Enrico

2016-06-01

To determine the differences in hemoglobin (Hb) levels in the first 2 days after birth in uncomplicated monochorionic twins in relation to birth order and mode of delivery. All consecutive uncomplicated monochorionic pregnancies with two live-born twins delivered at our center were included in this retrospective study. We recorded Hb levels at birth and on day 2, and analyzed Hb levels in association with birth order, mode of delivery, and time interval between delivery of twin 1 and 2. A total of 290 monochorionic twin pairs were analyzed, including 171 (59%) twins delivered vaginally and 119 (41%) twins born by cesarean section (CS). In twins delivered vaginally, mean Hb levels at birth and on day 2 were significantly higher in second-born twins compared to first-born twins: 17.8 versus 16.1 g/dL and 18.0 versus 14.8 g/dL, respectively (p < .01). Polycythemia was detected more often in second-born twins (12%, 20/166) compared to first-born twins (1%, 2/166; p < .01). Hb differences within twin pairs delivered by CS were not statistically or clinically significant. We found no association between inter-twin delivery time intervals and Hb differences. Second-born twins after vaginal delivery have higher Hb levels and more often polycythemia than their co-twin, but not when born by CS.

Low birth weight is associated with NIDDM in discordant monozygotic and dizygotic twin pairs

DEFF Research Database (Denmark)

Poulsen, P; Vaag, Allan; Kyvik, K O

1997-01-01

between the putative "NIDDM susceptibility genotype" and a genetically determined low weight at birth. It is also unclear whether differences in gestational age, maternal height, birth order and/or sex could explain the association. Twins are born of the same mother and have similar gestational ages......Previous studies have demonstrated an association between low weight at birth and risk of later development of non-insulin-dependent diabetes mellitus (NIDDM). It is not known whether this association is due to an impact of intrauterine malnutrition per se, or whether it is due to a coincidence....... Furthermore, monozygotic (MZ) twins have identical genotypes. Original midwife birth weight record determinations were traced in MZ and dizygotic (DZ) twins discordant for NIDDM. Birth weights were lower in the NIDDM twins (n = 2 x 14) compared with both their identical (MZ; n = 14) and non-identical (DZ; n...

A synthetic medical and sociological study of A-bomb exposed twin, 7

International Nuclear Information System (INIS)

Watanabe, Shoji; Satow, Yukio; Kyo, Taiichi

1984-01-01

The status of A-bomb exposure and family or relative relationship were investigated in seven twin pairs exposed to A-bomb (14 survivors). The survivors ranged in age between 4 and 24 years when they were exposed to A-bomb. Twins' relationship was comparatively strong. Both of the twins who were exposed to A-bomb tended to be closely connected with each other because of the fearful experience of A-bomb exposure and the subsequent hard social life. Even though one of the pair was not exposed to A-bomb, he (she) was likely to continue to help the other for a long time to restore from the disaster. (Namekawa, K.)

Gender mix in twins and fetal growth, length of gestation and adult cancer risk.

Science.gov (United States)

Luke, Barbara; Hediger, Mary; Min, Sung-Joon; Brown, Morton B; Misiunas, Ruta B; Gonzalez-Quintero, Victor Hugo; Nugent, Clark; Witter, Frank R; Newman, Roger B; Hankins, Gary D V; Grainger, David A; Macones, George A

2005-01-01

This study evaluated the effect of gender mix (the gender combinations of twin pairs) on fetal growth and length of gestation, and reviewed the literature on the long-term effects of this altered fetal milieu on cancer risk. In singletons, it is well established that females weigh less than males at all gestations, averaging 125-135 g less at full term. This gender difference is generally believed to be the result of the effect of androgens on fetal growth. The gender difference in fetal growth is greater before the third trimester and less towards term, with males growing not only more, but also earlier than females. Plurality is a known risk factor for reduced fetal growth and birthweight. Compared with singletons, the mean birthweight percentiles of twins fall substantially (by 10% or more) below the singleton 10th percentile by 28 weeks, below the singleton 50th percentile by 30 weeks, and below the singleton 90th percentile by 34 weeks. In unlike-gender twin pairs, it has been reported that the female prolongs gestation for her brother, resulting in a higher birthweight for the male twin than that of like-gender male twins. Other researchers have demonstrated that females in unlike-gender pairs had higher birthweights than females in like-gender pairs. Analyses from our consortium on 2491 twin pregnancies with known chorionicity showed longer gestations and faster rates of fetal growth in both males and females in unlike-gender pairs compared with like-gender male or female pairs, although these differences were not statistically significant. The post-natal effects for females growing in an androgenic-anabolic environment include increased sensation-seeking behaviour and aggression, lowered visual acuity, more masculine attitudes and masculinising effects of the auditory system and craniofacial growth. In contrast, there is no evidence to suggest that there might be a similar feminising effect on males from unlike-gender pairs. This hormonal exposure in utero

Molecular analysis of the gut microbiota of identical twins with Crohn's disease

Energy Technology Data Exchange (ETDEWEB)

Jansson, Janet; Dicksved, Johan; Halfvarson, Jonas; Rosenquist, Magnus; Jarnerot, Gunnar; Tysk, Curt; Apajalahti, Juha; Engstrand, Lars; Jansson, Janet K.

2008-03-14

Increasing evidence suggests that a combination of host genetics and the composition of the gut microbiota are important for development of Crohn's disease (CD). Our aim was to study identical twins with CD to determine microbial factors independently of host genetics. Fecal samples were studied from 10 monozygotic twin pairs with CD (discordant n=6, concordant n=4) and 8 healthy twin pairs. DNA was extracted, 16S rRNA genes were PCR amplified and T-RFLP fingerprints generated using general bacterial and Bacteroides group specific primers. The microbial communities were also profiled based on their % G+C contents. Bacteroides 16S rRNA genes were cloned and sequenced from a subset of the samples. The bacterial diversity in each sample and similarity indices between samples were estimated based on the T-RFLP data using a combination of statistical approaches. Healthy individuals had a significantly higher bacterial diversity compared to individuals with CD. The fecal microbial communities were more similar between healthy twins than between twins with CD, especially when these were discordant for the disease. The microbial community profiles of individuals with ileal CD were significantly different from healthy individuals and those with colonic CD. Also, CD individuals had a lower relative abundance of B. uniformis and higher relative abundances of B. ovatus and B. vulgatus. Our results suggest that genetics and/or environmental exposure during childhood in part determine the gut microbial composition. However, CD is associated with dramatic changes in the gut microbiota and this was particularly evident for individuals with ileal CD.

Differences in Religiousness in Opposite-Sex and Same-Sex Twins in a Secular Society

DEFF Research Database (Denmark)

Juel Ahrenfeldt, Linda; Lindahl-Jacobsen, Rune; Möller, Sören

2016-01-01

(RCOPE) for the assessment of positive and negative religious coping patterns. Differences between OS and SS twins were investigated using logistic regression for each sex. The analyses were adjusted for dependence within twin pairs. No significant differences in religiousness and religious coping were......Sex differences in religion are well known, with females generally being more religious than males, and shared environmental factors have been suggested to have a large influence on religiousness. Twins from opposite-sex (OS) and same-sex (SS) pairs may differ because of a dissimilar psycho...

Investigating Unique Environmental Influences of Parenting Practices on Youth Anxiety: A Monozygotic Twin Differences Study

Science.gov (United States)

Chen, Jie; Yu, Jing; Zhang, Jianxin

2016-01-01

The associations between parenting practices and adolescent anxiety symptoms were examined in both individual and monozygotic (MZ) twin differences levels. Participants were 804 pairs of Chinese MZ adolescent twins aged 10-18 years (M = 13.57, SD = 2.67, 52% females). Twins' anxiety symptoms were assessed by self- and parent-reports. Twins also…

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.

Verification of self-report of zygosity determined via DNA testing in a subset of the NAS-NRC twin registry 40 years later.

Science.gov (United States)

Reed, Terry; Plassman, Brenda L; Tanner, Caroline M; Dick, Danielle M; Rinehart, Shannon A; Nichols, William C

2005-08-01

The National Academy of Sciences -- National Research Council (NAS-NRC) twin panel, created nearly 50 years ago, had twin zygosity determined primarily via a similarity questionnaire that has been estimated to correctly classify at least 95% of twins. In the course of a study on the genetics of healthy ageing in the NAS-NRC twins, DNA was collected for genome-wide scanning and zygosity confirmation was examined in 343 participating pairs. The sample was supplemented from two other studies using NAS-NRC twins where one or both co-twins were suspected to have Alzheimer disease or another dementia, or Parkinson's disease. Overall 578 twin pairs with DNA were analyzed. Zygosity assignment for 96.8% (519/536) was confirmed via questionnaire. Among 42 pairs whose questionnaire responses were inconclusive for assigning zygosity, 50% were found to be monozygous (MZ) and 50% were dizygous (DZ). There was some evidence for greater misclassification of presumed DZ pairs in the healthy ageing study where participation favored pairs who were similar in having a favorable health history and willingness to volunteer without any element of perceived risk for a specific disease influencing participation.

Genetic and environmental factors in alexithymia: A population-based study of 8.785 Danish twin pairs

DEFF Research Database (Denmark)

Jørgensen, Michael Martini; Zachariae, Robert; Skytthe, Axel

2007-01-01

by shared (12-20%) and nonshared environmental effects (50-56%). CONCLUSION: The results from this large population-based sample suggest that genetic factors have a noticeable and similar impact on all facets of alexithymia. While the results suggested a moderate influence of shared environmental factors......BACKGROUND: The role of genetic and environmental factors for developing alexithymia is still unclear, and the aim of this study was to examine these factors in a large population-based sample of twins. METHODS: The Toronto Alexithymia Scale-20 (TAS-20) was included in a mail survey of 46...... modeling of the noncategorical data, an ACE model including additive genetic, shared environmental and nonshared environmental effects, provided the best fit for all three facets of alexithymia as well as total alexithymia scores, with heritabilities of 30-33% and the remaining variance being explained...

A Wavelet Kernel-Based Primal Twin Support Vector Machine for Economic Development Prediction

Directory of Open Access Journals (Sweden)

Fang Su

2013-01-01

Full Text Available Economic development forecasting allows planners to choose the right strategies for the future. This study is to propose economic development prediction method based on the wavelet kernel-based primal twin support vector machine algorithm. As gross domestic product (GDP is an important indicator to measure economic development, economic development prediction means GDP prediction in this study. The wavelet kernel-based primal twin support vector machine algorithm can solve two smaller sized quadratic programming problems instead of solving a large one as in the traditional support vector machine algorithm. Economic development data of Anhui province from 1992 to 2009 are used to study the prediction performance of the wavelet kernel-based primal twin support vector machine algorithm. The comparison of mean error of economic development prediction between wavelet kernel-based primal twin support vector machine and traditional support vector machine models trained by the training samples with the 3–5 dimensional input vectors, respectively, is given in this paper. The testing results show that the economic development prediction accuracy of the wavelet kernel-based primal twin support vector machine model is better than that of traditional support vector machine.

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

DEFF Research Database (Denmark)

von Bornemann Hjelmborg, Jacob; 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...... risk and liability. Results: The cumulative risk of prostate cancer was similar to that of the background population. The cumulative risk for twins whose co-twin was diagnosed with prostate cancer was greater for MZ than for DZ twins across all ages. Among concordantly affected pairs, the time between...... 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...

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

OBJECTIVE: We hypothesize that maternal transplacentally acquired antibodies may cause Attention Deficit/Hyperactivity Disorder (ADHD) symptoms years after birth, and tested the hypothesis in twins discordant for ADHD symptoms. METHOD: In a pre-screened sample of 7793 same sex twin pair's (4......-18years) questionnaire data on hyperactivity and inattention was collected. Blood samples taken 5days after birth from 190 ADHD-score discordant pairs (15% MZ) were analyzed for antibodies. RESULTS: Pneumococcus Polysaccaride 14 (PnPs14) was present in the ADHD high scoring twin more often than...... 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...

Upgrades for TwinSol facility

Energy Technology Data Exchange (ETDEWEB)

O’Malley, P.D.; Bardayan, D.W.; Kolata, J.J.; Hall, M.R.; Hall, O.; Allen, J. [Physics Department, University of Notre Dame, Notre Dame, IN 46556 (United States); Becchetti, F.D. [Physics Department, U. Michigan, Ann Arbor MI 48109 (United States)

2016-06-01

TwinSol, a pair of coupled, superconducting solenoids, was one of the first devices capable of producing beams of radioactive nuclei at energies near the Coulomb barrier. A primary beam from University of Notre Dame (UND) tandem accelerator is used to bombard a primary target producing a secondary beam in flight. TwinSol is used to gather, separate, and focus the recoils. Since it was commissioned at the UND in 1997, at least 58 publications have reported data from its use and there have been hundreds of collaborators from many different countries that use this device. Currently, plans are in place at the UND to provide several upgrades to TwinSol, including a multi-cell gas production target and the possible addition of a third solenoid. Upgrades currently in progress will be discussed along with future plans.

Childhood social class and cognitive aging in the Swedish Adoption/Twin Study of Aging.

Science.gov (United States)

Ericsson, Malin; Lundholm, Cecilia; Fors, Stefan; Dahl Aslan, Anna K; Zavala, Catalina; Reynolds, Chandra A; Pedersen, Nancy L

2017-07-03

In this report we analyzed genetically informative data to investigate within-person change and between-person differences in late-life cognitive abilities as a function of childhood social class. We used data from nine testing occasions spanning 28 y in the Swedish Adoption/Twin Study of Aging and parental social class based on the Swedish socioeconomic index. Cognitive ability included a general factor and the four domains of verbal, fluid, memory, and perceptual speed. Latent growth curve models of the longitudinal data tested whether level and change in cognitive performance differed as a function of childhood social class. Between-within twin-pair analyses were performed on twins reared apart to assess familial confounding. Childhood social class was significantly associated with mean-level cognitive performance at age 65 y, but not with rate of cognitive change. The association decreased in magnitude but remained significant after adjustments for level of education and the degree to which the rearing family was supportive toward education. A between-pair effect of childhood social class was significant in all cognitive domains, whereas within-pair estimates were attenuated, indicating genetic confounding. Thus, childhood social class is important for cognitive performance in adulthood on a population level, but the association is largely attributable to genetic influences.

Resemblances of Parents and Twins in Sport Participation and Heart Rate

NARCIS (Netherlands)

Boomsma, D.I.; van den Bree, M.B.; Orlebeke, J.F.; Molenaar, P.C.M.

1989-01-01

A model to analyze resemblances of twins and parents using LISREL is outlined and applied to sports participation and heart-rate data. Sports participation and heart rate were measured in 44 monozygotic and 46 dizygotic adolescent twin pairs and in their parents. Genetic factors influence variation

A twin study of schizoaffective-mania, schizoaffective-depression, and other psychotic syndromes.

Science.gov (United States)

Cardno, Alastair G; Rijsdijk, Frühling V; West, Robert M; Gottesman, Irving I; Craddock, Nick; Murray, Robin M; McGuffin, Peter

2012-03-01

The nosological status of schizoaffective disorders remains controversial. Twin studies are potentially valuable for investigating relationships between schizoaffective-mania, schizoaffective-depression, and other psychotic syndromes, but no such study has yet been reported. We ascertained 224 probandwise twin pairs [106 monozygotic (MZ), 118 same-sex dizygotic (DZ)], where probands had psychotic or manic symptoms, from the Maudsley Twin Register in London (1948-1993). We investigated Research Diagnostic Criteria schizoaffective-mania, schizoaffective-depression, schizophrenia, mania and depressive psychosis primarily using a non-hierarchical classification, and additionally using hierarchical and data-derived classifications, and a classification featuring broad schizophrenic and manic syndromes without separate schizoaffective syndromes. We investigated inter-rater reliability and co-occurrence of syndromes within twin probands and twin pairs. The schizoaffective syndromes showed only moderate inter-rater reliability. There was general significant co-occurrence between syndromes within twin probands and MZ pairs, and a trend for schizoaffective-mania and mania to have the greatest co-occurrence. Schizoaffective syndromes in MZ probands were associated with relatively high risk of a psychotic syndrome occurring in their co-twins. The classification of broad schizophrenic and manic syndromes without separate schizoaffective syndromes showed improved inter-rater reliability, but high genetic and environmental correlations between the two broad syndromes. The results are consistent with regarding schizoaffective-mania as due to co-occurring elevated liability to schizophrenia, mania, and depression; and schizoaffective-depression as due to co-occurring elevated liability to schizophrenia and depression, but with less elevation of liability to mania. If in due course schizoaffective syndromes show satisfactory inter-rater reliability and some specific etiological

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.

DNA Methylation Changes in the IGF1R Gene in Birth Weight Discordant Adult Monozygotic Twins

DEFF Research Database (Denmark)

Tsai, Pei-Chien; Van Dongen, Jenny; Tan, Qihua

2015-01-01

persists into adulthood. To investigate this further, we performed epigenome-wide association analyses of blood DNA methylation using Infinium HumanMethylation450 BeadChip profiles in 71 adult monozygotic (MZ) twin pairs who were extremely discordant for birth weight. A signal mapping to the IGF1R gene (cg...... were not significant. However, a meta-analysis across the four independent samples, in total 216 birth-weight discordant MZ twin pairs, showed a significant positive association between birth weight and DNA methylation differences at IGF1R (random-effects meta-analysis p = .04), and the effect...... was particularly pronounced in older twins (random-effects meta-analysis p = .008, 98 older birth-weight discordant MZ twin pairs). The results suggest that severe intra-uterine growth differences (birth weight discordance >20%) are associated with methylation changes in the IGF1R gene in adulthood, independent...

Birth order, gestational age, and risk of delivery related perinatal death in twins: retrospective cohort study

Science.gov (United States)

Smith, Gordon C S; Pell, Jill P; Dobbie, Richard

2002-01-01

Objective To determine whether twins born second are at increased risk of perinatal death because of complications during labour and delivery. Design Retrospective cohort study. Setting Scotland, 1992 and 1997. Participants All twin births at or after 24 weeks' gestation, excluding twin pairs in which either twin died before labour or delivery or died during or after labour and delivery because of congenital abnormality, non-immune hydrops, or twin to twin transfusion syndrome. Main outcome measure Delivery related perinatal deaths (deaths during labour or the neonatal period). Results Overall, delivery related perinatal deaths were recorded for 23 first twins only and 23 second twins only of 1438 twin pairs born before 36 weeks (preterm) by means other than planned caesarean section (P>0.99). No deaths of first twins and nine deaths of second twins (P=0.004) were recorded among the 2436 twin pairs born at or after 36 weeks (term). Discordance between first and second twins differed significantly in preterm and term births (P=0.007). Seven of nine deaths of second twins at term were due to anoxia during the birth (2.9 (95% confidence interval 1.2 to 5.9) per 1000); five of these deaths were associated with mechanical problems with the second delivery following vaginal delivery of the first twin. No deaths were recorded among 454 second twins delivered at term by planned caesarean section. Conclusions Second twins born at term are at higher risk than first twins of death due to complications of delivery. Previous studies may not have shown an increased risk because of inadequate categorisation of deaths, lack of statistical power, inappropriate analyses, and pooling of data about preterm births and term births. What is already known on this topicIt is difficult to assess the wellbeing of second twins during labourDeliveries of second twins are at increased risk of mechanical problems, such as cord prolapse and malpresentation, after vaginal delivery of first twins

Genetic influence on the associations between IGF-I and glucose metabolism in a cohort of elderly twins

DEFF Research Database (Denmark)

Jensen, Rikke Beck; Thankamony, Ajay; Holst, Klaus K.

2018-01-01

OBJECTIVE: IGF-I may be a marker of later metabolic and cardiovascular disease. The interactions between IGF-I and glucose metabolism are multifactorial, and there is potential confounding from several secondary effects. In this study, we examined the interaction between IGF-I and glucose...... metabolism in a large cohort of clinically well-characterized elderly twins. DESIGN: A total of 303 twin pairs of the same gender (606 twins) were included in the study; 125 monozygotic and 178 dizygotic twin pairs. METHODS: A clinical examination including a standard oral glucose tolerance test (OGTT.......11). In a multiple regression analysis (adjusting for age, gender and twin status), there was a negative association between IGF-I and insulin sensitivity (B: -0.13, SE 0.03, P cohort of 606 twins. The associations between IGF...

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.

A TWIN STUDY OF SCHIZOAFFECTIVE-MANIA, SCHIZOAFFECTIVE-DEPRESSION AND OTHER PSYCHOTIC SYNDROMES

OpenAIRE

Cardno, Alastair G; Rijsdijk, Frühling V; West, Robert M; Gottesman, Irving I; Craddock, Nick; Murray, Robin M; McGuffin, Peter

2011-01-01

The nosological status of schizoaffective disorders remains controversial. Twin studies are potentially valuable for investigating relationships between schizoaffective-mania, schizoaffective-depression and other psychotic syndromes, but no such study has yet been reported. We ascertained 224 probandwise twin pairs (106 monozygotic, 118 same-sex dizygotic), where probands had psychotic or manic symptoms, from the Maudsley Twin Register in London (1948–1993). We investigated Research Diagnosti...

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...

Ischiopagus and diprosopus in India: two pairs of conjoined twins perceived as incarnations of Hindu deities.

Science.gov (United States)

Tubbs, R Shane; Ditty, Benjamin; Bosmia, Anand N; Bosmia, Arpan N

2015-02-01

This article briefly reviews two specific types of conjoined twins, ischiopagus and diprosopus, and discusses recent cases of such twins born in India. Some members of the Hindu community worshiped these conjoined twins as incarnations of Hindu deities. In discussing this phenomenon, the authors aim to elucidate certain features of the faith tradition of Hinduism itself. The reception of these conjoined twins as incarnations of Hindu deities can be understood by examining two salient features of Hindu polytheism: the pictorial depiction of Hindu deities with multiple appendages and the concept of an incarnation, or avatar, of a Hindu deity.

Objective assessment of facial skin aging and the associated environmental factors in Japanese monozygotic twins

OpenAIRE

Ichibori, Ryoko; Fujiwara, Takashi; Tanigawa, Tomoko; Kanazawa, Shigeyuki; Shingaki, Kenta; Torii, Kosuke; Tomita, Koichi; Yano, Kenji; Sakai, Yasuo; Hosokawa, Ko

2014-01-01

Twin studies, especially those involving monozygotic (MZ) twins, facilitate the analysis of factors affecting skin aging while controlling for age, gender, and genetic susceptibility. The purpose of this study was to objectively assess various features of facial skin and analyze the effects of environmental factors on these features in MZ twins. At the Osaka Twin Research Center, 67 pairs of MZ twins underwent medical interviews and photographic assessments, using the VISIA® Complexion Analys...

Base pair probability estimates improve the prediction accuracy of RNA non-canonical base pairs.

Directory of Open Access Journals (Sweden)

Michael F Sloma

2017-11-01

Full Text Available Prediction of RNA tertiary structure from sequence is an important problem, but generating accurate structure models for even short sequences remains difficult. Predictions of RNA tertiary structure tend to be least accurate in loop regions, where non-canonical pairs are important for determining the details of structure. Non-canonical pairs can be predicted using a knowledge-based model of structure that scores nucleotide cyclic motifs, or NCMs. In this work, a partition function algorithm is introduced that allows the estimation of base pairing probabilities for both canonical and non-canonical interactions. Pairs that are predicted to be probable are more likely to be found in the true structure than pairs of lower probability. Pair probability estimates can be further improved by predicting the structure conserved across multiple homologous sequences using the TurboFold algorithm. These pairing probabilities, used in concert with prior knowledge of the canonical secondary structure, allow accurate inference of non-canonical pairs, an important step towards accurate prediction of the full tertiary structure. Software to predict non-canonical base pairs and pairing probabilities is now provided as part of the RNAstructure software package.

Base pair probability estimates improve the prediction accuracy of RNA non-canonical base pairs.

Science.gov (United States)

Sloma, Michael F; Mathews, David H

2017-11-01

Prediction of RNA tertiary structure from sequence is an important problem, but generating accurate structure models for even short sequences remains difficult. Predictions of RNA tertiary structure tend to be least accurate in loop regions, where non-canonical pairs are important for determining the details of structure. Non-canonical pairs can be predicted using a knowledge-based model of structure that scores nucleotide cyclic motifs, or NCMs. In this work, a partition function algorithm is introduced that allows the estimation of base pairing probabilities for both canonical and non-canonical interactions. Pairs that are predicted to be probable are more likely to be found in the true structure than pairs of lower probability. Pair probability estimates can be further improved by predicting the structure conserved across multiple homologous sequences using the TurboFold algorithm. These pairing probabilities, used in concert with prior knowledge of the canonical secondary structure, allow accurate inference of non-canonical pairs, an important step towards accurate prediction of the full tertiary structure. Software to predict non-canonical base pairs and pairing probabilities is now provided as part of the RNAstructure software package.

Continuity of Genetic and Environmental Influences on Cognition across the Life Span: A Meta-Analysis of Longitudinal Twin and Adoption Studies

Science.gov (United States)

Tucker-Drob, Elliot M.; Briley, Daniel A.

2014-01-01

The longitudinal rank-order stability of cognitive ability increases dramatically over the lifespan. Multiple theoretical perspectives have proposed that genetic and/or environmental mechanisms underlie the longitudinal stability of cognition, and developmental trends therein. However, the patterns of stability of genetic and environmental influences on cognition over the lifespan largely remain poorly understood. We searched for longitudinal studies of cognition that reported raw genetically-informative longitudinal correlations or parameter estimates from longitudinal behavior genetic models. We identified 150 combinations of time points and measures from 15 independent longitudinal samples. In total, longitudinal data came from 4,538 monozygotic twin pairs raised together, 7,777 dizygotic twin pairs raised together, 34 monozygotic twin pairs raised apart, 78 dizygotic twin pairs raised apart, 141 adoptive sibling pairs, and 143 non-adoptive sibling pairs, ranging in age from infancy through late adulthood. At all ages, cross-time genetic correlations and shared environmental correlations were substantially larger than cross-time nonshared environmental correlations. Cross-time correlations for genetic and shared environmental components were low during early childhood, increased sharply over child development, and remained relatively high from adolescence through late adulthood. Cross-time correlations for nonshared environmental components were low across childhood and increased gradually to moderate magnitudes in adulthood. Increasing phenotypic stability over child development was almost entirely mediated by genetic factors. Time-based decay of genetic and shared environmental stability was more pronounced earlier in child development. Results are interpreted in reference to theories of gene-environment interaction and correlation. PMID:24611582

Twinning in muskox and the cytogenetic investigation of a freemartin

Directory of Open Access Journals (Sweden)

N. J. Reindl

1993-12-01

Full Text Available The occurrence of twinning has been documented for muskox in both wild and captive populations. Of two known captive twin births only one set survived beyond 120 days. In both cases the twins were male-female pairs and both females showed abnormal sexual development. Two sets of stillborn twins have also been recorded. All four stillborn fetuses were female and none showed anomalies of the reproductive tract upon post-mortem examination. Blood cultures from the surviving male and female twins revealed that both were chimeric, indicating the admixture of fetal blood. Fibroblast cultures were normal for the respective sex of each individual. The freemartin heifer had anatomical abnormalities of the clitoris as well as the secondary sex characteristics of a male.

Mitochondrial DNA Copy Number in Sleep Duration Discordant Monozygotic Twins

DEFF Research Database (Denmark)

Wrede, Joanna E; Mengel-From, Jonas; Buchwald, Dedra

2015-01-01

STUDY OBJECTIVES: Mitochondrial DNA (mtDNA) copy number is an important component of mitochondrial function and varies with age, disease, and environmental factors. We aimed to determine whether mtDNA copy number varies with habitual differences in sleep duration within pairs of monozygotic twins...... structure to assess within-pair effects of sleep duration on mtDNA copy number. MEASUREMENTS AND RESULTS: Mean within-pair sleep duration difference per 24 hours was 94.3 minutes (SD 62.6 min). We found reduced sleep duration (β = 0.06; 95% CI 0.004, 0.12; P sleep efficiency (β = 0.51; 95% CI 0.......06, 0.95; P DNA copy number within twin pairs. Thus every 1-minute decrease in actigraphy-defined sleep duration was associated with a decrease in mtDNA copy number of 0.06. Likewise, a 1% decrease in actigraphy-defined sleep efficiency was associated...

Medical and sociological study on the A-bombed twins, 3

International Nuclear Information System (INIS)

Satow, Yukio; Okamoto, Naomasa; Watanabe, Shoji; Ohkita, Takeshi; Kurihara, Minoru

1980-01-01

Three A-bomb exposed and nonexposed pairs of monoxygotic twins were investigated. In two pairs of them, environmental factors had no apparent influence, and genetic factors were dominant. In the other one pair, one of which was a A-bomb survivor exposed at 1.5 km from the explosion center, environmental factors and various effects on them. (Ueda, J.)

Formation of families of twin galaxies by string loops

International Nuclear Information System (INIS)

Cowie, L.L.; Hu, E.M.

1987-01-01

It is argued that if strings are responsible for many of the quasar lens systems and for galaxy formation, then nearby string loops should produce a substantial number of groups of near-identical twin galaxies with near-constant separations. Groups with a few twin members should present a striking doubled appearance and should be easily recognizable. One example of this type of object (found serendipitously in a CCD frame of a distant quasar) is discussed which contains four such identical twins with separation from 2.0 to 2.5 arcsecs, lying in a region about 20 x 20 arcsecs. Morphologically it presents the appearance expected from a string-lensed region. However, the accurate velocity splittings between the pairs which would be required to distinguish this from a chance concatenation of binary pairs are not yet available. The latter is an implausible explanation but may be possible if there is a very high incidence of binaryism in a substantial fraction of distant groups. 20 references

Intragranular twinning, detwinning, and twinning-like lattice reorientation in magnesium alloys

International Nuclear Information System (INIS)

Wu, Wei; Gao, Yanfei; Li, Nan; Parish, Chad M.; Liu, Wenjun; Liaw, Peter K.; An, Ke

2016-01-01

Deformation twinning plays a critical role on improving metals or alloys ductility, especially for hexagonal close-packed materials with low symmetry crystal structure. A rolled Mg alloy was selected as a model system to investigate the extension twinning behaviors and characteristics of parent-twin interactions by nondestructive in situ 3D synchrotron X-ray microbeam diffraction. Besides twinning-detwinning process, the “twinning-like” lattice reorientation process was captured within an individual grain inside a bulk material during the strain reversal. The distributions of parent, twin, and reorientated grains and sub-micron level strain variation across the twin boundary are revealed. A theoretical calculation of the lattice strain confirms that the internal strain distribution in parent and twinned grains correlates with the experimental setup, grain orientation of parent, twin, and surrounding grains, as well as the strain path changes. The study suggests a novel deformation mechanism within the hexagonal close-packed structure that cannot be determined from surface-based characterization methods.

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

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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

An elasto-plastic self-consistent model with hardening based on dislocation density, twinning and de-twinning: Application to strain path changes in HCP metals

International Nuclear Information System (INIS)

Zecevic, Milovan; Knezevic, Marko; Beyerlein, Irene J.; Tomé, Carlos N.

2015-01-01

In this work, we develop a polycrystal mean-field constitutive model based on an elastic–plastic self-consistent (EPSC) framework. In this model, we incorporate recently developed subgrain models for dislocation density evolution with thermally activated slip, twin activation via statistical stress fluctuations, reoriented twin domains within the grain and associated stress relaxation, twin boundary hardening, and de-twinning. The model is applied to a systematic set of strain path change tests on pure beryllium (Be). Under the applied deformation conditions, Be deforms by multiple slip modes and deformation twinning and thereby provides a challenging test for model validation. With a single set of material parameters, determined using the flow-stress vs. strain responses during monotonic testing, the model predicts well the evolution of texture, lattice strains, and twinning. With further analysis, we demonstrate the significant influence of internal residual stresses on (1) the flow stress drop when reloading from one path to another, (2) deformation twin activation, (3) de-twinning during a reversal strain path change, and (4) the formation of additional twin variants during a cross-loading sequence. The model presented here can, in principle, be applied to other metals, deforming by multiple slip and twinning modes under a wide range of temperature, strain rate, and strain path conditions

The nature of pseudo-twinning modes on the basis of a twin classification scheme

International Nuclear Information System (INIS)

Singh, Jung B.; Sundararaman, M.; Krishnan, M.

2011-01-01

Pseudo-twins can form in ordered structures under high stress conditions. These twins are defined by lattice sites that are at twin positions but are incorrectly occupied by different species of atoms. The present note discusses if it is possible to further classify pseudo-twins into different modes based on the nature of associated twinning elements.

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

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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…

Attention problems and Attention-Deficit/Hyperactivity Disorder in discordant and concordant monozygotic twins: Evidence of environmental mediators.

NARCIS (Netherlands)

Lehn, H.; Derks, E.M.; Hudziak, J.; Heutink, P.; van Beijsterveldt, C.E.M.; Boomsma, D.I.

2007-01-01

OBJECTIVE: To study familial and nonfamilial environmental influences on attention problems and attention-deficit/hyperactivity disorder (ADHD) in monozygotic twins discordant and concordant-high and low for these traits. METHOD: Ninety-five twin pairs from The Netherlands Twin Register were

'Twin2twin' an innovative method of empowering midwives to strengthen their professional midwifery organisations.

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Cadée, Franka; Perdok, Hilde; Sam, Betty; de Geus, Myrte; Kweekel, Liselotte

2013-10-01

midwives need professional support from a national midwifery organisation to be able to provide the services that are by regulatory mechanisms and accreditation expected of them. Not all midwives in the world are united in a professional organisation. The aim of this project was to strengthen the midwifery organisations of Sierra Leone and the Netherlands. During the process of the project it was realised that the development of a platform of exchange at organisational level would be enhanced by introducing personal exchange between individual midwives. In response to this new insight the original project plan was adjusted by incorporating the twin2twin method. twin2twin is a feminist methodology of mutual exchange between twenty pairs of midwives from different organisations (in this case Sierra Leone and the Netherlands). The method can be distinguished by 10 specific steps. It was developed, used and (re)evaluated through focus group discussions, storytelling and written evaluations. twinning of organisations was strengthened by adding a human component to the process. With the use of the 'twin2twin' method, midwives were encouraged to invested in a professional and personal bond with their 'twin sister'. This bond was independent and went beyond the relatively short four year project period. Through personal engagement and mutual exchange of knowledge and skills, midwives empowered each other to build and strengthen their midwifery organisations both in Sierra Leone and the Netherlands. (Empowerment refers to the expansion in people's ability to make strategic life choices in a context where this ability was previously denied to them (Narayan, 2005); organisational empowerment includes processes and structures that enhance members' skills and provides them with the mutual support necessary to effect community level change (Zimmerman, 1995).). despite challenges we are convinced that twin2twin can be of additional benefit for the success of other projects

Genetic and environmental influences on risk of death due to infections assessed in Danish twins, 1943-2001

DEFF Research Database (Denmark)

Obel, Niels; Christensen, Kaare; Petersen, Inge

2010-01-01

Genetic differences have been proposed to play a strong role in risk of death from infectious diseases. The study base of 44,005 included all same-sex twin pairs born in 1870-2001, with both twins alive on January 1, 1943, or those born thereafter. Cause of death was obtained from the Danish Cause...... from infectious diseases could be demonstrated, the absolute effect of the genetic component on mortality was small....... genetic influence on the risk of death...

Leisure-time physical inactivity and association with body mass index: a Finnish Twin Study with a 35-year follow-up.

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Piirtola, Maarit; Kaprio, Jaakko; Waller, Katja; Heikkilä, Kauko; Koskenvuo, Markku; Svedberg, Pia; Silventoinen, Karri; Kujala, Urho M; Ropponen, Annina

2017-02-01

We investigated the stability and change of leisure-time physical inactivity in adult men and women during a 35-year follow-up. We also analysed the impact of long-term physical inactivity on the development of body mass index (BMI). : In this population-based cohort study, 5254 Finnish twin individuals (59% women) participated in four surveys in 1975, 1981, 1990 and 2011. Mean age at baseline was 23.9 years. Individual long-term leisure-time physical activity (LTPA) was categorized into seven classes varying from 'persistently inactive' to 'persistently active'. We used the multivariate multilevel mixed-effects linear regression model and paired-sample t-test in the analyses. Co-twin control design was used for examining within-pair associations. : Of men 11%, and of women 8%, were persistently inactive. Among both sexes, the mean BMI slope trajectories were steeper among the persistently inactive and those who became inactive than among those who were persistently active. Overall, the inactive participants gained 1.4 kg/m 2 [95% confidence interval (CI) 1.2 to 1.7] more in weight than did the active participants from 1975 to 2011. Among twin pairs discordant for LTPA, the corresponding difference was 1.4 kg/m 2 (95% CI 0.83 to 2.0) in dizygotic pairs and 0.68 kg/m 2 (95% CI 0.05 to1.3) in monozygotic pairs. Over a 35-year time span from young adulthood, persistently inactive participants and those who had become inactive had greater weight increases than those who were persistently active. This association was also found in twin-pair analyses, although attenuated in monozygotic pairs. This may support the importance of LTPA in weight management, although further causal inference is required. © The Author 2016; all rights reserved. Published by Oxford University Press on behalf of the International Epidemiological Association

Absence of Substantial Copy Number Differences in a Pair of Monozygotic Twins Discordant for Features of Autism Spectrum Disorder

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Marina Laplana

2014-01-01

Full Text Available Autism spectrum disorder (ASD is a highly heritable disease (~0.9 with a complex genetic etiology. It is initially characterized by altered cognitive ability which commonly includes impaired language and communication skills as well as fundamental deficits in social interaction. Despite the large amount of studies described so far, the high clinical diversity affecting the autism phenotype remains poorly explained. Recent studies suggest that rare genomic variations, in particular copy number variation (CNV, may account for a significant proportion of the genetic basis of ASD. The use of disease-discordant monozygotic twins represents a powerful strategy to identify de novo and inherited CNV in the disorder. Here we present the results of a comparative genome hybridization (CGH analysis with a pair of monozygotic twins affected of ASD with significant differences in their clinical manifestations that specially affect speech language impairment and communication skills. Array CGH was performed in three different tissues: blood, saliva, and hair follicle, in an attempt to identify germinal and somatic CNV regions that may explain these differences. Our results argue against a role of large CNV rearrangements as a molecular etiology of the observed differences. This forwards future research to explore de novo point mutation and epigenomic alterations as potential explanations of the observed clinical differences.

The similarity of twin brains; Die Aehnlichkeit von Zwillingsgehirnen

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Mohr, A.; Knauth, M.; Stippich, C.; Sartor, K. [Abt. Neuroradiologie, Univ. Heidelberg (Germany); Weisbrod, M. [Sektion Experimentelle Psychopathologie, Psychiatrische Klinik Univ. Heidelberg (Germany)

2001-06-01

To test the assumption underlying every morphometric twin study that the brains of monozygotic twins are almost identical. Methods: High resolution MRI of the neurocranium of 26 monozygotic twin pairs were acquired and the volumes of 36 cerebral structures were measured. The same twins served as control group after rear-ranging them into non-related pairs of same sex and matching them for age, body height and body weight. Results: For most of the examined structures the correlations within the twins were significant (R = 0,97-0,59). Except for total forebrain volume the controls showed no significant similarity. Conclusions: For almost every measured cerebral structure the assumption, that significant similarities exist between healthy monozygotic twins is correct. Therefore discordant monozygotic twins represent an excellent sample when investigating cerebral correlates of neurologic and psychiatric disorders. (orig.) [German] Pruefung der Grundannahme hirnmorphologischer Zwillingsstudien, dass die Gehirne eineiiger Zwillinge signifikant aehnlich sind. Methode: Hochaufloesende MRT-Datensaetze der Gehirne von 26 gesunden eineiigen Zwillingspaaren dienten als Grundlage der volumetrischen Vermessung von insgesamt 36 zerebralen Strukturen. Als Kontrollkollektiv wurden neue, nicht verwandte, aber gleichgeschlechtliche und nach Alter, Koerpergroesse und Koerpergewicht sehr aehnliche Paare gebildet. Ergebnisse: Fuer Hemisphaerenvolumen, graue und weisse Substanz des Frontal- und Temporallappens (R = 0,97-0,59) sowie fuer zahlreiche subkortikale Strukturen (R = 0,80-0,41) zeigten sich signifikante (p < 0,05) Korrelationen zwischen den Zwillingspaaren. Ausser fuer Grosshirnvolumen fanden sich bei den Kontrollpaaren keine signifikanten Aehnlichkeiten. Schlussfolgerung: Fuer die meisten der vermessenen zerebralen Areale ist die Annahme richtig, dass die Gehirne eineliger Zwillinge deutlich aehnlicher sind als die Gehirne nicht verwandter Personen. Bei der Suche nach

Twin studies of schizophrenia: from bow-and-arrow concordances to star wars Mx and functional genomics.

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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. Copyright 2000 Wiley-Liss, Inc.

Placental pathology, birthweight discordance, and growth restriction in twin pregnancy: results of the ESPRiT Study.

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Kent, Etaoin M; Breathnach, Fionnuala M; Gillan, John E; McAuliffe, Fionnuala M; Geary, Michael P; Daly, Sean; Higgins, John R; Hunter, Alyson; Morrison, John J; Burke, Gerard; Higgins, Shane; Carroll, Stephen; Dicker, Patrick; Manning, Fiona; Tully, Elizabeth; Malone, Fergal D

2012-09-01

We sought to evaluate the association between placental histological abnormalities and birthweight discordance and growth restriction in twin pregnancies. We performed a multicenter, prospective study of twin pregnancies. Placentas were examined for evidence of infarction, retroplacental hemorrhage, chorangioma, subchorial fibrin, or abnormal villus maturation. Association of placental lesions with chorionicity, birthweight discordance, and growth restriction were assessed. In all, 668 twin pairs were studied, 21.1% monochorionic and 78.9% dichorionic. Histological abnormalities were more frequent in placentas of smaller twins of birthweight discordant pairs (P = .02) and in placentas of small for gestational age infants (P = .0001) when compared to controls. The association of placental abnormalities with both birthweight discordance and small for gestational age was significant for dichorionic twins (P = .01 and .0001, respectively). No such association was seen in monochorionic twins. In a large, prospective, multicenter study, we observed a strong relationship between abnormalities of placental histology and birthweight discordance and growth restriction in dichorionic, but not monochorionic, twin pregnancies. Copyright © 2012 Mosby, Inc. All rights reserved.

Craniofacial morphology in Chinese female twins: a semi-longitudinal cephalometric study.

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Peng, Jing; Deng, Hui; Cao, CaiFang; Ishikawa, Masaaki

2005-12-01

It would be of benefit to have a better understanding of the relative effects of genetics and environmental factors on craniofacial parameters when undertaking orthodontic therapy and treatment planning. However, there is a lack of such information in pre-adolescents. The aim of this study was to verify the degree of genetic and environmental contribution to the growth of the facial skeleton in twins aged 6 to 12 years. The material comprised the lateral cephalograms of 89 pairs of female twins in Beijing, China, of whom 61 pairs were diagnosed by DNA analysis as monozygotic (MZ) and 28 pairs as dizygotic (DZ). Four main groups (with a starting age of 6, 7, 9 and 11 years) were studied in a semi-longitudinal manner, with a sub-group further investigated for 2-4 consecutive years. The total sample therefore consisted of 183 pairs (MZ 110, DZ 73) aged from 6 to 12 years. The depths of the cranial base, mid and lower face were measured, as well as anterior and posterior face height. A two-tailed t-test showed significant environmental effects on lower face depth (P < 0.01), whilst genetic effects on face height were also significant (P < 0.01). The results suggest that early orthodontic intervention would have a greater influence on the antero-posterior rather than on the vertical plane of growth.

Genetic liability to disability pension in women and men: a prospective population-based twin study.

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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

Twin Studies in Autism: What Might They Say about Genetic and Environmental Influences

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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.

Total and Trimester-Specific Gestational Weight Gain and Offspring Birth and Early Childhood Weight: A Prospective Cohort Study on Monozygotic Twin Mothers and Their Offspring.

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Scheers Andersson, Elina; Silventoinen, Karri; Tynelius, Per; Nohr, Ellen A; Sørensen, Thorkild I A; Rasmussen, Finn

2016-08-01

Gestational weight gain (GWG) has in numerous studies been associated with offspring birth weight (BW) and childhood weight. However, these associations might be explained by genetic confounding as offspring inherit their mother's genetic potential to gain weight. Furthermore, little is known about whether particular periods of pregnancy could influence offspring body weight differently. We therefore aimed to explore total and trimester-specific effects of GWG in monozygotic (MZ) twin mother-pairs on their offspring's BW, weight at 1 year and body mass index (BMI) at 5 and 10 years. MZ twin mothers born 1962-1975 were identified in national Swedish registers, and data on exposure and outcome variables was collected from medical records. We analyzed associations within and between twin pairs. We had complete data on the mothers' GWG and offspring BW for 82 pairs. The results indicated that total, and possibly also second and third trimester GWG were associated with offspring BW within the twin pairs in the fully adjusted model (β = 0.08 z-score units, 95% CI: 0.001, 0.17; β = 1.32 z-score units, 95% CI: -0.29, 2.95; and β = 1.02 z-score units, 95% CI: -0.50, 2.54, respectively). Our findings, although statistically weak, suggested no associations between GWG and offspring weight or BMI during infancy or childhood. Our study suggests that total, and possibly also second and third trimester, GWG are associated with offspring BW when taking shared genetic and environmental factors within twin pairs into account. Larger family-based studies with long follow-up are needed to confirm our findings.

Caffeine intake, toxicity and dependence and lifetime risk for psychiatric and substance use disorders: an epidemiologic and co-twin control analysis.

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Kendler, Kenneth S; Myers, John; O Gardner, Charles

2006-12-01

Although caffeine is the most commonly used psychoactive substance and often produces symptoms of toxicity and dependence, little is known, especially in community samples, about the association between caffeine use, toxicity and dependence and risk for common psychiatric and substance use disorders. Assessments of lifetime maximal caffeine use and symptoms of caffeine toxicity and dependence were available on over 3600 adult twins ascertained from the population-based Virginia Twin Registry. Lifetime histories of major depression (MD), generalized anxiety disorder (GAD) and panic disorder, alcohol dependence, adult antisocial behavior and cannabis and cocaine abuse/dependence were obtained at personal interview. Logistic regression analyses in the entire sample and within monozygotic (MZ) twin pairs were conducted in SAS. In the entire sample, measures of maximal caffeine use, heavy caffeine use, and caffeine-related toxicity and dependence were significantly and positively associated with all seven psychiatric and substance use disorders. However, within MZ twin pairs, controlling for genetic and family environmental factors, these associations, while positive, were all non-significant. These results were similar when excluding twins who denied regular caffeine use. Maximal lifetime caffeine intake and caffeine-associated toxicity and dependence are moderately associated with risk for a wide range of psychiatric and substance use disorders. Analyses of these relationships within MZ twin pairs suggest that most of the observed associations are not causal. Rather, familial factors, which are probably in part genetic, predispose to both caffeine intake, toxicity and dependence and the risk for a broad array of internalizing and externalizing disorders.

Effects of Light-Emitting Diode Therapy on Muscle Hypertrophy, Gene Expression, Performance, Damage, and Delayed-Onset Muscle Soreness: Case-control Study with a Pair of Identical Twins.

Science.gov (United States)

Ferraresi, Cleber; Bertucci, Danilo; Schiavinato, Josiane; Reiff, Rodrigo; Araújo, Amélia; Panepucci, Rodrigo; Matheucci, Euclides; Cunha, Anderson Ferreira; Arakelian, Vivian Maria; Hamblin, Michael R; Parizotto, Nivaldo; Bagnato, Vanderlei

2016-10-01

The aim of this study was to verify how a pair of monozygotic twins would respond to light-emitting diode therapy (LEDT) or placebo combined with a strength-training program during 12 weeks. This case-control study enrolled a pair of male monozygotic twins, allocated randomly to LEDT or placebo therapies. Light-emitting diode therapy or placebo was applied from a flexible light-emitting diode array (λ = 850 nm, total energy = 75 J, t = 15 seconds) to both quadriceps femoris muscles of each twin immediately after each strength training session (3 times/wk for 12 weeks) consisting of leg press and leg extension exercises with load of 80% and 50% of the 1-repetition maximum test, respectively. Muscle biopsies, magnetic resonance imaging, maximal load, and fatigue resistance tests were conducted before and after the training program to assess gene expression, muscle hypertrophy and performance, respectively. Creatine kinase levels in blood and visual analog scale assessed muscle damage and delayed-onset muscle soreness, respectively, during the training program. Compared with placebo, LEDT increased the maximal load in exercise and reduced fatigue, creatine kinase, and visual analog scale. Gene expression analyses showed decreases in markers of inflammation (interleukin 1β) and muscle atrophy (myostatin) with LEDT. Protein synthesis (mammalian target of rapamycin) and oxidative stress defense (SOD2 [mitochondrial superoxide dismutase]) were up-regulated with LEDT, together with increases in thigh muscle hypertrophy. Light-emitting diode therapy can be useful to reduce muscle damage, pain, and atrophy, as well as to increase muscle mass, recovery, and athletic performance in rehabilitation programs and sports medicine.

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

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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.

Genetic influences on musical specialization: a twin study on choice of instrument and music genre.

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Mosing, Miriam A; Ullén, Fredrik

2018-05-09

Though several studies show that genetic factors influence individual differences in musical engagement, aptitude, and achievement, no study to date has investigated whether specialization among musically active individuals in terms of choice of instrument and genre is heritable. Using a large twin cohort, we explored whether individual differences in instrument choice, instrument category, and the type of music individuals engage in can entirely be explained by the environment or are partly due to genetic influences. About 10,000 Swedish twins answered an extensive questionnaire about music-related traits, including information on the instrument and genre they played. Of those, 1259 same-sex twin pairs reported to either play an instrument or sing. We calculated the odds ratios (ORs) for concordance in music choices (if both twins played) comparing identical and nonidentical twin pairs, with significant ORs indicating that identical twins are more likely to engage in the same type of music-related behavior than are nonidentical twins. The results showed that for almost all music-related variables, the odds were significantly higher for identical twins to play the same musical instrument or music genre, suggesting significant genetic influences on such music specialization. Possible interpretations and implications of the findings are discussed. © 2018 New York Academy of Sciences.

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

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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.

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

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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

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.

Characterization of Gastric Microbiota in Twins.

Science.gov (United States)

Dong, Quanjiang; Xin, Yongning; Wang, Lili; Meng, Xinying; Yu, Xinjuan; Lu, Linlin; Xuan, Shiying

2017-02-01

Contribution of host genetic backgrounds in the development of gastric microbiota has not been clearly defined. This study was aimed to characterize the biodiversity, structure and composition of gastric microbiota among twins. A total of four pairs of twins and eight unrelated individuals were enrolled in the study. Antral biopsies were obtained during endoscopy. The bacterial 16S rRNA gene was amplified and pyrosequenced. Sequences were analyzed for the composition, structure, and α and β diversities of gastric microbiota. Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, and Fusobacteria were the most predominant phyla of gastric microbiota. Each individual, twins as well as unrelated individuals, harbored a microbiota of distinct composition. There was no evidence of additional similarity in the richness and evenness of gastric microbiota among co-twins as compared to unrelated individuals. Calculations of θ YC and PCoA demonstrated that the structure similarity of gastric microbial community between co-twins did not increase compared to unrelated individuals. In contrast, the structure of microbiota was altered enormously by Helicobacter pylori infection. These results suggest that host genetic backgrounds had little effect in shaping the gastric microbiota. This property of gastric microbiota could facilitate the studies discerning the role of microbiota from genetic grounds in the pathogenesis.

Does the sex of one's co-twin affect height and BMI in adulthood?

DEFF Research Database (Denmark)

Bogl, Leonie H; Jelenkovic, Aline; Vuoksimaa, Eero

2017-01-01

BACKGROUND: The comparison of traits in twins from opposite-sex (OS) and same-sex (SS) dizygotic twin pairs is considered a proxy measure of prenatal hormone exposure. To examine possible prenatal hormonal influences on anthropometric traits, we compared mean height, body mass index (BMI), and th...

[The Murcia Twin Registry. A resource for research on health-related behaviour].

Science.gov (United States)

Ordoñana, Juan R; Sánchez Romera, Juan F; Colodro-Conde, Lucía; Carrillo, Eduvigis; González-Javier, Francisca; Madrid-Valero, Juan J; Morosoli-García, José J; Pérez-Riquelme, Francisco; Martínez-Selva, José M

Genetically informative designs and, in particular, twin studies, are the most widely used methodology to analyse the relative contribution of genetic and environmental factors to inter-individual variability. These studies basically compare the degree of phenotypical similarity between monozygotic and dizygotic twin pairs. In addition to the traditional estimate of heritability, this kind of registry enables a wide variety of analyses which are unique due to the characteristics of the sample. The Murcia Twin Registry is population-based and focused on the analysis of health-related behaviour. The observed prevalence of health problems is comparable to that of other regional and national reference samples, which guarantees its representativeness. Overall, the characteristics of the Registry facilitate developing various types of research as well as genetically informative designs, and collaboration with different initiatives and consortia. Copyright © 2016 SESPAS. Publicado por Elsevier España, S.L.U. All rights reserved.

Has the "Equal Environments" assumption been tested in twin studies?

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Eaves, Lindon; Foley, Debra; Silberg, Judy

2003-12-01

A recurring criticism of the twin method for quantifying genetic and environmental components of human differences is the necessity of the so-called "equal environments assumption" (EEA) (i.e., that monozygotic and dizygotic twins experience equally correlated environments). It has been proposed to test the EEA by stratifying twin correlations by indices of the amount of shared environment. However, relevant environments may also be influenced by genetic differences. We present a model for the role of genetic factors in niche selection by twins that may account for variation in indices of the shared twin environment (e.g., contact between members of twin pairs). Simulations reveal that stratification of twin correlations by amount of contact can yield spurious evidence of large shared environmental effects in some strata and even give false indications of genotype x environment interaction. The stratification approach to testing the equal environments assumption may be misleading and the results of such tests may actually be consistent with a simpler theory of the role of genetic factors in niche selection.

Heritability of Schizophrenia and Schizophrenia Spectrum Based on the Nationwide Danish Twin Register

DEFF Research Database (Denmark)

Hilker, Rikke; Helenius, Dorte; Fagerlund, Birgitte

2018-01-01

sample. The estimated 79% heritability of SZ is congruent with previous reports and indicates a substantial genetic risk. The high genetic risk also applies to a broader phenotype of SZ spectrum disorders. The low concordance rate of 33% in monozygotic twins demonstrates that illness vulnerability......BACKGROUND: Twin studies have provided evidence that both genetic and environmental factors contribute to schizophrenia (SZ) risk. Heritability estimates of SZ in twin samples have varied methodologically. This study provides updated heritability estimates based on nationwide twin data...... the heritability of SZ to be 79%. When expanding illness outcome to include SZ spectrum disorders, the heritability estimate was almost similar (73%). CONCLUSIONS: The key strength of this study is the application of a novel statistical method accounting for censoring in the follow-up period to a nationwide twin...

Incidence of hand eczema in a population-based twin cohort

DEFF Research Database (Denmark)

Lerbaek, A; Kyvik, Kirsten Ohm; Ravn, H

2007-01-01

BACKGROUND: Population-based studies on the incidence of hand eczema are sparse. OBJECTIVES: The aim of this prospective follow-up study was to determine the incidence rate of hand eczema in a population-based twin cohort. Secondly, the role of genetic factors and other potential risk factors...... for hand eczema was investigated. METHODS: A questionnaire on self-reported hand eczema was answered by 5610 and 4128 twin individuals in 1996 and 2005, respectively. Data were analysed in a Poisson regression analysis. RESULTS: The crude incidence rate was 8.8 cases per 1000 person-years (95% confidence...... with an increased risk, whereas no association with age, sex, smoking or alcohol was found...

Atopic diseases in twins born after assisted reproduction.

Science.gov (United States)

Jäderberg, Ida; Thomsen, Simon F; Kyvik, Kirsten O; Skytthe, Axel; Backer, Vibeke

2012-03-01

We examined the risk of atopic diseases in twins born after assisted reproduction. Data on atopic diseases and assisted reproduction in 9694 twin pairs, 3-20 years of age, from the Danish Twin Registry were collected via multidisciplinary questionnaires. The risk of atopic diseases in twins born after assisted reproduction was compared with the risk in twins born after spontaneous conception using logistic regression and variance components analysis. Children born after assisted reproduction did not have a different risk of atopic outcomes (adjusted odds ratios [95% confidence intervals] for asthma: 0.95 [0.85, 1.07], P = 0.403; hay fever: 1.01 [0.86, 1.18], P = 0.918; and atopic dermatitis: 1.02 [0.81, 1.11], P = 0.773 respectively) compared with children born after spontaneous conception. Assisted reproduction did not modify the heritability of atopic diseases. This study does not support an association between assisted reproduction and development of atopic diseases. This result must be confirmed in subsequent studies, preferably of singleton populations. © 2011 Blackwell Publishing Ltd.

Epigenetic differences in monozygotic twins discordant for major depressive disorder.

Science.gov (United States)

Malki, K; Koritskaya, E; Harris, F; Bryson, K; Herbster, M; Tosto, M G

2016-06-14

Although monozygotic (MZ) twins share the majority of their genetic makeup, they can be phenotypically discordant on several traits and diseases. DNA methylation is an epigenetic mechanism that can be influenced by genetic, environmental and stochastic events and may have an important impact on individual variability. In this study we explored epigenetic differences in peripheral blood samples in three MZ twin studies on major depressive disorder (MDD). Epigenetic data for twin pairs were collected as part of a previous study using 8.1-K-CpG microarrays tagging DNA modification in white blood cells from MZ twins discordant for MDD. Data originated from three geographical regions: UK, Australia and the Netherlands. Ninety-seven MZ pairs (194 individuals) discordant for MDD were included. Different methods to address non independently-and-identically distributed (non-i.i.d.) data were evaluated. Machine-learning methods with feature selection centered on support vector machine and random forest were used to build a classifier to predict cases and controls based on epivariations. The most informative variants were mapped to genes and carried forward for network analysis. A mixture approach using principal component analysis (PCA) and Bayes methods allowed to combine the three studies and to leverage the increased predictive power provided by the larger sample. A machine-learning algorithm with feature reduction classified affected from non-affected twins above chance levels in an independent training-testing design. Network analysis revealed gene networks centered on the PPAR-γ (NR1C3) and C-MYC gene hubs interacting through the AP-1 (c-Jun) transcription factor. PPAR-γ (NR1C3) is a drug target for pioglitazone, which has been shown to reduce depression symptoms in patients with MDD. Using a data-driven approach we were able to overcome challenges of non-i.i.d. data when combining epigenetic studies from MZ twins discordant for MDD. Individually, the studies yielded

Multifactorial etiology of Torus mandibularis: study of twins.

Science.gov (United States)

Auškalnis, Adomas; Rutkūnas, Vygandas; Bernhardt, Olaf; Šidlauskas, Mantas; Šalomskienė, Loreta; Basevičienė, Nomeda

2015-01-01

The aim of this study is to investigate the multifactorial etiology of mandibular tori analyzing the influence of genetics, occlusal overload, various clinical variables and their interactions. Overall, plaster casts of 162 twins (81 twin pairs) were analyzed for the presence or absence of mandibular tori. Atypical wear facets on canine tips or incisors were recorded to diagnose bruxism. Angle Class, any kind of anterior open bite and positive, negative or flat curve of Wilson were recorded. Zygosity determination was carried out using a DNA test. Mandibular tori were found in 56.8% of the cases. In 93.6% of all monozygotic twin pairs both individuals had or did not have mandibular tori (κ=0.96±0.04; p<0.001), compared to 79.4% concordance of mandibular tori in dizygotic co-twins (κ=0.7±0.12; p<0.001). Prevalence of mandibular tori was significantly higher in the group of bruxers (67.5%) compared to non-bruxers (31.3%) (p<0.001). Significant association between mandibular tori and negative or flat curve of Wilson in the maxillary second premolars and first molars was found (OR=2.55, 95% CI (1.19-5.46), p=0.016). In all monozygotic bruxers, 97.1% showed concordance of mandibular tori presence in both co-twins compared to 78.9% dizygotic bruxers, and this difference is statistically significant (p=0.007). Our results suggest that the mandibular tori are of a multifactorial origin. Mandibular tori seem to have genetic predisposition, and may be associated with teeth grinding as well as with negative or flat CW in region of maxillary second premolar and first molar.

Risk factors for testicular cancer: a case-control study in twins.

Science.gov (United States)

Swerdlow, A J; De Stavola, B L; Swanwick, M A; Mangtani, P; Maconochie, N E

1999-06-01

Early life and anthropometric risk factors for testicular cancer were examined in a case-control study in England and Wales in which affected male twins were compared with their unaffected male co-twins. Questionnaire data was obtained for 60 twin pairs. Significantly raised risk of testicular cancer occurred in twins who had longer arms and legs than their co-twin. There was a significant excess of testicular cancer reported in non-twin brothers, as well as in twin brothers, of cases. Risk was also significantly raised in relation to cryptorchidism. The results on limb length suggest that factors, perhaps nutritional, affecting growth before puberty, may be causes of testicular cancer. The results on risk in brothers add to evidence of a large genetic component in aetiology of the tumour. The risk associated with cryptorchidism in the twins accords with the hypothesis that cryptorchidism is causally associated with testicular cancer because it is a cause of the malignancy, rather than because the same maternal factors experienced in utero cause both conditions.

Heritability and Genome-Wide Association Analyses of Serum Uric Acid in Middle and Old-Aged Chinese Twins

DEFF Research Database (Denmark)

Wang, Weijing; Zhang, Dongfeng; Xu, Chunsheng

2018-01-01

Serum uric acid (SUA), as the end product of purine metabolism, has proven emerging roles in human disorders. Here based on a sample of 379 middle and old-aged Chinese twin pairs, we aimed to explore the magnitude of genetic impact on SUA variation by performing sex-limitation twin modeling analy...... involved in functional genes and regulatory domains that mediate SUA level. Our findings provide clues to further elucidate molecular physiology of SUA homeostasis and identify new diagnostic biomarkers and therapeutic targets for hyperuricemia and gout....

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 (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 Simao 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...

Behavioral versus genetic correlates of lipoproteins and adiposity in identical twins discordant for exercise.

Science.gov (United States)

Williams, Paul T; Blanche, Patricia J; Krauss, Ronald M

2005-07-19

Lipoprotein and weight differences between vigorously active and sedentary monozygotic (MZ) twins were used to (1) estimate the effects of training while controlling for genotype and (2) estimate genetic concordance (ie, similarity) in the presence of divergent lifestyles. Thirty-five pairs of MZ twins (25 male, 10 female) were recruited nationally who were discordant for vigorous exercise (running distances differed by > or =40 km in male and > or =32 km in female twins). The active twins ran an average (mean+/-SD) of 63.0+/-20.4 km/wk, whereas the mostly sedentary twins averaged 7.0+/-13.5 km/wk. The active twins had significantly lower body mass index (difference+/-SE, -2.12+/-0.57 kg/m2, P=0.0007) and significantly higher HDL cholesterol (0.14+/-0.04 mmol/L, P=0.004), HDL2 (2.71+/-1.04 U, P=0.01), and apolipoprotein (apo) A-I (0.10+/-0.03 g/L, P=0.004). Despite the difference in lifestyle, when adjusted for sex, the correlations between the discordant MZ twin pairs were significant (PHDL cholesterol (r=0.69), apoA-I (r=0.58), and HDL2 (r=0.67). There was no significant MZ twin correlation for body mass index (r=0.17). None of the active twins having an overweight twin were themselves overweight. Behavior (vigorous exercise) may reduce genetic influences on body mass index. In contrast, genetics (or shared environment) substantially influences HDL cholesterol and HDL subclasses, even in the presence of extreme behavioral differences. There may be greater individual control over moderate degrees of obesity, whereas low HDL cholesterol may be largely predetermined and less effectively treated by vigorous exercise.

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

Twins are an important resource for evaluating the relative contribution of genetic and environmental factors in determining a phenotype. During the last decades, a number of twin studies have investigated the aetiology of several phenotypes related to thyroid autoimmunity. Taken together, these ....... Future twin studies should incorporate information on genetic, epigenetic and environmental variation thereby enhancing our ability to quantify the precise effect of specific risk factors......., and biometric twin modelling shows that approximately 75% of the total phenotypic variance in AITD is because of genetic effects. On the other hand, the lack of complete concordance in MZ twin pairs is proof of environmental and/or epigenetic factors also playing an important role. The impact of environmental...

Monozygotic twins discordant for ROHHAD phenotype.

Science.gov (United States)

Patwari, Pallavi P; Rand, Casey M; Berry-Kravis, Elizabeth M; Ize-Ludlow, Diego; Weese-Mayer, Debra E

2011-09-01

Rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation (ROHHAD) falls within a group of pediatric disorders with both respiratory control and autonomic nervous system dysregulation. Children with ROHHAD typically present after 1.5 years of age with rapid weight gain as the initial sign. Subsequently, they develop alveolar hypoventilation, autonomic nervous system dysregulation, and, if untreated, cardiorespiratory arrest. To our knowledge, this is the first report of discordant presentation of ROHHAD in monozygotic twins. Twin girls, born at term, had concordant growth and development until 8 years of age. From 8 to 12 years of age, the affected twin developed features characteristic of ROHHAD including obesity, alveolar hypoventilation, scoliosis, hypothalamic dysfunction (central diabetes insipidus, hypothyroidism, premature pubarche, and growth hormone deficiency), right paraspinal/thoracic ganglioneuroblastoma, seizures, and autonomic dysregulation including altered pain perception, large and sluggishly reactive pupils, hypothermia, and profound bradycardia that required a cardiac pacemaker. Results of genetic testing for PHOX2B (congenital central hypoventilation syndrome disease-defining gene) mutations were negative. With early recognition and conservative management, the affected twin had excellent neurocognitive outcome that matched that of the unaffected twin. The unaffected twin demonstrated rapid weight gain later in age but not development of signs/symptoms consistent with ROHHAD. This discordant twin pair demonstrates key features of ROHHAD including the importance of early recognition (especially hypoventilation), complexity of signs/symptoms and clinical course, and importance of initiating comprehensive, multispecialty care. These cases confound the hypothesis of a monogenic etiology for ROHHAD and indicate alternative etiologies including autoimmune or epigenetic phenomenon or a combination of genetic

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

Intrapair Similarity of Computer Self-Efficacy in Turkish Adolescent Twins

Science.gov (United States)

Deryakulu, Deniz; Mcilroy, David; Ursavas, Ömer Faruk; Çaliskan, Erkan

2016-01-01

The purpose of this study is to investigate genetic and environmental influences on computer self-efficacy. A total of 165 Turkish twin-pairs participated in the study. Participants' mean age was 12.45 (SD = 1.82). The results of paired t-test comparisons showed no significant differences in monozygotic, and both same-sex and opposite-sex…

Kicking Back Cognitive Ageing: Leg Power Predicts Cognitive Ageing after Ten Years in Older Female Twins.

Science.gov (United States)

Steves, Claire J; Mehta, Mitul M; Jackson, Stephen H D; Spector, Tim D

2016-01-01

Many observational studies have shown a protective effect of physical activity on cognitive ageing, but interventional studies have been less convincing. This may be due to short time scales of interventions, suboptimal interventional regimes or lack of lasting effect. Confounding through common genetic and developmental causes is also possible. We aimed to test whether muscle fitness (measured by leg power) could predict cognitive change in a healthy older population over a 10-year time interval, how this performed alongside other predictors of cognitive ageing, and whether this effect was confounded by factors shared by twins. In addition, we investigated whether differences in leg power were predictive of differences in brain structure and function after 12 years of follow-up in identical twin pairs. A total of 324 healthy female twins (average age at baseline 55, range 43-73) performed the Cambridge Neuropsychological Test Automated Battery (CANTAB) at two time points 10 years apart. Linear regression modelling was used to assess the relationships between baseline leg power, physical activity and subsequent cognitive change, adjusting comprehensively for baseline covariates (including heart disease, diabetes, blood pressure, fasting blood glucose, lipids, diet, body habitus, smoking and alcohol habits, reading IQ, socioeconomic status and birthweight). A discordant twin approach was used to adjust for factors shared by twins. A subset of monozygotic pairs then underwent magnetic resonance imaging. The relationship between muscle fitness and brain structure and function was assessed using linear regression modelling and paired t tests. A striking protective relationship was found between muscle fitness (leg power) and both 10-year cognitive change [fully adjusted model standardised β-coefficient (Stdβ) = 0.174, p = 0.002] and subsequent total grey matter (Stdβ = 0.362, p = 0.005). These effects were robust in discordant twin analyses, where within-pair

Study of 3-D stress development in parent and twin pairs of a hexagonal close-packed polycrystal: Part II - Crystal plasticity finite element modeling

DEFF Research Database (Denmark)

Abdolvand, Hamidreza; Majkut, Marta; Oddershede, Jette

2015-01-01

for each grain from the 3DXRD experiment is within the stress variation zone of the grain modeled in the CPFE simulation. Also, the CPFE average stress calculation for each grain is in good agreement with the measured average stress values. It is shown that upon considering the stress variations within......Stress heterogeneity within each individual grain of polycrystalline Zircaloy-2 is studied using a crystal plasticity finite element (CPFE) model. For this purpose, the weighted Voronoi tessellation method is used to construct 3D geometries of more than 2600 grains based on their center......-of-mass positions and volumes as measured by three-dimensional X-ray diffraction (3DXRD) microscopy. The constructed microstructure is meshed with different element densities and for different numbers of grains. Then a selected group of twin and parent pairs are studied. It is shown that the measured average stress...

Fast metastable hydrogen atoms from H2 molecules: twin atoms

Directory of Open Access Journals (Sweden)

Trimèche A.

2015-01-01

Full Text Available It is a difficult task to obtain “twin atoms”, i.e. pairs of massive particles such that one can perform experiments in the same fashion that is routinely done with “twin photons”. One possible route to obtain such pairs is by dissociating homonuclear diatomic molecules. We address this possibility by investigating the production of metastable H(2s atoms coming from the dissociation of cold H2 molecules produced in a Campargue nozzle beam crossing an electron beam from a high intensity pulsed electron gun. Dissociation by electron impact was chosen to avoid limitations of target molecular excited states due to selection rules. Detectors placed several centimeters away from the collision center, and aligned with respect to possible common molecular dissociation channel, analyze the neutral fragments as a function of their time-of-flight (TOF through Lyman-α detection. Evidence for the first time observed coincidence of pairs of H(2s atoms obtained this way is presented.

Perinatal hepatic infarction in twin-twin transfusion.

LENUS (Irish Health Repository)

O'Sullivan, M J

2012-02-03

We report a case of a twin pregnancy which was complicated by a twin-twin transfusion in which the recipient twin was noted to have an intra-abdominal echogenic mass. This twin died at two days of age of hepatic infarction. The donor twin was healthy at birth, at thirty weeks\\' gestation, and did not have any subsequent problems. Fetal intra-abdominal echogenicity may be a marker of hepatic infarction.

Separation surgery for total vertical craniopagus twins.

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Goh, Keith Y C

2004-08-01

A pair of conjoined twins aged 11 months underwent investigations, followed by surgical separation in Singapore General Hospital in April 2001. They were joined at the skull vertex and facing in opposite directions. Radiological investigations including cerebral angiography, magnetic resonance imaging and computerized tomographic scans were performed, leading to the diagnosis of total vertical craniopagus. There were two separate brains, with separate arterial circulations, but with a common superior sagittal sinus. Tissue expanders were inserted in the subgaleal space for 6 months of scalp expansion prior to surgery. Pre-operative planning involved the use of virtual reality equipment and life-sized polymer models of the conjoined skulls and brains. Surgical separation of the twins was achieved after approximately 100 h of operating time, using intraoperative image guidance, microsurgical techniques and intraoperative neurophysiologic monitoring. Reconstruction of the dura, calvarium and scalp was performed with artificial dura, absorbable plates and split skin grafts. Postoperative complications included focal cortical infarction, meningitis, and hydrocephalus. Despite these complications, the twins recovered satisfactorily and were discharged to their home country within 6 months. The 3-month outcome was minor disability in one twin and severe developmental delays in the other. Separation surgery is possible for complex cranially-conjoined twins but requires detailed planning and extensive surgical management.

[Longitudinal genetic effects on mandibular position of female twins from six to twelve years old].

Science.gov (United States)

Zhu, Chang-feng; Peng, Jing

2013-06-01

To find the longitudinal genetic effects on mandibular position in mixed dentition. The sample used in this study consisted of lateral cephalograms of eighty-nine pairs of female twins in Beijing. With a mixed longitudinal method, the effective twins were 183 pairs(monozygous 110 pairs and dizygous 73 ones). The genetic and environmental effects on mandibular position were analyzed by statistical methods in female twins from six to twelve years old. Statistical comparisons revealed significant (Pchin is the most subjective to environment change, then the mandibular angle, and the condyle is the least. Using N and S as references, the environmental influence on heights showed different order from the most to least changeable: The mandibular angle, the condyle and the chin. In later stage of our observation, the mandibular morphology and growth type might be family inherited. For environmental influences plays important roles on mandibular position, these findings can be used in orthodontic treatment planning.

Ties of silence--Family lived experience of selective mutism in identical twins.

Science.gov (United States)

Albrigtsen, Vårin; Eskeland, Benedicte; Mæhle, Magne

2016-04-01

This article is based on an in-depth interview with a pair of twins diagnosed with selective mutism and their parents 2 years after recovery. Selective mutism (SM) is a rare disorder, and identical twins sharing the condition are extremely rare. The twins developed SM simultaneously during their first year of school. The treatment and follow-up they received for several years are briefly described in this article. The interview explored the children's and their parents' narratives about the origin of the condition, the challenges it entailed in their daily lives, and what they found helpful in the treatment they were offered. In the interview, the children conveyed experiences that even the parents were unaware of and revealed examples of daily life-traumas for which they were unable to obtain support and help. The whole family was trapped in the silence. The twins and their parents emphasized different aspects in terms of what they believed were helpful. The implications of these findings for our understanding and treatment of children with SM are discussed, as well as the potential of service user involvement in child and adolescent mental health research. © The Author(s) 2015.

Differential models of twin correlations in skew for body-mass index (BMI).

Science.gov (United States)

Tsang, Siny; Duncan, Glen E; Dinescu, Diana; Turkheimer, Eric

2018-01-01

Body Mass Index (BMI), like most human phenotypes, is substantially heritable. However, BMI is not normally distributed; the skew appears to be structural, and increases as a function of age. Moreover, twin correlations for BMI commonly violate the assumptions of the most common variety of the classical twin model, with the MZ twin correlation greater than twice the DZ correlation. This study aimed to decompose twin correlations for BMI using more general skew-t distributions. Same sex MZ and DZ twin pairs (N = 7,086) from the community-based Washington State Twin Registry were included. We used latent profile analysis (LPA) to decompose twin correlations for BMI into multiple mixture distributions. LPA was performed using the default normal mixture distribution and the skew-t mixture distribution. Similar analyses were performed for height as a comparison. Our analyses are then replicated in an independent dataset. A two-class solution under the skew-t mixture distribution fits the BMI distribution for both genders. The first class consists of a relatively normally distributed, highly heritable BMI with a mean in the normal range. The second class is a positively skewed BMI in the overweight and obese range, with lower twin correlations. In contrast, height is normally distributed, highly heritable, and is well-fit by a single latent class. Results in the replication dataset were highly similar. Our findings suggest that two distinct processes underlie the skew of the BMI distribution. The contrast between height and weight is in accord with subjective psychological experience: both are under obvious genetic influence, but BMI is also subject to behavioral control, whereas height is not.

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.

Pair- ${v}$ -SVR: A Novel and Efficient Pairing nu-Support Vector Regression Algorithm.

Science.gov (United States)

Hao, Pei-Yi

This paper proposes a novel and efficient pairing nu-support vector regression (pair--SVR) algorithm that combines successfully the superior advantages of twin support vector regression (TSVR) and classical -SVR algorithms. In spirit of TSVR, the proposed pair--SVR solves two quadratic programming problems (QPPs) of smaller size rather than a single larger QPP, and thus has faster learning speed than classical -SVR. The significant advantage of our pair--SVR over TSVR is the improvement in the prediction speed and generalization ability by introducing the concepts of the insensitive zone and the regularization term that embodies the essence of statistical learning theory. Moreover, pair--SVR has additional advantage of using parameter for controlling the bounds on fractions of SVs and errors. Furthermore, the upper bound and lower bound functions of the regression model estimated by pair--SVR capture well the characteristics of data distributions, thus facilitating automatic estimation of the conditional mean and predictive variance simultaneously. This may be useful in many cases, especially when the noise is heteroscedastic and depends strongly on the input values. The experimental results validate the superiority of our pair--SVR in both training/prediction speed and generalization ability.This paper proposes a novel and efficient pairing nu-support vector regression (pair--SVR) algorithm that combines successfully the superior advantages of twin support vector regression (TSVR) and classical -SVR algorithms. In spirit of TSVR, the proposed pair--SVR solves two quadratic programming problems (QPPs) of smaller size rather than a single larger QPP, and thus has faster learning speed than classical -SVR. The significant advantage of our pair--SVR over TSVR is the improvement in the prediction speed and generalization ability by introducing the concepts of the insensitive zone and the regularization term that embodies the essence of statistical learning theory

Heritability of Performance Deficit Accumulation During Acute Sleep Deprivation in Twins

Science.gov (United States)

Kuna, Samuel T.; Maislin, Greg; Pack, Frances M.; Staley, Bethany; Hachadoorian, Robert; Coccaro, Emil F.; Pack, Allan I.

2012-01-01

Study Objectives: To determine if the large and highly reproducible interindividual differences in rates of performance deficit accumulation during sleep deprivation, as determined by the number of lapses on a sustained reaction time test, the Psychomotor Vigilance Task (PVT), arise from a heritable trait. Design: Prospective, observational cohort study. Setting: Academic medical center. Participants: There were 59 monozygotic (mean age 29.2 ± 6.8 [SD] yr; 15 male and 44 female pairs) and 41 dizygotic (mean age 26.6 ± 7.6 yr; 15 male and 26 female pairs) same-sex twin pairs with a normal polysomnogram. Interventions: Thirty-eight hr of monitored, continuous sleep deprivation. Measurements and Results: Patients performed the 10-min PVT every 2 hr during the sleep deprivation protocol. The primary outcome was change from baseline in square root transformed total lapses (response time ≥ 500 ms) per trial. Patient-specific linear rates of performance deficit accumulation were separated from circadian effects using multiple linear regression. Using the classic approach to assess heritability, the intraclass correlation coefficients for accumulating deficits resulted in a broad sense heritability (h2) estimate of 0.834. The mean within-pair and among-pair heritability estimates determined by analysis of variance-based methods was 0.715. When variance components of mixed-effect multilevel models were estimated by maximum likelihood estimation and used to determine the proportions of phenotypic variance explained by genetic and nongenetic factors, 51.1% (standard error = 8.4%, P sleep deprivation. Citation: Kuna ST; Maislin G; Pack FM; Staley B; Hachadoorian R; Coccaro EF; Pack AI. Heritability of performance deficit accumulation during acute sleep deprivation in twins. SLEEP 2012;35(9):1223-1233. PMID:22942500

The Effect of Birth Order on Neonatal Morbidity and Mortality in Very Preterm Twins.

Science.gov (United States)

Mei-Dan, Elad; Shah, Jyotsna; Lee, Shoo; Shah, Prakesh S; Murphy, Kellie E

2017-07-01

Objective  This retrospective cohort study examined the effect of birth order on neonatal morbidity and mortality in very preterm twins. Study Design  Using 2005 to 2012 data from the Canadian Neonatal Network, very preterm twins born between 24 0/7 and 32 6/7 weeks of gestation were included. Odds of morbidity and mortality of second-born cotwins compared with first-born cotwins were examined by matched-pair analysis. Outcomes were neonatal death, severe brain injury (intraventricular hemorrhage grade 3 or 4 or persistent periventricular echogenicity), bronchopulmonary dysplasia, severe retinopathy of prematurity (ROP) (> stage 2), necrotizing enterocolitis (≥ stage 2), and respiratory distress syndrome (RDS). Multivariable analysis was performed adjusting for confounders. Result  There were 6,636 twins (3,318 pairs) included with a mean gestational age (GA) of 28.9 weeks. A higher rate of small for GA occurred in second-born twins (10 vs. 6%). Mortality was significantly lower for second-born twins (4.3 vs. 5.3%; adjusted odds ratio: 0.75; 95% confidence interval [CI]: 0.59-0.95). RDS (66 vs. 60%; adjusted odds ratio: 1.40; 95% CI: 1.29-1.52) and severe retinopathy (9 vs. 7%; adjusted odds ratio: 1.46; 95% CI: 1.07-2.01) were significantly higher in second-born twins. Conclusion  Thus, while second-born twins had reduced odds of mortality, they also had increased odds of RDS and ROP. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Rationale, Design, and Methodological Aspects of the BUDAPEST-GLOBAL Study (Burden of Atherosclerotic Plaques Study in Twins-Genetic Loci and the Burden of Atherosclerotic Lesions).

Science.gov (United States)

Maurovich-Horvat, Pál; Tárnoki, Dávid L; Tárnoki, Ádám D; Horváth, Tamás; Jermendy, Ádám L; Kolossváry, Márton; Szilveszter, Bálint; Voros, Viktor; Kovács, Attila; Molnár, Andrea Á; Littvay, Levente; Lamb, Hildo J; Voros, Szilard; Jermendy, György; Merkely, Béla

2015-12-01

The heritability of coronary atherosclerotic plaque burden, coronary geometry, and phenotypes associated with increased cardiometabolic risk are largely unknown. The primary aim of the Burden of Atherosclerotic Plaques Study in Twins-Genetic Loci and the Burden of Atherosclerotic Lesions (BUDAPEST-GLOBAL) study is to evaluate the influence of genetic and environmental factors on the burden of coronary artery disease. By design this is a prospective, single-center, classical twin study. In total, 202 twins (61 monozygotic pairs, 40 dizygotic same-sex pairs) were enrolled from the Hungarian Twin Registry database. All twins underwent non-contrast-enhanced computed tomography (CT) for the detection and quantification of coronary artery calcium and for the measurement of epicardial fat volumes. In addition, a single non-contrast-enhanced image slice was acquired at the level of L3-L4 to assess abdominal fat distribution. Coronary CT angiography was used for the detection and quantification of plaque, stenosis, and overall coronary artery disease burden. For the primary analysis, we will assess the presence and volume of atherosclerotic plaques. Furthermore, the 3-dimensional coronary geometry will be assessed based on the coronary CT angiography datasets. Additional phenotypic analyses will include per-patient epicardial and abdominal fat quantity measurements. Measurements obtained from monozygotic and dizygotic twin pairs will be compared to evaluate the genetic or environmental effects of the given phenotype. The BUDAPEST-GLOBAL study provides a unique framework to shed some light on the genetic and environmental influences of cardiometabolic disorders. © 2015 Wiley Periodicals, Inc.

Structural health monitoring (vibration) as a tool for identifying structural alterations of the lumbar spine: a twin control study.

Science.gov (United States)

Kawchuk, Gregory N; Hartvigsen, Jan; Edgecombe, Tiffany; Prasad, Narasimha; van Dieen, Jaap H

2016-03-11

Structural health monitoring (SHM) is an engineering technique used to identify mechanical abnormalities not readily apparent through other means. Recently, SHM has been adapted for use in biological systems, but its invasive nature limits its clinical application. As such, the purpose of this project was to determine if a non-invasive form of SHM could identify structural alterations in the spines of living human subjects. Lumbar spines of 10 twin pairs were visualized by magnetic resonance imaging then assessed by a blinded radiologist to determine whether twin pairs were structurally concordant or discordant. Vibration was then applied to each subject's spine and the resulting response recorded from sensors overlying lumbar spinous processes. The peak frequency, area under the curve and the root mean square were computed from the frequency response function of each sensor. Statistical analysis demonstrated that in twins whose structural appearance was discordant, peak frequency was significantly different between twin pairs while in concordant twins, no outcomes were significantly different. From these results, we conclude that structural changes within the spine can alter its vibration response. As such, further investigation of SHM to identify spinal abnormalities in larger human populations is warranted.

Novel epigenetic changes unveiled by monozygotic twins discordant for smoking habits.

Science.gov (United States)

Allione, Alessandra; Marcon, Francesca; Fiorito, Giovanni; Guarrera, Simonetta; Siniscalchi, Ester; Zijno, Andrea; Crebelli, Riccardo; Matullo, Giuseppe

2015-01-01

Exposure to cigarette smoking affects the epigenome and could increase the risk of developing diseases such as cancer and cardiovascular disorders. Changes in DNA methylation associated with smoking may help to identify molecular pathways that contribute to disease etiology. Previous studies are not completely concordant in the identification of differentially methylated regions in the DNA of smokers. We performed an epigenome-wide DNA methylation study in a group of monozygotic (MZ) twins discordant for smoking habits to determine the effect of smoking on DNA methylation. As MZ twins are considered genetically identical, this model allowed us to identify smoking-related DNA methylation changes independent from genetic components. We investigated the whole blood genome-wide DNA methylation profiles in 20 MZ twin pairs discordant for smoking habits by using the Illumina HumanMethylation450 BeadChip. We identified 22 CpG sites that were differentially methylated between smoker and non-smoker MZ twins by intra-pair analysis. We confirmed eight loci already described by other groups, located in AHRR, F2RL3, MYOG1 genes, at 2q37.1 and 6p21.33 regions, and also identified several new loci. Moreover, pathway analysis showed an enrichment of genes involved in GTPase regulatory activity. Our study confirmed the evidence of smoking-related DNA methylation changes, emphasizing that well-designed MZ twin models can aid the discovery of novel DNA methylation signals, even in a limited sample population.

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 

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...

Genetic and environmental influences on adolescents' smoking involvement: a multi-informant twin study.

Science.gov (United States)

Seglem, Karoline Brobakke; Waaktaar, Trine; Ask, Helga; Torgersen, Svenn

2015-03-01

Studying monozygotic and dizygotic adolescent twin pairs of both sexes reared together, the present study examined the extent to which the variance in smoking involvement is attributable to genetic and environmental effects, and to what extent there are sex differences in the etiology. Questionnaire data on how often the adolescent had ever smoked tobacco was collected from a population-based twin sample consisting of seven national birth cohorts (ages 12-18), their mothers, and their fathers (N = 1,394 families). The data was analyzed with multivariate genetic modeling, using a multi-informant design. The etiological structure of smoking involvement was best represented in an ACE common pathway model, with smoking defined as a latent factor loading onto all three informants' reports. Estimates could be set equal across sexes. Results showed that adolescent lifetime smoking involvement was moderately heritable (37 %). The largest influence was from the shared environment (56 %), while environmental effects unique to each twin had minimal influence (7 %).

The Application of Structural Equation Modeling to Maternal Ratings of Twins' Behavior and Emotional Problems.

Science.gov (United States)

Silberg, Judy L.; And Others

1994-01-01

Applied structural equation modeling to twin data to assess impact of genetic and environmental factors on children's behavioral and emotional functioning. Applied models to maternal ratings of behavior of 515 monozygotic and 749 dizygotic twin pairs. Importance of genetic, shared, and specific environmental factors for explaining variation was…

Radical-pair based avian magnetoreception

Science.gov (United States)

Procopio, Maria; Ritz, Thorsten

2014-03-01

Behavioural experiments suggest that migratory birds possess a magnetic compass sensor able to detect the direction of the geomagnetic. One hypothesis for the basis of this remarkable sensory ability is that the coherent quantum spin dynamics of photoinduced radical pair reactions transduces directional magnetic information from the geomagnetic field into changes of reaction yields, possibly involving the photoreceptor cryptochrome in the birds retina. The suggested radical-pair based avian magnetoreception has attracted attention in the field of quantum biology as an example of a biological sensor which might exploit quantum coherences for its biological function. Investigations on such a spin-based sensor have focussed on uncovering the design features for the design of a biomimetic magnetic field sensor. We study the effects of slow fluctuations in the nuclear spin environment on the directional signal. We quantitatively evaluate the robustness of signals under fluctuations on a timescale longer than the lifetime of a radical pair, utilizing two models of radical pairs. Our results suggest design principles for building a radical-pair based compass sensor that is both robust and highly directional sensitive.

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

not appear to play an important role in determining risk for frontal, occipital or temporal lobe epilepsy. These results suggest that, while genetic factors contribute to risk for major syndrome types, determined when possible, their contribution to risk for localization-related syndrome sub......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...

A synthetic medical and sociological study on twins exposed by atomic bomb, 8

International Nuclear Information System (INIS)

Satow, Yukio; Watanabe, Shoji; Kyo, Taiichi

1984-01-01

The relationship between immunoglobulin (IgG, IgA, IgM) levels and the exposure status was examined in 13 enzygotic twin pairs who had been exposed to atomic bomb under the same or different conditions and who had no disease showing changes in immunoglobulin levels. The difference in immunoglobulin levels tended to be smaller between the twins exposed under the same conditions and to be larger between the twins exposed under the different conditions. This should be further studied because there were some exceptions in this study. (Namekawa, K.)

Quantitative XRD analysis of {110} twin density in biotic aragonites.

Science.gov (United States)

Suzuki, Michio; Kim, Hyejin; Mukai, Hiroki; Nagasawa, Hiromichi; Kogure, Toshihiro

2012-12-01

{110} Twin densities in biotic aragonite have been estimated quantitatively from the peak widths of specific reflections in powder X-ray diffraction (XRD) patterns, as well as direct confirmation of the twins using transmission electron microscopy (TEM). Influence of the twin density on the peak widths in the XRD pattern was simulated using DIFFaX program, regarding (110) twin as interstratification of two types of aragonite unit layers with mirrored relationship. The simulation suggested that the twin density can be estimated from the difference of the peak widths between 111 and 021, or between 221 and 211 reflections. Biotic aragonite in the crossed-lamellar microstructure (three species) and nacreous microstructure (four species) of molluscan shells, fish otoliths (two species), and a coral were investigated. The XRD analyses indicated that aragonite crystals in the crossed-lamellar microstructure of the three species contain high density of the twins, which is consistent with the TEM examination. On the other hand, aragonite in the nacre of the four species showed almost no difference of the peak widths between the paired reflections, indicating low twin densities. The results for the fish otoliths were varied between the species. Such variation of the twin density in biotic aragonites may reflect different schemes of crystal growth in biomineralization. Copyright © 2012 Elsevier Inc. All rights reserved.

Monozygotic twins with CAPN5 autosomal dominant neovascular inflammatory vitreoretinopathy.

Science.gov (United States)

Rowell, Hannah A; Bassuk, Alexander G; Mahajan, Vinit B

2012-01-01

The purpose of this study was to describe the clinical findings in a set of monozygotic twins with autosomal dominant neovascular inflammatory vitreoretinopathy (ADNIV) over a 23-year period. A pair of female twins were examined between 26 and 49 years of age. The concordance and discordance of their clinical features were determined. The CAPN5 gene was sequenced using genomic DNA. Both twins of an affected father demonstrated Stage I ADNIV with mild vitreous cells and a negative b-wave on electroretinography. Genetic analysis confirmed a guanine to thymine nucleotide (c.728G>T, pArg243Leu) mutation in the CAPN5 gene. Over the course of 23 years, each twin progressed to stage III disease, showing posterior uveitis, cystoid macular edema, intraocular fibrosis, early retinal neovascularization, retinal degeneration, and cataract. Disease progression varied moderately between each twin and was asymmetrical between eyes. Twin A had 20/70 and 20/125 in the right and left eye, respectively, and underwent vitrectomy surgery and intravitreal injections with bevacizumab for recurrent cystoid macular edema. Twin B maintained 20/20 and 20/40 in the right and left eye, respectively without intervention. There was asymmetry between the eyes and some discordance in the rate of disease progression in these monozygotic twins with ADNIV. The overall high disease concordance suggests genetic factors play a major role in clinical manifestations in CAPN5 vitreoretinopathy.

Genetic and environmental effects on same-sex sexual behavior: a population study of twins in Sweden.

Science.gov (United States)

Långström, Niklas; Rahman, Qazi; Carlström, Eva; Lichtenstein, Paul

2010-02-01

There is still uncertainty about the relative importance of genes and environments on human sexual orientation. One reason is that previous studies employed self-selected, opportunistic, or small population-based samples. We used data from a truly population-based 2005-2006 survey of all adult twins (20-47 years) in Sweden to conduct the largest twin study of same-sex sexual behavior attempted so far. We performed biometric modeling with data on any and total number of lifetime same-sex sexual partners, respectively. The analyses were conducted separately by sex. Twin resemblance was moderate for the 3,826 studied monozygotic and dizygotic same-sex twin pairs. Biometric modeling revealed that, in men, genetic effects explained .34-.39 of the variance, the shared environment .00, and the individual-specific environment .61-.66 of the variance. Corresponding estimates among women were .18-.19 for genetic factors, .16-.17 for shared environmental, and 64-.66 for unique environmental factors. Although wide confidence intervals suggest cautious interpretation, the results are consistent with moderate, primarily genetic, familial effects, and moderate to large effects of the nonshared environment (social and biological) on same-sex sexual behavior.

Comparison of sequencing based CNV discovery methods using monozygotic twin quartets.

Directory of Open Access Journals (Sweden)

Marc-André Legault

Full Text Available The advent of high throughput sequencing methods breeds an important amount of technical challenges. Among those is the one raised by the discovery of copy-number variations (CNVs using whole-genome sequencing data. CNVs are genomic structural variations defined as a variation in the number of copies of a large genomic fragment, usually more than one kilobase. Here, we aim to compare different CNV calling methods in order to assess their ability to consistently identify CNVs by comparison of the calls in 9 quartets of identical twin pairs. The use of monozygotic twins provides a means of estimating the error rate of each algorithm by observing CNVs that are inconsistently called when considering the rules of Mendelian inheritance and the assumption of an identical genome between twins. The similarity between the calls from the different tools and the advantage of combining call sets were also considered.ERDS and CNVnator obtained the best performance when considering the inherited CNV rate with a mean of 0.74 and 0.70, respectively. Venn diagrams were generated to show the agreement between the different algorithms, before and after filtering out familial inconsistencies. This filtering revealed a high number of false positives for CNVer and Breakdancer. A low overall agreement between the methods suggested a high complementarity of the different tools when calling CNVs. The breakpoint sensitivity analysis indicated that CNVnator and ERDS achieved better resolution of CNV borders than the other tools. The highest inherited CNV rate was achieved through the intersection of these two tools (81%.This study showed that ERDS and CNVnator provide good performance on whole genome sequencing data with respect to CNV consistency across families, CNV breakpoint resolution and CNV call specificity. The intersection of the calls from the two tools would be valuable for CNV genotyping pipelines.

Excess Mortality in Patients Diagnosed With Hypothyroidism: A Nationwide Cohort Study of Singletons and Twins

Science.gov (United States)

Thvilum, Marianne; Brandt, Frans; Almind, Dorthe; Christensen, Kaare; Brix, Thomas Heiberg

2013-01-01

Background: Although hypothyroidism is associated with increased morbidity, an association with increased mortality is still debated. Our objective was to investigate, at a nationwide level, whether a diagnosis of hypothyroidism influences mortality. Methods: In an observational cohort study from January 1, 1978 until December 31, 2008 using record-linkage data from nationwide Danish health registers, 3587 singletons and 682 twins diagnosed with hypothyroidism were identified. Hypothyroid individuals were matched 1:4 with nonhypothyroid controls with respect to age and gender and followed over a mean period of 5.6 years (range 0–30 years). The hazard ratio (HR) for mortality was calculated using Cox regression analyses. Comorbidity was evaluated using the Charlson score (CS). Results: In singletons with hypothyroidism, the mortality risk was increased (HR 1.52; 95% confidence interval [CI]: 1.41–1.65). Although the effect attenuated, hypothyroidism remained associated with increased mortality when evaluating subjects with a CS = 0 (HR 1.23; 95% CI: 1.05–1.44). In twin pairs discordant for hypothyroidism, the hypothyroid twin had excess mortality compared with the corresponding euthyroid cotwin (HR 1.40; 95% CI 0.95–2.05). However, after stratifying for zygosity, hypothyroidism was associated with excess mortality in dizygotic twin pairs (HR 1.61; 95% CI 1.00–2.58), whereas the association attenuated in monozygotic pairs (HR 1.06; 95% CI 0.55–2.05). Conclusions: Hypothyroidism is associated with an excess mortality of around 50%, which to some degree is explained by comorbidity. In addition, the finding of an association between hypothyroidism and mortality within disease discordant dizygotic but not monozygotic twin pairs indicates that the association between hypothyroidism and mortality is also influenced by genetic confounding. PMID:23365121

The genetic basis for cognitive ability, memory, and depression symptomatology in middle-aged and elderly chinese twins

DEFF Research Database (Denmark)

Xu, Chunsheng; Sun, Jianping; Ji, Fuling

2015-01-01

The genetic influences on aging-related phenotypes, including cognition and depression, have been well confirmed in the Western populations. We performed the first twin-based analysis on cognitive performance, memory and depression status in middle-aged and elderly Chinese twins, representing...... the world's largest and most rapidly aging population. The sample consisted of 384 twin pairs with a median age of 50 years. Cognitive function was measured using the Montreal Cognitive Assessment (MoCA) scale; memory was assessed using the revised Wechsler Adult Intelligence scale; depression...... with heritability 0.44 for cognition and 0.56 for memory. Multivariate analysis by the reduced Cholesky model estimated significant genetic (rG = 0.69) and unique environmental (rE = 0.25) correlation between cognitive ability and memory. The model also estimated weak but significant inverse genetic correlation...

Risk aversion and religious behaviour: Analysis using a sample of Danish twins.

Science.gov (United States)

Nielsen, Jytte Seested; Bech, Mickael; Christensen, Kaare; Kiil, Astrid; Hvidt, Niels Christian

2017-08-01

Economics offers an analytical framework to consider human behaviour including religious behaviour. Within the realm of Expected Utility Theory, religious belief and activity could be interpreted as an insurance both for current life events and for afterlife rewards. Based on that framework, we would expect that risk averse individuals would demand a more generous protection plan which they may do by devoting more effort and resources into religious activities such as church attendance and prayer, which seems to be in accordance with previous empirical results. However, a general concern regards the problems of spurious correlations due to underlying omitted or unobservable characteristics shaping both religious activities and risk attitudes. This paper examines empirically the demand for religion by analysing the association between risk attitudes on the one hand, and church attandance and prayer frequency on the other controlling for unobservable variables using survey data of Danish same-sex twin pairs. We verify the correlation between risk preferences and religion found previously by carrying out cross-sectional analyses. We also show that the association between risk attitudes and religious behaviour is driven by the subgroup of individuals who believe in an afterlife. In addition, when re-analysing our results using panel data analyses which cancel out shared factors among twin pairs, we find that the correlation found between risk aversion and religious behaviour is no longer significant indicating that other factors might explain differences in religious behaviour. Caution is needed in the interpretation of our results as the insignificant association between risk aversion and religious behaviour in the panel data analyses potentially might be due to measurement error causing attenuation bias or lack of variation within twin pairs rather than the actual absence of an association. Copyright © 2017 Elsevier B.V. All rights reserved.

Integrated fiber Michelson interferometer based on poled hollow twin-core fiber.

Science.gov (United States)

Liu, Zhihai; Bo, Fusen; Wang, Lei; Tian, Fengjun; Yuan, Libo

2011-07-01

We propose an integrated fiber Michelson interferometer based on a poled hollow twin-core fiber. The Michelson interferometer can be used as an electro-optic modulator by thermal poling one core of the twin-core fiber and introducing second-order nonlinearity in the fiber. The proposed fiber Michelson interferometer is experimentally demonstrated under driving voltages at the frequency range of 149 to 1000 Hz. The half-wave voltage of the poled fiber is 135 V, and the effective second-order nonlinear coefficient χ² is 1.23 pm/V.

Longitudinal genetic analysis of brain volumes in normal elderly male twins

OpenAIRE

Lessov-Schlaggar, Christina N.; Hardin, Jill; DeCarli, Charles; Krasnow, Ruth E.; Reed, Terry; Wolf, Philip A.; Swan, Gary E.; Carmelli, Dorit

2010-01-01

This study investigated the role of genetic and environmental influences on individual differences in brain volumes measured at two time points in normal elderly males from the National Heart, Lung, and Blood Institute Twin Study. The MRI scans were conducted four years apart on 33 monozygotic and 33 dizygotic male twin pairs, aged 68 to 77 years when first scanned. Volumetric measures of total brain and total cerebrospinal fluid were significantly heritable at baseline (over 70%). For both v...

Is that me or my twin? Lack of self-face recognition advantage in identical twins.

Directory of Open Access Journals (Sweden)

Matteo Martini

Full Text Available Despite the increasing interest in twin studies and the stunning amount of research on face recognition, the ability of adult identical twins to discriminate their own faces from those of their co-twins has been scarcely investigated. One's own face is the most distinctive feature of the bodily self, and people typically show a clear advantage in recognizing their own face even more than other very familiar identities. Given the very high level of resemblance of their faces, monozygotic twins represent a unique model for exploring self-face processing. Herein we examined the ability of monozygotic twins to distinguish their own face from the face of their co-twin and of a highly familiar individual. Results show that twins equally recognize their own face and their twin's face. This lack of self-face advantage was negatively predicted by how much they felt physically similar to their co-twin and by their anxious or avoidant attachment style. We speculate that in monozygotic twins, the visual representation of the self-face overlaps with that of the co-twin. Thus, to distinguish the self from the co-twin, monozygotic twins have to rely much more than control participants on the multisensory integration processes upon which the sense of bodily self is based. Moreover, in keeping with the notion that attachment style influences perception of self and significant others, we propose that the observed self/co-twin confusion may depend upon insecure attachment.

Spatiotemporal configuration dependent pairing of nerve events in dark-adapted human vision

NARCIS (Netherlands)

Bouman, M.A.

2002-01-01

In the model presented here, in the dark any single quantum absorption in a rod or cone produces a subliminal excitation. Subliminal excitations from both halves of a twin unit pair in the retina for the perception of light from the stimulus. A twin unit contains either two red or two green cones.

A longitudinal twin study of the association between childhood autistic traits and psychotic experiences in adolescence

OpenAIRE

Taylor, Mark J.; Robinson, Elise B.; Happ?, Francesca; Bolton, Patrick; Freeman, Daniel; Ronald, Angelica

2015-01-01

Background: This twin study investigated whether autistic traits during childhood were associated with adolescent psychotic experiences. Methods: Data were collected from a community sample of approximately 5000 twin pairs, which included 32 individuals with diagnosed autism spectrum conditions (ASC). Parents rated autistic traits in the twins at four points between ages 8–16 years. Positive, negative, and cognitive psychotic experiences were assessed at age 16 years using self- and parent-re...

Influence of acquired obesity on coronary vessel wall late gadolinium enhancement in discordant monozygote twins

International Nuclear Information System (INIS)

Makowski, Marcus R.; Jansen, Christian H.P.; Ebersberger, Ullrich; Spector, Tim D.; Schaeffter, Tobias; Razavi, Reza; Mangino, Massimo; Botnar, Rene M.; Greil, Gerald F.

2017-01-01

The aim of this study was to investigate the impact of BMI on late gadolinium enhancement (LGE) of the coronary artery wall in identical monozygous twins discordant for BMI. Coronary LGE represents a useful parameter for the detection and quantification of atherosclerotic coronary vessel wall disease. Thirteen monozygote female twin pairs (n = 26) with significantly different BMIs (>1.6 kg/m2) were recruited out of >10,000 twin pairs (TwinsUK Registry). A coronary 3D-T2prep-TFE MR angiogram and 3D-IR-TFE vessel wall scan were performed prior to and following the administration of 0.2 mmol/kg of Gd-DTPA on a 1.5 T MR scanner. The number of enhancing coronary segments and contrast to noise ratios (CNRs) of the coronary wall were quantified. An increase in BMI was associated with an increased number of enhancing coronary segments (5.3 ± 1.5 vs. 3.5 ± 1.6, p < 0.0001) and increased coronary wall enhancement (6.1 ± 1.1 vs. 4.8 ± 0.9, p = 0.0027) compared to matched twins with lower BMI. This study in monozygous twins indicates that acquired factors predisposing to obesity, including lifestyle and environmental factors, result in increased LGE of the coronary arteries, potentially reflecting an increase in coronary atherosclerosis in this female study population. (orig.)

Influence of acquired obesity on coronary vessel wall late gadolinium enhancement in discordant monozygote twins

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Makowski, Marcus R. [King' s College London, Division of Imaging Sciences and Biomedical Engineering, London (United Kingdom); Wellcome Trust and EPSRC Medical Engineering Centre, London (United Kingdom); King' s College London, BHF Centre of Excellence, London (United Kingdom); King' s College London, NIHR Biomedical Research Centre, London (United Kingdom); Charite-Universitaetsmedizin, Department of Radiology, Berlin (Germany); Jansen, Christian H.P. [King' s College London, Division of Imaging Sciences and Biomedical Engineering, London (United Kingdom); Ebersberger, Ullrich; Spector, Tim D. [Heart Center Munich-Bogenhausen, Department of Cardiology and Intensive Care Medicine, Munich (Germany); Schaeffter, Tobias; Razavi, Reza [King' s College London, Division of Imaging Sciences and Biomedical Engineering, London (United Kingdom); Wellcome Trust and EPSRC Medical Engineering Centre, London (United Kingdom); King' s College London, BHF Centre of Excellence, London (United Kingdom); King' s College London, NIHR Biomedical Research Centre, London (United Kingdom); Mangino, Massimo [King' s College London, Department of Twin Research and Genetic Epidemiology, London (United Kingdom); National Institute for Health Research (NIHR) Biomedical Research Centre at Guy' s and St. Thomas' Foundation Trust, London (United Kingdom); Botnar, Rene M. [King' s College London, Division of Imaging Sciences and Biomedical Engineering, London (United Kingdom); Wellcome Trust and EPSRC Medical Engineering Centre, London (United Kingdom); King' s College London, BHF Centre of Excellence, London (United Kingdom); King' s College London, NIHR Biomedical Research Centre, London (United Kingdom); Greil, Gerald F. [King' s College London, Division of Imaging Sciences and Biomedical Engineering, London (United Kingdom); Wellcome Trust and EPSRC Medical Engineering Centre, London (United Kingdom); King' s College London, BHF Centre of Excellence, London (United Kingdom); King' s College London, NIHR Biomedical Research Centre, London (United Kingdom)

2017-11-15

The aim of this study was to investigate the impact of BMI on late gadolinium enhancement (LGE) of the coronary artery wall in identical monozygous twins discordant for BMI. Coronary LGE represents a useful parameter for the detection and quantification of atherosclerotic coronary vessel wall disease. Thirteen monozygote female twin pairs (n = 26) with significantly different BMIs (>1.6 kg/m2) were recruited out of >10,000 twin pairs (TwinsUK Registry). A coronary 3D-T2prep-TFE MR angiogram and 3D-IR-TFE vessel wall scan were performed prior to and following the administration of 0.2 mmol/kg of Gd-DTPA on a 1.5 T MR scanner. The number of enhancing coronary segments and contrast to noise ratios (CNRs) of the coronary wall were quantified. An increase in BMI was associated with an increased number of enhancing coronary segments (5.3 ± 1.5 vs. 3.5 ± 1.6, p < 0.0001) and increased coronary wall enhancement (6.1 ± 1.1 vs. 4.8 ± 0.9, p = 0.0027) compared to matched twins with lower BMI. This study in monozygous twins indicates that acquired factors predisposing to obesity, including lifestyle and environmental factors, result in increased LGE of the coronary arteries, potentially reflecting an increase in coronary atherosclerosis in this female study population. (orig.)

Origins of Individual Differences in Imitation: Links with Language, Pretend Play, and Socially Insightful Behavior in Two-Year-Old Twins

Science.gov (United States)

McEwen, Fiona; Happe, Francesca; Bolton, Patrick; Rijsdijk, Fruhling; Ronald, Angelica; Dworzynski, Katharina; Plomin, Robert

2007-01-01

Imitation, vocabulary, pretend play, and socially insightful behavior were investigated in 5,206 same- and opposite-sex 2-year-old twin pairs in the United Kingdom. Individual differences in imitative ability were due to modest heritability (30%), while environmental factors shared between twins (42%) and unique to each twin (28%) also made…

Cognitive Functioning after Surgery in Middle-aged and Elderly Danish Twins

DEFF Research Database (Denmark)

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

2016-01-01

,503 middle-aged and elderly twins. METHODS: Results from five cognitive tests were compared in twins exposed to surgery, classified as major, minor, hip and knee replacement, or other, with those of a reference group without surgery using linear regression adjusted for sex and age. Genetic and shared......BACKGROUND: Postoperative cognitive dysfunction is common, but it remains unclear whether there are long-term adverse cognitive effects of surgery combined with anesthesia. The authors examined the association between exposure to surgery and level of cognitive functioning in a sample of 8...... environmental confounding was addressed in intrapair analyses of 87 monozygotic and 124 dizygotic same-sexed twin pairs in whom one had a history of major surgery and the other did not. RESULTS: Statistically significantly lower composite cognitive score was found in twins with at least one major surgery...

Functional and effective whole brain connectivity using magnetoencephalography to identify monozygotic twin pairs

NARCIS (Netherlands)

Demuru, M.; Gouw, A.; Hillebrand, A.; Stam, C J; van Dijk, B W; Scheltens, P.; Tijms, B.M.; Konijnenberg, E.; ten Kate-Booij, M.J.; den Braber, A; Smit, D J A; Boomsma, D I; Visser, P J

2017-01-01

Resting-state functional connectivity patterns are highly stable over time within subjects. This suggests that such 'functional fingerprints' may have strong genetic component. We investigated whether the functional (FC) or effective (EC) connectivity patterns of one monozygotic twin could be used

Genetic influences on exercise participation in 37.051 twin pairs from seven countries.

NARCIS (Netherlands)

Stubbe, J.H.; Boomsma, D.I.; Vink, J.M.; Cornes, B.; Martin, N.G.; Skytthe, A.; Kyvik, K.; Rose, R.J.; Kujala, U.; Kaprio, J.; Harris, J.R.; Pedersen, N.L.; Hunkin, J.; Spector, T.D.; de Geus, E.J.C.

2006-01-01

Background. A sedentary lifestyle remains a major threat to health in contemporary societies. To get more insight in the relative contribution of genetic and environmental influences on individual differences in exercise participation, twin samples from seven countries participating in the

Does marriage inhibit antisocial behavior?: An examination of selection vs causation via a longitudinal twin design.

Science.gov (United States)

Burt, S Alexandra; Donnellan, M Brent; Humbad, Mikhila N; Hicks, Brian M; McGue, Matt; Iacono, William G

2010-12-01

Previous studies have indicated that marriage is negatively associated with male antisocial behavior. Although often interpreted as a causal association, marriage is not a random event. As such, the association may stem from selection processes, whereby men less inclined toward antisocial behavior are more likely to marry. To evaluate selection vs causation explanations of the association between marriage and desistence from antisocial behavior. Co-twin control analyses in a prospective twin study provided an analogue of the idealized counterfactual model of causation. The co-twin control design uses the unmarried co-twin of a married twin to estimate what the married twin would have looked like had he remained unmarried. Discordant monozygotic (MZ) twins are particularly informative because they share a common genotype and rearing environment. General community study. Two hundred eighty-nine male-male twin pairs (65.1% MZ) from the Minnesota Twin Family Study underwent assessment at 17, 20, 24, and 29 years of age. None of the participants were married at 17 years of age, and 2.6% were married at 20 years of age. By 29 years of age, 58.8% of the participants were or had been married. A tally of criterion C symptoms of DSM-III-R antisocial personality disorder, as assessed via structured clinical interview. Mean differences in antisocial behavior across marital status at age 29 years were present even at 17 and 20 years of age, suggesting a selection process. However, the within-pair effect of marriage was significant for MZ twins, such that the married twin engaged in less antisocial behavior following marriage than his unmarried co-twin. Results were equivalent to those in dizygotic twins and persisted when controlling for prior antisocial behavior. Results indicate an initial selection effect, whereby men with lower levels of antisocial behavior are more likely to marry. However, this tendency to refrain from antisocial behavior appears to be accentuated by the

A population-based Swedish Twin and Sibling Study of cannabis, stimulant and sedative abuse in men.

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Kendler, Kenneth S; Ohlsson, Henrik; Maes, Hermine H; Sundquist, Kristina; Lichtenstein, Paul; Sundquist, Jan

2015-04-01

Prior studies, utilizing interview-based assessments, suggest that most of the genetic risk factors for drug abuse (DA) are non-specific with a minority acting specifically on risk for abuse of particular psychoactive substance classes. We seek to replicate these findings using objective national registry data. We examined abuse of cannabis, stimulants (including cocaine) and sedatives ascertained from national Swedish registers in male-male monozygotic (1720 pairs) and dizygotic twins (1219 pairs) combined with near-age full siblings (76,457 pairs) to provide sufficient power. Modeling was performed using Mx. A common pathway model fitted better than an independent pathway model. The latent liability to DA was highly heritable but also influenced by shared environment. Cannabis, stimulant and sedative abuse all loaded strongly on the common factor. Estimates for the total heritability for the three forms of substance abuse ranged from 64 to 70%. Between 75 and 90% of that genetic risk was non-specific, coming from the common factor with the remainder deriving from substance specific genetic risk factors. By contrast, all of the shared environmental effects, which accounted for 18-20% of the variance in liability, were non-specific. In accord with prior studies based on personal interviews, the large preponderance of genetic risk factors for abuse of specific classes of psychoactive substance are non-specific. These results suggest that genetic variation in the primary sites of action of the psychoactive drugs, which differ widely across most drug classes, play a minor role in human individual differences in risk for DA. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Remembering Irving I. Gottesman: Twin Research Colleague and Friend Extraordinaire/Research Studies: Face-Lift Technique Comparison in Identical Twins; Raising Preterm Twins; Fetal Behavior in Dichorionic Twin Pregnancies; Co-Bedding and Stress Reduction in Twins/Public Interest: Identical Co-Twins' Same Day Delivery; Teaching Twins in Bosnia; Twin Auctioneers; Sister, the Play.

Science.gov (United States)

Segal, Nancy L

2016-12-01

Dr Irving I. Gottesman, a colleague, friend, and long-time member of the International Society of Twin Studies passed away on June 29, 2016. His contributions to twin research and some personal reflections are presented to honor both the man and the memory. This tribute is followed by short reviews of twin research concerning differences between cosmetic surgical techniques, the rearing of preterm twins, behavioral observations of dichorionic fetal twins, and the outcomes of co-bedding twins with reference to stress reduction. Interesting and informative articles in the media describe identical co-twins who delivered infants on the same day, educational policies regarding twins in Bosnia and the United Kingdom, unusual practices of twin auctioneers, and a theatrical production, Sister, featuring identical twins in the leading roles.

Does educational status impact adult mortality in Denmark? A twin approach

DEFF Research Database (Denmark)

Madsen, Mia; Andersen, Anne-Marie Nybo; Christensen, Kaare

2010-01-01

-1935, and no effect modification by zygosity was observed. Hence, the results are most compatible with an effect of early family environment in explaining the educational inequality in mortality. However, large educational differences were still reflected in mortality risk differences within twin pairs, thus......To disentangle an independent effect of educational status on mortality risk from direct and indirect selection mechanisms, the authors used a discordant twin pair design, which allowed them to isolate the effect of education by means of adjustment for genetic and environmental confounding per...... 1980-2008. Both standard cohort and intrapair analyses were conducted separately for zygosity, gender, and birth cohort. Educational differences in mortality were demonstrated in the standard cohort analyses but attenuated in the intrapair analyses in all subgroups but men born during 1921...

Einstein-Podolsky-Rosen paradox in single pairs of images.

Science.gov (United States)

Lantz, Eric; Denis, Séverine; Moreau, Paul-Antoine; Devaux, Fabrice

2015-10-05

Spatially entangled twin photons provide a test of the Einstein-Podolsky-Rosen (EPR) paradox in its original form of position (image plane) versus impulsion (Fourier plane). We show that recording a single pair of images in each plane is sufficient to safely demonstrate an EPR paradox. On each pair of images, we have retrieved the fluctuations by subtracting the fitted deterministic intensity shape and then have obtained an intercorrelation peak with a sufficient signal to noise ratio to safely distinguish this peak from random fluctuations. A 95% confidence interval has been determined, confirming a high degree of paradox whatever the considered single pairs. Last, we have verified that the value of the variance of the difference between twin images is always below the quantum (poissonian) limit, in order to ensure the particle character of the demonstration. Our demonstration shows that a single image pattern can reveal the quantum and non-local behavior of light.

[Adult twins].

Science.gov (United States)

Charlemaine, Christiane

2006-12-31

This paper explores the deep roots of closeness that twins share in their youngest age and their effect on their destiny at the adult age. Psychologists believe the bond between twins begins in utero and develops throughout the twins' lives. The four patterns of twinship described show that the twin bond is determined by the quality of parenting that twins receive in their infancy and early childhood. Common problems of adult twins bring about difficulties to adapt in a non-twin world. The nature versus nurture controversy has taken on new life focusing on inter-twin differences and the importance of parent-child interaction as fundamental to the growth and development of personality.

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

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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.

Twin anemia polycythemia sequence

NARCIS (Netherlands)

Slaghekke, Femke

2014-01-01

In this thesis we describe that Twin Anemia Polycythemia Sequence (TAPS) is a form of chronic feto-fetal transfusion in monochorionic (identical) twins based on a small amount of blood transfusion through very small anastomoses. For the antenatal diagnosis of TAPS, Middle Cerebral Artery – Peak

A longitudinal, population-based twin study of avoidant and obsessive-compulsive personality disorder traits from early to middle adulthood.

Science.gov (United States)

Gjerde, L C; Czajkowski, N; Røysamb, E; Ystrom, E; Tambs, K; Aggen, S H; Ørstavik, R E; Kendler, K S; Reichborn-Kjennerud, T; Knudsen, G P

2015-12-01

The phenotypic stability of avoidant personality disorder (AVPD) and obsessive-compulsive personality disorder (OCPD) has previously been found to be moderate. However, little is known about the longitudinal structure of genetic and environmental factors for these disorders separately and jointly, and to what extent genetic and environmental factors contribute to their stability. AVPD and OCPD criteria were assessed using the Structured Interview for DSM-IV Personality in 2793 young adult twins (1385 pairs, 23 singletons) from the Norwegian Institute of Public Health Twin Panel at wave 1 and 2282 (986 pairs, 310 singletons) of these on average 10 years later at wave 2. Longitudinal biometric models were fitted to AVPD and OCPD traits. For twins who participated at both time-points, the number of endorsed sub-threshold criteria for both personality disorders (PDs) decreased 31% from wave 1 to wave 2. Phenotypic correlations between waves were 0.54 and 0.37 for AVPD and OCPD, respectively. The heritability estimates of the stable PD liabilities were 0.67 for AVPD and 0.53 for OCPD. The genetic correlations were 1.00 for AVPD and 0.72 for OCPD, while the unique environmental influences correlated 0.26 and 0.23, respectively. The correlation between the stable AVPD and OCPD liabilities was 0.39 of which 63% was attributable to genetic influences. Shared environmental factors did not significantly contribute to PD variance at either waves 1 or 2. Phenotypic stability was moderate for AVPD and OCPD traits, and genetic factors contributed more than unique environmental factors to the stability both within and across phenotypes.

Genetic and environmental influences on non-specific neck pain in early adolescence: A classical twin study

Science.gov (United States)

Ståhl, Minna K; El-Metwally, Ashraf A; Mikkelsson, Marja K; Salminen, Jouko J; Pulkkinen, Lea R; Rose, Richard J; Kaprio, Jaakko A

2012-01-01

Background Prevalence of neck pain has increased among adolescents. The origins of adult chronic neck pain may lie in late childhood, but for early prevention, more information is needed about its aetiology. We investigated the relative roles of genetic and environmental factors in early adolescent neck pain with a classic twin study. Methods Frequency of neck pain was assessed with a validated pain questionnaire in a population-based sample of nearly 1800 pairs of 11–12-year-old Finnish twins. Twin pair similarity for neck pain was quantified by polychoric correlations, and variance components were estimated with biometric structural equation modelling. Results Prevalence of neck pain reported at least once monthly was 38% and at least once weekly 16%, with no significant differences between gender or zygosity. A greater polychoric correlation in liability to neck pain was found in monozygotic (0.67) than for dizygotic pairs (0.38), suggesting strong genetic influences. Model-fitting indicated that 68% (95% CI 62 to 74) of the variation in liability to neck pain could be attributed to genetic effects, with the remainder attributed to unshared environmental effects. No evidence for sex-specific genetic effects or for sex differences in the magnitude of genetic effects was found. Conclusions Genetic and unique environmental factors seem to play the most important roles in liability to neck pain in early adolescence. Future research should be directed to identifying pathways for genetic influences on neck pain and in exploring effectiveness of interventions that target already identified environmental risk factors. PMID:23139100

The Placenta in Twin-to-Twin Transfusion Syndrome and Twin Anemia Polycythemia Sequence.

Science.gov (United States)

Couck, Isabel; Lewi, Liesbeth

2016-06-01

Twin-to-twin transfusion syndrome (TTTS) and twin anemia polycythemia sequence (TAPS) are complications unique to monochorionic twin pregnancies and their shared circulation. Both are the result of the transfusion imbalance in the intertwin circulation. TTTS is characterized by an amniotic fluid discordance, whereas in TAPS, there is a severe discordance in hemoglobin levels. The article gives an overview of the typical features of TTTS and TAPS placentas.

Antenatal management of twin-twin transfusion syndrome and twin anemia-polycythemia sequence.

Science.gov (United States)

Slaghekke, Femke; Zhao, Depeng P; Middeldorp, Johanna M; Klumper, Frans J; Haak, Monique C; Oepkes, Dick; Lopriore, Enrico

2016-08-01

Twin-twin transfusion syndrome (TTTS) and twin anemia polycythemia sequence (TAPS) are severe complications in monochorionic twin pregnancies associated with high mortality and morbidity risk if left untreated. Both diseases result from imbalanced inter-twin blood transfusion through placental vascular anastomoses. This review focuses on the differences in antenatal management between TTTS and TAPS. Expert commentary: The optimal management for TTTS is fetoscopic laser coagulation of the vascular anastomoses, preferably using the Solomon technique in which the whole vascular equator is coagulated. The Solomon technique is associated with a reduction of residual anastomosis and a reduction in post-operative complications. The optimal management for TAPS is not clear and includes expectant management, intra-uterine transfusion with or without partial exchange transfusion and fetoscopic laser surgery.

Time trends in the natural dizygotic twinning rate.

Science.gov (United States)

Derom, Catherine; Gielen, Marij; Peeters, Hilde; Frijns, Jean-Pierre; Zeegers, Maurice P A

2011-08-01

The natural dizygotic (DZ) twinning rate has been proposed as a reliable and useful measure of human fecundity, if adjusted for maternal age at twin birth. The aim of this study was to analyze age-adjusted trends in natural DZ twinning rates over the past 40 years using data from the 'East Flanders Prospective Twin Survey (EFPTS)'. This study involved 4835 naturally conceived twin pregnancies between 1969 and 2009 from the population-based Belgian 'EFPTS'. Age-adjusted trends in the incidence of natural DZ twin pregnancies were calculated using a generalized linear model with Poisson distribution. Both the natural DZ twinning rates and maternal age at twin birth increased in a linear fashion from 1969 to 2009. When age-adjusted, we found that the trend in the natural DZ twinning rate was stable during the whole time period. According to our population-based data and after age-adjustment, a stable natural DZ twinning rate could be observed over the last four decades. Under the assumption that the spontaneous DZ twinning rate is a sensor of fecundity, this indicates a stable 'high' fecundity for this population.

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

Science.gov (United States)

Hasselbalch, Ann L; Silventoinen, Karri; Keskitalo, Kaisu; Pietiläinen, Kirsi H; Rissanen, Aila; Heitmann, Berit L; Kyvik, Kirsten O; Sørensen, Thorkild I A; Kaprio, Jaakko

2010-04-01

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 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 predisposition. Environmental factors shared by the co-twins (e.g., childhood environment) seem to have no significant effects on bread consumption and preference in adulthood.

Environmental influence of problematic social relationships on adolescents' daily cortisol secretion: a monozygotic twin-difference study.

Science.gov (United States)

Brendgen, M; Ouellet-Morin, I; Lupien, S J; Vitaro, F; Dionne, G; Boivin, M

2017-02-01

This study investigated the potential environmental effects of peer victimization and the quality of relationships with parents and friends on diurnal cortisol secretion in mid-adolescence. This study used the monozygotic (MZ) twin-difference design to control for genetic effects and thus estimate the unique environmental influences on diurnal cortisol. Participants were 136 MZ twin pairs (74 female pairs) for whom cortisol was assessed four times per day over four collection days grouped in a 2-week period in grade 8 (mean age = 14.07 years). Participants also provided self-reports of peer victimization from grade 4 to grade 8 and of the relationship quality with the mother, father and best friend in grade 8. The expected pattern of diurnal cortisol secretion was observed, with high levels at awakening followed by an increase 30 min later and a progressive decrease subsequently. Controlling for a host of confounders, only within-twin pair differences in peer victimization and a problematic relationship with the mother were significantly linked to twin differences in diurnal cortisol secretion. Specifically, whereas a more problematic mother-child relationship was associated with morning cortisol secretion, peer victimization was linked to cortisol secretion later in the day (diurnal slope). Controlling for genetic influences and other confounders, stressful relationships with peers and the mother exert unique and time-specific environmental influences on the pattern of diurnal cortisol secretion in mid-adolescence.

Effect of morphological and functional changes in the secundines on biometric parameters of newborns from dichorionic twin pregnancies.

Science.gov (United States)

Waszak, Małgorzata; Cieślik, Krystyna; Pietryga, Marek; Lewandowski, Jacek; Chuchracki, Marek; Nowak-Markwitz, Ewa; Bręborowicz, Grzegorz

2016-01-01

The aim of the study was to determine if, and to what extent, structural and functional changes of the secundines influence biometric parameters of neonates from dichorionic twin pregnancies. The study included neonates from dichorionic, diamniotic twin pregnancies, along with their secundines. Based on histopathological examination of the secundines, the mass and dimensions of the placenta, length and condition of the umbilical cord, chorionicity, focal lesions, and microscopic placental abnormalities were determined for 445 pairs of twins. Morphological development of examined twins was characterized on the basis of their six somatic traits, while birth status of the newborns was assessed based on their Apgar scores. Statistical analysis included Student t-tests, Snedecor's F-tests, post-hoc tests, non-parametric chi-squared Pearson's tests, and determination of Spearman coefficients of rank correlation. The lowest values of analyzed somatic traits were observed in twins who had placentas with velamentous or marginal cord insertion. Inflammatory lesions in the placenta and placental abruption turned out to have the greatest impact of all analyzed abnormalities of the secundines. Inflammatory lesions in the placenta were associated with lower values of biometric parameters and a greater likelihood of preterm birth. Neonates with a history of placental abruption were characterized by significantly lower birth weight and smaller chest circumference. Morphological changes in the secundines have a limited impact on biometric parameters of neonates from dichorionic twin pregnancies. In turn, functional changes exert a significant effect and more often contribute to impaired fetal development.

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

Digital Twins in Health Care: Ethical Implications of an Emerging Engineering Paradigm.

Science.gov (United States)

Bruynseels, Koen; Santoni de Sio, Filippo; van den Hoven, Jeroen

2018-01-01

Personalized medicine uses fine grained information on individual persons, to pinpoint deviations from the normal. 'Digital Twins' in engineering provide a conceptual framework to analyze these emerging data-driven health care practices, as well as their conceptual and ethical implications for therapy, preventative care and human enhancement. Digital Twins stand for a specific engineering paradigm, where individual physical artifacts are paired with digital models that dynamically reflects the status of those artifacts. When applied to persons, Digital Twins are an emerging technology that builds on in silico representations of an individual that dynamically reflect molecular status, physiological status and life style over time. We use Digital Twins as the hypothesis that one would be in the possession of very detailed bio-physical and lifestyle information of a person over time. This perspective redefines the concept of 'normality' or 'health,' as a set of patterns that are regular for a particular individual , against the backdrop of patterns observed in the population. This perspective also will impact what is considered therapy and what is enhancement, as can be illustrated with the cases of the 'asymptomatic ill' and life extension via anti-aging medicine. These changes are the consequence of how meaning is derived, in case measurement data is available. Moral distinctions namely may be based on patterns found in these data and the meanings that are grafted on these patterns. Ethical and societal implications of Digital Twins are explored. Digital Twins imply a data-driven approach to health care. This approach has the potential to deliver significant societal benefits, and can function as a social equalizer, by allowing for effective equalizing enhancement interventions. It can as well though be a driver for inequality, given the fact that a Digital Twin might not be an accessible technology for everyone, and given the fact that patterns identified across a

Are twins at risk of cancer: results from the Swedish family-cancer database.

Science.gov (United States)

Hemminki, Kari; Chen, Bowang

2005-10-01

A few twin studies on cancer have addressed questions on the possible carcinogenic or protective effects of twining by comparing the occurrence of cancer in twins and singletons. The nationwide Swedish Family-Cancer Database of 10.2 million individuals and 69,654 0- to 70-year-old twin pairs were used to calculate standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for all main cancers compared to singletons. The overall risk of cancer in same- or different-sex twins was at the same level as the risk for singletons. Testicular cancer, particularly seminoma, was increased among same-sex twins (1.54) and all twins to an SIR of 1.38. Among other tumors, neurinomas and non-thyroid endocrine gland tumors were increased. Colorectal cancers and leukemia were decreased among all twins. Melanoma and squamous cell skin cancer were decreased in male same-sex twins. The data on this unselected population of twins suggest that twinning per se is not a risk factor of cancer. In utero hormonal exposures or postnatal growth stimulation may be related to the risk of testicular cancer and pituitary tumors. Protective effects against colorectal cancer may be related to a beneficial diet, and in melanoma and skin cancer, to socioeconomic factors. The study involved multiple comparisons, and internal consistency between the results was one of the main factors considered for their plausibility. The results should encourage others working on twin and singleton populations to examine the specific associations and emerging hypotheses.

Heritability of spinal pain and consequences of spinal pain: a comprehensive genetic epidemiologic analysis using a population-based sample of 15,328 twins ages 20-71 years

DEFF Research Database (Denmark)

Hartvigsen, Jan; Nielsen, Jan; Kyvik, Kirsten Ohm

2009-01-01

on 15,328 twin individuals (44% monozygotic and 56% dizygotic) from complete twin pairs were included. Genetic susceptibility explained approximately 38% of lumbar pain, 32% of thoracic pain, and 39% of neck pain. For patterns of pain, estimates were 7% for lumbar/thoracic, 24% for lumbar/cervical, 0......% for thoracic/cervical, and 35% for pain in all 3 areas. Moderate to high genetic correlations indicated a common genetic basis for many spinal pain syndromes. In general, heritability was higher for women, and only a minor age effect was seen. CONCLUSION: Heritability estimates for pain in different spinal......OBJECTIVE: To assess the relative contribution of genetic and environmental factors to different definitions of spinal pain and consequences of spinal pain. METHODS: The Danish Twin Registry contains detailed survey information on spinal pain and its consequences in twins ages 20-71 years...

Optimization of twin gear-based pretreatment of rice straw for bioethanol production

International Nuclear Information System (INIS)

Ahmed, Muhammad Ajaz; Rehman, Muhammd Saif Ur; Terán-Hilares, Ruly; Khalid, Saira; Han, Jong-In

2017-01-01

Highlights: • Twin gear reactor is a continuous high solids pretreatment reactor. • RSM was applied to optimize twin gear pretreatment for enzymatic digestibility. • 89% enzymatic digestibility was achieved under optimum conditions. • Thermomechanical pretreatment altered the structural features of rice straw. - Abstract: A laboratory twin-gear reactor (TGR) was investigated as a new means for the pretreatment of high solid lignocelluloses. Response surface methodology based on Box Behnken Design was used to optimize the enzymatic digestibility with respect to the pretreatment process variables: temperature of 50–90 °C, NaOH concentration of 2–6% and no. of cycles of 30–60. The results revealed that the TGR-based pretreatment led to the significant structural alterations through increases in pore size, pore volume, cellulose crystallinity and surface area. SEM images also confirmed the surface modifications in the pretreated rice straw. A response surface quadratic model predicted 90% of the enzymatic digestibility, and it was confirmed experimentally and through the analysis of variance (ANOVA) as well. The TGR extrusion proved to be an effective means for exceedingly high solids lignocellulose.

Craniopagus twins: a comparative study of radiological findings and surgery (with a review of literatures)

International Nuclear Information System (INIS)

Yang Zhiyun; Luo Baining; Wu Xinjian

2005-01-01

Objective: To improve the understanding of craniopagus twins through a case report and literature review. Method: A pair of female craniopagus twins was examined with CT and MRI and angiography. The radiological findings were compared with operation. Results: The operation result was in consistent with imaging findings. Conclusion: Modern radiological modalities can evaluate complex deformity, which play an important role in the orthopedic procedures. (authors)

Does Learning to Read Improve Intelligence? A Longitudinal Multivariate Analysis in Identical Twins from Age 7 to 16

Science.gov (United States)

Ritchie, Stuart J.; Bates, Timothy C.; Plomin, Robert

2015-01-01

Evidence from twin studies points to substantial environmental influences on intelligence, but the specifics of this influence are unclear. This study examined one developmental process that potentially causes intelligence differences: learning to read. In 1,890 twin pairs tested at 7, 9, 10, 12, and 16 years, a cross-lagged…

Association of Educational Level and Marital Status With Obesity: A Study of Chinese Twins.

Science.gov (United States)

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

2018-04-01

The prevalence of overweight and obesity is growing rapidly in many countries. Socioeconomic inequalities might be important for this increase. The aim of this study was to determine associations of body mass index (BMI), overweight and obesity with educational level and marital status in Chinese twins. Participants were adult twins recruited through the Chinese National Twin Registry (CNTR), aged 18 to 79 years, and the sample comprised 10,448 same-sex twin pairs. Current height, weight, educational attainment, and marital status were self-reported. Regression analyses and structural equation models were conducted to evaluate BMI, overweight, and obesity associated with educational level and marital status in both sexes. At an individual level, both educational level and marital status were associated with higher BMI and higher risk of being overweight and obesity in men, while in women the effects of educational level on BMI were in the opposite direction. In within-Monozygotic (MZ) twin-pair analyses, the effects of educational level on BMI disappeared in females. Bivariate structural equation models showed that genetic factors and shared environmental confounded the relationship between education and BMI in females, whereas marital status was associated with BMI on account of significant positive unique environmental correlation apart in both sexes. The present data suggested that marital status and BMI were associated, independent of familiar factors, for both sexes of this study population, while common genetic and shared environmental factors contributed to education-associated disparities in BMI in females.

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...

Blood DNA methylation age is not associated with cognitive functioning in middle-aged monozygotic twins

DEFF Research Database (Denmark)

Starnawska, A; Tan, Q; Lenart, A

2016-01-01

The epigenetic clock, also known as DNA methylation age (DNAmAge), represents age-related changes of DNA methylation at multiple sites of the genome and is suggested to be a biomarker for biological age. Elevated blood DNAmAge is associated with all-cause mortality, with the strongest effects...... reported in a recent intrapair twin study where epigenetically older twins had increased mortality risk in comparison to their co-twins. In the study presented here, we hypothesize that DNAmAge in blood is associated with cross-sectional and longitudinal cognitive abilities in middle-aged individuals....... In 486 monozygotic twins, we investigated the association of DNAmAge, difference between DNAmAge and chronological age and age acceleration with cognition. Despite using a powerful paired twin design, we found no evidence for association of blood DNAmAge with cognitive abilities. This observation...

Monozygotic twins with CAPN5 autosomal dominant neovascular inflammatory vitreoretinopathy

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Rowell HA

2012-12-01

Full Text Available Hannah A Rowell,1,2 Alexander G Bassuk,3,4 Vinit B Mahajan1,21Omics Laboratory, 2Department of Ophthalmology and Visual Sciences, 3Department of Pediatrics, 4Department of Neurology, University of Iowa, Iowa City, IA, USABackground: The purpose of this study was to describe the clinical findings in a set of monozygotic twins with autosomal dominant neovascular inflammatory vitreoretinopathy (ADNIV over a 23-year period.Methods: A pair of female twins were examined between 26 and 49 years of age. The concordance and discordance of their clinical features were determined. The CAPN5 gene was sequenced using genomic DNA.Results: Both twins of an affected father demonstrated Stage I ADNIV with mild vitreous cells and a negative b-wave on electroretinography. Genetic analysis confirmed a guanine to thymine nucleotide (c.728G>T, pArg243Leu mutation in the CAPN5 gene. Over the course of 23 years, each twin progressed to stage III disease, showing posterior uveitis, cystoid macular edema, intraocular fibrosis, early retinal neovascularization, retinal degeneration, and cataract. Disease progression varied moderately between each twin and was asymmetrical between eyes. Twin A had 20/70 and 20/125 in the right and left eye, respectively, and underwent vitrectomy surgery and intravitreal injections with bevacizumab for recurrent cystoid macular edema. Twin B maintained 20/20 and 20/40 in the right and left eye, respectively without intervention.Conclusion: There was asymmetry between the eyes and some discordance in the rate of disease progression in these monozygotic twins with ADNIV. The overall high disease concordance suggests genetic factors play a major role in clinical manifestations in CAPN5 vitreoretinopathy.Keywords: autosomal dominant neovascular inflammatory vitreoretinopathy, ADNIV, CAPN5, calpain-5, monozygotic twins

Optical refractometer based on an asymmetrical twin-core fiber Michelson interferometer.

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Zhou, Ai; Zhang, Yanhui; Li, Guangping; Yang, Jun; Wang, Yuzhuo; Tian, Fengjun; Yuan, Libo

2011-08-15

We report and demonstrate an optical refractometer based on a compact fiber Michelson interferometer. The Michelson interferometer is composed of an asymmetrical twin-core fiber containing a central core and a side core. By chemically etching a segment of the twin-core fiber until the side core is exposed, the effective index of the side core in the etched region is sensitive to the environmental refractive index, which leads to a shift of the transmission spectrum of the Michelson interferometer. The experimental results show that such a device has a refractive index resolution of more than 800 nm/refractive index unit in the range of 1.34-1.37. © 2011 Optical Society of America

Molecular dynamics simulation of albite twinning and pericline twinning in low albite

International Nuclear Information System (INIS)

Li, Bin; Knowles, Kevin M

2013-01-01

Two twinning laws, the albite law and the pericline law, are the predominant growth twinning modes in triclinic plagioclase feldspars such as low albite, NaAlSi 3 O 8 , in which the aluminum and silicon atoms are in an ordered arrangement on the tetrahedral sites of the aluminosilicate framework. In the terminology used formally to describe deformation twinning in a triclinic lattice, these twin laws can be described as Type I and Type II twin laws, respectively, with the pericline twin law being conjugate to the albite twin law. In this study, twin boundaries have been constructed for low albite according to these two twinning laws and studied by molecular dynamics simulation. The results show that suitably constructed twin boundary models are quite stable for both albite twinning and pericline twinning during molecular dynamics simulation. The calculated twin boundary energy of an albite twin is significantly lower than that of a pericline twin, in accord with the experimental observation that albite twinning is the more commonly observed mode seen in plagioclase feldspars. The results of the molecular dynamics simulations also agree with conclusions from the prior work of Starkey that glide twinning in low albite is not favoured energetically. (paper)

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

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

2013-03-01

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 difference scores revealed that authoritative parenting (the presence of consistent discipline and lack of harsh parenting) and peer problems simultaneously influenced each other. Authoritative parenting reduced peer problems, and peer problems increased authoritative parenting. Neither consistent discipline nor harsh parenting alone was associated with peer problems. These results suggest that maternal authoritative parenting works protectively in regard to children's peer problems, and peer problems can evoke such effective parenting. © 2012 Blackwell Publishing Ltd.

Cerebral metabolism, anatomy, and cognition in monozygotic twins discordant for dementia of the Alzheimer type.

Science.gov (United States)

Luxenberg, J S; May, C; Haxby, J V; Grady, C; Moore, A; Berg, G; White, B J; Robinette, D; Rapoport, S I

1987-03-01

One pair of monozygotic twins discordant for dementia of the Alzheimer type (DAT) was studied using neuropsychological testing, quantitative x-ray computed tomography (QCT) and magnetic resonance imaging (MRI) of the brain. Cerebral glucose metabolism was measured using positron emission tomography (PET) and 2-[18-F]fluoro-2-deoxy-D-glucose (FDG). The affected twin had a seven year history of progressive cognitive impairment and was severely demented. Neuropsychological testing of the affected twin demonstrated marked deficits in all areas of cognitive function. The asymptomatic twin showed some impairment on tests of perceptual organisation and delayed recall. The affected twin had loss of gray matter and ventricular enlargement on QCT and MRI compared with healthy controls (p less than 0.05). He also had frontal and parietal lobe hypometabolism and increased asymmetry of metabolism on PET compared to both his twin and healthy age-matched controls (p less than 0.05). PET, QCT, and MRI distinguished changes in the twin with DAT compared with his brother and healthy controls. Although the subtle neuropsychological abnormalities of the asymptomatic twin may be signs of early DAT, they were not accompanied by any changes in regional cerebral metabolism or brain structure.

Indigenous Manufacturing realization of TWIN Source

Science.gov (United States)

Pandey, R.; Bandyopadhyay, M.; Parmar, D.; Yadav, R.; Tyagi, H.; Soni, J.; Shishangiya, H.; Sudhir Kumar, D.; Shah, S.; Bansal, G.; Pandya, K.; Parmar, K.; Vuppugalla, M.; Gahlaut, A.; Chakraborty, A.

2017-04-01

TWIN source is two RF driver based negative ion source that has been planned to bridge the gap between single driver based ROBIN source (currently operational) and eight river based DNB source (to be operated under IN-TF test facility). TWIN source experiments have been planned at IPR keeping the objective of long term domestic fusion programme to gain operational experiences on vacuum immersed multi driver RF based negative ion source. High vacuum compatible components of twin source are designed at IPR keeping an aim on indigenous built in attempt. These components of TWIN source are mainly stainless steel and OFC-Cu. Being high heat flux receiving components, one of the major functional requirements is continuous heat removal via water as cooling medium. Hence for the purpose stainless steel parts are provided with externally milled cooling lines and that shall be covered with a layer of OFC-cu which would be on the receiving side of high heat flux. Manufacturability of twin source components requires joining of these dissimilar materials via process like electrode position, electron beam welding and vacuum brazing. Any of these manufacturing processes shall give a vacuum tight joint having proper joint strength at operating temperature and pressure. Taking the indigenous development effort vacuum brazing (in non-nuclear environment) has been opted for joining of dissimilar materials of twin source being one of the most reliable joining techniques and commercially feasible across the suppliers of country. Manufacturing design improvisation for the components has been done to suit the vacuum brazing process requirement and to ease some of the machining without comprising over the functional and operational requirements. This paper illustrates the details on the indigenous development effort, design improvisation to suits manufacturability, vacuum brazing basics and its procedures for twin source components.

Psychiatric outcomes of bullying victimization: a study of discordant monozygotic twins.

Science.gov (United States)

Silberg, J L; Copeland, W; Linker, J; Moore, A A; Roberson-Nay, R; York, T P

2016-07-01

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. 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. 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. Bullying victimization in childhood is a significant environmental trauma and should be included in any mental health assessment of children and young adults.

Therapeutic modalities of twin to twin transfusion syndrome

Directory of Open Access Journals (Sweden)

Šulović N.

2015-01-01

Full Text Available Twin to twin transfusion syndrome (TTTTS accounts for approximately 10% of monochorionic twin pregnancies and, if left untreated, is associated with high morbidity and mortality rate. A net transfusion of blood flow from one fetus (donor twin to the other (recipient twin via placental vascular anastomoses has been supposed as the major etiology of TTTTS. The donor twin becomes hypovolemic and oliguria, oligohydramnios, and a variable degree of growth restriction develop, whereas the recipient twin manifests polyuria, polyhydramnios, and hydrops in response to hypervolemia. TTTTS can be treated by either serial amniocentesis or selective fetoscopic laser coagulation of the communicating vessels. The rationale for removal of large volumes of amniotic fluid is to prevent preterm delivery secondary to polyhydramnios and to improve fetal circulation by reducing pressure on the chorionic plate. On the other hand, the goal of laser therapy is to occlude vascular anastomoses, thereby interrupting intertwin blood exchange. Although laser treatment is associated with increased survival rate and reduced neurologic complications, compared with amnioreduction, it requires highly specialized centers, whereas serial amniocentesis has the advantage of being performed worldwide. Therefore, the optimal treatment for pregnancies complicated with TTTTS is still controversial.

The effect of chorionicity and twin-to-twin delivery time interval on short-term outcome of the second twin

DEFF Research Database (Denmark)

Hjortø, Sofie; Nickelsen, Carsten; Petersen, Janne

2013-01-01

Abstract Objectives: To investigate the effect of chorionicity and twin-to-twin delivery time interval on short-term outcome in the second twin. Additionally, to investigate predictors of adverse outcome in both twins. Methods: Data included vaginally delivered twins (≥ 36 weeks) from Copenhagen ...

Evolution of the Annealing Twin Density during δ-Supersolvus Grain Growth in the Nickel-Based Superalloy Inconel™ 718

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Yuan Jin

2015-12-01

Full Text Available Grain growth experiments were performed on Inconel™ 718 to investigate the possible correlation of the annealing twin density with grain size and with annealing temperature. Those experiments were conducted at different temperatures in the δ supersolvus domain and under such conditions that only capillarity forces were involved in the grain boundary migration process. In the investigated range, there is a strong inverse correlation of the twin density with the average grain size. On the other hand, the twin density at a given average grain size is not sensitive to annealing temperature. Consistent with previous results for pure nickel, the twin density evolution in Inconel™ 718 is likely to be mainly controlled by the propagation of the pre-existing twins of the growing grains; i.e., the largest ones of the initial microstructure. Almost no new twin boundaries are created during the grain growth process itself. Therefore, the twin density at a given average grain size is mainly dependent on the twin density in the largest grains of the initial microstructure and independent of the temperature at which grains grow. Based on the observations, a mean field model is proposed to predict annealing twin density as a function of grain size during grain growth.

Hydration of Watson-Crick base pairs and dehydration of Hoogsteen base pairs inducing structural polymorphism under molecular crowding conditions.

Science.gov (United States)

Miyoshi, Daisuke; Nakamura, Kaori; Tateishi-Karimata, Hisae; Ohmichi, Tatsuo; Sugimoto, Naoki

2009-03-18

It has been revealed recently that molecular crowding, which is one of the largest differences between in vivo and in vitro conditions, is a critical factor determining the structure, stability, and function of nucleic acids. However, the effects of molecular crowding on Watson-Crick and Hoogsteen base pairs remain unclear. In order to investigate directly and quantitatively the molecular crowding effects on base pair types in nucleic acids, we designed intramolecular parallel- and antiparallel-stranded DNA duplexes consisting of Hoogsteen and Watson-Crick base pairs, respectively, as well as an intramolecular parallel-stranded triplex containing both types of base pairs. Thermodynamic analyses demonstrated that the values of free energy change at 25 degrees C for Hoogsteen base-pair formations decreased from +1.45 +/- 0.15 to +1.09 +/- 0.13 kcal mol(-1), and from -1.89 +/- 0.13 to -2.71 +/- 0.11 kcal mol(-1) in the intramolecular duplex and triplex, respectively, when the concentration of PEG 200 (polyethylene glycol with average molecular weight 200) increased from 0 to 20 wt %. However, corresponding values for Watson-Crick formation in the duplex and triplex increased from -10.2 +/- 0.2 to -8.7 +/- 0.1 kcal mol(-1), and from -10.8 +/- 0.2 to -9.2 +/- 0.2 kcal mol(-1), respectively. Furthermore, it was revealed that the opposing effects of molecular crowding on the Hoogsteen and Watson-Crick base pairs were due to different behaviors of water molecules binding to the DNA strands.

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...

Risk and protective factors for Parkinson's disease: a study in Swedish twins.

Science.gov (United States)

Wirdefeldt, Karin; Gatz, Margaret; Pawitan, Yudi; Pedersen, Nancy L

2005-01-01

Many studies have shown a protective effect of cigarette smoking on Parkinson's disease. However, criticism has been raised concerning confounding by genetic factors. We investigated the associations between Parkinson's disease and smoking, alcohol, coffee, area of living, and education in a co-twin control study. Because twins are matched for genetic and familial environmental factors, this design controls for confounding by these factors. We also examined control subjects unrelated to cases. Exposure information was taken from questionnaires answered in the 1960s and 1970s. Parkinson's disease cases were identified through the Swedish Inpatient Discharge Register (IDR) and the Cause of Death Register. In the unrelated control subject comparison, 476 Parkinson's disease cases and 2,380 control subjects were included. In the co-twin control comparison, 415 same-sex twin pairs were included. There was an inverse association between smoking and Parkinson's disease using unrelated control subjects and co-twin control cases. There was no association between Parkinson's disease and alcohol, coffee, or area of living. High educational level was associated with Parkinson's disease in the unrelated control subject comparison but not in the co-twin control comparison. We confirm the protective effect of smoking on Parkinson's disease and establish that the association is only partially explained by genetic and familial environmental factors.

Twin Research and the Arts: Interconnections / Twin Research: Twin Studies of Sexual Orientation; A Historical Biological Twin Gem; GWAS Approach to Who Has Twins / Newsworthy: Twins on College Campuses; 'Brainprint': Personal Identification by Brain Waves.

Science.gov (United States)

Segal, Nancy L

2016-08-01

The interrelatedness between twin research and the arts is explored via a new play about a famous case. In the 1960s, identical twin David Bruce Reimer was accidentally castrated as an infant during circumcision to correct a urinary problem. The decision to raise him as a girl, and the consequences of that decision, are explored in the new theatrical production of Boy. Other examples of the arts mirroring science, and vice versa, are described. Next, brief reviews and summaries of twin research on sexual orientation, 1860s' knowledge of placental arrangements and twinning mechanisms, and genes underlying multiple birth conception and fertility related measures are provided. This article concludes with a look at twins on college campuses and the identification of individuals by their brain waves. A correction and clarification regarding my article on the Brazilian Twin Registry in the last issue of THG (Segal, 2016) is also provided.

Genetic and Environmental Influences on Correlations Between Hearing and Cognitive Functions in Middle and Older Chinese Twins

DEFF Research Database (Denmark)

Xu, Chunsheng; Zhang, Dongfeng; Tian, Xiaocao

2017-01-01

, including 0.5 kHz, 1 kHz, 2 kHz, 4 kHz, 8 kHz, and 12.5 kHz, with the lower hearing thresholds indicating better hearing function. Cognitive and hearing functions were measured on 379 complete twin pairs (240 monozygotic and 139 dizygotic pairs) with a median age of 50 years (range: 40-80 years). Bivariate...... twin models were fitted to quantify the genetic and environmental components of the correlations between hearing and cognitive functions. The analysis showed significantly high genetic correlation between 2 kHz of hearing and cognition (r G = -1.00, 95% CI [-1.00, -0.46]) and moderate genetic...

Association of Depressive Symptoms and Heart Rate Variability in Vietnam War-Era Twins: A Longitudinal Twin Difference Study.

Science.gov (United States)

Huang, Minxuan; Shah, Amit; Su, Shaoyong; Goldberg, Jack; Lampert, Rachel J; Levantsevych, Oleksiy M; Shallenberger, Lucy; Pimple, Pratik; Bremner, J Douglas; Vaccarino, Viola

2018-05-16

Depressive symptoms are associated with lower heart rate variability (HRV), an index of autonomic dysregulation, but the direction of the association remains unclear. To investigate the temporal association between depression and HRV. A longitudinal, cross-lagged twin difference study, with baseline assessments from March 2002 to March 2006 (visit 1) and a 7-year follow-up (visit 2) at an academic research center with participants recruited from a national twin registry. Twins (n = 166) from the Vietnam Era Twin Registry, who served in the US military during the Vietnam War, and were discordant for depression at baseline were recruited. At both visits, depressive symptoms were measured using the Beck Depression Inventory-II (BDI-II), and HRV was measured through 24-hour electrocardiogram monitoring. To assess the direction of the association, within-pair differences in multivariable mixed-effects regression models were examined, and standardized β coefficients for both pathways were calculated. The associations were evaluated separately in monozygotic and dizygotic twins. In the final analytic sample (N = 146), all participants were men, 138 (95%) were white, and the mean (SD) age was 54 (3) years at baseline. Results showed consistent associations between visit 1 HRV and visit 2 BDI score across all HRV domains and models (β coefficients ranging from -0.14 to -0.29), which were not explained by antidepressants or other participant characteristics. The magnitude of the association was similar in the opposite pathway linking visit 1 BDI score to visit 2 HRV, with β coefficients ranging from 0.05 to -0.30, but it was largely explained by antidepressant use. In stratified analysis by zygosity, significant associations were observed in monozygotic and dizygotic twins for the path linking visit 1 HRV to visit 2 BDI score, although the associations were slightly stronger in dizygotic twins. The association between depression and autonomic dysregulation

Dental caries and associated factors in twins with Down syndrome: a case report.

Science.gov (United States)

Moreira, Maurício José Santos; Schwertner, Carolina; Dall'Onder, Ana Paula; Klaus, Natália Mincato; Parolo, Clarissa Cavalcanti Fatturi; Hashizume, Lina Naomi

2017-03-01

Down syndrome (DS) is the most common genetic disorder in humans, but its incidence in monozygotic twins is extremely rare. The aim of this study was to determine the factors associated with dental caries in a pair of monozygotic twin girls with DS, where one had caries experience and the other did not. Clinical examination, salivary Streptococcus mutans (S. mutans) levels and their genotypic diversity, the biochemical composition of the dental biofilm, the frequency of sucrose consumption, and toothbrushing habits were assessed from the twin girls. Twin with caries experience showed higher levels of S. mutans in the saliva and lower concentrations of calcium, phosphate, and fluoride and higher concentrations of extracellular polysaccharides in the biofilm compared to her sister. Genotypic diversity of S. mutans was also higher in the twin with caries experience. Dental biofilm composition showed different patterns of cariogenicity between the two sisters, which may also by itself explain the difference in the dental caries between them. © 2016 Special Care Dentistry Association and Wiley Periodicals, Inc.

Sleep Duration, Mortality, and Heredity-A Prospective Twin Study.

Science.gov (United States)

Åkerstedt, Torbjörn; Narusyte, Jurgita; Alexanderson, Kristina; Svedberg, Pia

2017-10-01

A number of studies have shown a U-shaped association between sleep duration and mortality. Since sleep duration is partly genetically determined, it seems likely that its association with mortality is also genetically influenced. The purpose of the present study was to investigate the influence on heredity on the association between sleep duration and mortality. We used a cohort of 14267 twins from the Swedish Twin Registry. A Cox proportional hazards regression analysis, adjusted for a number of covariates, confirmed a clear U shape with a hazard ratio (HR) = 1.34 and 95% confidence interval (CI) = 1.15-1.57 for a sleep duration of ≤6.5 hours and HR = 1.18 (CI = 1.07-1.30) for sleep of ≥9.5 hours. Reference value was 7.0 hours. A co-twin analysis of 1942 twins discordant on mortality showed a HR = 2.66 (CI = 1.17-6.04) for long (≥9.5 hours) sleep in monzygotic twins and an HR = 0.66 (CI = 0.20-2.14) for short (sleep. In dizygotic twins, no association was significant. The heritability for mortality was 28% for the whole group, while it was 86% for short sleepers and 42% for long sleepers. Thus, the link with mortality for long sleep appears to be more due to environmental factors than to heredity, while heritability dominates among short sleepers. We found that both long and short sleep were associated with higher total mortality, that the difference in mortality within twin pairs is associated with long sleep, and that short sleep has a higher heritability for mortality, while long sleep is associated with more environmental influences on mortality. © Sleep Research Society 2017. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

Twin-singleton differences in cognitive abilities in a sample of Africans in Nigeria.

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Hur, Yoon-Mi; Lynn, Richard

2013-08-01

Recent studies comparing cognitive abilities between contemporary twins and singletons in developed countries have suggested that twin deficits in cognitive abilities no longer exist. We examined cognitive abilities in a sample of twins and singletons born recently in Nigeria to determine whether recent findings can be replicated in developing countries. Our sample consisted of 413 pairs of twins and 280 singletons collected from over 45 public schools in Abuja and its neighboring states in Nigeria. The ages of twins and singletons ranged from 9 to 20 years with a mean (SD) of 14.6 years (2.2 years) for twins and 16.1 years (1.8 years) for singletons. Zygosity of the same-sex twins was determined by analysis of 16 deoxyribonucleic acid markers. We asked participants to complete a questionnaire booklet that included Standard Progressive Matrices-Plus Version (SPM+), Mill-Hill Vocabulary Scale (MHV), Family Assets Questionnaire, and demographic questions. The data were corrected for sex and age and then analyzed using maximum likelihood model-fitting analysis. Although twins and singletons were comparable in family social class indicators, singletons did better than twins across all the tests (d = 0.10 to 0.35). The average of d for SPM+ total [0.32; equivalent to 4.8 Intelligence Quotient (IQ) points] and d for MHV (0.24; equivalent to 3.6 IQ points) was 0.28 (equivalent to 4.2 IQ points), similar to the twin-singleton gap found in old cohorts in developed countries. We speculate that malnutrition, poor health, and educational systems in Nigeria may explain the persistence of twin deficits in cognitive abilities found in our sample.

The relationship between avoidant personality disorder and social phobia: a population-based twin study.

Science.gov (United States)

Reichborn-Kjennerud, Ted; Czajkowski, Nikolai; Torgersen, Svenn; Neale, Michael C; Ørstavik, Ragnhild E; Tambs, Kristian; Kendler, Kenneth S

2007-11-01

The purpose of this study was to determine the sources of comorbidity for social phobia and dimensional representations of avoidant personality disorder by estimating to what extent the two disorders are influenced by common genetic and shared or unique environmental factors versus the extent to which these factors are specific to each disorder. Young adult female-female twin pairs (N=1,427) from the Norwegian Institute of Public Health Twin Panel were assessed at personal interview for avoidant personality disorder and social phobia using the Structured Interview for DSM-IV Personality and the Composite International Diagnostic Interview. Bivariate Cholesky models were fitted using the Mx statistical program. The best-fitting model included additive genetic and unique environmental factors only. Avoidant personality disorder and social phobia were influenced by the same genetic factors, whereas the environmental factors influencing the two disorders were uncorrelated. Within the limits of statistical power, these results suggest that there is a common genetic vulnerability to avoidant personality disorder and social phobia in women. An individual with high genetic liability will develop avoidant personality disorder versus social phobia entirely as a result of the environmental risk factors unique to each disorder. The results are in accordance with the hypothesis that psychobiological dimensions span the axis I and axis II disorders.

The etiology of mathematical and reading (dis)ability covariation in a sample of Dutch twins.

Science.gov (United States)

Markowitz, Ezra M; Willemsen, Gonneke; Trumbetta, Susan L; van Beijsterveldt, Toos C E M; Boomsma, Dorret I

2005-12-01

The genetic etiology of mathematical and reading (dis)ability has been studied in a number of distinct samples, but the true nature of the relationship between the two remains unclear. Data from the Netherlands Twin Register was used to determine the etiology of the relationship between mathematical and reading (dis)ability in adolescent twins. Ratings of mathematical and reading problems were obtained from parents of over 1500 twin pairs. Results of bivariate structural equation modeling showed a genetic correlation around .60, which explained over 90% of the phenotypic correlation between mathematical and reading ability. The genetic model was the same for males and females.

X-ray diffraction studies on merohedrally twinned Δ1–62NtNBCe1-A crystals of the sodium/bicarbonate cotransporter

International Nuclear Information System (INIS)

Gill, Harindarpal S.; Dutcher, Lauren; Boron, Walter F.; Patel, Samir; Guay-Woodford, Lisa M.

2013-01-01

A truncated mutant missing the first 62 residues of the N-terminal, cytoplasmic domain of the sodium-bicarbonate NBCe1-A cotransporter crystallizes in space group P3 1 with pseudo-P3 1 21 symmetry and a hemihedral twin fraction of 33.0%. Twinned fractions and twin-pair statistics over binned resolutions confirm that the calculated twin fraction is associated with hemihedral twinning and not to non-crystallographic symmetry. NBCe1-A membrane-embedded macromolecules that cotransport sodium and bicarbonate ions across the bilayer serve to maintain acid–base homeostasis throughout the body. Defects result in a number of renal and eye disorders, including type-II renal tubular acidosis and cataracts. Here, crystals of a human truncated mutant of the cytoplasmic N-terminal domain of NBCe1 (Δ1–62NtNBCe1-A) are reported that diffract X-rays to 2.4 Å resolution. The crystal symmetry of Δ1–62NtNBCe1-A is of space group P3 1 with pseudo-P3 1 21 symmetry and it has a hemihedral twin fraction of 33.0%. The crystals may provide insight into the pathogenic processes observed in a subset of patients with truncating and point mutations in the gene encoding NBCe1

Spatial properties of twin-beam correlations at low- to high-intensity transition

Czech Academy of Sciences Publication Activity Database

Machulka, R.; Haderka, Ondřej; Peřina Jr., J.; Lamperti, M.; Allevi, A.; Bondani, M.

2014-01-01

Roč. 22, č. 11 (2014), 13374-13379 ISSN 1094-4087 R&D Projects: GA ČR GAP205/12/0382 Institutional support: RVO:68378271 Keywords : twin-beam correlations * photon pairs * speckle patterns Subject RIV: BH - Optics, Masers, Lasers Impact factor: 3.488, year: 2014

Theoretical study of GC+/GC base pair derivatives

International Nuclear Information System (INIS)

Meng Fancui; Wang Huanjie; Xu Weiren; Liu Chengbu

2005-01-01

The geometries of R (R=CH 3 , CH 3 O, F, NO 2 ) substituted GC base pair derivatives and their cations have been optimized at B3LYP/6-31G* level and the substituent effects on the neutral and cationic geometric structures and energies have been discussed. The inner reorganization energies of various base pair derivatives and the native GC base pair have been calculated to discuss the substituent effects on the reorganization energy. NBO (natural bond orbital) analysis has been carried out on both the neutral and the cationic systems to investigate the differences of the charge distributions and the electronic structures. The outcomes indicate that 8-CH 3 O-G:C has the greatest reorganization energy and 8-NO 2 -G:C has the least, while the other substituted base pairs have a reorganization energy close to that of G:C. The one charge is mostly localized on guanine part after ionization and as high as 0.95e. The bond distances of N1-N3'andN2-O2' in the cationic base pair derivatives shortened and that of O6-N4' elongated as compared with the corresponding bond distances of the neutral GC base pair derivatives

Theoretical analysis of noncanonical base pairing interactions in ...

Indian Academy of Sciences (India)

PRAKASH KUMAR

Noncanonical base pairs in RNA have strong structural and functional implications but are currently not considered ..... Full optimizations of the systems were also carried out using ... of the individual bases in the base pair through the equation.

Multiclass Posterior Probability Twin SVM for Motor Imagery EEG Classification.

Science.gov (United States)

She, Qingshan; Ma, Yuliang; Meng, Ming; Luo, Zhizeng

2015-01-01

Motor imagery electroencephalography is widely used in the brain-computer interface systems. Due to inherent characteristics of electroencephalography signals, accurate and real-time multiclass classification is always challenging. In order to solve this problem, a multiclass posterior probability solution for twin SVM is proposed by the ranking continuous output and pairwise coupling in this paper. First, two-class posterior probability model is constructed to approximate the posterior probability by the ranking continuous output techniques and Platt's estimating method. Secondly, a solution of multiclass probabilistic outputs for twin SVM is provided by combining every pair of class probabilities according to the method of pairwise coupling. Finally, the proposed method is compared with multiclass SVM and twin SVM via voting, and multiclass posterior probability SVM using different coupling approaches. The efficacy on the classification accuracy and time complexity of the proposed method has been demonstrated by both the UCI benchmark datasets and real world EEG data from BCI Competition IV Dataset 2a, respectively.

The effects of stress-tension on depression and anxiety symptoms: evidence from a novel twin modelling analysis.

Science.gov (United States)

Davey, C G; López-Solà, C; Bui, M; Hopper, J L; Pantelis, C; Fontenelle, L F; Harrison, B J

2016-11-01

Negative mood states are composed of symptoms of depression and anxiety, and by a third factor related to stress, tension and irritability. We sought to clarify the nature of the relationships between the factors by studying twin pairs. A total of 503 monozygotic twin pairs completed the Depression Anxiety Stress Scales (DASS), an instrument that assesses symptoms of depression, anxiety and stress-tension. We applied a recently developed twin regression methodology - Inference about Causation from Examination of FAmiliaL CONfounding (ICE FALCON) - to test for evidence consistent with the existence of 'causal' influences between the DASS factors. There was evidence consistent with the stress-tension factor having a causal influence on both the depression (p anxiety factors (p = 0.001), and for the depression factor having a causal influence on the anxiety factor (p stress-tension in the structure of negative mood states, and that interventions that target it may be particularly effective in reducing depression and anxiety symptoms.

Placental share and hemoglobin level in relation to birth weight in twin anemia-polycythemia sequence.

Science.gov (United States)

Zhao, D; Slaghekke, F; Middeldorp, J M; Duan, T; Oepkes, D; Lopriore, E

2014-12-01

Twin anemia-polycythemia sequence (TAPS) is a newly described form of chronic twin transfusion. Previous observational studies noted a discordance between birth weight and individual placental share in TAPS. The purpose of this study was to investigate if fetal growth in monochorionic (MC) twins with TAPS is determined by placental share or by the net inter-twin blood transfusion. All consecutive MC twin placentas of live-born twin pairs with and without TAPS examined at our center between June 2002 and February 2014 were included in this study. Hemoglobin (Hb) levels and individual placental share were evaluated at birth and correlated with birth weight share. We excluded MC twin pregnancies with twin-twin transfusion syndrome. A total of 270 MC twin pregnancies (TAPS group, n = 20; control group without TAPS, n = 250) were included in this study. Donors with TAPS had a lower birth weight than recipients in 90% (18/20) of cases, but a larger placental share in 65% (13/20) of cases. In the TAPS group, birth weight share was positively correlated with Hb share at birth (P < 0.01) but not with placental share (P = 0.54). In the control group without TAPS, birth weight share was strongly correlated with placental share (P < 0.01) but not with Hb share (P = 0.14). A relatively larger placental share may enable the survival of the anemic twin in TAPS. In contrast with uncomplicated MC twins, fetal growth in MC twins with TAPS is determined primarily by the net inter-twin blood transfusion instead of placental share. Copyright © 2014 Elsevier Ltd. All rights reserved.

Simulations of stress-induced twinning and de-twinning: A phase field model

International Nuclear Information System (INIS)

Hu Shenyang; Henager, Chuck H.; Chen Longqing

2010-01-01

Twinning in certain metals or under certain conditions is a major plastic deformation mode. Here we present a phase field model to describe twin formation and evolution in a polycrystalline fcc metal under loading and unloading. The model assumes that twin nucleation, growth and de-twinning is a process of partial dislocation nucleation and slip on successive habit planes. Stacking fault energies, energy pathways (γ surfaces), critical shear stresses for the formation of stacking faults and dislocation core energies are used to construct the thermodynamic model. The simulation results demonstrate that the model is able to predict the nucleation of twins and partial dislocations, as well as the morphology of the twin nuclei, and to reasonably describe twin growth and interaction. The twin microstructures at grain boundaries are in agreement with experimental observation. It was found that de-twinning occurs during unloading in the simulations, however, a strong dependence of twin structure evolution on loading history was observed.

Twins and Kindergarten Separation: Divergent Beliefs of Principals, Teachers, Parents, and Twins

Science.gov (United States)

Gordon, Lynn Melby

2015-01-01

Should principals enforce mandatory separation of twins in kindergarten? Do school separation beliefs of principals differ from those of teachers, parents of twins, and twins themselves? This survey questioned 131 elementary principals, 54 kindergarten teachers, 201 parents of twins, and 112 twins. A majority of principals (71%) believed that…

Genetic influences on exercise participation in 37,051 twin pairs from seven countries.

Directory of Open Access Journals (Sweden)

Janine H Stubbe

2006-12-01

Full Text Available A sedentary lifestyle remains a major threat to health in contemporary societies. To get more insight in the relative contribution of genetic and environmental influences on individual differences in exercise participation, twin samples from seven countries participating in the GenomEUtwin project were used.Self-reported data on leisure time exercise behavior from Australia, Denmark, Finland, Norway, The Netherlands, Sweden and United Kingdom were used to create a comparable index of exercise participation in each country (60 minutes weekly at a minimum intensity of four metabolic equivalents.Modest geographical variation in exercise participation was revealed in 85,198 subjects, aged 19-40 years. Modeling of monozygotic and dizygotic twin resemblance showed that genetic effects play an important role in explaining individual differences in exercise participation in each country. Shared environmental effects played no role except for Norwegian males. Heritability of exercise participation in males and females was similar and ranged from 48% to 71% (excluding Norwegian males.Genetic variation is important in individual exercise behavior and may involve genes influencing the acute mood effects of exercise, high exercise ability, high weight loss ability, and personality. This collaborative study suggests that attempts to find genes influencing exercise participation can pool exercise data across multiple countries and different instruments.

Twin-twin transfusion syndrome: etiology, severity and rational management

NARCIS (Netherlands)

van Gemert, M. J.; Umur, A.; Tijssen, J. G.; Ross, M. G.

2001-01-01

The twin-twin transfusion syndrome is a serious complication of monochorionic twin pregnancies. Partly as a result of an inadequate understanding of the pathophysiology of the syndrome, there is a lack of consensus in clinical management. We sought to review the available information on the etiology

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.

Low Cognitive Functioning in Nondemented 80+-Year-Old Twins Is Not Heritable.

Science.gov (United States)

Petrill, Stephen A.; Johansson, Boo; Pedersen, Nancy L.; Berg, Stig; Plomin, Robert; Ahern, Frank; McClearn, Gerald E.

2001-01-01

Studied the genetic influence of low cognitive functioning in 200 pairs of twins aged at least 80 years and identified as not demented. Results suggest that the heritability of low cognitive functioning in this group was nonsignificant, but above-average cognitive functioning shows substantial group heritability. (SLD)

The mobility of growth twins synthesized by sputtering: Tailoring the twin thickness

International Nuclear Information System (INIS)

Velasco, Leonardo; Hodge, Andrea M.

2016-01-01

The current work presents a protean twin thickness contour zone map that illustrates how the nucleation and the mobility of twin boundaries affects the twin thickness of sputtered films. The twin thickness contour zone map can be used as a versatile guide to synthesize fully nanotwinned films with tailored twin thicknesses in materials with a wide range of stacking fault energies. The nucleation and mobility of twin boundaries was studied in four Cu alloys of different compositions (Cu-6wt.%Al, Cu-4wt.%Al, Cu-2wt.%Al, and Cu-10wt.%Ni), having stacking fault energies ranging from 6 mJ/m 2 to 60 mJ/m 2 . The films were synthesized by magnetron sputtering and characterized by transmission electron microscopy, where the twin thickness varied from 2 nm to 35 nm. Our experimental results show that it is possible to control the twin thickness. Three main mechanisms are explained to describe twin nucleation and twin boundary mobility, which are correlated to the interplay of specific sputtering conditions and the deposition temperature.

Brain reward responses to food stimuli among female monozygotic twins discordant for BMI

NARCIS (Netherlands)

Doornweerd, Stieneke; De Geus, Eco J; Barkhof, Frederik; van Bloemendaal, Liselotte; Boomsma, Dorret I; van Dongen, J.; Drent, Madeleine L; Willemsen, Gonneke; Veltman, Dick J; IJzerman, Richard G

2017-01-01

Obese individuals are characterized by altered brain reward responses to food. Despite the latest discovery of obesity-associated genes, the contribution of environmental and genetic factors to brain reward responsiveness to food remains largely unclear. Sixteen female monozygotic twin pairs with a

Brain reward responses to food stimuli among female monozygotic twins discordant for BMI

NARCIS (Netherlands)

Doornweerd, Stieneke; De Geus, Eco J; Barkhof, Frederik; van Bloemendaal, Liselotte; Boomsma, Dorret I; van Dongen, J.; Drent, Madeleine L; Willemsen, Gonneke; Veltman, Dick J; IJzerman, Richard G

2018-01-01

Obese individuals are characterized by altered brain reward responses to food. Despite the latest discovery of obesity-associated genes, the contribution of environmental and genetic factors to brain reward responsiveness to food remains largely unclear. Sixteen female monozygotic twin pairs with a

The Mid-Atlantic Twin Registry, revisited.

Science.gov (United States)

Lilley, Emily C H; Silberg, Judy L

2013-02-01

The Mid-Atlantic Twin Registry (MATR) is a population-based registry of more than 56,000 twins primarily born or living in Virginia, North Carolina, and South Carolina. The MATR employs several methods of ascertaining twins, and devotes considerable resources to tracking and maintaining communication with MATR participants. Researchers may utilize the MATR for administration of research services including study recruitment, collection of DNA, archival data set creation, as well as data collection through mailed, phone, or online surveys. In addition, the MATR houses the MATR Repository, with over 1,200 blood samples available for researchers interested in DNA genotyping. For over 35 years MATR twins have participated in research studies with investigators from diverse scientific disciplines and various institutions. These studies, which have resulted in numerous publications, have covered a range of topics, including the human microbiome, developmental psychopathology, depression, anxiety, substance use, epigenetics of aging, children of twins, pre-term birth, social attitudes, seizures, eating disorders, as well as sleep homeostasis. Researchers interested in utilizing twins are encouraged to contact the MATR to discuss potential research opportunities.

Comparative examinations on the activity and variant selection of twinning during tension and compression of magnesium alloys

Energy Technology Data Exchange (ETDEWEB)

Liu, Dejia [College of Materials Science and Engineering, Chongqing University, Chongqing (China); School of Mechatronics Engineering, East China Jiaotong University, Nanchang (China); Xin, Renlong, E-mail: rlxin@cqu.edu.cn [College of Materials Science and Engineering, Chongqing University, Chongqing (China); State Key Laboratory of Mechanical Transmission, Chongqing University, Chongqing (China); Hongni, Yu; Liu, Zhe; Zheng, Xuan [College of Materials Science and Engineering, Chongqing University, Chongqing (China); Liu, Qing, E-mail: qingliu@cqu.edu.cn [College of Materials Science and Engineering, Chongqing University, Chongqing (China)

2016-03-21

In the present study, an Mg weld with β-type fiber texture was produced by friction stir welding (FSW) and then was subjected to tension and compression along the transverse direction (TD). The deformed microstructure by 5% strain was examined in various regions of the Mg weld by electron backscatter diffraction (EBSD) technique. It was found that profuse twinning was activated in stir zone (SZ) -side after tension and in SZ-center and crown zone (CZ) -center after compression due to the presence of relatively large Schmid factor (SF). However, a few twins (2–3%) were also observed in SZ-center after tension and in SZ-side after compression. In this case, the twins have very small and even negative SF. For the twins with large SF, they were likely connected at grain boundaries forming twin pairs, while for those with small or negative SF, they were mostly confined within grains. For connected twins, most of the active variants have favorable SF and geometric compatibility factor (m′). However, the distributions of SF and m′ are different between the twins formed in compression and tension. For isolated twins, the adjacent grains connected with the twins were generally in favorable orientation for basal slip, and the selection of twin variants was likely affected by m′ between the most favorable basal slip and the twins.

Twinning rate in a sample from a Brazilian hospital with a high standard of reproductive care

Directory of Open Access Journals (Sweden)

Gloria Maria Duccini Dal Colletto

Full Text Available CONTEXT: Epidemiological studies on twin births have been motivated mostly by the positive correlation between twinning rate and human fertility, prematurity, low birth weight, increased risk of infant death and long term risk for morbidity. OBJECTIVE: This paper intends to estimate the incidence of multiple births in a private hospital in Brazil with a high standard of reproductive care, and to evaluate the effects of maternal age, gestation order and assisted fertilization on twinning rate. DESIGN: Retrospective analysis. SETTING: First-class tertiary private hospital, São Paulo, Brazil. PARTICIPANTS: The multiple birth rate was investigated among 7,997 deliveries from 1995 to 1998, including 7,786 singletons, 193 twins, 17 triplets and one quadruplet. RESULTS: The rates per 1,000 dizygotic and monozygotic pairs and for triplets were estimated as 19.51, 4.50 and 2.13, respectively. The dizygotic and triplet rates were the highest observed in Brazil up to the present day. The twinning rate among primigravidae older than 30 years was very high (45.02 per 1,000 and was due to a disproportionately high frequency of dizygotic pairs. The triplet rate was also very high among the mothers of this age group (5.71 per 1,000. These facts are strong indicators that these women were the ones most frequently submitted to assisted reproductive techniques. The mean maternal age of the studied population was about six years higher than that estimated for mothers in the general population of southeastern Brazil. Primigravidae aged under 30 years as well as multigravidae showed similar twinning rates, which were almost 20 per 1,000. Among the deliveries of multigravidae older than 30 years, an unusually high frequency of monozygotic twins was observed (7.04 per 1,000, probably as a consequence of the residual effect of long-term use of oral contraceptives. CONCLUSIONS: The dizygotic twinning rate increased from 13.51 to 28.98 per 1,000 over the four years

Natural Homologous Triploidization and DNA Methylation in SARII-628, a Twin-seedling Line of Rice (Oryza sativa

Directory of Open Access Journals (Sweden)

Hai PENG

2007-12-01

Full Text Available A total of five pairs of diploid-triploid twin-seedlings (a diploid seedling and a triploid seedling emerged from a grain were selected out from 4500 pairs of seedlings from SARII-628, a twin-seedling rice line. SSR analysis indicated that no difference between the diploid seedling and corresponding triploid seedling in a twin-seedling was found at the 310 loci, indicating that there was no obvious change in DNA primary structure. A modified AFLP technique ‘MSAP (methylation-sensitive AFLP’ was used to analyze methylation mutation. Although no methylation mutation was noted among the five diploids, 29 methylation mutation loci were found from the corresponding triploids. This suggested that methylation mutation happened rapidly on M0 generation after natural homologous triploidization. The mutations were classified into 10 types, including 3 increased types, 3 decreased types and 4 undecided types of methylation-degrees. The bands of 22 loci were sequenced and then those sequences were searched through website. The result showed that the methylation mutation involved into the whole rice genome and the 12 pairs of chromosomes. The mutation trend was site-related and there were different mutation loci for different triploids, which foretold that SARII-628 would have different evolution fates after natural homologous triploidization.

Quasi-causal associations of physical activity and neighborhood walkability with body mass index: a twin study.

Science.gov (United States)

Duncan, Glen E; Cash, Stephanie Whisnant; Horn, Erin E; Turkheimer, Eric

2015-01-01

Physical activity, neighborhood walkability, and body mass index (BMI, kg/m(2)) associations were tested using quasi-experimental twin methods. We hypothesized that physical activity and walkability were independently associated with BMI within twin pairs, controlling for genetic and environmental background shared between them. Data were from 6376 (64% female; 58% identical) same-sex pairs, University of Washington Twin Registry, 2008-2013. Neighborhood walking, moderate-to-vigorous physical activity (MVPA), and BMI were self-reported. Residential address was used to calculate walkability. Phenotypic (non-genetically informed) and biometric (genetically informed) regression was employed, controlling for age, sex, and race. Walking and MVPA were associated with BMI in phenotypic analyses; associations were attenuated but significant in biometric analyses (PsWalkability was not associated with BMI, however, was associated with walking (but not MVPA) in both phenotypic and biometric analyses (Pswalkability is not associated with BMI, it is associated with neighborhood walking (but not MVPA) accounting for shared background, suggesting a causal relationship between them. Copyright © 2014 Elsevier Inc. All rights reserved.

[Intrapair comparisons of diet and food preference in adult twins].

Science.gov (United States)

Kato, Kenji; Hayakawa, Kazuo; Onoi, Miyuki; Shimizu, Tadahiko; Yura, Akiko; Yokoyama, Yoshie; Kanamori, Masao

2002-12-01

An investigation was conducted on the influence of genetic and lifestyle factors related to the determination of eating behavior of human beings. The objective was to obtain information about lifestyle factors that may help health professionals intervene in terms of the prevention of diet-related diseases. The subjects were 180 pairs of adult twins aged over thirty, comprising of 134 monozygotic (MZ) and 46 dizygotic (DZ) pairs. Every subject was given an interview concerning dietary habits, food preference, food intake, as a part of medical examination. The intake of food containing salt and fat, the intake of food meals, the frequency of daily meals, and the frequency of eating 18 sorts of food were assessed on an individual basis, with a questionnaire on nutrition. The expected and observed values of intrapair concordance rates were calculated, and compared within each zygosity, using the chi-square test. Significant differences between the expected and observed for intrapair concordance rates were shown with monozygotic twins, regarding every category of question. Comparing MZ pairs who had lived apart before their twenties with the other MZ pairs, the latter had a tendency to show significant differences between the expected and observed values of intrapair concordance rate, regarding every category of question. In each case, the observed values were higher than the expected values. The study implied that both genetic and lifestyle factors influence the determinants of eating behavior of human beings. This finding shows the importance of understanding individual characteristics of food preference and eating behavior for intervention regarding lifestyle factors for prevention of diet-related diseases.

Same Genes, Different Brains: Neuroanatomical Differences Between Monozygotic Twins Discordant for Musical Training.

Science.gov (United States)

de Manzano, Örjan; Ullén, Fredrik

2018-01-01

Numerous cross-sectional and observational longitudinal studies show associations between expertise and regional brain anatomy. However, since these designs confound training with genetic predisposition, the causal role of training remains unclear. Here, we use a discordant monozygotic (identical) twin design to study expertise-dependent effects on neuroanatomy using musical training as model behavior, while essentially controlling for genetic factors and shared environment of upbringing. From a larger cohort of monozygotic twins, we were able to recruit 18 individuals (9 pairs) that were highly discordant for piano practice. We used structural and diffusion magnetic resonance imaging to analyze the auditory-motor network and within-pair differences in cortical thickness, cerebellar regional volumes and white-matter microstructure/fractional anisotropy. The analyses revealed that the musically active twins had greater cortical thickness in the auditory-motor network of the left hemisphere and more developed white matter microstructure in relevant tracts in both hemispheres and the corpus callosum. Furthermore, the volume of gray matter in the left cerebellar region of interest comprising lobules I-IV + V, was greater in the playing group. These findings provide the first clear support for that a significant portion of the differences in brain anatomy between experts and nonexperts depend on causal effects of training. © The Author 2017. Published by Oxford University Press.

Digital Twins in Health Care: Ethical Implications of an Emerging Engineering Paradigm

Directory of Open Access Journals (Sweden)

Koen Bruynseels

2018-02-01

Full Text Available Personalized medicine uses fine grained information on individual persons, to pinpoint deviations from the normal. ‘Digital Twins’ in engineering provide a conceptual framework to analyze these emerging data-driven health care practices, as well as their conceptual and ethical implications for therapy, preventative care and human enhancement. Digital Twins stand for a specific engineering paradigm, where individual physical artifacts are paired with digital models that dynamically reflects the status of those artifacts. When applied to persons, Digital Twins are an emerging technology that builds on in silico representations of an individual that dynamically reflect molecular status, physiological status and life style over time. We use Digital Twins as the hypothesis that one would be in the possession of very detailed bio-physical and lifestyle information of a person over time. This perspective redefines the concept of ‘normality’ or ‘health,’ as a set of patterns that are regular for a particular individual, against the backdrop of patterns observed in the population. This perspective also will impact what is considered therapy and what is enhancement, as can be illustrated with the cases of the ‘asymptomatic ill’ and life extension via anti-aging medicine. These changes are the consequence of how meaning is derived, in case measurement data is available. Moral distinctions namely may be based on patterns found in these data and the meanings that are grafted on these patterns. Ethical and societal implications of Digital Twins are explored. Digital Twins imply a data-driven approach to health care. This approach has the potential to deliver significant societal benefits, and can function as a social equalizer, by allowing for effective equalizing enhancement interventions. It can as well though be a driver for inequality, given the fact that a Digital Twin might not be an accessible technology for everyone, and given the fact

Digital Twins in Health Care: Ethical Implications of an Emerging Engineering Paradigm

Science.gov (United States)

Bruynseels, Koen; Santoni de Sio, Filippo; van den Hoven, Jeroen

2018-01-01

Personalized medicine uses fine grained information on individual persons, to pinpoint deviations from the normal. ‘Digital Twins’ in engineering provide a conceptual framework to analyze these emerging data-driven health care practices, as well as their conceptual and ethical implications for therapy, preventative care and human enhancement. Digital Twins stand for a specific engineering paradigm, where individual physical artifacts are paired with digital models that dynamically reflects the status of those artifacts. When applied to persons, Digital Twins are an emerging technology that builds on in silico representations of an individual that dynamically reflect molecular status, physiological status and life style over time. We use Digital Twins as the hypothesis that one would be in the possession of very detailed bio-physical and lifestyle information of a person over time. This perspective redefines the concept of ‘normality’ or ‘health,’ as a set of patterns that are regular for a particular individual, against the backdrop of patterns observed in the population. This perspective also will impact what is considered therapy and what is enhancement, as can be illustrated with the cases of the ‘asymptomatic ill’ and life extension via anti-aging medicine. These changes are the consequence of how meaning is derived, in case measurement data is available. Moral distinctions namely may be based on patterns found in these data and the meanings that are grafted on these patterns. Ethical and societal implications of Digital Twins are explored. Digital Twins imply a data-driven approach to health care. This approach has the potential to deliver significant societal benefits, and can function as a social equalizer, by allowing for effective equalizing enhancement interventions. It can as well though be a driver for inequality, given the fact that a Digital Twin might not be an accessible technology for everyone, and given the fact that patterns

Magnetosphere dynamics during the 14 November 2012 storm inferred from TWINS, AMPERE, Van Allen Probes, and BATS-R-US-CRCM

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Buzulukova, Natalia; Goldstein, Jerry; Fok, Mei-Ching; Glocer, Alex; Valek, Phil; McComas, David; Korth, Haje; Anderson, Brian

2018-01-01

During the 14 November 2012 geomagnetic storm, the Van Allen Probes spacecraft observed a number of sharp decreases (dropouts) in particle fluxes for ions and electrons of different energies. In this paper, we investigate the global magnetosphere dynamics and magnetosphere-ionosphere (M-I) coupling during the dropout events using multipoint measurements by Van Allen Probes, TWINS, and AMPERE together with the output of the two-way coupled global BATS-R-US-CRCM model. We find different behavior for two pairs of dropouts. For one pair, the same pattern was repeated: (1) weak nightside Region 1 and 2 Birkeland currents before and during the dropout; (2) intensification of Region 2 currents after the dropout; and (3) a particle injection detected by TWINS after the dropout. The model predicted similar behavior of Birkeland currents. TWINS low-altitude emissions demonstrated high variability during these intervals, indicating high geomagnetic activity in the near-Earth tail region. For the second pair of dropouts, the structure of both Birkeland currents and ENA emissions was relatively stable. The model also showed quasi-stationary behavior of Birkeland currents and simulated ENA emissions with gradual ring current buildup. We confirm that the first pair of dropouts was caused by large-scale motions of the OCB (open-closed boundary) during substorm activity. We show the new result that this OCB motion was associated with global changes in Birkeland (M-I coupling) currents and strong modulation of low-altitude ion precipitation. The second pair of dropouts is the result of smaller OCB disturbances not related to magnetospheric substorms. The local observations of the first pair of dropouts result from a global magnetospheric reconfiguration, which is manifested by ion injections and enhanced ion precipitation detected by TWINS and changes in the structure of Birkeland currents detected by AMPERE. This study demonstrates that multipoint measurements along with the global

The genetic and environmental determinants of the association between brain abnormalities and schizophrenia: the schizophrenia twins and relatives consortium.

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van Haren, Neeltje E M; Rijsdijk, Fruhling; Schnack, Hugo G; Picchioni, Marco M; Toulopoulou, Timothea; Weisbrod, Matthias; Sauer, Heinrich; van Erp, Theo G; Cannon, Tyrone D; Huttunen, Matti O; Boomsma, Dorret I; Hulshoff Pol, Hilleke E; Murray, Robin M; Kahn, Rene S

2012-05-15

Structural brain abnormalities are consistently found in schizophrenia (Sz) and have been associated with the familial risk for the disorder. We aim to define the relative contributions of genetic and nongenetic factors to the association between structural brain abnormalities and Sz in a uniquely powered cohort (Schizophrenia Twins and Relatives consortium). An international multicenter magnetic resonance imaging collaboration was set up to pool magnetic resonance imaging scans from twin pairs in Utrecht (The Netherlands), Helsinki (Finland), London (United Kingdom), and Jena (Germany). A sample of 684 subjects took part, consisting of monozygotic twins (n = 410, with 51 patients from concordant and 52 from discordant pairs) and dizygotic twins (n = 274, with 39 patients from discordant pairs). The additive genetic, common, and unique environmental contributions to the association between brain volumes and risk for Sz were estimated by structural equation modeling. The heritabilities of most brain volumes were significant and ranged between 52% (temporal cortical gray matter) and 76% (cerebrum). Heritability of cerebral gray matter did not reach significance (34%). Significant phenotypic correlations were found between Sz and reduced volumes of the cerebrum (-.22 [-.30/-.14]) and white matter (-.17 [-.25/-.09]) and increased volume of the third ventricle (.18 [.08/.28]). These were predominantly due to overlapping genetic effects (77%, 94%, and 83%, respectively). Some of the genes that transmit the risk for Sz also influence cerebral (white matter) volume. Copyright © 2012 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Proteomic Assessment of Fluid Shifts and Association with Visual Impairment and Intracranial Pressure in Twin Astronauts

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Rana, Brinda K.; Stenger, Michael B.; Lee, Stuart M. C.; Macias, Brandon R.; Siamwala, Jamila; Piening, Brian Donald; Hook, Vivian; Ebert, Doug; Patel, Hemal; Smith, Scott;

Características de superdotação em um par de gêmeos monozigóticos Characteristics of giftedness in a pair of monozygotic twins

Directory of Open Access Journals (Sweden)

Carolina Sertã Passos

2011-12-01

Full Text Available Com objetivo de comparar características de superdotação em um par de gêmeos monozigóticos, mais especificamente criatividade, motivação e capacidade superior, foram utilizados dados provenientes de um programa que identifica estudantes talentosos com o Modelo das Portas Giratórias. Os gêmeos responderam, também, ao Teste Torrance de Pensamento Criativo, à Escala de Avaliação da Motivação para Aprender de Alunos do Ensino Fundamental e à Bateria de Provas de Raciocínio. Eles possuem superdotação acadêmica e artística, sendo que um deles possui, também, altas habilidades para liderança e comunicação. Verificou-se que eles apresentaram elevada criatividade, principalmente verbal. O envolvimento com a tarefa, que neste estudo foi reduzido à motivação para aprender, não está presente em níveis superiores nos gêmeos. Mais semelhanças que diferenças entre os irmãos, talvez por eles compartilharem genes e ambientes, foram identificadas.Data from program that identifies talent through the Revolving Door Identification Model was used to compare characteristics of giftedness of a pair of monozygotic twins, specifically focusing on creativity, motivation and high ability. The twins also answered the Torrance Test of Creative Thinking, the Scale of Motivation to Learn in Elementary School Students and the Battery of Reasoning Tests. They have academic and artistic giftedness; one of them also has high leadership and communication skills. It was found that they showed great creativity, mainly verbal. Task commitment, which in this study was limited to motivation to learn, is not present at higher levels for the twins. More similarities than differences between the two brothers were identified, possibly because they share genes and environments.

Dancing Twins: Stellar Hierarchies That Formed Sequentially?

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Tokovinin, Andrei

2018-04-01

This paper draws attention to the class of resolved triple stars with moderate ratios of inner and outer periods (possibly in a mean motion resonance) and nearly circular, mutually aligned orbits. Moreover, stars in the inner pair are twins with almost identical masses, while the mass sum of the inner pair is comparable to the mass of the outer component. Such systems could be formed either sequentially (inside-out) by disk fragmentation with subsequent accretion and migration, or by a cascade hierarchical fragmentation of a rotating cloud. Orbits of the outer and inner subsystems are computed or updated in four such hierarchies: LHS 1070 (GJ 2005, periods 77.6 and 17.25 years), HIP 9497 (80 and 14.4 years), HIP 25240 (1200 and 47.0 years), and HIP 78842 (131 and 10.5 years).

Grammar Clinical Marker Yields Substantial Heritability for Language Impairments in 16-Year-Old Twins.

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Dale, Philip S; Rice, Mabel L; Rimfeld, Kaili; Hayiou-Thomas, Marianna E

2018-01-22

There is a need for well-defined language phenotypes suitable for adolescents in twin studies and other large-scale research projects. Rice, Hoffman, and Wexler (2009) have developed a grammatical judgment measure as a clinical marker of language impairment, which has an extended developmental range to adolescence. We conducted the first twin analysis, along with associated phenotypic analyses of validity, of an abridged, 20-item version of this grammatical judgment measure (GJ-20), based on telephone administration using prerecorded stimuli to 405 pairs of 16-year-olds (148 monozygotic and 257 dizygotic) drawn from the Twins Early Development Study (Haworth, Davis, & Plomin, 2012). The distribution of scores is markedly skewed negatively, as expected for a potential clinical marker. Low performance on GJ-20 is associated with lower maternal education, reported learning disability (age 7 years), and low scores on language tests administered via the Twins Early Development Study (age 16 years) as well as General Certificate of Secondary Education English and Math examination performance (age 16 years). Liability threshold estimates for the genetic influence on low performance on GJ-20 are substantial, ranging from 36% with a lowest 10% criterion to 74% for a lowest 5% criterion. The heritability of GJ-20 scores, especially at more extreme cutoffs, along with the score distribution and association with other indicators of language impairments, provides additional evidence for the potential value of this measure as a clinical marker of specific language impairment.

Silver(I)-Mediated Base Pairs in DNA Sequences Containing 7-Deazaguanine/Cytosine: towards DNA with Entirely Metallated Watson-Crick Base Pairs.

Science.gov (United States)

Méndez-Arriaga, José M; Maldonado, Carmen R; Dobado, José A; Galindo, Miguel A

2018-03-26

DNA sequences comprising noncanonical 7-deazaguanine ( 7C G) and canonical cytosine (C) are capable of forming Watson-Crick base pairs via hydrogen bonds as well as silver(I)-mediated base pairs by coordination to central silver(I) ions. Duplexes I and II containing 7C G and C have been synthesized and characterized. The incorporation of silver(I) ions into these duplexes has been studied by means of temperature-dependent UV spectroscopy, circular dichroism, and DFT calculations. The results suggest the formation of DNA molecules comprising contiguous metallated 7C G-Ag I -C Watson-Crick base pairs that preserve the original B-type conformation. Furthermore, additional studies performed on duplex III indicated that, in the presence of Ag I ions, 7C G-C and 7C A-T Watson-Crick base pairs ( 7C A, 7-deazadenine; T, thymine) can be converted to metallated 7C G-Ag I -C and 7C A-Ag I -T base pairs inside the same DNA molecule whilst maintaining its initial double helix conformation. These findings are very important for the development of customized silver-DNA nanostructures based on a Watson-Crick complementarity pattern. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Genetic and Environmental Regulation on Longitudinal Change of Metabolic Phenotypes in Danish and Chinese Adult Twins

DEFF Research Database (Denmark)

Li, Shuxia; Kyvik, Kirsten Ohm; Pang, Zengchang

2016-01-01

OBJECTIVE: The rate of change in metabolic phenotypes can be highly indicative of metabolic disorders and disorder-related modifications. We analyzed data from longitudinal twin studies on multiple metabolic phenotypes in Danish and Chinese twins representing two populations of distinct ethnic...... pairs traced for about 7 years with a mean baseline age of 39.5 years (range: 23-64). The classical twin models were fitted to the longitudinal change in each phenotype (Δphenotype) to estimate the genetic and environmental contributions to the variation in Δphenotype. RESULTS: Moderate to high...... contributions by the unique environment were estimated for all phenotypes in both Danish (from 0.51 for low density lipoprotein cholesterol up to 0.72 for triglycerides) and Chinese (from 0.41 for triglycerides up to 0.73 for diastolic blood pressure) twins; low to moderate genetic components were estimated...

Cannabis Involvement and Nonsuicidal Self-Injury: A Discordant Twin Approach.

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Few, Lauren R; Grant, Julia D; Nelson, Elliot C; Trull, Timothy J; Grucza, Richard A; Bucholz, Kathleen K; Verweij, Karin J H; Martin, Nicholas G; Statham, Dixie J; Madden, Pamela A F; Heath, Andrew C; Lynskey, Michael T; Agrawal, Arpana

2016-11-01

Cannabis use, particularly at an early age, has been linked to suicidal thoughts and behavior, but minimal work has examined the association between cannabis use and lifetime nonsuicidal self-injury (NSSI). The current study aims to characterize the overlap between lifetime and early cannabis use and NSSI and to examine genetic and environmental mechanisms of this association. Adult male and female twins from the Australian Twin Registry (N = 9,583) were used to examine the odds of NSSI associated with lifetime cannabis use and early cannabis use (i.e., accounting for the age at onset of cannabis use and NSSI. Lifetime cannabis use (odds ratio [OR] = 2.84, 95% CI [2.23, 3.61]) and early cannabis use were associated with increased odds of NSSI (OR = 2.15, 95% CI [1.75, 2.65]), and this association remained when accounting for covariates. The association was only significant, however, in MZ twin pairs discordant for early cannabis use (OR = 3.20, 95% CI [1.17, 8.73]). Replication analyses accounting for the temporal ordering of cannabis use and NSSI yielded similar findings of nominal significance. Results suggest that NSSI is associated with cannabis involvement via differing mechanisms. For lifetime cannabis use, the lack of association in discordant pairs suggests the role of shared genes and family environment. However, in addition to such shared familial influences, person-specific and putatively causal factors contribute to the relationship between early cannabis use and NSSI. Therefore, delaying the onset of cannabis use may reduce exposure to influences that exacerbate vulnerabilities to NSSI.

Attitudes to Gun Control in an American Twin Sample: Sex Differences in the Causes of Variation.

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Eaves, Lindon J; Silberg, Judy L

2017-10-01

The genetic and social causes of individual differences in attitudes to gun control are estimated in a sample of senior male and female twin pairs in the United States. Genetic and environmental parameters were estimated by weighted least squares applied to polychoric correlations for monozygotic (MZ) and dizygotic (DZ) twins of both sexes. The analysis suggests twin similarity for attitudes to gun control in men is entirely genetic while that in women is purely social. Although the volunteer sample is small, the analysis illustrates how the well-tested concepts and methods of genetic epidemiology may be a fertile resource for deepening our scientific understanding of biological and social pathways that affect individual risk to gun violence.