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Sample records for adult twin study

  1. [Adult twins].

    PubMed

    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. PMID:17352324

  2. The USC Adult Twin Cohorts: International Twin Study and California Twin Program.

    PubMed

    Cozen, Wendy; Hwang, Amie E; Cockburn, Myles G; Hamilton, Ann S; Zadnick, John; Mack, Thomas M

    2013-02-01

    The study of twin subjects permits the documentation of crude heritability and may promote the identification of specific causal alleles. We believe that at the current time, the chief research advantage of twins as subjects, especially monozygotic twins, is that the commonality of their genetic and cultural identity simplifies the interpretation of biological associations. In order to study genetic and environmental determinants of cancer and chronic diseases, we developed two twin registries, maintained at the University of Southern California: The International Twin Study (ITS) and the California Twin Program (CTP). The ITS is a volunteer registry of twins with cancer and chronic disease consisting of 17,245 twin pairs affected by cancer and chronic disease, respectively, ascertained by advertising in periodicals from 1980-1991. The CTP is a population-based registry of California-born twin pairs ascertained by linking the California birth records to the State Department of Motor Vehicles. Over 51,000 individual California twins representing 36,965 pairs completed and returned 16-page questionnaires. Cancer diagnoses in the California twins are updated by regular linkage to the California Cancer Registry. Over 5,000 cancer patients are represented in the CTP. Twins from both registries have participated extensively in studies of breast cancer, melanoma, lymphoma, multiple sclerosis, systemic lupus erythematosus, diabetes mellitus type 1, mammographic density, smoking, and other traits and conditions. PMID:23218448

  3. Genetic determinants of bone mass in adults. A twin study.

    PubMed Central

    Pocock, N A; Eisman, J A; Hopper, J L; Yeates, M G; Sambrook, P N; Eberl, S

    1987-01-01

    The relative importance of genetic factors in determining bone mass in different parts of the skeleton is poorly understood. Lumbar spine and proximal femur bone mineral density and forearm bone mineral content were measured by photon absorptiometry in 38 monozygotic and 27 dizygotic twin pairs. Bone mineral density was significantly more highly correlated in monozygotic than in dizygotic twins for the spine and proximal femur and in the forearm of premenopausal twin pairs, which is consistent with significant genetic contributions to bone mass at all these sites. The lesser genetic contribution to proximal femur and distal forearm bone mass compared with the spine suggests that environmental factors are of greater importance in the aetiology of osteopenia of the hip and wrist. This is the first demonstration of a genetic contribution to bone mass of the spine and proximal femur in adults and confirms similar findings of the forearm. Furthermore, bivariate analysis suggested that a single gene or set of genes determines bone mass at all sites. PMID:3624485

  4. Twin-based study of the complex interplay between childhood maltreatment, socioeconomic status and adult memory.

    PubMed

    Goldberg, Ximena; Alemany, Silvia; Fatjó-Vilas, Mar; González-Ortega, Itxaso; González-Pinto, Ana; Cuesta, Manuel J; Fañanás, Lourdes

    2013-08-01

    Childhood maltreatment and low socioeconomic status (SES) are considered stressful environmental events with lasting detrimental effects on adult mental health and associated cognitive performance, such as memory. However, the association between childhood maltreatment and low SES remains unclear, probably due to design limitations and putative confounding factors. Particular concerns have been raised on genetic influences, as genetic background may modulate the effects of environmental stressors. The aim of the present study was to examine the effect of childhood maltreatment on adult memory in low- and high-SES subjects, free of confounding due to other environmental and genetic influences. A monozygotic twin design based on 188 healthy adult subjects (94 twin pairs) from the general population was conducted. This design based on genetically identical individuals allowed disentangling the unique environmental effects of childhood maltreatment on memory, which was explored in low and high SES. Results showed that the unique environmental effects of childhood maltreatment were only evident in the high-SES group (β = -0.22; SE = 0.08; p < 0.01; 95 % CI = -0.375 to -0.066). By contrast, no evidence for this effect could be detected in the more stressful low-SES group. These results suggest that enriched environments may provide a more stable context where early stressful experiences can influence cognitive processes. This study provides preliminary support for the inclusion of environmental enrichment in studies addressing the impact of childhood maltreatment on adult cognition and psychiatric disorders. PMID:23188190

  5. The effects of shared environment on adult intelligence: a critical review of adoption, twin, and MZA studies.

    PubMed

    Kaplan, Jack S

    2012-09-01

    There has been a vigorous debate for decades concerning the heritability of intelligence. In recent years, the debate has been focused on whether the components of IQ variability change with age and on separating environmental effects into shared and unshared components. Citing evidence from adoption studies, studies comparing identical and fraternal twins, and studies of identical twins raised apart, some prominent psychologists have concluded that the shared environment has a significant effect on the intelligence of children but little or no effect on the intelligence of adults. In this article, the evidence from such studies is reviewed. The article reaches the conclusion that while there is some evidence from adoption studies supporting the claim that shared environment has little or no effect on adult intelligence, that evidence is inconclusive and is inconsistent with evidence from twin studies and from studies of identical twins reared apart. PMID:22746221

  6. Coordination difficulty and internalizing symptoms in adults: A twin/sibling study.

    PubMed

    Waszczuk, Monika A; Leonard, Hayley C; Hill, Elisabeth L; Rowe, Richard; Gregory, Alice M

    2016-05-30

    Increased anxiety and depression symptoms have been reported in individuals with neurodevelopmental disorders, and have been found to be associated with motor coordination difficulties, but little is known about the etiology of these associations. This study aimed to assess genetic, shared (making twins/siblings alike) and non-shared (individual-specific) environmental influences on the association between poor coordination and symptoms of anxiety and depressed mood using a sample of adult twin and sibling pairs. Participants were asked about their coordination skill and anxiety and depression symptoms. About half of the variance in coordination difficulty was explained by familial (combined genetic and shared environmental) influences, with the remaining variance explained by non-shared environmental influences. Phenotypic associations between coordination and anxiety (r=.46) and depression symptoms (r=.44) were largely underpinned by shared familial liability for the three traits. Non-shared environment accounted for about a third of the phenotypic association. Results suggest that both familial and non-shared environmental influences play a role in the etiology of coordination difficulty and its association with internalizing symptoms. The current study highlights that both biological and environmental pathways shared between these symptoms should be examined in future research to inform prevention and treatment approaches in clinical settings. PMID:27137955

  7. Genetic factors in evolution of sleep length--a longitudinal twin study in Finnish adults.

    PubMed

    Hublin, Christer; Partinen, Markku; Koskenvuo, Markku; Kaprio, Jaakko

    2013-10-01

    Genetic factors affect many aspects of sleep, such as sleep length. We investigated the contribution of genetic factors to stability and change of sleep length among adults over a 15-year period. In this representative follow-up study we used the Finnish Twin Cohort as the study population. Questionnaire surveys were performed in 1975 (response rate 89%, 11,041 twin pairs; age ≥18 years), 1981 (84%, 9323; ≥24 years) and 1990 (77%, 4507; 33-60 years). Sleep was categorized as short (<7 h), average or long (>8 h). Pairwise similarity in monozygotic and dizygotic pairs was examined at each survey by age group and sex. Quantitative genetic modelling was used to estimate cross-sectional and longitudinal genetic effects. The proportion of variance in sleep length at one point in time that was accounted for by genetic effects was very stable over the study period, being 0.31 in 1975, 0.32 in 1981 and 0.30 in 1990. Longitudinal genetic modelling indicated that the correlations of genetic effects between the three measurement points were high: 0.85 between 1975 and 1981; 0.93 between 1981 and 1990; and 0.76 between 1975 and 1990. Despite a high contribution of environmental effects, their correlations over time were modest: 0.31 between 1975 and 1981; 0.33 between 1981 and 1990; and 0.18 between 1975 and 1990. In conclusion, genetic factors have a modest but stable effect on the evolution of sleep length over a long time span in adults. Multiple measures are a more robust basis for genetic analyses than a single cross-sectional measure. PMID:23509990

  8. Associations Between Fast-Food Consumption and Body Mass Index: A Cross-Sectional Study in Adult Twins.

    PubMed

    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. PMID:26005202

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

    PubMed

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

    2012-07-01

    Skin-picking disorder (SPD) is a disabling psychiatric condition that can lead to skin damage and other medical complications. Epidemiological data is scarce and its causes are unknown. The present study examined the prevalence and heritability of skin-picking symptoms in a large sample of twins. A total of 2,518 twins completed a valid and reliable self-report measure of skin-picking behavior. The prevalence of clinically significant skin picking was established using empirically derived cut-offs. Twin modeling methods were employed to decompose the variance in the liability to skin picking into additive genetic and shared and non-shared environmental factors. A total of 1.2% of twins scored above the cut-off, indicative of clinically significant skin picking. All these participants were women. Univariate model-fitting analyses (female twins only, N = 2,191) showed that genetic factors accounted for approximately 40% (95% CI 19-58%) of the variance in skin picking, with non-shared environmental factors and measurement error accounting for the remaining variance (60% [95% CI 42-81%]). Shared environmental factors were negligible. It is concluded that pathological skin picking is relatively prevalent problem, particularly among women, and that it tends to run in families primarily due to genetic factors. Non-shared environmental factors are also likely to play an important role in its etiology. PMID:22619132

  10. Increased Frequency of Micronuclei in Adults with a History of Childhood Sexual Abuse: A Discordant Monozygotic Twin Study

    PubMed Central

    York, Timothy P.; Brumelle, Jenni; Juusola, Jane; Kendler, Kenneth S.; Eaves, Lindon J.; Amstadter, Ananda B.; Aggen, Steven H.; Jones, Kimberly H.; Ferreira-Gonzalez, Andrea; Jackson-Cook, Colleen

    2013-01-01

    Background Childhood sexual abuse (CSA) is a traumatic life event associated with an increased lifetime risk for psychopathology/morbidity. The long-term biological consequences of CSA-elicited stress on chromosomal stability in adults are unknown. The primary aim of this study was to determine if the rate of acquired chromosomal changes, measured using the cytokinesis-block micronucleus assay on stimulated peripheral blood lymphocytes, differs in adult female monozygotic twins discordant for CSA. Methods Monozygotic twin pairs discordant for CSA were identified from a larger population-based sample of female adult twins for whom the experience of CSA was assessed by self-report (51 individuals including a reference sample). Micronuclei (MN) contain chromatin from structurally normal or abnormal chromosomes that are excluded from the daughter nuclei during cell division and serve as a biomarker to assess acquired chromosomal instability. Results Female twins exposed to CSA exhibited a 1.63-fold average increase in their frequency of MN compared to their nonexposed genetically identical cotwins (Paired t-test, t16 = 2.65, P = 0.017). No additional effects of familial factors were detected after controlling for the effect of CSA exposure. A significant interaction between CSA history and age was observed, suggesting that the biological effects of CSA on MN formation may be cumulative. Conclusions These data support a direct link between CSA exposure and MN formation measured in adults that is not attributable to genetic or environmental factors shared by siblings. Further research is warranted to understand the biological basis for the observed increase in acquired chromosomal findings in people exposed to CSA and to determine if acquired somatic chromosomal abnormalities/somatic clonal mosaicism might mediate the adult pathology associated with CSA. PMID:23383158

  11. Genetic and environmental influences on spontaneous micronuclei frequencies in children and adults: a twin study.

    PubMed

    Jones, Kimberly H; York, Timothy P; Juusola, Jane; Ferreira-Gonzalez, Andrea; Maes, Hermine H; Jackson-Cook, Colleen

    2011-11-01

    The primary aim of this study was to quantify genetic and environmental influences on the frequency of spontaneously occurring micronuclei in children and adults. To meet this aim, a total of 63 male and female twin pairs and 19 singletons (145 individuals) were evaluated, ranging in age from 7 to 85 years. Micronuclei frequencies significantly increased with age for both genders (r = 0.49, P < 0.001), with the lowest and highest rates being seen in the 7- to 9 (mean = 0.56%, SD = .28) and 60- to 69-year-olds (mean = 2.12%, SD = 1.0), respectively. This age effect was significantly more pronounced in females than males (P = 0.017). In addition to the main effect of age, the completion of puberty in either gender (P = 0.036) and menopause in females (P = 0.024) was associated with a significant increase in micronuclei frequencies. Genetic model fitting indicated that influences from both additive genetic (65.2% of variance) and unique environmental (34.8% of variance) sources best explained the observed micronuclei frequencies in monozygotic and dizygotic twin pairs. Self-reported health conditions associated with an increased frequency of micronuclei included a history of allergies (P < 0.007) and migraines (P = 0.026). Multivitamin use was also associated with increased micronuclei frequencies (P = 0.004). In contrast, significantly lower micronuclei frequencies were associated with arthritis (P = 0.002), as well as consuming fruit (P = 0.014), green, leafy vegetables (P < 0.001) and/or folate-enriched bread (P = 0.035). A sex-specific effect, resulting in a significantly increased frequency of micronuclei with tobacco usage, was observed for females (but not males). Gender differences also moderated the impact of vitamin D and calcium consumption. In conclusion, the frequency of spontaneously arising micronuclei in humans is a complex trait, being influenced by both heritable genetic and environmental components. Recognition of factors contributing to baseline

  12. Tobacco use and reported bruxism in young adults: A nationwide Finnish Twin Cohort Study

    PubMed Central

    Ahlberg, J.; Hublin, C.; Lobbezoo, F.; Rose, R. J.; Murtomaa, H.; Kaprio, J.

    2010-01-01

    Introduction: Higher levels of smoking, leading to increased levels of nicotine and dopamine release, may be more strongly related to bruxism, although this relationship has remained unclear. Thus, the aim of the present study was to investigate the possible effect of cumulative tobacco use on bruxism in a large sample of young adults. Methods: The material of the present study derives from the FinnTwin16, which consists of five birth cohorts born in 1975–1979. A total of 3,124 subjects (mean age 24 years, range 23–27 years) provided data in 2000–2002 on frequency of bruxism and tobacco use. Multinomial logistic regression was used to explore the relationships of frequency of bruxism with smoking and smokeless tobacco use while controlling covariates (alcohol intoxication, alcohol problems [Rutgers Alcohol Problem Index, RAPI], illicit drug use, psychological distress [General Health Questionnaire], and coffee use). Results: Based on subjective response and multivariate analyses, weekly bruxers were more than two times more likely to report heavy smoking than never bruxers (odds ratio [OR] 2.5, 95 % CI 1.8–3.4). The significant association between heavy smoking and bruxism held when the effects of other tobacco use and multiple covariates were controlled. In addition, the use of smokeless tobacco emerged as an independent risk factor for bruxism. Discussion: Given the observed associations with both heavy smoking and smokeless tobacco and a dose–response relationship, the present results support our hypothesis of a link between nicotine intake and bruxism. PMID:20427458

  13. A review of the evidence from family, twin and adoption studies for a genetic contribution to adult psychiatric disorders.

    PubMed

    Shih, Regina A; Belmonte, Pamela L; Zandi, Peter P

    2004-11-01

    Family, twin and adoption studies have provided major evidence for the role of genetics in numerous psychiatric disorders including obsessive-compulsive disorder, panic disorder, major depressive disorder, bipolar disorder, schizophrenia and Alzheimer's disease. As the search for patterns of inheritance and candidate genes of these complex disorders continues, we review relevant findings from quantitative genetic studies and outline the main challenges for the field of psychiatric genetics to focus on in order to more definitively establish the underpinnings of genetic and environmental influences of adult psychopathology. PMID:16194760

  14. [Twin studies in psychiatry].

    PubMed

    Kringlen, E

    1999-09-20

    Twin research in medicine and psychology has blossomed during the last decades. A brief presentation of twin research methods is given, followed by a review of psychiatric studies, particularly Norwegian ones. The Nordic investigations are of great importance because many of these studies have been able to avoid shortcomings in sampling by linking national twin registers to disease registers. This procedure is of consequence for the estimation of heritability. Twin research shows that the genetic contribution to Alzheimer's disease, manic-depressive (bipolar) disorder, schizophrenia and childhood autism is relatively strong, whereas genetic factors play a minor role in common depressions, anxiety and somatoform disorders, and alcohol abuse. Since the concordance rates are far from 100 percent in most of these illnesses, environmental factors must also be important. PMID:10533417

  15. Assessment of Generalized Anxiety Disorder Diagnostic Criteria in the National Comorbidity Survey and Virginia Adult Twin Study of Psychiatric and Substance Use Disorders

    ERIC Educational Resources Information Center

    Kubarych, Thomas S.; Aggen, Steven H.; Hettema, John M.; Kendler, Kenneth S.; Neale, Michael C.

    2008-01-01

    The authors investigated measurement properties of the "Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition," generalized anxiety disorder (GAD) criteria in the National Comorbidity Survey and the Virginia Adult Twin Study of Psychiatric and Substance Use Disorders (VATSPSUD). The two studies used different widely used…

  16. A family study of adult twins with and without a history of childhood abuse: stability of retrospective reports of maltreatment and associated family measures.

    PubMed

    Nelson, Elliot C; Lynskey, Michael T; Heath, Andrew C; Madden, Pamela A F; Martin, Nicholas G

    2010-04-01

    Childhood sexual abuse (CSA) and physical abuse (CPA) are well-established risk-factors for a wide of range of proximal and distal outcomes. The lack of availability of an optimal design for examining abuse and its consequences has resulted in the use of various approaches, each having its own limitations. We describe the Childhood Trauma Study, which ascertained families from a large young adult Australian twin cohort on the basis of twins' responses to screening questions assessing CSA and CPA. We report data from 3407 participants including twins, non-twin siblings, and their parents. Our data demonstrate the feasibility of using a comprehensive assessment to evaluate retrospective history of childhood abuse in an adult sample. We observed that risk for each form of abuse increased incrementally with the number of parents with alcohol problems. Psychometric properties of our measures of CSA and CPA including reasonable long-term stability, construct validity, and evidence of familial corroboration compare favorably with those of other reports in which samples were considerably younger and assessments were repeated over shorter intervals. PMID:20397742

  17. Birth Weight and Adult IQ, but Not Anxious-Depressive Psychopathology, Are Associated with Cortical Surface Area: A Study in Twins

    PubMed Central

    Córdova-Palomera, Aldo; Fatjó-Vilas, Mar; Falcón, Carles; Bargalló, Nuria; Alemany, Silvia; Crespo-Facorro, Benedicto; Nenadic, Igor; Fañanás, Lourdes

    2015-01-01

    Background Previous research suggests that low birth weight (BW) induces reduced brain cortical surface area (SA) which would persist until at least early adulthood. Moreover, low BW has been linked to psychiatric disorders such as depression and psychological distress, and to altered neurocognitive profiles. Aims We present novel findings obtained by analysing high-resolution structural MRI scans of 48 twins; specifically, we aimed: i) to test the BW-SA association in a middle-aged adult sample; and ii) to assess whether either depression/anxiety disorders or intellectual quotient (IQ) influence the BW-SA link, using a monozygotic (MZ) twin design to separate environmental and genetic effects. Results Both lower BW and decreased IQ were associated with smaller total and regional cortical SA in adulthood. Within a twin pair, lower BW was related to smaller total cortical and regional SA. In contrast, MZ twin differences in SA were not related to differences in either IQ or depression/anxiety disorders. Conclusion The present study supports findings indicating that i) BW has a long-lasting effect on cortical SA, where some familial and environmental influences alter both foetal growth and brain morphology; ii) uniquely environmental factors affecting BW also alter SA; iii) higher IQ correlates with larger SA; and iv) these effects are not modified by internalizing psychopathology. PMID:26086820

  18. Twin methodology in epigenetic studies.

    PubMed

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

    2015-01-01

    Since the final decades of the last century, twin studies have made a remarkable contribution to the genetics of human complex traits and diseases. With the recent rapid development in modern biotechnology of high-throughput genetic and genomic analyses, twin modelling is expanding from analysis of diseases to molecular phenotypes in functional genomics especially in epigenetics, a thriving field of research that concerns the environmental regulation of gene expression through DNA methylation, histone modification, microRNA and long non-coding RNA expression, etc. The application of the twin method to molecular phenotypes offers new opportunities to study the genetic (nature) and environmental (nurture) contributions to epigenetic regulation of gene activity during developmental, ageing and disease processes. Besides the classical twin model, the case co-twin design using identical twins discordant for a trait or disease is becoming a popular and powerful design for epigenome-wide association study in linking environmental exposure to differential epigenetic regulation and to disease status while controlling for individual genetic make-up. It can be expected that novel uses of twin methods in epigenetic studies are going to help with efficiently unravelling the genetic and environmental basis of epigenomics in human complex diseases. PMID:25568460

  19. Modeling genetic and environmental influences in the etiology of conduct disorder: a study of 2,682 adult twin pairs.

    PubMed

    Slutske, W S; Heath, A C; Dinwiddie, S H; Madden, P A; Bucholz, K K; Dunne, M P; Statham, D J; Martin, N G

    1997-05-01

    The etiology of conduct disorder (CD) was examined retrospectively in a sample of 2,682 male, female, and unlike-sex adult twin pairs from the community-based Australian Twin Register. Model-fitting analyses indicated a substantial genetic influence on risk for CD, accounting for 71% of the variance (95% confidence interval [CI] = 32-79%). There was not a statistically significant effect of the shared environment in the best-fitting model of CD, but a modest effect of the shared environment on the risk for CD could not be rejected (95% CI = 0-32%). The magnitude of genetic and environmental influences for CD liability did not vary significantly for boys and girls, and the specific genetic and environmental mechanisms important for the development of CD appeared to be largely the same for both sexes. The fit of a multiple-threshold model raises the possibility that CD may not necessarily be a discrete entity but rather an extreme of the normal variation in conduct-disordered behavior found in the general population. PMID:9131847

  20. The mediating effect of parental neglect on adolescent and young adult anti-sociality: a longitudinal study of twins and their parents.

    PubMed

    Eaves, Lindon J; Prom, Elizabeth C; Silberg, Judy L

    2010-07-01

    The causes of correlation between parental treatment and offspring behavior are ambiguous since genetic and social factors are correlated in typical family studies. The problem is complicated by the need to characterize the effects of genes and environment on both juvenile and adult behavioral outcomes. A model is developed for the resemblance between juvenile and adult twins and their parents that allows some of these effects to be resolved. Data on childhood adversity, parental anti-social behavior, and longitudinal adult and juvenile anti-social behavior were obtained from 1,412 families of adolescent and young adult twins. A structural model is fitted that allows for the effects of genetic and social transmission of information from parents to children. Environmental effects of parents may be mediated through measured features of the home environment. Parameters were estimated by diagonal weighted least squares applied to the 33 distinct polychoric correlations between relatives and between variables within and between ages. Sub-hypotheses were tested. Results confirmed that effects of genes and environment were both highly significant. Genetic effects were large in juveniles and largely age and sex-specific. Approximately 30% of the variation due to the shared environment was due to the effect of childhood adversity. The remaining shared environmental effects are unexplained. Adversity is affected significantly by maternal anti-social behavior. The correlation between paternal ASP and adversity may be explained by antisocial fathers selecting (or creating) antisocial mothers. All significant environmental effects of parental ASP are mediated through the measure of adversity. Though transmission of ASP is both genetic and social, passive genotype-environment correlation is very small. Assortative mating for ASP has barely detectable consequence for the genetic correlation between siblings. The longitudinal study of twins and their parents makes it possible to

  1. Coexisting Psychiatric Problems and Stressful Life Events in Adults with Symptoms of ADHD--A Large Swedish Population-Based Study of Twins

    ERIC Educational Resources Information Center

    Friedrichs, Bettina; Igl, Wilmar; Larsson, Henrik; Larsson, Jan-Olov

    2012-01-01

    Objective: To explore the associations of subtypes of adult ADHD with other psychiatric problems, stressful life events, and sex differences. Method: Odds ratios were calculated using information from 17,899 participants from a population-based survey of adult twins born in Sweden between 1959 and 1985. Results: Symptoms of attention deficit…

  2. 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.

    PubMed

    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. PMID:27121223

  3. Adolescent Alcohol Abuse and Adverse Adult Outcomes: Evaluating Confounds with Drinking-Discordant Twins

    PubMed Central

    Rose, Richard J.; Winter, Torsten; Viken, Richard J.; Kaprio, Jaakko

    2014-01-01

    Background Adolescent alcohol abuse is associated with adverse outcomes in early adulthood, but differences in familial status and structure and household and community environments correlate with both adolescent drinking and adverse adult outcomes and may explain their association. We studied drinking-discordant twin pairs to evaluate such confounds to ask: Will between-family associations replicate in within-family comparisons? Methods With longitudinal data from > 3,000 Finnish twins, we associated drinking problems at age 18½ with 13 outcomes assessed at age 25; included were sustained substance abuse, poor health, physical symptoms, early coital debut, multiple sexual partners, life dissatisfaction, truncated education, and financial problems. We assessed associations among twins as individuals with linear regression adjusted for correlated observations; within-family analyses of discordant twin pairs followed, comparing paired means for adult outcomes among co-twins discordant for adolescent problem drinking. Defining discordance by extreme scores on self-reported problem drinking at age 18½ permitted parallel analyses of twins as individuals and discordant twin pairs. Alternate definitions of pair-wise discordance and difference score correlations across the entire twin sample yielded supplementary analyses. Results All individual associations were highly significant for all definitions of discordance we employed. Depending on definitions of discordance, 11 to 13 comparisons of all drinking-discordant twin pairs and 3 to 6 comparisons of discordant monozygotic twin pairs replicated between-family associations. For most outcomes, effect size attenuated from individual level analysis to that within discordant MZ twin pairs providing evidence of partial confounding in associations reported in earlier research. The exception was the General Health Questionnaire; at age 25, GHQ-12 had equivalent associations with age 18½ RAPI across all comparisons

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

    PubMed Central

    Li, Shuxia; Kyvik, Kirsten Ohm; Pang, Zengchang; Zhang, Dongfeng; Duan, Haiping; Tan, Qihua; Hjelmborg, Jacob; Kruse, Torben; Dalgård, Christine

    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, cultural, social-economic backgrounds and geographical environments. Materials and Methods The study covered a relatively large sample of 502 pairs of Danish adult twins followed up for a long period of 12 years with a mean age at intake of 38 years (range: 18–65) and a total of 181 Chinese adult twin 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 for long-term change in most of the phenotypes in Danish twins except for triglycerides and hip circumference. Compared with Danish twins, the Chinese twins tended to have higher genetic control over the longitudinal changes in lipids (except high density lipoprotein cholesterol) and glucose, higher unique environmental contribution to blood pressure but no genetic contribution to longitudinal change in body mass traits. Conclusion Our results emphasize the major contribution of unique environment to the observed intra-individual variation in all metabolic phenotypes in both samples, and meanwhile reveal differential patterns of genetic and common environmental regulation on changes over time in metabolic phenotypes across the two samples. PMID:26862898

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

    PubMed

    Segal, Nancy L

    2016-04-01

    The lives of the illustrious monozygotic (MZ) twins, Victor A. and Vincent L. McKusick, are described. Victor earned the distinction as the 'Father of Medical Genetics', while Vincent was a legendary Chief Justice of the Maine Supreme Court. This dual biographical account is followed by two timely reports of twinning rates, a study of MZ twin discordance for Russell-Silver Syndrome (RSS) and a study of twins' language skills. Twin stories in the news include babies born to identical twin couples, a case of switched identity, the death of Princess Ashraf (Twin) and a new mother of twins who is also Yahoo's CEO. PMID:26934824

  6. Brief Report: Autistic Traits in Twins vs. Non-Twins--A Preliminary Study

    ERIC Educational Resources Information Center

    Ho, Alexander; Todd, Richard D.; Constantino, John N.

    2005-01-01

    Previous studies have suggested that among affected sib pairs with autism there is an increase in the frequency of twins over what would be expected in comparison to the prevalence of twins in the general population. In this study we sought to determine whether "sub-threshold" autistic traits were more pronounced in twins than in non-twins. The…

  7. Breastfeeding Twins: A Qualitative Study

    PubMed Central

    Alvur, Tuncay Muge; Kose, Dilek; Nemut, Tijen

    2013-01-01

    The purpose of this qualitative research was to explore the needs and difficulties of mothers who had multiple babies at Sakarya County by focusing on their breastfeeding experience. Ten mothers who gave birth to multiple infants participated in the study voluntarily. The framework method of data analysis was applied systematically both within and across cases, with categories and themes identified by reading transcripts of interviews. Major themes generated from focus narrative interviews are described. These themes are: willingness of mothers to breastfeed and continue, management of breastfeeding, use of pacifier, daily life, ınstructions of healthcare personnel, and advices from practice of experienced mothers. This study showed that women were aware of the importance of mother's milk for their babies. They all, somehow, made intensive efforts to breastfeed their twins. Women who expect and/or have multiple babies need much more support and guidance, which may include advice for nutritional and daily care. PMID:24592592

  8. [Hungarian twin studies: results of four decades].

    PubMed

    Tárnoki, Ádám Domonkos; Tárnoki, Dávid László; Horváth, Tamás; Métneki, Júlia; Littvay, Levente

    2013-10-01

    Twin studies play a role in examining the contribution of genetic variations and environmental factors responsible for the determination of phenotypic variables and of genetic linkage between genotypes. Hungarian twin studies, supported by three twin registries (among them two twin-database), date back to 1970s. Studies mainly focused on various congenital abnormalities, the effect of contraceptive pills and folic acid on the frequency of twin pregnancies, as well as psychosexual and alcohol consumptional behaviors. Monogenic Mendelian inheritance of lactose (mal)absorption was demonstrated for the first time. Hungarian Twin Registry was founded in 2007, which contributed to the current understanding on the background of several disorders, e.g. metabolic syndrome and atherosclerosis. As part of an international twin study, among others, arterial stiffness, central blood pressure, carotid intima/media thickness, venous biomechanics, body composition, lung function and smoking characteristics were also assessed. Absence of genetic background in non-alcoholic fatty liver disease and high inheritance of carotid plaque characteristics were demonstrated for the first time. The review also aims to summarize future plans of the Hungarian Twin Registry. PMID:24077161

  9. Brief report: autistic traits in twins vs. non-twins--a preliminary study.

    PubMed

    Ho, Alexander; Todd, Richard D; Constantino, John N

    2005-02-01

    Previous studies have suggested that among affected sib pairs with autism there is an increase in the frequency of twins over what would be expected in comparison to the prevalence of twins in the general population. In this study we sought to determine whether sub-threshold autistic traits were more pronounced in twins than in non-twins. The Social Responsiveness Scale (SRS) was administered in an epidemiologic twin sample (n=802) and in a separate population-based sample of non-twins ascertained from a local school district (n=255). For males (but not females), the mean SRS score was significantly higher among twins than among non-twins. As has been suggested for autism, twin status may incur increased liability to subthreshold autistic symptomatology, particularly in males. PMID:15796128

  10. Twin Studies: A Unique Epidemiological Tool

    PubMed Central

    Sahu, Monalisha; Prasuna, Josyula G

    2016-01-01

    Twin studies are a special type of epidemiological studies designed to measure the contribution of genetics as opposed to the environment, to a given trait. Despite the facts that the classical twin studies are still being guided by assumptions made back in the 1920s and that the inherent limitation lies in the study design itself, the results suggested by earlier twin studies have often been confirmed by molecular genetic studies later. Use of twin registries and various innovative yet complex software packages such as the (SAS) and their extensions (e.g., SAS PROC GENMOD and SAS PROC PHREG) has increased the potential of this epidemiological tool toward contributing significantly to the field of genetics and other life sciences. PMID:27385869

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

    PubMed Central

    Rushton, J. Philippe

    2004-01-01

    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. PMID:15615684

  12. Twins Eye Study in Tasmania (TEST): Rationale and Methodology to Recruit and Examine Twins

    PubMed Central

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

    2013-01-01

    Visual impairment is a leading cause for morbidity and poor quality of life in our community. Unravelling the mechanisms underpinning important blinding diseases could allow for preventative or curative steps to be implemented. Twin siblings provide a unique opportunity in biology to discover genes associated with numerous eye diseases and ocular biometry. Twins are particularly useful for quantitative trait analysis through genome-wide association and linkage studies. Although many studies involving twins rely on twin registries, we present our approach to the Twins Eye Study in Tasmania to provide insight into possible recruitment strategies, expected participation rates and potential examination strategies that can be considered by other researchers for similar studies. Five separate avenues for cohort recruitment were adopted: 1) piggy-backing existing studies where twins had been recruited; 2); utilising the national twin registry; 3) word of mouth and local media publicity; 4) directly approaching schools; and finally 5) collaborating with other research groups studying twins. PMID:19803772

  13. Determination of Zygosity in Adult Chinese Twins Using the 450K Methylation Array versus Questionnaire Data.

    PubMed

    Wang, Biqi; Gao, Wenjing; Yu, Canqing; Cao, Weihua; Lv, Jun; Wang, Shengfeng; Pang, Zengchang; Cong, Liming; Wang, Hua; Wu, Xianping; Li, Liming

    2015-01-01

    Previous studies have shown that both single nucleotide polymorphisms (SNPs) and questionnaires-based method can be used for twin zygosity determination, but few validation studies have been conducted using Chinese populations. In the current study, we recruited 192 same sex Chinese adult twin pairs to evaluate the validity of using genetic markers-based method and questionnaire-based method in zygosity determination. We considered the relatedness analysis based on more than 0.6 million SNPs genotyping as the golden standards for zygosity determination. After quality control, qualified twins were left for relatedness analysis based on identical by descent calculation. Then those same sex twin pairs were included in the zygosity questionnaire validation analysis. Logistic regression model was applied to assess the discriminant ability of age, sex and the three questions in zygosity determination. Leave one out cross-validation was used as a measurement of internal validation. The results of zygosity determination based on 65 SNPs in 450k methylation array were all consistent with genotyping. Age, gender, questions of appearance confused by strangers and previously perceived zygosity consisted of the most predictable model with a consistency rate of 0.8698, cross validation predictive error of 0.1347. For twin studies with genotyping and\\or 450k methylation array, there would be no need to conduct other zygosity testing for the sake of costs consideration. PMID:25927701

  14. Determination of Zygosity in Adult Chinese Twins Using the 450K Methylation Array versus Questionnaire Data

    PubMed Central

    Wang, Biqi; Gao, Wenjing; Yu, Canqing; Cao, Weihua; Lv, Jun; Wang, Shengfeng; Pang, Zengchang; Cong, Liming; Wang, Hua; Wu, Xianping; Li, Liming

    2015-01-01

    Previous studies have shown that both single nucleotide polymorphisms (SNPs) and questionnaires-based method can be used for twin zygosity determination, but few validation studies have been conducted using Chinese populations. In the current study, we recruited 192 same sex Chinese adult twin pairs to evaluate the validity of using genetic markers-based method and questionnaire-based method in zygosity determination. We considered the relatedness analysis based on more than 0.6 million SNPs genotyping as the golden standards for zygosity determination. After quality control, qualified twins were left for relatedness analysis based on identical by descent calculation. Then those same sex twin pairs were included in the zygosity questionnaire validation analysis. Logistic regression model was applied to assess the discriminant ability of age, sex and the three questions in zygosity determination. Leave one out cross-validation was used as a measurement of internal validation. The results of zygosity determination based on 65 SNPs in 450k methylation array were all consistent with genotyping. Age, gender, questions of appearance confused by strangers and previously perceived zygosity consisted of the most predictable model with a consistency rate of 0.8698, cross validation predictive error of 0.1347. For twin studies with genotyping and\\or 450k methylation array, there would be no need to conduct other zygosity testing for the sake of costs consideration. PMID:25927701

  15. Colorado longitudinal twin study of reading disability.

    PubMed

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

    2007-12-01

    The primary objectives of the present study are to introduce the Colorado Longitudinal Twin Study of Reading Disability, the first longitudinal twin study in which subjects have been specifically selected for having a history of reading difficulties, and to present some initial assessments of the stability of reading performance and cognitive abilities in this sample. Preliminary examination of the test scores of 124 twins with a history of reading difficulties and 154 twins with no history of reading difficulties indicates that over the 5- to 6-year interval between assessments, cognitive and reading performance are highly stable. As a group, those subjects with a history of reading difficulties had substantial deficits relative to control subjects on all measures at initial assessment, and significant deficits remained at follow-up. The stability noted for all cognitive and achievement measures was highest for a composite measure of reading, whose average stability correlation across groups was 0.80. Results of preliminary behavior genetic analyses for this measure indicated that shared genetic influences accounted for 86% and 49% of the phenotypic correlations between the two assessments for twin pairs with and without reading difficulties, respectively. In addition, genetic correlations reached unity for both groups, suggesting that the same genetic influences are manifested at both time points. PMID:18060583

  16. One CNV Discordance in NRXN1 Observed Upon Genome-wide Screening in 38 Pairs of Adult Healthy Monozygotic Twins.

    PubMed

    Magnusson, Patrik K E; Lee, Donghwan; Chen, Xu; Szatkiewicz, Jin; Pramana, Setia; Teo, Shumei; Sullivan, Patrick F; Feuk, Lars; Pawitan, Yudi

    2016-04-01

    Monozygotic (MZ) twins stem from the same single fertilized egg and therefore share all their inherited genetic variation. This is one of the unequivocal facts on which genetic epidemiology and twin studies are based. To what extent this also implies that MZ twins share genotypes in adult tissues is not precisely established, but a common pragmatic assumption is that MZ twins are 100% genetically identical also in adult tissues. During the past decade, this view has been challenged by several reports, with observations of differences in post-zygotic copy number variations (CNVs) between members of the same MZ pair. In this study, we performed a systematic search for differences of CNVs within 38 adult MZ pairs who had been misclassified as dizygotic (DZ) twins by questionnaire-based assessment. Initial scoring by PennCNV suggested a total of 967 CNV discordances. The within-pair correlation in number of CNVs detected was strongly dependent on confidence score filtering and reached a plateau of r = 0.8 when restricting to CNVs detected with confidence score larger than 50. The top-ranked discordances were subsequently selected for validation by quantitative polymerase chain reaction (qPCR), from which one single ~120kb deletion in NRXN1 on chromosome 2 (bp 51017111-51136802) was validated. Despite involving an exon, no sign of cognitive/mental consequences was apparent in the affected twin pair, potentially reflecting limited or lack of expression of the transcripts containing this exon in nerve/brain. PMID:26899349

  17. Antenatal genetic studies in twin pregnancies.

    PubMed

    Redwine, F O; Cruikshank, D P; Brown, J

    1984-01-01

    The diagnosis of multiple gestation at the time of genetic amniocentesis is a routine occurrence. In a combined series of 2765 patients referred for antenatal genetic studies from the Medical College of Virginia and the University of Iowa, 34 twin pregnancies were encountered (1.2%). Twenty-six of the patients with twins were referred for advanced maternal age. The other indications were previous neural tube defects (1), previous trisomy 21 (2), known carriers of Tay Sachs disease (2), previous Turner's syndrome (1), family history of trisomy 21 (1), and one pregnancy was referred because of an abnormal ultrasound. Amniocentesis procedures, outcome of the twin pregnancies, and genetic counseling issues, are discussed. PMID:6741416

  18. A Pediatric Twin Study of Brain Morphometry

    ERIC Educational Resources Information Center

    Wallace, Gregory L.; Schmitt, J. Eric; Lenroot, Rhoshel; Viding, Essi; Ordaz, Sarah; Rosenthal, Michael A.; Molloy, Elizabeth A.; Clasen, Liv S.; Kendler, Kenneth S.; Neale, Michael C.; Giedd, Jay N.

    2006-01-01

    Background: Longitudinal pediatric neuroimaging studies have demonstrated increasing volumes of white matter and regionally-specific inverted U shaped developmental trajectories of gray matter volumes during childhood and adolescence. Studies of monozygotic and dyzygotic twins during this developmental period allow exploration of genetic and…

  19. Gleanings from Identical Twins Studying Science.

    ERIC Educational Resources Information Center

    Mascazine, John R.

    This paper explains and summarizes the results of a study that investigated the ways in which monozygotic (identical) and dizygotic (fraternal) twins learn. Their individual learning style elements were specifically investigated according to the Dunn and Dunn model. This paper discusses the themes, unique needs, and characteristics monozygotic…

  20. Preadolescent development: case studies in twins.

    PubMed Central

    Frank, R. A.; Cohen, D. J.

    1980-01-01

    The authors studied eight sets of healthy twins, ranging in physical maturity from prepubertal to late pubertal, and their parents, to assess psychological changes in early adolescence. A phase-specific psychosocial regression correlates with the biological onset of puberty. We present preliminary findings related to twinship, parental reactions, and longitudinal development, based on detailed case studies. Parents experienced increased conflict, detachment, and pride in response to their twins' psychosocial development at puberty. The more advanced child in a pair tended to lead in all spheres of adjustment-school success, heterosexual interest, peer friendships, and independent behavior. Although the more advanced child began to break away from his twin, in general the twin relationships remained close. Differences in personality traits and rate of psychosocial development within a twinship tended to remain consistent or to become accentuated. They were occasionally narrowed but rarely reversed from early childhood through early adolescence. Some of the differences were fostered by dissimilar patterns of identifying with the parents. PMID:7195631

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

    ERIC Educational Resources Information Center

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

    2013-01-01

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

  2. Size at birth and adult fat mass in twin sheep are determined in early gestation

    PubMed Central

    Hancock, S N; Oliver, M H; McLean, C; Jaquiery, A L; Bloomfield, F H

    2012-01-01

    Size at birth is related to adult health outcomes. Twins are born smaller than singletons; this has been assumed to be secondary to limited nutrient supply in late gestation. We hypothesised that growth trajectory in twins, and the adult consequences of being conceived a twin, are determined in early gestation. Twin pregnancies in sheep were randomised to reduction of one twin on day 42 of a 148 day pregnancy by intra-thoracic KCl (Reductions, n = 46) or a sham procedure (Twins, n = 22). Singleton-bearing ewes also underwent a sham procedure (n = 27). Ewes lambed spontaneously. Linear measures of size at birth were similar in Twins and Reductions, and significantly less than in Singletons. Birthweight was lower in Twins and Reductions than in Singletons, and less in Twins than in Reductions (means (SEM): Singletons, liveborn n = 23: 6.59 (0.17) kg; Twins, liveborn n = 36: 5.23 (0.16) kg; Reductions, liveborn n = 27: 5.76 (0.15) kg; all comparisons P < 0.05). Reductions grew most rapidly between birth and weaning (Singletons, 20.0 (0.4) g kg−1 day−1; Twins, 20.0 (0.3) g kg−1 day−1; Reductions, 21.0 (0.3) g kg−1 day−1, P < 0.05) and were of similar weight as Singletons by weaning; Twins remained smaller by weaning but grew most rapidly thereafter (Singletons, 1.6 (0.1) g kg−1 day−1; Twins, 2.1 (0.1) g kg−1 day−1; Reductions, 1.6 (0.1) g kg−1 day−1, P < 0.01), so that all groups had similar weight at 2 years. However, Twins and Reductions had greater percentage fat mass than Singletons at 2 years (Singletons, 11.1 (1.1)%; Twins, 14.8 (1.2)%; Reductions, 15.5 (1.1)%, P < 0.05). Thus, in twins, fetal growth trajectory, linear size at birth and adult fat mass are largely determined in early gestation. If this is also true in humans, there are important implications for interventions aimed at optimising fetal growth and pregnancy outcome. PMID:22183720

  3. HEREDITARY FACTORS IN NORMAL PERSONALITY TRAITS (AS MEASURED BY INVENTORIES). LOUISVILLE TWIN STUDY, RESEARCH REPORT NUMBER 19.

    ERIC Educational Resources Information Center

    VANDENBERG, STEVEN G.

    RESEARCH ON HEREDITARY FACTORS IN NORMAL PERSONALITY TRAITS, AS MEASURED BY INVENTORIES, HAS BEEN LIMITED BY THE FOLLOWING FACTORS--(1) DATA DRAWN FROM ADOLESCENT, NOT ADULT, TWINS, (2) OMISSION OF MENTALLY ILL TWINS, (3) SMALL SIZE OF SAMPLES, (4) VARIABILITY STUDIED ONLY WITHIN FAMILY, (5) SMALL, ISOLATED, UNCOORDINATED STUDIES, AND (6) PROBLEMS…

  4. Genetic and Environmental Influences on Two Measures of Speed of Information Processing and Their Relation to Psychometric Intelligence: Evidence from the German Observational Study of Adult Twins.

    ERIC Educational Resources Information Center

    Neubauer, Alioscha C.; Spinath, Frank M.; Riemann, Rainer; Angleitner, Alois; Borkenau, Peter

    2000-01-01

    Administered 2 elementary cognitive task (ECT) tests and 2 psychometric intelligence tests to 169 monozygotic and 131 dizygotic pairs of twins in Germany. Reaction times correlated negatively with psychometric intelligence, and habitability estimates were substantial for both psychometric intelligence and reaction times on the ECTs. Multivariate…

  5. Spectroscopic study of solar twins and analogues

    NASA Astrophysics Data System (ADS)

    Datson, Juliet; Flynn, Chris; Portinari, Laura

    2015-02-01

    Context. Many large stellar surveys have been and are still being carried out, providing huge amounts of data, for which stellar physical parameters will be derived. Solar twins and analogues provide a means to test the calibration of these stellar catalogues because the Sun is the best-studied star and provides precise fundamental parameters. Solar twins should be centred on the solar values. Aims: This spectroscopic study of solar analogues selected from the Geneva-Copenhagen Survey (GCS) at a resolution of 48 000 provides effective temperatures and metallicities for these stars. We test whether our spectroscopic parameters, as well as the previous photometric calibrations, are properly centred on the Sun. In addition, we search for more solar twins in our sample. Methods: The methods used in this work are based on literature methods for solar twin searches and on methods we developed in previous work to distinguish the metallicity-temperature degeneracies in the differential comparison of spectra of solar analogues versus a reference solar reflection spectrum. Results: We derive spectroscopic parameters for 148 solar analogues (about 70 are new entries to the literature) and verify with a-posteriori differential tests that our values are well-centred on the solar values. We use our dataset to assess the two alternative calibrations of the GCS parameters; our methods favour the latest revision. We show that the choice of spectral line list or the choice of asteroid or time of observation does not affect the results. We also identify seven solar twins in our sample, three of which are published here for the first time. Conclusions: Our methods provide an independent means to differentially test the calibration of stellar catalogues around the values of a well-known benchmark star, which makes our work interesting for calibration tests of upcoming Galactic surveys. Based on observations made with ESO Telescopes at the La Silla Observatory under programme ID 077.D

  6. The Adult Netherlands Twin Register: twenty-five years of survey and biological data collection.

    PubMed

    Willemsen, Gonneke; Vink, Jacqueline M; Abdellaoui, Abdel; den Braber, Anouk; van Beek, Jenny H D A; Draisma, Harmen H M; van Dongen, Jenny; van 't Ent, Dennis; Geels, Lot M; van Lien, Rene; Ligthart, Lannie; Kattenberg, Mathijs; Mbarek, Hamdi; de Moor, Marleen H M; Neijts, Melanie; Pool, Rene; Stroo, Natascha; Kluft, Cornelis; Suchiman, H Eka D; Slagboom, P Eline; de Geus, Eco J C; Boomsma, Dorret I

    2013-02-01

    Over the past 25 years, the Adult Netherlands Twin Register (ANTR) has collected a wealth of information on physical and mental health, lifestyle, and personality in adolescents and adults. This article provides an overview of the sources of information available, the main research findings, and an outlook for the future. Between 1991 and 2012, longitudinal surveys were completed by twins, their parents, siblings, spouses, and offspring. Data are available for 33,957 participants, with most individuals having completed two or more surveys. Smaller projects provided in-depth phenotyping, including measurements of the autonomic nervous system, neurocognitive function, and brain imaging. For 46% of the ANTR participants, DNA samples are available and whole genome scans have been obtained in more than 11,000 individuals. These data have resulted in numerous studies on heritability, gene x environment interactions, and causality, as well as gene finding studies. In the future, these studies will continue with collection of additional phenotypes, such as metabolomic and telomere length data, and detailed genetic information provided by DNA and RNA sequencing. Record linkage to national registers will allow the study of morbidity and mortality, thus providing insight into the development of health, lifestyle, and behavior across the lifespan. PMID:23298648

  7. The Adult Netherlands Twin Register: Twenty-Five Years of Survey and Biological Data Collection

    PubMed Central

    Willemsen, Gonneke; Vink, Jacqueline M.; Abdellaoui, Abdel; den Braber, Anouk; van Beek, Jenny H. D. A.; Draisma, Harmen H. M.; van Dongen, Jenny; van ‘t Ent, Dennis; Geels, Lot M.; van Lien, Rene; Ligthart, Lannie; Kattenberg, Mathijs; Mbarek, Hamdi; de Moor, Marleen H. M.; Neijts, Melanie; Pool, Rene; Stroo, Natascha; Kluft, Cornelis; Suchiman, H. Eka D.; Slagboom, P. Eline; de Geus, Eco J. C.; Boomsma, Dorret I.

    2013-01-01

    Over the past 25 years, the Adult Netherlands Twin Register (ANTR) has collected a wealth of information on physical and mental health, lifestyle, and personality in adolescents and adults. This article provides an overview of the sources of information available, the main research findings, and an outlook for the future. Between 1991 and 2012, longitudinal surveys were completed by twins, their parents, siblings, spouses, and offspring. Data are available for 33,957 participants, with most individuals having completed two or more surveys. Smaller projects provided in-depth phenotyping, including measurements of the autonomic nervous system, neurocognitive function, and brain imaging. For 46% of the ANTR participants, DNA samples are available and whole genome scans have been obtained in more than 11,000 individuals. These data have resulted in numerous studies on heritability, gene × environment interactions, and causality, as well as gene finding studies. In the future, these studies will continue with collection of additional phenotypes, such as metabolomic and telomere length data, and detailed genetic information provided by DNA and RNA sequencing. Record linkage to national registers will allow the study of morbidity and mortality, thus providing insight into the development of health, lifestyle, and behavior across the lifespan. PMID:23298648

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

    PubMed

    Deryakulu, Deniz; Calışkan, Erkan

    2012-04-01

    The present study investigated computer anxiety within a sample of Turkish twins aged 10-18. A total of 185 twin-pairs participated in the study. Of the twins, 64 pairs (34.6 percent) were monozygotic (MZ) and 121 pairs (65.4 percent) were dizygotic (DZ). Of the 121 DZ twins, 54 pairs (44.63 percent) were same-sex twins and 67 pairs (55.37 percent) were opposite-sex twins. Computer anxiety was assessed using Computer Anxiety Rating Scale-Turkish Version (CARS-TV), one of the three main scales of "Measuring Technophobia Instruments" developed by Rosen and Weil. The results of paired t test comparisons showed no significant differences in MZ and same-sex DZ twin-pairs' levels of computer anxiety. On the other hand, a significant difference was found in opposite-sex DZ twin-pairs' level of computer anxiety. Interesting enough, males appeared to be more computer anxious than their female co-twins. In the present study, using Falconer's formula, heritability estimate for computer anxiety was derived from correlations based on MZ and DZ twins' mean scores on CARS-TV. The results showed that 57 percent of the variance in computer anxiety was from genetics and 41.5 percent was from nonshared environmental factors. Shared environmental influence, on the other hand, was very small and negligible. Interpretations of results and potential directions for future research are presented. PMID:22394420

  9. 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.

    PubMed

    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. PMID:25662422

  10. Cross-sectional schooling-health associations misrepresented causal schooling effects on adult health and health-related behaviors: evidence from the Chinese Adults Twins Survey.

    PubMed

    Behrman, Jere R; Xiong, Yanyan; Zhang, Junsen

    2015-02-01

    Adult health outcomes and health behaviors are often associated with schooling. However, such associations do not necessarily imply that schooling has causal effects on health with the signs or magnitudes found in the cross-sectional associations. Schooling may be proxying for unobserved factors related to genetics and family background that directly affect both health and schooling. Recently several studies have used within-monozygotic (MZ) twins methods to control for unobserved factors shared by identical twins. Within-MZ estimates for developed countries are generally smaller than suggested by cross-sectional associations, consistent with positive correlations between unobserved factors that determine schooling and those that determine health. This study contributes new estimates of cross-sectional associations and within-MZ causal effects using the Chinese Adults Twins Survey, the first study of its type for developing countries. The cross-sectional estimates suggest that schooling is significantly associated with adult health-related behaviors (smoking, drinking, exercising) but not with own or spouse health outcomes (general health, mental health, overweight, chronic diseases). However, within-MZ-twins estimators change the estimates for approximately half of these health indicators, in one case declining in absolute magnitudes and becoming insignificant and in the other cases increasing in absolute magnitudes. Within-MZ estimates indicate significant pro-health effects for at least one of the indicators for own health (better mental health), own health-related behaviors (less smoking) and spouse health (less overweight). PMID:25464872

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

    PubMed Central

    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

  12. Cognitive deficits and magnetic resonance spectroscopy in adult monozygotic twins with lead poisoning.

    PubMed Central

    Weisskopf, Marc G; Hu, Howard; Mulkern, Robert V; White, Roberta; Aro, Antonio; Oliveira, Steve; Wright, Robert O

    2004-01-01

    Seventy-one-year-old identical twin brothers with chronic lead poisoning were identified from an occupational medicine clinic roster. Both were retired painters, but one brother (J.G.) primarily removed paint and had a history of higher chronic lead exposure. Patella and tibia bone lead concentrations measured by K-X-ray fluorescence in each brother were 5-10 times those of the general population and about 2.5 times higher in J.G. than in his brother (E.G.). Magnetic resonance spectroscopy (MRS) studies examined N-acetylaspartate:creatine ratios, a marker of neuronal density. Ratios were lower in J.G. than in his brother. Scores on neurocognitive tests that assess working memory/executive function were below expectation in both twins. Short-term memory function was dramatically worse in J.G. than in his brother. These results demonstrate some of the more subtle long-term neurologic effects of chronic lead poisoning in adults. In particular, they suggest the presence of frontal lobe dysfunction in both twins, but more dramatic hippocampal dysfunction in the brother with higher lead exposure. The MRS findings are consistent with the hypothesis that chronic lead exposure caused neuronal loss, which may contribute to the impairment in cognitive function. Although a causal relation cannot be inferred, the brothers were genetically identical, with similar life experiences. Although these results are promising, further study is necessary to determine whether MRS findings correlate both with markers of lead exposure and tests of cognitive function. Nevertheless, the results point to the potential utility of MRS in determining mechanisms of neurotoxicity not only for lead but also for other neurotoxicants as well. PMID:15064171

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

    NASA Astrophysics Data System (ADS)

    Lira, Adiyani; Sung, Joohon

    2015-12-01

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

  14. Suicidal Ideation, Depression, and Conduct Disorder in a Sample of Adolescent and Young Adult Twins

    ERIC Educational Resources Information Center

    Linker, Julie; Gillespie, Nathan A.; Maes, Hermine; Eaves, Lindon; Silberg, Judy L.

    2012-01-01

    The co-occurrence of suicidal ideation, depression, and conduct disturbance is likely explained in part by correlated genetic and environmental risk factors. Little is known about the specific nature of these associations. Structured interviews on 2,814 twins from the Virginia Twin Study of Adolescent Behavioral Development (VTSABD) and Young…

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

    PubMed

    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. PMID:22506305

  16. Further possible physiological connectedness between identical twins: the London study.

    PubMed

    Parker, Adrian; Jensen, Christian

    2013-01-01

    Four pairs of monozygotic twins were tested for synchronous responses that occurred in the physiological data of one twin during the period when the other twin was exposed to shock and surprise stimuli. Each of the five stimuli was presented in random order, producing five blocks of trial periods within each 25-minute session per twin. There were eight possible trial periods within each block. The choice of the trial periods, that is, the exact time placement of the shock stimuli within the blocks, was determined randomly. Data from six sessions with the four pairs of twins were used by the same polygraph expert who was successful in a previous study in identifying these trial periods. In accordance with the previously determined protocol for the experiment, six of these trials were passed on, leaving 24 trial blocks for which assessments were made as to which period the stimulus had occurred. Six of these gave hits, whereas three hits were expected by chance and four of these six correct placements were made by one of the pairs of twins. The data provide further justification for a major study in this area using the outlined methodology with selected pairs of twins. PMID:23294817

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

    PubMed Central

    2014-01-01

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

  18. NASA HRP Twins Research Study with Craig Kundrot

    NASA Video Gallery

    On March 7, NASA announced the selection of 10 investigations for the study of identical twin astronauts Scott and Mark Kelly and, in doing so, launched human space life science research into a new...

  19. Trauma Exposure and Axis I Psychopathology: A Co-twin Control Analysis in Norwegian Young Adults

    PubMed Central

    Brown, Ruth C.; Berenz, Erin C.; Aggen, Steven H.; Gardner, Charles O.; Knudsen, Gun Peggy; Reichborn-Kjennerud, Ted; Kendler, Kenneth S.; Amstadter, Ananda B.

    2014-01-01

    Broad associations between trauma exposure (TE) and Axis I psychopathology have been noted in the literature. However, it is not clear if TE is directly associated with Axis I disorders or if the relationship is better accounted for by familial factors (i.e., early environment and/or genetic factors). The current investigation used the co-twin control method in a large sample of adult twin pairs from the Norwegian Twin Registry (N = 2,776), including 449 twin pairs discordant for DSM-IV Criterion A TE. History of TE and Axis I psychopathology was assessed using DSM-IV based clinical interview. Results suggested that TE was significantly associated with greater likelihood of meeting criteria for major depression, dysthymia, anxiety, substance abuse, eating disorders, and somatization disorder in the general population (odds ratios [OR] ranging from 1.33 to 2.21). Among twins discordant for TE, results suggested that TE may exert a direct influence on major depression, dysthymia, anxiety, substance abuse, eating disorders, and somatization disorder. Shared familial effects may also account for at least some of the relationship between TE and major depression. TE may play an important role in the development of a wide range of Axis I psychopathology above and beyond familial factors. Research and clinical implications are discussed. PMID:25544868

  20. A Twin Study of Mathematics Disability.

    ERIC Educational Resources Information Center

    Alarcon, Marciela; DeFries, John C.; Light, Jacquelyn Gillis; Pennington, Bruce F.

    1997-01-01

    Comparison of twins (40 identical and 23 fraternal) for mathematics deficits (MD), in which at least one member had a mathematics disability, found evidence for a significant genetic etiology. However, tests for the differential etiology of MD as a function of reading performance level were nonsignificant. (Author/DB)

  1. Adult monozygotic twins discordant for intra-uterine growth have indistinguishable genome-wide DNA methylation profiles

    PubMed Central

    2013-01-01

    Background Low birth weight is associated with an increased adult metabolic disease risk. It is widely discussed that poor intra-uterine conditions could induce long-lasting epigenetic modifications, leading to systemic changes in regulation of metabolic genes. To address this, we acquire genome-wide DNA methylation profiles from saliva DNA in a unique cohort of 17 monozygotic monochorionic female twins very discordant for birth weight. We examine if adverse prenatal growth conditions experienced by the smaller co-twins lead to long-lasting DNA methylation changes. Results Overall, co-twins show very similar genome-wide DNA methylation profiles. Since observed differences are almost exclusively caused by variable cellular composition, an original marker-based adjustment strategy was developed to eliminate such variation at affected CpGs. Among adjusted and unchanged CpGs 3,153 are differentially methylated between the heavy and light co-twins at nominal significance, of which 45 show sensible absolute mean β-value differences. Deep bisulfite sequencing of eight such loci reveals that differences remain in the range of technical variation, arguing against a reproducible biological effect. Analysis of methylation in repetitive elements using methylation-dependent primer extension assays also indicates no significant intra-pair differences. Conclusions Severe intra-uterine growth differences observed within these monozygotic twins are not associated with long-lasting DNA methylation differences in cells composing saliva, detectable with up-to-date technologies. Additionally, our results indicate that uneven cell type composition can lead to spurious results and should be addressed in epigenomic studies. PMID:23706164

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

    PubMed

    Orey, Byron D'Andra; Park, Hyung

    2012-02-01

    The preponderance of research on the study of ethnocentrism has primarily attributed such attitudes to learned behavior. The research here advances the argument that both socialization and genetic inheritance contribute to the development of ethnocentric attitudes and behavior. This analysis employs the Minnesota Twins Political Survey data consisting of 596 complete twin pairs. Using the classical twin design, we employed structural equation modeling to model the covariance of twins in regards to additive genetic effects, shared environmental effects, and unique environmental effects (i.e., the classic ACE model). The findings reveal that genetic inheritance is significant in explaining the variance in genetic attitudes. Specifically, genetic inheritance explains 18% of the variance, with the overwhelming 82% being explained by the unique environment. PMID:22784455

  3. Twin classics: research that always inspires/Twin studies: elder twin relationships; Superfecundated twinning in chimpanzees; Conjoined twinning and embryo transfer; Reduced frequency of in vitro multiples/Professional and human interest: first identical twin renal transplant; Identical triplet wedding; Spanakos twins: boxers; Twins in space; Political twins.

    PubMed

    Segal, Nancy L

    2015-08-01

    Ten classic works in twin research are described. These volumes are rich in data, interpretation, and impact, and contain life history material that adds depth and dimension to the quantitative findings. Next, research on social relationships in older twins, superfecundated twinning in chimpanzees; effects of embryo transfer on conjoined twinning and the reduced frequency of in vitro multiples is reviewed. Finally, there has been considerable public interest surrounding the first identical twin renal transplant, an identical triplet wedding; identical twin boxers, a twin living in space, and a politically active twin pair. PMID:26148718

  4. A twin-case study of developmental number sense impairment.

    PubMed

    Davidse, Neeltje J; de Jong, Maria T; Shaul, Shelley; Bus, Adriana G

    2014-01-01

    The current study reports on 9-year-old monozygotic twin girls who fail to make any progress in learning basic mathematics in primary education. We tested the hypothesis that the twins' core maths problems were deficits in number sense that manifested as impairments in approximate and small number systems, resulting in impairment in nonsymbolic as well as in symbolic processing. While age-matched controls (eight typically developing girls) scored highly, the twins scored at chance on all number sense tasks. More specifically, on a nonsymbolic comparison task, even in the simplest ratio condition of 1:2, and on a subitizing task including only numbers under 4, the twins performed at chance and significantly below the same age control group. Responsiveness to an intervention promoting number sense is discussed. As differences between verbal and performance IQ suggest, there seems to be a high degree of specificity in the twins' developmental number sense delays. The concomitant impairments for visual-spatial processing and working memory in the twins might explain the failure to develop number sense. PMID:24479698

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

    ERIC Educational Resources Information Center

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

    2013-01-01

    This study assessed the genetic and environmental contributions to peer difficulties in the early school years. Twins' peer difficulties were assessed longitudinally in kindergarten (796 twins, "M"[subscript age] = 6.1 years), Grade 1 (948 twins, "M"[subscript age] = 7.1 years), and Grade 4 (868 twins, "M"[subscript age] = 10 years) through…

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  7. A twin study on age-related macular degeneration.

    PubMed Central

    Meyers, S M

    1994-01-01

    A prospective twin study on age-related macular degeneration (AMD) recruited 83 monozygotic pairs, 28 dizygotic pairs, and one triplet set from 1986 through 1993. Zygosity was determined by genetic testing of red cell markers, HLA antigens, or specific DNA loci. There were no twin pairs in which I collected data on only one twin. To decrease ascertainment bias, after 1991 the recruitment notice did not mention AMD, and I did not ask about a history of eye disease before the eye examination. Because of this, twin pairs recruited from 1986 through 1991 were statistically analyzed separately from those after January 1, 1992. From 1986 through 1991, 23 twin pairs were recruited; 11 monozygotic and 2 dizygotic pairs had nonAMD retinal changes or no retinal abnormalities, 9 monozygotic pairs with AMD were all concordant, and 1 dizygotic pair was discordant for basal laminar drusen. The concordance rate of AMD did not differ significantly between monozygotic and dizygotic twin pairs (P = .10) for 1986 through 1991. In 1992 and 1993, 88 twin pairs and one triplet set were recruited; 49 monozygotic and 19 dizygotic pairs had nonAMD retinal changes or no retinal abnormalities, 14 monozygotic pairs with AMD were all concordant, and 2 of 7 dizygotic pairs were concordant for AMD. The nonidentical triplets (1 with and 2 without AMD) were categorized as one of the discordant dizygotic pairs in the statistical evaluation. In nontwin age-matched (within 2 or 5 years of age) or age- and sex-matched sibling pairs the concordance rate of AMD ranged from 16% to 25%. The concordance rate of AMD was significantly higher in monozygotic than in dizygotic twins (P = .001) for 1992 and 1993. The concordance rate was higher for monozygotic twin pairs recruited in 1992 and 1993 than in any of the four subsets of nontwin age-method or age- and sex-matched sibling pairs (P < .0001). Overall, from 1986 through 1993, 23 of 23 monozygotic and 2 of 8 dizygotic twin pairs were concordant for AMD

  8. PennTwins: A Population-Based Cohort for Twin Studies

    PubMed Central

    Coccaro, Emil F.; Jacobson, Kristen C.

    2014-01-01

    The current article describes the creation and composition of the PennTwins Cohort and provides details on the demographic characteristics of the sample. The PennTwins Cohort was developed using a population-based method of ascertainment and currently has 9401 28- to 47-year-old twins, including 2225 confirmed twin pairs and 4951 twins whose co-twins have not yet registered. Zygosity data have been used to identify 919 monozygotic, 634 same-sex dizygotic, and 445 opposite-sex dizygotic pairs. GeoCode data on gender, age, and certain demographic characteristics were obtained for the addresses of all twins who were mailed invitations to be part of the cohort. Analysis of the available data show only very small differences between twins who are currently part of the PennTwins Cohort and potential twins who either did not respond to recruitment or who could not be located. Similarly, only very small demographic differences exist between twins from complete pairs and twins whose co-twins are not yet registered, and there are no differences across zygosity. Thus, despite a relatively low overall response rate (12% of all twins born in Pennsylvania from 1959–1978), there is no evidence that the sample differs in any meaningful respect from the larger population. PMID:17254443

  9. Centenary Celebration for Scottish Missionary Mary Slessor: A Lasting Legacy for Twins/Twin Research: Twins With Kleinfelter's Syndrome; Twin Research on Atopic Diseases; Twin Study of Autism; Psychotherapy with Twins / General Interest: Female Twin Pole-Vaulters; Longest Twin Birth Interval; Pair of Franco-Cuban Vocalists; Croatian Twin Models.

    PubMed

    Segal, Nancy L

    2015-06-01

    The centenary celebration for Scottish missionary, Mary Slessor, took place on February 14, 2015 in Melle, Belgium. Slessor saved many newborn twins and their mothers from death and disownment by members of their community, including their families, who believed twins harbored evil spirits. The events of this unusual and significant gathering are described. Next, twin research and reports concerning Kleinfelter's disease, atopic diseases, autism and psychotherapy are presented. General interest subjects include identical female twin pole-vaulters, the longest twin birth interval, Franco-Cuban twin vocalists, and Croatian twin models. PMID:25906830

  10. Genetic and Environmental Influences on Traits of Gender Identity Disorder: A Study of Japanese Twins Across Developmental Stages.

    PubMed

    Sasaki, Shoko; Ozaki, Koken; Yamagata, Shinji; Takahashi, Yusuke; Shikishima, Chizuru; Kornacki, Tamara; Nonaka, Koichi; Ando, Juko

    2016-10-01

    The present study examined: (1) gender and age differences of mean gender identity disorder (GID) trait scores in Japanese twins; (2) the validity of the prenatal hormone transfer theory, which predicts that, in dizygotic (DZ) twin pairs, twins with an opposite-gender co-twin more frequently exhibit GID traits than twins with a same-gender co-twin; and (3) the magnitude of genetic and environmental influences on GID traits as a function of age and gender. Data from 1450 male twin pairs, 1882 female twin pairs, and 1022 DZ male-female pairs ranging from 3 to 26 years of age were analyzed. To quantify individual variances in GID traits, each participant completed four questionnaire items based on criteria for GID from the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR). Our most important findings were: (1) Japanese females exhibited GID traits more frequently than males and Japanese children exhibited GID traits less frequently than adolescents and adults (among females, the prevalence was 1.6 % in children, 10 % in adolescents, and 12 % in adults; among males, the prevalence was 0.5, 2, and 3 %, respectively); (2) the data did not support the prenatal hormone transfer theory for GID traits; and (3) a large part of the variance for GID traits in children was accounted for by familial factors; however, the magnitude was found to be greater in children than in adolescents or adults, particularly among females. This study suggests that although the prevalence is likely to increase, familial effects are likely to decrease as individuals age. PMID:27507021

  11. A Comparison of Anthropometric, Metabolic, and Reproductive Characteristics of Young Adult Women from Opposite-Sex and Same-Sex Twin Pairs

    PubMed Central

    Korsoff, Pirkko; Bogl, Leonie H.; Korhonen, Päivi; Kangas, Antti J.; Soininen, Pasi; Ala-Korpela, Mika; Rose, Richard J.; Kaaja, Risto; Kaprio, Jaakko

    2014-01-01

    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 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 the 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 these phenotypes later in life. PMID:24639667

  12. Studies of light-twin wing-body interference

    NASA Technical Reports Server (NTRS)

    Thomson, W. G.; Wentz, W. H., Jr.

    1983-01-01

    The results of an analytical study of aerodynamic interference effects for a light twin aircraft are presented. The data presented concentrates on the influence of a wing on a body (the fuselage). Wind tunnel comparisons of three fillets are included, with corresponding computational analysis. Results indicate that potential flow analysis is useful to guide the design of intersection fairings, but experimental tuning is still required. While the study specifically addresses a light twin aircraft, the methods are applicable to a wide variety of aircraft.

  13. 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.

    PubMed

    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. PMID:27436054

  14. [Discordance analysis of monozygotic twin pairs. Case study on psychogenesis].

    PubMed

    Schepank, H

    1975-01-01

    We performed a discordance-analysis on six pairs of identical twins. They were selected from a large series of neurotic patients who came to visit one of two psychoanalytic outpatient departments. The results of this elaborate case studies are discussed here. The classical twin methods usually will help to clear the question of naturenurture-relation. Contrary to this the aim of discordance-analysis is to proof specific environmental factors which influence development of neurotic illness. The application of this method is rarely possible, because several conditions have to be fullfilled: The patients have to be identical twins; they must be available and willing to undergo psychoanalytic interview; apart from this they must present discordant neurotic complaints.--By a very exact analysis of the early childhood influences we can draw conclusions about psychogenesis of neutotic illness in later life. This method owns extraordinary advantages because of the existence of a control person with identical genetic outfit. PMID:1231414

  15. A multivariate twin study of early literacy in Japanese Kana

    PubMed Central

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

    2013-01-01

    This first Japanese twin study of early literacy development investigated the extent to which genetic and environmental factors influence individual differences in prereading skills in 238 pairs of twins at 42 months of age. Twin pairs were individually tested on measures of phonological awareness, kana letter name/sound knowledge, receptive vocabulary, visual perception, nonword repetition, and digit span. Results obtained from univariate behavioral-genetic analyses yielded little evidence for genetic influences, but substantial shared-environmental influences, for all measures. Phenotypic confirmatory factor analysis suggested three correlated factors: phonological awareness, letter name/sound knowledge, and general prereading skills. Multivariate behavioral genetic analyses confirmed relatively small genetic and substantial shared environmental influences on the factors. The correlations among the three factors were mostly attributable to shared environment. Thus, shared environmental influences play an important role in the early reading development of Japanese children. PMID:23997545

  16. Heredity, Environment, & Personality: A Study of 850 Sets of Twins.

    ERIC Educational Resources Information Center

    Loehlin, John C.; Nichols, Robert C.

    This book reports on a study of 850 pairs of twins who were tested to determine the influence of heredity and environment on individual differences in personality, academic ability, and interests. It presents the background, research design, and procedure of the study, tabulations of the test results, and extensive analyses of the findings.…

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

    PubMed

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

    2015-08-01

    Sleep paralysis is a relatively common but under-researched phenomenon. In this paper we examine prevalence in a UK sample and associations with candidate risk factors. This is the first study to investigate the heritability of sleep paralysis in a twin sample and to explore genetic associations between sleep paralysis and a number of circadian expressed single nucleotide polymorphisms. Analyses are based on data from the Genesis1219 twin/sibling study, a community sample of twins/siblings from England and Wales. In total, data from 862 participants aged 22-32 years (34% male) were used in the study. This sample consisted of monozygotic and dizygotic twins and siblings. It was found that self-reports of general sleep quality, anxiety symptoms and exposure to threatening events were all associated independently with sleep paralysis. There was moderate genetic influence on sleep paralysis (53%). Polymorphisms in the PER2 gene were associated with sleep paralysis in additive and dominant models of inheritance-although significance was not reached once a Bonferroni correction was applied. It is concluded that factors associated with disrupted sleep cycles appear to be associated with sleep paralysis. In this sample of young adults, sleep paralysis was moderately heritable. Future work should examine specific polymorphisms associated with differences in circadian rhythms and sleep homeostasis further in association with sleep paralysis. PMID:25659590

  18. Parenting and risk for mood, anxiety and substance use disorders: a study in population-based male twins

    PubMed Central

    Gardner, Charles O.; Kendler, Kenneth S.; Hettema, John M.

    2013-01-01

    Background Previous studies consistently identified a relationship between parenting behavior and psychopathology. In this study, we extended prior analyses performed in female twins to a large sample of twins from male–male pairs. Methods We used interview data on 2,609 adult male twins from a population-based twin registry. We examined the association between three retrospectively reported parenting dimensions (coldness, protectiveness, and authoritarianism) and lifetime history of seven common psychiatric and substance use disorders. Using univariate structural equation modeling, we also examined the influence of the genetic and environmental factors on parenting. Results Examined individually, coldness was consistently associated with risk for a broad range of adult psychopathology. Averaged odds of psychiatric disorders associated with parenting were increased between 26 and 36 %. When the three parenting dimensions were examined together, coldness remained significant for major depression, phobia, and generalized anxiety disorder. Controlling for other disorders, the associations between the parenting dimensions and psychopathology were non-specific. Twin fitting model demonstrated that modest heritability accounted for parenting, whereas most variance resulted from the non-shared environment. Conclusions Based on our current and prior findings, there is broad similarity in the impact of parenting on adult psychopathology between men and women. PMID:23344783

  19. Schooling has smaller or insignificant effects on adult health in the US than suggested by cross-sectional associations: new estimates using relatively large samples of identical twins.

    PubMed

    Amin, Vikesh; Behrman, Jere R; Kohler, Hans-Peter

    2015-02-01

    Numerous theoretical reasons have been posited about why more schooling might improve health. Adult health outcomes and behaviors generally are significantly associated with schooling. However, such associations do not necessarily imply that schooling has causal effects on health outcomes and behaviors. Causal estimates based on schooling variation from policies and from within-MZ (monozygotic) twins have reached mixed conclusions. This study contributed new estimates of cross-sectional associations and within-MZ causal effects using three relatively large US twins samples. The estimates suggested that schooling was significantly associated with numerous health outcomes and behaviors. However, with within-MZ twins control for unobserved factors, schooling was no longer associated with most indicators of better health (with the exception of self-reported health), while it continued to be associated with outcomes such as fertility and spousal schooling. Similar patterns were observed for spousal schooling. PMID:25110343

  20. Monozygotic twins' colour-number association: a case study.

    PubMed

    Hancock, Peter

    2006-02-01

    A case study of a pair of monozygotic twins, both of whom show a strong and enduring colour-number association, is reported. The origin of the colours, in a jigsaw puzzle, is known. Neither reports conscious photisms typical of synaesthesia, but a Stroop task of naming the colours of digits shows an interference effect with incongruent colours. PMID:16683487

  1. A Twin Study of Personality and Temperament during Middle Childhood.

    ERIC Educational Resources Information Center

    Matheny, Adam P., Jr.; Dolan, Anne Brown

    1980-01-01

    In a study of 105 twin pairs, correlations for identical pairs were significantly higher than fraternal pairs on all but one factor: tough-mindedness. Data suggested several components and the total organization of those components of personality and temperament are genetically influenced. (Author)

  2. DNA methylation studies using twins: what are they telling us?

    PubMed

    Bell, Jordana T; Spector, Tim D

    2012-01-01

    Recent studies have identified both heritable DNA methylation effects and differential methylation in disease-discordant identical twins. Larger sample sizes, replication, genetic-epigenetic analyses and longitudinal assays are now needed to establish the role of epigenetic variants in disease. PMID:23078798

  3. The Learning Styles of Monozygotic Twins Studying Science.

    ERIC Educational Resources Information Center

    Mascazine, John R.

    The background research on learning styles spans several decades, though much of it is quantitative data obtained using survey methods. Similarly, the research involving twins and their unique genetic condition historically predates the interest and knowledge of learning styles. This study seeks to explore both of these areas with the objective of…

  4. Numerical study of the stress state of a deformation twin in magnesium

    DOE PAGESBeta

    Arul Kumar, M.; Kanjarla, A. K.; Niezgoda, S. R.; Lebensohn, R. A.; Tomé, C. N.

    2014-11-26

    Here, we present a numerical study of the distribution of the local stress state associated with deformation twinning in Mg, both inside the twinned domain and in its immediate neighborhood, due to the accommodation of the twinning transformation shear. A full-field elastoviscoplastic formulation based on fast Fourier transformation is modified to include the shear transformation strain associated with deformation twinning. We performed two types of twinning transformation simulations with: (i) the twin completely embedded inside a single crystal and (ii) the twin front terminating at a grain boundary. We show that: (a) the resulting stress distribution is more strongly determinedmore » by the shear transformation than by the intragranular character of the twin or the orientation of the neighboring grain; (b) the resolved shear stress on the twin plane along the twin direction is inhomogeneous along the twin–parent interface; and (c) there are substantial differences in the average values of the shear stress in the twin and in the parent grain that contains the twin. We discuss the effect of these local stresses on twin propagation and growth, and the implications of our findings for the modeling of deformation twinning.« less

  5. Numerical study of the stress state of a deformation twin in magnesium

    SciTech Connect

    Arul Kumar, M.; Kanjarla, A. K.; Niezgoda, S. R.; Lebensohn, R. A.; Tomé, C. N.

    2014-11-26

    Here, we present a numerical study of the distribution of the local stress state associated with deformation twinning in Mg, both inside the twinned domain and in its immediate neighborhood, due to the accommodation of the twinning transformation shear. A full-field elastoviscoplastic formulation based on fast Fourier transformation is modified to include the shear transformation strain associated with deformation twinning. We performed two types of twinning transformation simulations with: (i) the twin completely embedded inside a single crystal and (ii) the twin front terminating at a grain boundary. We show that: (a) the resulting stress distribution is more strongly determined by the shear transformation than by the intragranular character of the twin or the orientation of the neighboring grain; (b) the resolved shear stress on the twin plane along the twin direction is inhomogeneous along the twin–parent interface; and (c) there are substantial differences in the average values of the shear stress in the twin and in the parent grain that contains the twin. We discuss the effect of these local stresses on twin propagation and growth, and the implications of our findings for the modeling of deformation twinning.

  6. Numerical study of the stress state of a deformation twin in magnesium

    SciTech Connect

    Arul Kumar, M.; Kanjarla, A. K.; Niezgoda, S. R.; Lebensohn, R. A.; Tomé, C. N.

    2015-02-01

    We present here a numerical study of the distribution of the local stress state associated with deformation twinning in Mg, both inside the twinned domain and in its immediate neighborhood, due to the accommodation of the twinning transformation shear. A full-field elastoviscoplastic formulation based on fast Fourier transformation is modified to include the shear transformation strain associated with deformation twinning. We have performed two types of twinning transformation simulations with: (i) the twin completely embedded inside a single crystal and (ii) the twin front terminating at a grain boundary. We show that: (a) the resulting stress distribution is more strongly determined by the shear transformation than by the intragranular character of the twin or the orientation of the neighboring grain; (b) the resolved shear stress on the twin plane along the twin direction is inhomogeneous along the twin–parent interface; and (c) there are substantial differences in the average values of the shear stress in the twin and in the parent grain that contains the twin. We discuss the effect of these local stresses on twin propagation and growth, and the implications of our findings for the modeling of deformation twinning.

  7. Paraphilic Sexual Interests and Sexually Coercive Behavior: A Population-Based Twin Study.

    PubMed

    Baur, Elena; Forsman, Mats; Santtila, Pekka; Johansson, Ada; Sandnabba, Kenneth; Långström, Niklas

    2016-07-01

    Prior research with selected clinical and forensic samples suggests associations between paraphilic sexual interests (e.g., exhibitionism and sexual sadism) and sexually coercive behavior. However, no study to date used a large, representative and genetically informative population sample to address the potential causal nature of this association. We used self-report data on paraphilic and sexually coercive behavior from 5990 18- to 32-year-old male and female twins from a contemporary Finnish population cohort. Logistic regression and co-twin control models were employed to examine if paraphilic behaviors were causally related to coercive behavior or if suggested links were confounded by familial (genetic or common family environment) risk factors. Results indicated that associations between four out of five tested paraphilic behaviors (exhibitionism, masochism, sadism, and voyeurism, respectively) and sexually coercive behavior were moderate to strong. Transvestic fetishism was not independently associated with sexual coercion. Comparisons of twins reporting paraphilic behavior with their paraphilic behavior-discordant twin further suggested that associations were largely independent of shared genetic and environmental confounds, consistent with a causal association. In conclusion, similar to previously reported predictive effects of paraphilias on sexual crime recidivism, paraphilic behavior among young adults in the general population increases sexual offending risk. Further, early identification of paraphilic interest and preventive interventions with at-risk individuals might also reduce perpetration of first-time sexual violence. PMID:26754158

  8. Risk Factors Influencing Smoking Behavior: A Turkish Twin Study

    PubMed Central

    Öncel, Sevgi Yurt; Dick, Danielle M.; Maes, Hermine H.; Alıev, Fazil

    2015-01-01

    Aim In this study, we introduce the first twin study in Turkey, focusing on smoking behavior, and laying the foundation to register all twins born in Turkey for research purposes. Using Turkish twins will contribute to our understanding of health problems in the context of cultural differences. Materials and methods We assessed 309 twin pairs (339 males and 279 females) aged between 15 and 45 years living in the Kırıkkale and Ankara regions of Turkey, and administered a health and lifestyle interview that included questions about smoking status and smoking history. We analyzed the data using descriptive statistics, t-tests, chi-square tests, and bivariate and multivariate clustered logistic regression. In addition, we fit bivariate Structural Equation Models (SEM) to determine contributions of latent genetic and environmental factors to smoking outcomes in this sample. Results One hundred seventy-eight participants (28.8%) were identified as smokers, smoking every day for a month or longer, of whom 79.2% were males and 20.8% were females. Mean values for number of cigarettes per day and the Fagerstrom Test of Nicotine Dependence (FTND; Fagerstrom, 1978) score were higher in males than in females, and age of onset was earlier in males. There was a significant positive correlation between the FTND score and number of cigarettes smoked per day, and a significant negative correlation between both variables and age at onset of smoking. Our study showed that gender, presence of a smoking twin in the family, age, alcohol use, marital status, daily sports activities, and feeling moody all played a significant role in smoking behavior among twins. The twin analysis suggested that 79.5% of the liability to FTND was influenced by genetic factors and 20.5% by unique environment, while familial resemblance for smoking initiation was best explained by common environmental factors. Conclusions Marked differences in the prevalence of smoking behavior in men versus women were

  9. Genetic and environmental influences on eating behavior - a study of twin pairs reared apart or reared together

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study examined the relative influence of genetic versus environmental factors on specific aspects of eating behavior. Adult monozygotic twins (22 pairs and 3 singleton reared apart, 38 pairs and 9 singleton reared together, age 18-76 years, BMI 17-43 kg/m2) completed the Three Factor Eating Que...

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

    PubMed

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

    2016-07-01

    Rare are the family studies that include siblings affected by pemphigus vulgaris (PV) and in whom HLA class II alleles are related. HLA-DR and -DQ genotyping and profiling of antibodies against desmogleins (Dsg) 1 and Dsg3 were performed in ten members of a family including monozygotic twins affected by PV. The twin sisters were heterozygotes; they presented the haplotypes most commonly associated with increased susceptibility to PV (DRB1∗04:02-DQA1∗03:01-DQB1∗03:02 and DRB1∗14:04-DQA1∗01:01-DQB1∗05:03). Their parents and five siblings had only one or none of these two haplotypes in combination with the alleles or haplotypes associated with resistance to PV (DRB1∗07:01-DQA1∗02:01-DQB1∗02:02 and DRB1∗13:01-DQA1∗01:03-DQB1∗06:03). Only the monozygotic twins presented IgG antibodies against both Dsg1 and Dsg3. According to our knowledge based on a review of published literature on the topic, this is the first report of PV affecting monozygotic twins. PMID:27177496

  11. Intra-Monozygotic Twin Pair Discordance and Longitudinal Variation of Whole-Genome Scale DNA Methylation in Adults

    PubMed Central

    Zhang, Su-Hua; Chen, Jinzhong; Lu, Daru; Shen, Min; Li, Chengtao

    2015-01-01

    Monozygotic twins share identical genomic DNA and are indistinguishable using conventional genetic markers. Increasing evidence indicates that monozygotic twins are epigenetically distinct, suggesting that a comparison between DNA methylation patterns might be useful to approach this forensic problem. However, the extent of epigenetic discordance between healthy adult monozygotic twins and the stability of CpG loci within the same individual over a short time span at the whole-genome scale are not well understood. Here, we used Infinium HumanMethylation450 Beadchips to compare DNA methylation profiles using blood collected from 10 pairs of monozygotic twins and 8 individuals sampled at 0, 3, 6, and 9 months. Using an effective and unbiased method for calling differentially methylated (DM) CpG sites, we showed that 0.087%–1.530% of the CpG sites exhibit differential methylation in monozygotic twin pairs. We further demonstrated that, on whole-genome level, there has been no significant epigenetic drift within the same individuals for up to 9 months, including one monozygotic twin pair. However, we did identify a subset of CpG sites that vary in DNA methylation over the 9-month period. The magnitude of the intra-pair or longitudinal methylation discordance of the CpG sites inside the CpG islands is greater than those outside the CpG islands. The CpG sites located on shores appear to be more suitable for distinguishing between MZ twins. PMID:26248206

  12. Genetic influences on osteoarthritis in women: a twin study.

    PubMed Central

    Spector, T. D.; Cicuttini, F.; Baker, J.; Loughlin, J.; Hart, D.

    1996-01-01

    OBJECTIVES--To assess the relative contribution of genetic and environmental factors to common forms of osteoarthritis of the hands and knees. DESIGN--Classic twin study with unselected twins who were screened radiologically for osteoarthritis. SUBJECTS--130 identical and 120 non-identical female twins aged 48-70 recruited from a London based twin register and through a national media campaign. MAIN OUTCOME MEASURES--Similarity in identical compared with non-identical twin pairs for radiographic changes at the interphalangeal and first carpometacarpal joints of the hands and the tibiofemoral joint and patellofemoral joint of the knee expressed as intraclass correlations. RESULTS--The intraclass correlations of radiographic osteophytes and narrowing at most sites and the presence of Heberden's nodes and knee pain were higher in the identical pairs. The intraclass correlation of the total radiographic osteoarthritis score in identical pairs (rMZ) was 0.64 (SE 0.05) compared with 0.38 (0.08) in non-identical pairs. The proportion of genetic variance of total osteoarthritis score (osteophytes and narrowing) with modelling techniques was estimated at 0.54 (95% confidence interval 0.43 to 0.65) and ranged from 0.39 to 0.65 for different sites and features (p < 0.001) after adjustment for age and weight. CONCLUSIONS--These results demonstrate for the first time a clear genetic effect for radiographic osteoarthritis of the hand and knee in women, with a genetic influence ranging from 39-65%, independent of known environmental or demographic confounders. The results of this study should lead to further work on isolating the gene or genes involved in the pathogenesis of the common disabling disease. PMID:8616305

  13. A Longitudinal Twin Study of Skewed X Chromosome-Inactivation

    PubMed Central

    Wong, Chloe Chung Yi; Caspi, Avshalom; Williams, Benjamin; Houts, Renate; Craig, Ian W.; Mill, Jonathan

    2011-01-01

    X-chromosome inactivation (XCI) is a pivotal epigenetic mechanism involved in the dosage compensation of X-linked genes between males and females. In any given cell, the process of XCI in early female development is thought to be random across alleles and clonally maintained once established. Recent studies, however, suggest that XCI might not always be random and that skewed inactivation may become more prevalent with age. The factors influencing such XCI skewing and its changes over time are largely unknown. To elucidate the influence of stochastic, heritable and environmental factors in longitudinal changes in XCI, we examined X inactivation profiles in a sample of monozygotic (MZ) (n = 23) and dizygotic (DZ) (n = 22) female twin-pairs at ages 5 and 10 years. Compared to MZ twins who were highly concordant for allelic XCI ratios, DZ twins showed much lower levels of concordance. Whilst XCI patterns were moderately stable between ages 5 and 10 years, there was some drift over time with an increased prevalence of more extreme XCI skewing at age 10. To our knowledge, this study represents the earliest longitudinal assessment of skewed XCI patterns, and suggests that skewed XCI may already be established in early childhood. Our data also suggest a link between MZ twinning and the establishment of allelic XCI ratios, and demonstrate that acquired skewing in XCI after establishment is primarily mediated by stochastic mechanisms. These data have implications for our understanding about sex differences in complex disease, and the potential causes of phenotypic discordance between MZ female twins. PMID:21445353

  14. ADHD Symptoms, Autistic Traits, and Substance Use and Misuse in Adult Australian Twins

    PubMed Central

    De Alwis, Duneesha; Agrawal, Arpana; Reiersen, Angela M; Constantino, John N; Henders, Anjali; Martin, Nicholas G; Lynskey, Michael T

    2014-01-01

    Objective: Attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder frequently co-occur. Several studies show increased risk of substance use disorders in ADHD, yet there is limited information related to how ADHD symptoms, autistic traits, and their combined effects are associated with nicotine, alcohol, and cannabis use and use disorders in the general population. Method: Cross-sectional interview and self-report questionnaire data from 3,080 young adult Australian twins (mean age 31.9 years) were used to assess ADHD symptoms, autistic traits, substance use, and substance use disorders. Substance use disorders—based on Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria—were assessed in the full sample as well as in those who reported substance use. Logistic regression analyses were used for comparing the associations between ADHD symptoms, autistic traits, substance use, and substance misuse after conduct disorder, sex, age, and zygosity were controlled for. Results: Greater ADHD symptoms and autistic traits scores were associated with elevated levels of regular smoking; cannabis use; and nicotine, alcohol, and cannabis use disorders, even after conduct disorder was adjusted for. In contrast, for alcohol use, those with high autistic traits scores were less likely to report drinking to intoxication. However, upon initiation, and similar to the findings for nicotine and cannabis, they were at elevated risk for developing alcohol dependence. Conclusions: Increased liability to ADHD and elevated autistic traits scores were associated with substance use and misuse, with the exception of alcohol use. Given the social underpinnings of drinking, persons with autistic traits may be less likely to engage in it; however, upon engagement in drinking, their vulnerability to alcohol dependence is elevated. PMID:24650814

  15. Effects of Smoking on Coronary Microcirculatory Function: A Twin Study

    PubMed Central

    Rooks, Cherie; Faber, Tracy; Votaw, John; Veledar, Emir; Goldberg, Jack; Raggi, Paolo; Quyyumi, Arshed A.; Bremner, J. Douglas; Vaccarino, Viola

    2011-01-01

    Background In asymptomatic smokers, coronary microcirculatory dysfunction, assessed by coronary flow reserve (CFR), is an early indicator of cardiovascular risk. Inflammation and oxidative stress may be the mechanisms through which smoking affects the microvasculature. Objectives The purpose of this study was to determine the relationship between smoking and CFR, taking into account potential shared genetic effects. Methods We examined 360 male middle aged twins (288 non-smokers and 72 smokers), including 46 twin pairs discordant for current smoking. Coronary flow reserve (CFR) in response to adenosine was measured with positron emission tomography [N13] ammonia and quantitation of coronary blood flow at rest and after adenosine stress. Inflammation was assessed by measuring interleukin-6 and C-reactive protein, and oxidative stress was determined by measuring plasma hydroperoxides, glutathione (GSH), the oxidized form of GSH, GSSG, and the ratio of GSH to GSSG. Results CFR was significantly lower in smokers compared to nonsmokers (2.25 vs. 2.75, p<0.01). This relationship persisted after accounting for known cardiovascular disease risk factors, and was marginally affected by adjusting for inflammatory and oxidative stress biomarkers. In addition, in smoking-discordant twin pairs, CFR in the smoking twin was significantly lower than in the non-smoking co-twin (2.25 vs. 2.67, p = 0.03) even after adjustment for cardiovascular risk factors. Conclusions Our results demonstrate the adverse effects of smoking in the early phases of cardiovascular disease. Mechanisms other than peripherally-measured inflammation and oxidative stress are involved. PMID:21315354

  16. A Study of Developmental Speech and Language Disorders in Twins.

    ERIC Educational Resources Information Center

    Lewis, Barbara A.; Thompson, Lee A.

    1992-01-01

    Fifty-seven same-sex twin sets (32 monozygotic and 25 dizygotic) were examined for concordance of speech and language disorders. Monozygotic twins had a higher concordance than dizygotic twins and also were more similar in the types of disorders they presented than dizygotic twins. Positive family histories were reported for both groups.…

  17. Computational and experimental studies of light twin aerodynamic interference

    NASA Technical Reports Server (NTRS)

    Thomson, W. G.; Wentz, W. H., Jr.; Ostowari, C.

    1982-01-01

    The results of an analytical and experimental study of aerodynamic interference effects for a light twin aircraft are presented. Both the influence of a body (either fuselage or nacelle) on a wing and the influence of a wing on a body are studied. The wing studied uses a new natural laminar flow airfoil with variable camber movable trailing edge. A three-dimensional panel method program utilizing surface source and surface doublet singularities was used to design wing-nacelle and wing-fuselage fairings. Experiments were conducted using a 1/6 scale reflection plane model. Forces, pressures, and surface flow visualization results are presented. Results indicate that potential flow analysis is useful to guide the design of intersection fairings, but experimental tuning is still required. While the study specifically addressed a light twin aircraft, the methods are applicable to a wide variety of aircraft.

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

    ERIC Educational Resources Information Center

    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…

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

    ERIC Educational Resources Information Center

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

    2011-01-01

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

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

    PubMed

    Segal, Nancy L; Mulligan, Christy A

    2014-04-01

    A reunion of 38-year-old female monozygotic twins took place in Daegu, South Korea, on January 14, 2014. Scientific and personal perspectives on this extraordinary event are provided. A review of timely twin research follows, covering the effects of multiple births on IQ and body size, lifestyle and physical fitness associations, a rare case of a dizygotic twin with blood chimerism and definitional issues surrounding amniocentesis-related loss in multiple birth pregnancies. Interesting and informative mention of twins in the media includes twin doctors, a twin freedom fighter, the availability of college scholarships for twins, a new book about the Piccard family (two of whose members were twins), and co-twins born before and after the new year. A follow-up to a previous mention of identical twin biatheletes is also provided. PMID:24589452

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

    PubMed

    Martini, Matteo; Bufalari, Ilaria; Stazi, Maria Antonietta; Aglioti, Salvatore Maria

    2015-01-01

    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. PMID:25853249

  2. Functional neuroimaging study in identical twin pairs discordant for regular cigarette smoking.

    PubMed

    Lessov-Schlaggar, Christina N; Lepore, Rebecca L; Kristjansson, Sean D; Schlaggar, Bradley L; Barnes, Kelly Anne; Petersen, Steven E; Madden, Pamela A F; Heath, Andrew C; Barch, Deanna M

    2013-01-01

    Despite the tremendous public health and financial burden of cigarette smoking, relatively little is understood about brain mechanisms that subserve smoking behavior. This study investigated the effect of lifetime regular smoking on brain processing in a reward guessing task using functional magnetic resonance imaging and a co-twin control study design in monozygotic (MZ) twin pairs that maximally controls for genetic and family background factors. Young adult (24-34 years) MZ female twin pairs (n = 15 pairs), discordant for regular smoking defined using Centers for Disease Control criteria as having smoked ≥100 cigarettes in their lifetime, were recruited from an ongoing genetic epidemiological longitudinal study of substance use and psychopathology. We applied hypothesis-driven region of interest (ROI) and whole-brain analyses to investigate the effect of regular smoking on reward processing. Reduced response to reward and punishment in regular compared with never-regular smokers was seen in hypothesis-driven ROI analysis of bilateral ventral striatum. Whole-brain analysis identified bilateral reward-processing regions that showed activation differences in response to winning or losing money but no effect of regular smoking; and frontal/parietal regions, predominantly in the right hemisphere, that showed robust effect of regular smoking but no effect of winning or losing money. Altogether, using a study design that maximally controls for group differences, we found that regular smoking had modest effects on striatal reward processing regions but robust effects on cognitive control/attentional systems. PMID:22340136

  3. Attachment to inanimate objects and early childcare: A twin study

    PubMed Central

    Fortuna, Keren; Baor, Liora; Israel, Salomon; Abadi, Adi; Knafo, Ariel

    2014-01-01

    Extensive non-maternal childcare plays an important role in children’s development. This study examined a potential coping mechanism for dealing with daily separation from caregivers involved in childcare experience – children’s development of attachments toward inanimate objects. We employed the twin design to estimate relative environmental and genetic contributions to the presence of object attachment, and assess whether childcare explains some of the environmental variation in this developmental phenomenon. Mothers reported about 1122 3-year-old twin pairs. Variation in object attachment was accounted for by heritability (48%) and shared environment (48%), with childcare quantity accounting for 2.2% of the shared environment effect. Children who spent half-days in childcare were significantly less likely to attach to objects relative to children who attended full-day childcare. PMID:24904499

  4. Applications of twin analysis to studying meteorite impact structures

    NASA Astrophysics Data System (ADS)

    Schedl, Andrew

    2006-04-01

    This paper describes a technique, twin analysis of dolomite and calcite, which was used to estimate the level of erosion of an impact crater. If the age of impact is known, the level of erosion gives the amount of sediments present at that time. The estimate of the level of erosion, and the presence or absence of tectonic strains in calcite constrains the age of impact. This technique might also be useful in identifying deeply eroded impact structures. Twin analysis gives the greatest shortening direction, ɛ1. Tilt corrected ɛ1 directions converge at or above the present day surface, if a shallow gas explosion or meteorite impact explains the structure, rather than a deep gas or cryptovolcanic explosion. The energy density recorded by twinning distinguishes an impact from a shallow gas explosion for structures ≤ 100 m diameter. At Serpent Mound, a well-established impact structure, ɛ1 directions converge at 1400 ± 390 m (95% confidence interval of the mean) above the present day structure and the sample closest to the center of the structure records an energy density of 1.7 × 10 7 J/m 3. These results are consistent with previous studies showing that Serpent Mound is an impact (e.g., [R.W. Carlton, C. Koeberl, M.T. Baranoski, G.A. Schumacker, Discovery of microscopic evidence for shock metamorphism at the Serpent Mound structure, south-central Ohio: confirmation of an origin by impact, Earth and Planet. Sci. Lett. 162 (1998) 177-185]). The level of erosion and other data suggests that Serpent Mound formed between 290 and 256 Ma and was originally 8.5 to 11 km in diameter. Dolomite twinning is not observed at Serpent Mound suggesting that this technique may only be useful for studying larger, more deeply eroded structures.

  5. TWIN BINARIES: STUDIES OF STABILITY, MASS TRANSFER, AND COALESCENCE

    SciTech Connect

    Lombardi, J. C.; Holtzman, W.; Gearity, K.; Dooley, K. L.; Kalogera, V.; Rasio, F. A.

    2011-08-20

    Motivated by suggestions that binaries with almost equal-mass components ('twins') play an important role in the formation of double neutron stars and may be rather abundant among binaries, we study the stability of synchronized close and contact binaries with identical components in circular orbits. In particular, we investigate the dependency of the innermost stable circular orbit on the core mass, and we study the coalescence of the binary that occurs at smaller separations. For twin binaries composed of convective main-sequence stars, subgiants, or giants with low-mass cores (M{sub c} {approx}< 0.15M, where M is the mass of a component), a secular instability is reached during the contact phase, accompanied by a dynamical mass transfer instability at the same or at a slightly smaller orbital separation. Binaries that come inside this instability limit transfer mass gradually from one component to the other and then coalesce quickly as mass is lost through the outer Lagrangian points. For twin giant binaries with moderate to massive cores (M{sub c} {approx}> 0.15M), we find that stable contact configurations exist at all separations down to the Roche limit, when mass shedding through the outer Lagrangian points triggers a coalescence of the envelopes and leaves the cores orbiting in a central tight binary. In addition to the formation of binary neutron stars, we also discuss the implications of our results for the production of planetary nebulae with double degenerate central binaries.

  6. Musical activity and emotional competence – a twin study

    PubMed Central

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

    2014-01-01

    The hypothesis was tested that musical activities may contribute to the prevention of alexithymia. We tested whether musical creative achievement and musical practice are associated with lower alexithymia. 8000 Swedish twins aged 27–54 were studied. Alexithymia was assessed using the Toronto Alexithymia Scale-20. Musical achievement was rated on a 7-graded scale. Participants estimated number of hours of music practice during different ages throughout life. A total life estimation of number of accumulated hours was made. They were also asked about ensemble playing. In addition, twin modelling was used to explore the genetic architecture of the relation between musical practice and alexithymia. Alexithymia was negatively associated with (i) musical creative achievement, (ii) having played a musical instrument as compared to never having played, and – for the subsample of participants that had played an instrument – (iii) total hours of musical training (r = -0.12 in men and -0.10 in women). Ensemble playing added significant variance. Twin modelling showed that alexithymia had a moderate heritability of 36% and that the association with musical practice could be explained by shared genetic influences. Associations between musical training and alexithymia remained significant when controlling for education, depression, and intelligence. Musical achievement and musical practice are associated with lower levels of alexithymia in both men and women. Musical engagement thus appears to be associated with higher emotional competence, although effect sizes are small. The association between musical training and alexithymia appears to be entirely genetically mediated, suggesting genetic pleiotropy. PMID:25076933

  7. Chorionicity and Heritability Estimates from Twin Studies: The Prenatal Environment of Twins and Their Resemblance Across a Large Number of Traits.

    PubMed

    van Beijsterveldt, C E M; Overbeek, L I H; Rozendaal, L; McMaster, M T B; Glasner, T J; Bartels, M; Vink, J M; Martin, N G; Dolan, C V; Boomsma, D I

    2016-05-01

    There are three types of monozygotic (MZ) twins. MZ twins can either share one chorion and one amnion, each twin can have its own amnion, or MZ twins can-like dizygotic twins-each have their own chorion and amnion. Sharing the same chorion may create a more similar/dissimilar prenatal environment and bias heritability estimates, but most twin studies do not distinguish between these three types of MZ twin pairs. The aim of this paper is to investigate the effect of chorion sharing on the similarity within MZ twin pairs for a large number of traits. Information on chorion status was obtained for the Netherlands twin register (NTR) by linkage to the records from the database of the dutch pathological anatomy national automated archive (PALGA). Record linkage was successful for over 9000 pairs. Effect of chorion type was tested by comparing the within-pair similarity between monochorionic (MC) and dichorionic (DC) MZ twins on 66 traits including weight, height, motor milestones, child problem behaviors, cognitive function, wellbeing and personality. For only 10 traits, within-pair similarity differed between MCMZ and DCMZ pairs. For traits influenced by birth weight (e.g. weight and height in young children) we expected that MC twins would be more discordant. This was found for 5 out of 13 measures. When looking at traits where blood supply is important, we saw MCMZ twins to be more concordant than DCMZ's for 3 traits. We conclude that the influence on the MZ twin correlation of the intra-uterine prenatal environment, as measured by sharing a chorion type, is small and limited to a few phenotypes. This implies that the assumption of equal prenatal environment of mono- and DC MZ twins, which characterizes the classical twin design, is largely tenable. PMID:26410687

  8. NO CLEAR LINK BETWEEN G LOADINGS AND HERITABILITY: A TWIN STUDY FROM KOREA.

    PubMed

    Choi, Yu Yong; Cho, Sun Hee; Lee, Kun Ho

    2015-08-01

    A fundamental theoretical question in intelligence research is to what extent the g factor and heritability coefficients of the subtests of an IQ battery are correlated. Five studies from Western countries showed modest to strong positive correlations (range = .43-.77), and six studies from a Japanese meta-analysis showed zero to modest correlations (range = -0.01-0.59). The Western and Japanese studies were compared with a Korean sample of 24 monozygotic and 20 dizygotic young adult twin pairs administered the Korean Wechsler Adult Intelligence Scale-Revised (WAIS-R). A univariate twin model was applied to all subscale scores leading to estimates of heritability for all scales. g loadings were also computed using principal-axis factor analysis. Finally, the correlation between the heritabilities and the g loadings of these scales were computed. The correlations of r = -.15 were not in line with previous studies. It could be that Spearman's hypothesis is less strongly confirmed for Northeast Asians, but it is also possible that the study will be an outlier in a future meta-analysis. More primary research and a meta-analysis of all studies are needed. PMID:26126212

  9. Is That Me or My Twin? Lack of Self-Face Recognition Advantage in Identical Twins

    PubMed Central

    Martini, Matteo; Bufalari, Ilaria; Stazi, Maria Antonietta; Aglioti, Salvatore Maria

    2015-01-01

    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. PMID:25853249

  10. The cognitive and identity development of twins at 16 years of age: a follow-up study of 32 twin pairs.

    PubMed

    Akerman, Britta Alin; Suurvee, Eve

    2003-08-01

    This is a follow up study of twins within the Stockholm area, including 32 families and their twins attending grade nine. The twins have been followed from birth to 16 years of age. The main purpose of this study from its inception was to assess mental and cognitive development at different ages. Another aim was to see how the twins who were born prematurely are developing during the school ages. A third aim has been to gain a deeper insight into the relationship between co-twins and the development of their identities, which is the focus of this paper. Several ability tests have been used, as well as questionnaires about interests, attitudes toward school, and leisure activities. At the 16-year follow-up, a psychological method, the Wartegg drawing test, designed to examine identity, ego strength, dependency, ambition, anxiety, willpower, creativity, empathy and coping strategies has been used. The results indicate that it is difficult for twins to develop independence and a positive identity, as they have to emancipate themselves both from their parents and from their co-twins. Some differences in identity, anxiety and ambition were observed between female and male twins, MZ and DZ twins, preterm and fullterm twins. Prematurity, sex and zygosity no longer had any relation to cognitive development at 16 years of age. PMID:14511442

  11. Does education lower allostatic load? A co-twin control study.

    PubMed

    Hamdi, Nayla R; South, Susan C; Krueger, Robert F

    2016-08-01

    Many studies have found that education is associated with better health, but the causal basis of this association is unclear. The current study used a co-twin control design to examine if differences in years of education within twin pairs predict allostatic load. The strength of this design is that it controls for genetic and other familial confounds shared between twins. The sample consisted of 381 twins (with 292 twins from 146 complete pairs; mean age=57; 61% female) who participated in the biomarker project of the Midlife Development in the United States (MIDUS) study. Individual-level analyses showed a significant, negative association between years of education and allostatic load, but this association was explained entirely by familial influences shared between twins. The results of this study suggest that schooling does not itself protect against allostatic load. PMID:26778778

  12. The Prenatal Environment in Twin Studies: A Review on Chorionicity.

    PubMed

    Marceau, Kristine; McMaster, Minni T B; Smith, Taylor F; Daams, Joost G; van Beijsterveldt, Catharina E M; Boomsma, Dorret I; Knopik, Valerie S

    2016-05-01

    A literature search was conducted to identify articles examining the association of chorionicity (e.g., whether twins share a single chorion and thus placenta or have separate chorions/placentas) and genetics, psychiatry/behavior, and neurological manifestations in humans twins and higher-order multiples. The main aim was to assess how frequently chorionicity has been examined in relation to heritability estimates, and to assess which phenotypes may be most sensitive to, or affected by, bias in heritability estimates because of chorionicity. Consistent with the theory that some chorionicity effects could lead to overestimation and others to underestimation of heritability, there were instances of each across the many phenotypes reviewed. However, firm conclusions should not be drawn since some of the outcomes were only examined in one or few studies and often sample sizes were small. While the evidence for bias due to chorionicity was mixed or null for many outcomes, results do, however, consistently suggest that heritability estimates are underestimated for measures of birth weight and early growth when chorionicity is not taken into account. PMID:26944881

  13. Studies of the dynamics of the twin-lift system

    NASA Technical Reports Server (NTRS)

    Curtiss, H. C., Jr.

    1988-01-01

    A full set of equations of motion for the twin lift system, linearized about a hover trim condition were derived and presented. It is shown that this full set of equations of motion decouples into simpler sets of equations of motion if the aerodynamic coupling derivatives of the helicopters are neglected. One of these decoupled sets of equations of motion (referred to as the planar set) was studied at length. The other decoupled set (referred to as the nonplanar set) is examined here. It is shown that when the geometric configuration of the twin-lift is symmetric that a further decoupling is possible into antisymmetric and symmetric sets of equations. One set of these reduced equations of motion referred to as the antisymmetric set is directly equivalent to the longitudinal motion of a single helicopeter with a sling load. The second set, referred to as the symmetric set corresponds to the rotation of the entire system without load motion. As in the case of the planar symmetric motion, the location of the tether attachment point influences the stability of the nonplanar symmetric mode. The trend is opposite however in the nonplanar case in that an attachment point below the helicopter center of gravity gives a favorable effect on the stability. The effect is not as strong however as the unfavorable effect on the planar symmetric mode.

  14. Substantial genetic link between IQ and working memory: implications for molecular genetic studies on schizophrenia. the European twin study of schizophrenia (EUTwinsS).

    PubMed

    Goldberg, Ximena; Alemany, Silvia; Rosa, Araceli; Picchioni, Marco; Nenadic, Igor; Owens, Sheena F; Rijsdijk, Fruhling; Rebollo, Irene; Sauer, Heinrich; Murray, Robin M; Fañanás, Lourdes; Toulopoulou, Timothea

    2013-06-01

    While evidence is accumulating to support specific neurocognitive deficits as putative endophenotypes for schizophrenia, the heritability of these deficits in healthy subjects and whether they share common genetic influences, is not well established. In the present study, 529 healthy adult twins from two centers within the European Twin Study Network on Schizophrenia (EUTwinsS) were assessed on two domains that are consistently found to be particularly compromised in schizophrenia. Specifically, Intellectual Quotient Score (IQ) and the Letter-Number Sequencing Test (LNS), a measure of working memory, were measured in all twins. Latent variable components were explored through structural equation modeling, and common genetic underpinnings were examined using bivariate analyses. Results showed that the phenotypic correlation between IQ and working memory was almost entirely attributed to shared genetic variance (95.5%). We discuss the potential use of a combined measure of IQ and working memory to improve the power of molecular studies in detecting the genetic mechanisms underlying schizophrenia. PMID:23650229

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

    PubMed

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

    2016-07-01

    Both genetic and environmental factors are known to play a role in our ability to perceive music, but the degree to which they influence different aspects of music cognition is still unclear. We investigated the relative contribution of genetic and environmental effects on melody perception in 384 young adult twins [69 full monozygotic (MZ) twin pairs, 44 full dizygotic (DZ) twin pairs, 70 MZ twins without a co-twin, and 88 DZ twins without a co-twin]. The participants performed three online music tests requiring the detection of pitch changes in a two-melody comparison task (Scale) and key and rhythm incongruities in single-melody perception tasks (Out-of-key, Off-beat). The results showed predominantly additive genetic effects in the Scale task (58 %, 95 % CI 42-70 %), shared environmental effects in the Out-of-key task (61 %, 49-70 %), and non-shared environmental effects in the Off-beat task (82 %, 61-100 %). This highly different pattern of effects suggests that the contribution of genetic and environmental factors on music perception depends on the degree to which it calls for acquired knowledge of musical tonal and metric structures. PMID:26650514

  16. Pain sensitivity and opioid analgesia: a pharmacogenomic twin study.

    PubMed

    Angst, Martin S; Phillips, Nicholas G; Drover, David R; Tingle, Martha; Ray, Amrita; Swan, Gary E; Lazzeroni, Laura C; Clark, J David

    2012-07-01

    Opioids are the cornerstone medication for the management of moderate to severe pain. Unfortunately, vast inter-individual differences in dose requirements complicate their effective and safe clinical use. Mechanisms underlying such differences are incompletely understood, are likely multifactorial, and include genetic and environmental contributions. While accumulating evidence suggests that variants of several genes account for some of the observed response variance, the relative contribution of these factors remains unknown. This study used a twin paradigm to provide a global estimate of the genetic and environmental contributions to inter-individual differences in pain sensitivity and analgesic opioid effects. Eighty one monozygotic and 31 dizygotic twin pairs successfully underwent a computer-controlled infusion with the μ-opioid agonist alfentanil in a single occasion, randomized, double-blind and placebo-controlled study design. Pain sensitivity and analgesic effects were assessed with experimental heat and cold pressor pain models along with important covariates including demographic factors, depression, anxiety, and sleep quality. Significant heritability was detected for cold pressor pain tolerance and opioid-mediated elevations in heat and cold pressor pain thresholds. Genetic effects accounted for 12-60% of the observed response variance. Significant familial effects accounting for 24-32% of observed variance were detected for heat and cold pressor pain thresholds and opioid-mediated elevation in cold pressor pain tolerance. Significant covariates included age, gender, race, education, and anxiety. Results provide a strong rationale for more detailed molecular genetic studies to elucidate mechanisms underlying inter-individual differences in pain sensitivity and analgesic opioid responses. Such studies will require careful consideration of the studied pain phenotype. PMID:22444188

  17. A Twin-Family Study of General IQ

    ERIC Educational Resources Information Center

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

    2008-01-01

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

  18. Genetic and Environmental Etiologies of Reading Disability: A Twin Study.

    ERIC Educational Resources Information Center

    LaBuda, Michele C.; DeFries, J. C.

    1988-01-01

    Data analysis of 134 twin pairs from the Colorado Reading Project found that approximately 40 percent of the deficit observed in disabled readers is because of genetic factors, 35 percent because of environmental influences shared by twin pairs, and 25 percent because of environmental factors unique to the individual and/or error variance.…

  19. The Heritability of Inhibited and Uninhibited Behavior: A Twin Study.

    ERIC Educational Resources Information Center

    Robinson, JoAnn L.; And Others

    1992-01-01

    Behaviors of monozygotic and dizygotic twins that were indicative of wariness were observed when the twins were 14, 20, and 24 months of age. An index of inhibition constructed from observations showed internal consistency at all ages and stability across ages. Heritability was a factor at all ages. (BC)

  20. A study of multibiometric traits of identical twins

    NASA Astrophysics Data System (ADS)

    Sun, Zhenan; Paulino, Alessandra A.; Feng, Jianjiang; Chai, Zhenhua; Tan, Tieniu; Jain, Anil K.

    2010-04-01

    The increase in twin births has created a requirement for biometric systems to accurately determine the identity of a person who has an identical twin. The discriminability of some of the identical twin biometric traits, such as fingerprints, iris, and palmprints, is supported by anatomy and the formation process of the biometric characteristic, which state they are different even in identical twins due to a number of random factors during the gestation period. For the first time, we collected multiple biometric traits (fingerprint, face, and iris) of 66 families of twins, and we performed unimodal and multimodal matching experiments to assess the ability of biometric systems in distinguishing identical twins. Our experiments show that unimodal finger biometric systems can distinguish two different persons who are not identical twins better than they can distinguish identical twins; this difference is much larger in the face biometric system and it is not significant in the iris biometric system. Multimodal biometric systems that combine different units of the same biometric modality (e.g. multiple fingerprints or left and right irises.) show the best performance among all the unimodal and multimodal biometric systems, achieving an almost perfect separation between genuine and impostor distributions.

  1. Genetic and environmental influences on impulsivity: A meta-analysis of twin, family and adoption studies

    PubMed Central

    Bezdjian, Serena; Baker, Laura A.; Tuvblad, Catherine

    2011-01-01

    A meta-analysis of twin, family and adoption studies was conducted to estimate the magnitude of genetic and environmental influences on impulsivity. The best fitting model for 41 key studies (58 independent samples from 14 month old infants to adults; N = 27,147) included equal proportions of variance due to genetic (0.50) and non-shared environmental (0.50) influences, with genetic effects being both additive (0.38) and non-additive (0.12). Shared environmental effects were unimportant in explaining individual differences in impulsivity. Age, sex, and study design (twin vs. adoption) were all significant moderators of the magnitude of genetic and environmental influences on impulsivity. The relative contribution of genetic effects (broad sense heritability) and unique environmental effects were also found to be important throughout development from childhood to adulthood. Total genetic effects were found to be important for all ages, but appeared to be strongest in children. Analyses also demonstrated that genetic effects appeared to be stronger in males than in females. Method of assessment (laboratory tasks vs. questionnaires), however, was not a significant moderator of the genetic and environmental influences on impulsivity. These results provide a structured synthesis of existing behavior genetic studies on impulsivity by providing a clearer understanding of the relative genetic and environmental contributions in impulsive traits through various stages of development. PMID:21889436

  2. Persistence or Change in Leisure-Time Physical Activity Habits and Waist Gain During Early Adulthood: A Twin-Study

    PubMed Central

    Rottensteiner, Mirva; Pietiläinen, Kirsi H.; Kaprio, Jaakko; Kujala, Urho M.

    2014-01-01

    Objective To determine the relationship between persistence or change in leisure-time physical activity habits and waist gain among young adults. Design and Methods Population-based cohort study among 3383 Finnish twin individuals (1578 men) from five birth cohorts (1975–1979), who answered questionnaires at mean ages of 24.4 y (SD 0.9) and 33.9 y (SD 1.2), with reported self-measured waist circumference. Persistence or change in leisure-time physical activity habits was defined based on thirds of activity metabolic equivalent h/day during follow-up (mean 9.5 y; SD 0.7). Results Decreased activity was linked to greater waist gain compared to increased activity (3.6 cm, P<0.001 for men; 3.1 cm, P<0.001 for women). Among same-sex activity discordant twin pairs, twins who decreased activity gained an average 2.8 cm (95%CI 0.4 to 5.1, P=0.009) more waist than their co-twins who increased activity (n=85 pairs); among MZ twin pairs (n=43), the difference was 4.2 cm (95%CI 1.2 to 7.2, P=0.008). Conclusions Among young adults, an increase in leisure-time physical activity or staying active during a decade of follow-up was associated with less waist gain, but any decrease in activity level, regardless baseline activity, led to waist gain that was similar to that associated with being persistently inactive. PMID:24839266

  3. Insights From Twin Research: Conference at Royal Childrens Hospital, Melbourne, Australia / Twin Studies: Timing of Monozygotic Splitting and Commentary; Gestational Diabetes; ICOMBO'S Post-Partum Depression Study; Photographs of Conjoined Twins / Human Interest: Rare Quadruplets; Mistaken Identity on the Soccer Field; Prenatal Laser Surgery on Triplets; Twins Born to Prince and Princess of Monaco.

    PubMed

    Segal, Nancy L

    2015-04-01

    Highlights from a conference, 'Healthier Kids: Insights From Twin Research', held in Melbourne, Australia on December 5, 2014, are summarized. In addition to informative and exciting presentations and discussions of recent findings, three key themes emerged: (1) results from twin research have important implications for non-twins, (2) researchers from diverse disciplines should be encouraged to participate actively in twin research, and (3) investigators, twins and families need to work more collaboratively. Next, papers and studies concerning the biological bases of monozygotic (MZ) twinning, gestational diabetes and post-partum depression are reviewed. Finally, general interest reports of rare quadruplets, mistaken identity, prenatal laser surgery and a royal twin birth are provided. PMID:25740114

  4. Aversive and Reinforcing Opioid Effects: A Pharmacogenomic Twin Study

    PubMed Central

    Angst, Martin S.; Lazzeroni, Laura C.; Phillips, Nicholas G.; Drover, David R.; Tingle, Martha; Ray, Amrita; Swan, Gary E.; Clark, J. David

    2012-01-01

    Background The clinical utility of opioids is limited by adverse drug effects including respiratory depression, sedation, nausea, and pruritus. In addition, abuse of prescription opioids is problematic. Gaining a better understanding of the genetic and environmental mechanisms contributing to an individual’s susceptibility to adverse opioid effects is essential to identify patients at risk. Methods A classical twin study paradigm provided estimates for the genetic and familial (genetic and/or shared environment) contribution to acute adverse and affective opioid responses; all secondary outcomes of a larger data set. One hundred and twenty one twin pairs were recruited in a single occasion, randomized, double-blind and placebo controlled study. The mu-opioid receptor agonist alfentanil and saline placebo were administered as target-controlled infusions under carefully monitored laboratory conditions. Measured outcomes included respiratory depression, sedation, nausea, pruritus, drug liking and drug disliking. Demographic information was collected, and aspects of mood and sleep were evaluated. Results Significant heritability was detected for respiratory depression (30%), nausea (59%) and drug disliking (36%). Significant familial effects were detected for sedation (29%), pruritus (38%), dizziness (32%), and drug liking (26%). Significant covariates included age, gender, race, ethnicity, education, mood and depression. Covariates affected sedation, pruritus, drug liking and disliking, and dizziness. Conclusions This study demonstrates that large scale efforts to collect quantitative and well-defined opioid response data are not only feasible but also produce data that are suitable for genetic analysis. Genetic, environmental and demographic factors work together to control adverse and reinforcing opioid responses, but contribute differently to specific responses. PMID:22713632

  5. Twin Study on Heritability of Activity, Attention, and Impulsivity as Assessed by Objective Measures

    ERIC Educational Resources Information Center

    Heiser, Philip; Heinzel-Gutenbrunner, Monika; Frey, Joachim; Smidt, Judith; Grabarkiewicz, Justyna; Friedel, Susann; Kuhnau, Wolfgang; Schmidtke, Jorg; Remschmidt, Helmut; Hebebrand, Johannes

    2006-01-01

    Objective: The purpose of this study was to assess heritability of activity, attention, and impulsivity by comparing young monozygotic (MZ) twins with dizygotic (DZ) twins using objective measures. Method: The OPTAx test is an infrared motion analysis to record the movement pattern during a continuous performance test. Seventeen MZ and 12 same…

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

    ERIC Educational Resources Information Center

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

    2013-01-01

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

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

    ERIC Educational Resources Information Center

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

    2012-01-01

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

  8. Parallel Lives, Different Outcomes: A Twin Study of Academic Productivity in U.S. School Districts

    ERIC Educational Resources Information Center

    Hanna, Robert; Morris, Bo

    2014-01-01

    This paper explores what happens to similar groups of children educated in different school districts. In this case, the "twins" in the study are groups of students who live in the same state in similar geographies and who share certain demographic characteristics. For this report, "twin districts" have very similar sizes and…

  9. A detailed systematic anatomical study of monocephalic conjoined symmetric twin lambs

    PubMed Central

    Kamali, Y.; Khaksar, Z.; Sharaki, A.R.; Rasouli, B.; Kajbafi, M.

    2014-01-01

    A case of conjoined twins with monocephalus, thoracopagus, partial abdominopagus, tetrabrachius and tetrascelus in lambs complicated with several defects of skeletal, cardiovascular, gastrointestinal, and urogenital systems is reported. The twins were dead and delivered by cesarean section. This case report highlights the detailed anatomical study of defects in different systems due to an abnormal birth defect. PMID:26623352

  10. Genetic Etiology of Spelling Deficits in the Colorado and London Twin Studies of Reading Disability.

    ERIC Educational Resources Information Center

    Defries, J. C.; And Others

    1991-01-01

    Fits spelling data from identical and fraternal twins to a basic multiple regression model. Finds that about 60% of the deficit of probands was due to heritable influences. Finds a nonsignificant sex difference. Suggests collaborative analyses of data from additional twin studies of reading disability to facilitate more rigorous tests. (RS)

  11. The Equal Environments Assumption of Classical Twin Studies May Not Hold

    ERIC Educational Resources Information Center

    Richardson, Ken; Norgate, Sarah

    2005-01-01

    The classical twin method -- comprising comparisons of monozygotic (MZ) and dizygotic (DZ) twins -- in the domain of cognitive abilities and attainments has led to wide acceptance of results suggesting a large amount of additive genetic variance, with far-reaching implications both for the nature of future studies on the causes of cognitive…

  12. Vocal fold bowing in elderly male monozygotic twins: a case study.

    PubMed

    Tanner, Kristine; Sauder, Cara; Thibeault, Susan L; Dromey, Christopher; Smith, Marshall E

    2010-07-01

    This case study examined case histories, diagnostic features, and treatment response in two 79-year-old male monozygotic (identical) twins with vocal fold bowing, exploring both genetic and environmental factors. DNA concordance was examined via cheek swab. Case histories, videostroboscopy, auditory- and visual-perceptual assessment, electromyography, acoustic measures, and Voice Handicap ratings were undertaken. Both twins underwent surgical intervention and subsequent voice therapy. Monozygosity was confirmed for DNA polymorphisms, with 10 of 10 concordance for STR DNA markers. For both twins, auditory- and visual-perceptual assessments indicated severe bowing, hoarseness, and breathiness, although Twin 1 was judged to be extremely severe. Differences in reference to root-mean-square amplitudes were observed for thyroarytenoid and lateral cricoarytenoid muscles, with smaller relative amplitudes observed for the Twin 1 versus Twin 2. No consistent voice improvement was observed after surgical intervention(s), despite improved mid-membranous vocal fold closure. Marked reductions in Voice Handicap Index total scores were observed after behavioral voice therapy, coinciding with increased mid-membranous and posterior laryngeal (interarytenoid) glottal closure. No substantive differences in acoustic measures were observed. Vocal fold bowing was more severe for Twin 1 versus Twin 2 despite identical heritability factors. Overall voice improvement with treatment was greater for Twin 2 than Twin 1. Environmental factors might partially account for the differences observed between the twins, including variability in their responsiveness to behavioral voice therapy. Voice therapy was useful in improving mid-membranous and posterior laryngeal closure, although dysphonia remained severe in both cases. PMID:19664899

  13. Epidemiology of twinning in the National Birth Defects Prevention Study, 1997–2007

    PubMed Central

    Dawson, April L.; Tinker, Sarah C.; Jamieson, Denise J.; Hobbs, Charlotte A.; Rasmussen, Sonja A.; Reefhuis, Jennita

    2015-01-01

    Background Our objective was to evaluate associations between twinning and maternal demographic factors and periconceptional exposures among infants with and without orofacial clefts. Methods We used data from the National Birth Defects Prevention Study; 228 twins and 8,242 singletons without birth defects (controls), and 117 twins and 2,859 singletons with orofacial clefts, born 1997–2007, were included in the analyses. Because of the occurrence of twinning due to the use of assisted reproductive technologies, logistic regression models were computed to estimate odds ratios (OR) and 95% confidence intervals (CIs) for each exposure, stratified by fertility treatment use. To evaluate factors by zygosity, we used sex-pairing data and a simulation approach to estimate the zygosity of like-sex twin pairs for unassisted conceptions. Results Among control mothers who did not use fertility treatments, predictors of twinning included non-Hispanic black maternal race (adjusted OR: 1.6, 95% CI: 1.0–2.4), and tobacco smoking (1.6, 1.1–2.4). Among control mothers who used fertility treatments, older maternal age, higher income, and state of residence were associated with twinning. Associations were generally stronger among mothers of dizygotic (estimated) twins than monozygotic (estimated) twins. Results for mothers of infants with isolated orofacial clefts were similar to those of controls. Conclusion We observed an increased twinning frequency with increasing maternal age, but factors such as maternal race/ethnicity and socioeconomic status may also contribute. Among women receiving fertility treatments, factors associated with twinning suggested a relation with treatment specifics (e.g., treatment type and number of embryos implanted) and availability of insurance coverage. PMID:25359509

  14. A test of the equal-environment assumption in twin studies of psychiatric illness.

    PubMed

    Kendler, K S; Neale, M C; Kessler, R C; Heath, A C; Eaves, L J

    1993-01-01

    The traditional twin method is predicated on the equal-environment assumption (EEA)--that monozygotic (MZ) and dizygotic (DZ) twins are equally correlated in their exposure to environmental events of etiologic importance for the trait under study. In 1968, Scarr proposed a test of the EEA which examines the impact of phenotypic similarity in twins of perceived versus true zygosity. We apply this test for the EEA to five common psychiatric disorders (major depression, generalized anxiety disorder, phobia, bulimia, and alcoholism), as assessed by personal interview, in 1030 female-female twin pairs from the Virginia Twin Registry with known zygosity. We use a newly developed model-fitting approach which treats perceived zygosity as a form of specified familial environment. In 158 of the 1030 pairs (15.3%), one or both twins disagreed with the project-assigned zygosity. Model fitting provided no evidence for a significant influence of perceived zygosity on twin resemblance for any of the five disorders. Although limited in power, these results support the validity of the EEA in twin studies of psychiatric disorders. PMID:8476388

  15. Physical similarity and the equal-environment assumption in twin studies of psychiatric disorders.

    PubMed

    Hettema, J M; Neale, M C; Kendler, K S

    1995-07-01

    The equal-environment assumption (EEA), upon which twin methodology is based, was examined for the impact of physical similarity on phenotypic resemblance in five common psychiatric disorders: major depression, generalized anxiety disorder, phobia, alcoholism, and bulimia. A population-based sample of 882 female-female twin pairs of known zygosity was rated for similarity of appearance by color photographs. Psychiatric diagnoses were made by clinical assessment of personal interviews of the twins. Structural equation modeling of the data using physical similarity as a form of specified common environment provided no evidence for a significant effect of physical resemblance on concordance for major depression, generalized anxiety disorder, phobia, and alcoholism, thereby supporting the validity of the EEA in twin studies of these disorders. Results for bulimia, on the other hand, suggest, within the limitations of this study, that physical similarity may significantly influence twin resemblance for this disorder. PMID:7575361

  16. No evidence for effects of family environment on asthma. A retrospective study of Norwegian twins.

    PubMed

    Harris, J R; Magnus, P; Samuelsen, S O; Tambs, K

    1997-07-01

    The risk of developing asthma contingent upon the co-twins' history of asthma was analyzed in a population-based study of 5,864 Norwegian twins. A primary aim was to assess the significance of shared environment for the development of asthma from infancy through age 25. Retrospective reports were collected when the twins were 18 to 25 yr of age. The risk of developing asthma, contingent upon the co-twin's history of asthma, was estimated using survival analyses, and genetic and environmental sources of variation in liability for asthma were analyzed with structural equation models. The cumulative incidence of asthma was 6% for males and 5.4% for females. The relative risk of developing asthma among twins whose co-twin had a positive history of asthma compared with those whose co-twin had no history of asthma was 17.9 (95% CI, 10.3 to 31.0) for identical, and 2.3 (95% CI, 1.2 to 4.4) for fraternal twins. Although shared environment encompasses many of the exposures that are putative risk factors for asthma in this age range, there is no evidence of shared environmental influences for asthma. Rather, 75% of the variation in liability for asthma was explained by genetic effects and the remaining variation was due to nonshared environmental influences. These results suggest that the familial risk for asthma is primarily, genetic. PMID:9230724

  17. The Louisville Twin Study: Developmental Synchronies in Behavior.

    ERIC Educational Resources Information Center

    Wilson, Ronald S.

    1983-01-01

    Results show individual differences in intelligence progressively stabilizing by school age, with each child following a distinct pattern of mental development. Monozygotic twins became increasingly concordant over an Hes and were closely matched on developmental trends. (Author/RH)

  18. Is "g" an Entity? A Japanese Twin Study Using Syllogisms and Intelligence Tests

    ERIC Educational Resources Information Center

    Shikishima, Chizuru; Hiraishi, Kai; Yamagata, Shinji; Sugimoto, Yutaro; Takemura, Ryo; Ozaki, Koken; Okada, Mitsuhiro; Toda, Tatsushi; Ando, Juko

    2009-01-01

    Using a behavioral genetic approach, we examined the validity of the hypothesis concerning the singularity of human general intelligence, the "g" theory, by analyzing data from two tests: the first consisted of 100 syllogism problems and the second a full-scale intelligence test. The participants were 448 Japanese young adult twins (167 pairs of…

  19. Intended Sensitive and Harsh Caregiving Responses to Infant Crying: The Role of Cry Pitch and Perceived Urgency in an Adult Twin Sample

    ERIC Educational Resources Information Center

    Out, Dorothee; Pieper, Suzanne; Bakermans-Kranenburg, Marian J.; Zeskind, Philip Sanford; van IJzendoorn, Marinus H.

    2010-01-01

    Objective: To examine the underlying mechanisms of adults' intended caregiving responses to cry sounds in a behavioral genetic design and to investigate the role of cry pitch and perceived urgency in sensitive and harsh caregiving responses. Methods: The sample consisted of 184 adult twin pairs (18-69 years), including males and females, parents…

  20. Heritability of the neural response to emotional pictures: evidence from ERPs in an adult twin sample

    PubMed Central

    Venables, Noah C.; Proudfit, Greg Hajcak; Patrick, Christopher J.

    2015-01-01

    Affect-modulated event-related potentials (ERPs) are increasingly used to study psychopathology and individual differences in emotion processing. Many have suggested that variation in these neural responses reflects genetically mediated risk. However, to date, no studies have demonstrated genetic contributions to affect-modulated ERPs. The present study therefore sought to examine the heritability of a range of ERPs elicited during affective picture viewing. One hundred and thirty monozygotic and 124 dizygotic twin pairs passively viewed 30 pleasant, 30 neutral and 30 unpleasant images for 6 s each. The early posterior negativity was scored for each subject; in addition, the P300/late positive potential (LPP) was scored in multiple time windows and sites. Results indicate that the centro-parietal P300 (occurring between 300 and 600 ms) is subject to substantial genetic contributions. Furthermore, variance in the P300 elicited by affective stimuli was moderately heritable even after controlling for the P300 elicited by neutral stimuli. Later and more frontal activation (i.e. between 1000 and 3000 ms) also showed evidence of heritablity. Early parietal, and perhaps later frontal portions of the P300/LPP complex, may therefore represent promising neurobehavioral markers of genetically influenced processing of emotional information. PMID:24795435

  1. Temperament and Character in the Child and Adolescent Twin Study in Sweden (CATSS): Comparison to the General Population, and Genetic Structure Analysis

    PubMed Central

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

    2013-01-01

    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 shared

  2. Different Origin of Auditory and Phonological Processing Problems in Children with Language Impairment: Evidence from a Twin Study.

    ERIC Educational Resources Information Center

    Bishop, D. V. M.; Bishop, Sonia J.; Bright, Peter; James, Cheryl; Delaney, Tom; Tallal, Paula

    1999-01-01

    A study involving 55 children with a language impairment and 76 with normal language investigated the heritability of auditory processing impairment in same-sex twins (ages 7 to 13, selected from a sample of 37 pairs). Although correlations between co-twins were high, lack of significant difference between monozygotic and dizygotic twins suggested…

  3. Registry of adolescent and young adult twins in the Tokyo area.

    PubMed

    Shikishima, Chizuru; Ando, Juko; Ono, Yutaka; Toda, Tatsushi; Yoshimura, Kimio

    2006-12-01

    Since established in 1998, the Keio Twin Project (KTP) has been dedicated to investigating genetic and environmental sources contributing to human psychological traits in adolescence and young adulthood. A population-based twin registry was constructed by the KTP through the use of official residential records in the Tokyo area, and to date requests to participate in our research have generated 1040 pairs of twins and triplets of age 14 to 30, forming one of the largest twin registries in Asia. Our comprehensive datasets, obtained through questionnaires, performance tests, and physical measurements, cover a wide range of human traits: personality, psychiatry, mental health, sociality, cognition, and physical index. Demographic variables and environment of upbringing are also sought by twins and by some parents. This extensive information allows us to clarify the genetic and environmental overlap across multiple traits as well as specificities unique to single traits. Adding an evolutionary psychology perspective to the behavior genetics framework is currently being attempted in order to develop a grand theory of human genetics. PMID:17254414

  4. A longitudinal study of epigenetic variation in twins

    PubMed Central

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

    2010-01-01

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

  5. The Longitudinal Israeli Study of Twins (LIST)-an integrative view of social development.

    PubMed

    Avinun, Reut; Knafo, Ariel

    2013-02-01

    The Longitudinal Israeli Study of Twins (LIST) is a social developmental study, which implements social-developmental, molecular genetic, epigenetic, and behavioral genetic methods to advance knowledge on the development of individual differences in social behavior. Twins are followed from the age of three and both observational and parental-questionnaire data are collected on their empathy, temperament, and pro-social behavior. The parenting styles of parents are also evaluated using self-reports and observations and DNA samples are collected from parents and twins. In the current paper, we provide a review of our recent work and discuss the future aims of the LIST. PMID:23394191

  6. 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.

    PubMed

    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. PMID:24774649

  7. Twin studies of posttraumatic stress disorder: differentiating vulnerability factors from sequelae.

    PubMed

    Kremen, William S; Koenen, Karestan C; Afari, Niloofar; Lyons, Michael J

    2012-02-01

    Posttraumatic stress disorder (PTSD) is defined by one's response to an environmental event. However, genetic factors are important in determining people's response to that event, and even their likelihood of being exposed to particular traumatic events in the first place. Classical twin designs can decompose genetic and environmental sources of variance. Such studies are reviewed extensively elsewhere, and we cover them only briefly in this review. Instead, we focus primarily on the identical co-twin control design. This design makes it possible to resolve the "chicken-egg" dilemma inherent in standard case-control designs, namely, distinguishing risk from sequelae. Abnormalities that are present in both the twin with PTSD and the unaffected co-twin suggest pre-existing vulnerability indicators. These include smaller hippocampal volume, large cavum septum pellucidum, more neurological soft signs, lower general intellectual ability, and poorer performance in the specific cognitive abilities of executive function, attention, declarative memory, and processing of contextual cues. In contrast, abnormalities in a twin with PTSD that are not present in the identical co-twin suggest consequences of PTSD or trauma exposure. These include psychophysiological responding, higher resting anterior cingulate metabolism, event-related potential abnormalities associated with attentional processes, recall intrusions, and possibly some types of chronic pain. Most co-twin control studies of PTSD have been small and come from the same twin registry of middle-aged male veterans. Consequently, there is a great need for replication and extension of the findings, particularly in women and younger individuals. The creation of new twin registries would do much toward accomplishing this goal. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'. PMID:21443892

  8. The Stability of Genetic Determination from Age 2 to Age 9: A Longitudinal Twin Study.

    ERIC Educational Resources Information Center

    Lytton, Hugh; And Others

    A longitudinal investigation of the social and cognitive development of male twins was conducted when twins were 2.5 years of age, and again when they were 8- to 10-years-old. This study was designed to re-examine the heritability of the traits studied at the earlier age and, thus, to address the question of the stability of genetic determination.…

  9. Sexual Behavior in Young Adulthood: A Population-Based Twin Study

    PubMed Central

    Mustanski, Brian; Viken, Richard J.; Kaprio, Jaakko; Winter, Torsten; Rose, Richard J.

    2007-01-01

    Objective With behavior genetic analyses of data from young adult twins, we evaluated theoretical perspectives that differentially emphasize biological dispositions, social/cultural factors, or universal pathways to explain individual differences in sexual behaviors. Design We fit biometric sex limitation models to three aspects of sexual behavior reported by 4,925 Finnish twins aged 23–27. The sample, from five consecutive birth cohorts, of 2,448 twin pairs (886 sister-sister, 862 brother-sister, 700 brother-brother), included 785 monozygotic and 801 same-sex dizygotic pairs. In addition to model fitting data from twin pairs, we conducted analyses on twins as individuals to test for independence of initiation of sexual behavior from onset age and number of partners. Main Outcome Measures From a postal questionnaire, we obtained self-report information on initiation/abstinence of sexual intercourse, onset age, and number of sexual partners. Results Genetic and non-shared environmental influences were significant for all three measures. There were trends for common environmental influences on initiation and, in females, age at first intercourse. Some differential effects in males and females were found. Results comparing onset age and number of partners among experienced twins from pairs concordant and discordant for initiation found genetic and environmental influences on initiation/abstinence overlapped those found for the other aspects of sexual behavior. Conclusions These results document genetic variation in individual differences in sexual behavior of young adults. Incorporating genetic dispositions into integrated models of sexual behavior will facilitate more effective health promotion and risk taking intervention. PMID:17845112

  10. An Update on the Florida State Twin Registry

    PubMed Central

    Taylor, Jeanette E.; Hart, Sara A.; Mikolajewski, Amy J.

    2012-01-01

    The Florida State Twin Registry began in 2002 through a pilot study of personality disorders and executive cognitive functioning in adult twins. Since 2006, the registry has grown substantially as part of the Learning Disability Research Center at Florida State University that recently began its second funding cycle through the National Institute of Child Health and Development. An update on the Florida State Twin Registry sample, focus, and measures is provided as well as future directions. PMID:23067863

  11. MAOA Genotype, Childhood Trauma and Subclinical Atherosclerosis: A Twin Study

    PubMed Central

    Zhao, Jinying; Bremner, James D.; Goldberg, Jack; Quyyumi, Arshed A.; Vaccarino, Viola

    2013-01-01

    Objective A functional promoter polymorphism in the MAOA gene has been implicated in neuropsychiatric disorders and also moderates the association between early life stress and mental disorders, which often co-occur with cardiovascular disease. No study has examined the relationship between MAOA genotype, childhood trauma and subclinical atherosclerosis. The objective of this investigation was to examine whether childhood trauma moderates the association between MAOA genotype and subclinical atherosclerosis. Methods A sample including 289 middle-aged male twin pairs was studied. Subclinical atherosclerosis was assessed by brachial flow-mediated dilation (FMD) using ultrasound. Childhood trauma, before age 18, was measured with the Early Trauma Inventory and included physical, emotional, and sexual abuse as well as general trauma. Generalized estimating equation models were used to test the main and interactive effects of the MAOA genotype and each domain of childhood trauma on FMD, adjusting for known risk factors. Results General trauma was the most prevalent childhood trauma (28.4%), followed by physical abuse (25.0%), emotional abuse (19.4%) and sexual abuse (11.6%). MAOA genotype was not associated with any domain of childhood trauma (β ≥ 0.36). There was no significant evidence for a main effect for the MAOA genotype (β = 0.02, p = 0.82) or childhood trauma (0.005 < β < 0.10, p > 0.54) on early atherosclerosis. However, a significant interaction was observed between MAOA genotype and physical (βinteraction = 0.37, p = 0.026) or emotional abuse (βinteraction = 0.43, p = 0.025) on subclinical atherosclerosis. Conclusion This study provides initial evidence that childhood trauma modulates the impact of MAOA variant on subclinical atherosclerosis, independent of traditional cardiovascular risk factors. PMID:23723362

  12. A Twin Study of the Etiology of High Reading Ability.

    ERIC Educational Resources Information Center

    Boada, Richard; Willcutt, Erik G.; Tunick, Rachel A.; Chhabildas, Nomita A.; Olson, Richard K.; DeFries, John C.; Pennington, Bruce F.

    2002-01-01

    Examines the etiology of high reading ability in twin pairs. Suggests that reading ability and its cognitive correlates are on a continuous distribution, with both extremes of the distribution being similarly heritable. Supports the hypothesis that the same cognitive processes that are associated with dyslexia are important for the development of…

  13. Exploring Genetic and Environmental Effects in Dysphonia: A Twin Study

    ERIC Educational Resources Information Center

    Simberg, Susanna; Santtila, Pekka; Soveri, Anna; Varjonen, Markus; Sala, Eeva; Sandnabba, N. Kenneth

    2009-01-01

    Purpose: To explore the existence of genetic effects as well as the interaction between potential genetic effects and a voice-demanding occupation on dysphonia. Method: One thousand seven hundred and twenty-eight Finnish twins (555 male; 1,173 female) born between 1961 and 1989 completed a questionnaire concerning vocal symptoms and occupation.…

  14. Difficulty in SLI Diagnosis: A Case Study of Identical Twins

    ERIC Educational Resources Information Center

    Tommerdahl, Jodi; Drew, Marguerite

    2008-01-01

    This paper examines identical 12-year-old twins with language difficulties, one of whom falls into the diagnostic remit of SLI while the other does not due to IQ differences. Further diagnostic testing was carried out and their language was analysed to determine whether their diagnoses were reflected by different linguistic abilities. Results show…

  15. A Longitudinal Twin Study of Intelligence in the Second Year.

    ERIC Educational Resources Information Center

    Reznick, J. Steven; And Others

    1997-01-01

    Examined data from 408 pairs of identical, same-sex fraternal twins at 14, 20, and 24 months to assess cognitive development and to identify genetic and environmental influences on phenotypic similarity. Found various patterns of development for separate constructs, for females versus males on each construct, and for individuals across constructs.…

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

    ERIC Educational Resources Information Center

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

    2010-01-01

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

  17. A Twin Study of Objectively Assessed Personality in Childhood.

    ERIC Educational Resources Information Center

    Plomin, Robert; Foch, Terryl T.

    1980-01-01

    Obtained objective measures of activity, fidgeting, vigilance, selective attention, and aggression for a sample of 87 twin pairs in late childhood. Little evidence for genetic influence on behavior was found. Between-family environmental sources of variance were far more important than within-family factors. (Author/RH)

  18. Genetic and environmental effects on openness to experience, agreeableness, and conscientiousness: an adoption/twin study.

    PubMed

    Bergeman, C S; Chipuer, H M; Plomin, R; Pedersen, N L; McClearn, G E; Nesselroade, J R; Costa, P T; McCrae, R R

    1993-06-01

    Previous research has indicated that extraversion and neuroticism are substantially affected both by genotype and environment. This study assesses genetic and environmental influences on the other three components of the five-factor model of personality: Openness to Experience, Agreeableness, and Conscientiousness. An abbreviated version of the NEO Personality Inventory (NEO-PI) was administered to 82 pairs of identical twins and 171 pairs of fraternal twins reared apart and 132 pairs of identical twins and 167 pairs of fraternal twins reared together. Estimates of genetic and environmental effects for Openness and Conscientiousness were similar to those found in other studies of personality: Genetic influence was substantial and there was little evidence of shared rearing environment. Results for Agreeableness were different: Genetic influence accounted for only 12% of the variance and shared rearing environment accounted for 21% of the variance. Few significant gender or age differences for genetic and environmental parameters were found in model-fitting analyses. PMID:8345444

  19. Twin Studies of Atopic Dermatitis: Interpretations and Applications in the Filaggrin Era

    PubMed Central

    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 about filaggrin and its role in the atopic march and provide suggestions for future research in this area. Methods. We identified all twin studies (published after 1970) that have calculated the concordance rate and/or the heritability of AD, or the genetic and environmental correlations between AD and asthma. Results. Reported concordance rates for AD ranged, respectively. From 0.15 to 0.86 for MZ and from 0.05 to 0.41 for DZ twins, with an overall ratio of MZ : DZ twins of approximately three. The heritability of AD was estimated to be approximately 75%, and the association between AD and asthma was around 85% explained by genetic pleiotropy. Conclusions. Genetic factors account for most of the variability in AD susceptibility and for the association between AD and asthma. Controversy remains as to whether the atopic diseases are causally related or whether they are diverse clinical manifestations of a common, underlying (genetic) disease trait. Future twin studies may help solve this enigma. PMID:26448767

  20. Twin Mitochondrial Sequence Analysis.

    PubMed

    Bouhlal, Yosr; Martinez, Selena; Gong, Henry; Dumas, Kevin; Shieh, Joseph T C

    2013-09-01

    When applying genome-wide sequencing technologies to disease investigation, it is increasingly important to resolve sequence variation in regions of the genome that may have homologous sequences. The human mitochondrial genome challenges interpretation given the potential for heteroplasmy, somatic variation, and homologous nuclear mitochondrial sequences (numts). Identical twins share the same mitochondrial DNA (mtDNA) from early life, but whether the mitochondrial sequence remains similar is unclear. We compared an adult monozygotic twin pair using high throughput-sequencing and evaluated variants with primer extension and mitochondrial pre-enrichment. Thirty-seven variants were shared between the twin individuals, and the variants were verified on the original genomic DNA. These studies support highly identical genetic sequence in this case. Certain low-level variant calls were of high quality and homology to the mitochondrial DNA, and they were further evaluated. When we assessed calls in pre-enriched mitochondrial DNA templates, we found that these may represent numts, which can be differentiated from mtDNA variation. We conclude that twin identity extends to mitochondrial DNA, and it is critical to differentiate between numts and mtDNA in genome sequencing, particularly since significant heteroplasmy could influence genome interpretation. Further studies on mtDNA and numts will aid in understanding how variation occurs and persists. PMID:24040623

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

    PubMed

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

    2015-06-01

    Asthma is a common childhood disease and several risk factors have been identified; however, the impact of genes and environment is not fully understood. The aim of the Swedish Twin study On Prediction and Prevention of Asthma (STOPPA) is to identify environmental (birth characteristics and early life) and genetic (including epigenetic) factors as determinants for asthmatic disease. Based on the Child and Adolescent Twin Study in Sweden (CATSS) (parental interview at 9 or 12 years, N ~23,900) and an asthma and/or wheezing algorithm, we identified a sample of monozygotic (MZ) and dizygotic (DZ) same-sexed twin pairs. The twin pairs were classified as asthma concordant (ACC), asthma discordant (ADC) and healthy concordant (HCC). A sample of 9- to 14-year-old twins and their parents were invited to participate in a clinical examination. Background characteristics were collected in questionnaires and obtained from the National Health Registers. A clinical examination was performed to test lung function and capacity (spirometry with reversibility test and exhaled nitric oxide) and collect blood (serology and DNA), urine (metabolites), feces (microbiota), and saliva (cortisol). In total, 376 twin pairs (752 individual twins) completed the study, response rate 52%. All participating twins answered the questionnaire and >90% participated in lung function testing, blood-, and saliva sampling. This article describes the design, recruitment, data collection, measures, and background characteristics, as well as ongoing and planned analyses in STOPPA. Potential gains of the study include the identification of biomarkers, the emergence of candidates for drug development, and new leads for prevention of asthma and allergic disease. PMID:25900604

  2. Conjoined twins.

    PubMed

    Pearce, K M; Mohler, C P; Housel, D; Schipul, A H; Crosby, W M

    1995-06-01

    Conjoined twins, otherwise known as Siamese twins, have fascinated physicians and laymen alike for centuries. The minimal diagnostic criteria for conjoined twins is the fusion of some portion of mononuclear or monozygotic twins. PMID:7629608

  3. The Genetic and Environmental Contributions to Internet Use and Associations With Psychopathology: A Twin Study.

    PubMed

    Long, Elizabeth C; Verhulst, Brad; Neale, Michael C; Lind, Penelope A; Hickie, Ian B; Martin, Nicholas G; Gillespie, Nathan A

    2016-02-01

    Excessive internet use has been linked to psychopathology. Therefore, understanding the genetic and environmental risks underpinning internet use and their relation to psychopathology is important. This study aims to explore the genetic and environmental etiology of internet use measures and their associations with internalizing disorders and substance use disorders. The sample included 2,059 monozygotic (MZ) and dizygotic (DZ) young adult twins from the Brisbane Longitudinal Twin Study (BLTS). Younger participants reported more frequent internet use, while women were more likely to use the internet for interpersonal communication. Familial aggregation in 'frequency of internet use' was entirely explained by additive genetic factors accounting for 41% of the variance. Familial aggregation in 'frequency of use after 11 pm', 'using the internet to contact peers', and 'using the internet primarily to access social networking sites' was attributable to varying combinations of additive genetic and shared environmental factors. In terms of psychopathology, there were no significant associations between internet use measures and major depression (MD), but there were positive significant associations between 'frequency of internet use' and 'frequency of use after 11 pm' with social phobia (SP). 'Using the internet to contact peers' was positively associated with alcohol abuse, whereas 'using the internet to contact peers' and 'using the internet primarily to access social networking sites' were negatively associated with cannabis use disorders and nicotine symptoms. Individual differences in internet use can be attributable to varying degrees of genetic and environmental risks. Despite some significant associations of small effect, variation in internet use appears mostly unrelated to psychopathology. PMID:26693596

  4. The Genetic and Environmental Contributions to Internet Use and Associations With Psychopathology: A Twin Study

    PubMed Central

    Long, Elizabeth C.; Verhulst, Brad; Neale, Michael C.; Lind, Penelope A.; Hickie, Ian B.; Martin, Nicholas G.; Gillespie, Nathan A.

    2016-01-01

    Excessive internet use has been linked to psychopathology. Therefore, understanding the genetic and environmental risks underpinning internet use and their relation to psychopathology is important. This study aims to explore the genetic and environmental etiology of internet use measures and their associations with internalizing disorders and substance use disorders. The sample included 2,059 monozygotic (MZ) and dizygotic (DZ) young adult twins from the Brisbane Longitudinal Twin Study (BLTS). Younger participants reported more frequent internet use, while women were more likely to use the internet for interpersonal communication. Familial aggregation in ‘frequency of internet use’ was entirely explained by additive genetic factors accounting for 41% of the variance. Familial aggregation in ‘frequency of use after 11 pm’, ‘using the internet to contact peers’, and ‘using the internet primarily to access social networking sites’ was attributable to varying combinations of additive genetic and shared environmental factors. In terms of psychopathology, there were no significant associations between internet use measures and major depression (MD), but there were positive significant associations between ‘frequency of internet use’ and ‘frequency of use after 11 pm’ with social phobia (SP). ‘Using the internet to contact peers’ was positively associated with alcohol abuse, whereas ‘using the internet to contact peers’ and ‘using the internet primarily to access social networking sites’ were negatively associated with cannabis use disorders and nicotine symptoms. Individual differences in internet use can be attributable to varying degrees of genetic and environmental risks. Despite some significant associations of small effect, variation in internet use appears mostly unrelated to psychopathology. PMID:26693596

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  6. Behavioral and Environmental Modification of the Genetic Influence on Body Mass Index: A Twin Study.

    PubMed

    Horn, Erin E; Turkheimer, Eric; Strachan, Eric; Duncan, Glen E

    2015-07-01

    Body mass index (BMI) has a strong genetic basis, with a heritability around 0.75, but is also influenced by numerous behavioral and environmental factors. Aspects of the built environment (e.g., environmental walkability) are hypothesized to influence obesity by directly affecting BMI, by facilitating or inhibiting behaviors such as physical activity that are related to BMI, or by suppressing genetic tendencies toward higher BMI. The present study investigated relative influences of physical activity and walkability on variance in BMI using 5079 same-sex adult twin pairs (70 % monozygotic, 65 % female). High activity and walkability levels independently suppressed genetic variance in BMI. Estimating their effects simultaneously, however, suggested that the walkability effect was mediated by activity. The suppressive effect of activity on variance in BMI was present even with a tendency for low-BMI individuals to select into environments that require higher activity levels. Overall, our results point to community- or macro-level interventions that facilitate individual-level behaviors as a plausible approach to addressing the obesity epidemic among US adults. PMID:25894925

  7. Behavioral and environmental modification of the genetic influence on body mass index: A twin study

    PubMed Central

    Horn, Erin E.; Turkheimer, Eric; Strachan, Eric; Duncan, Glen E.

    2015-01-01

    Body mass index (BMI) has a strong genetic basis, with a heritability around 0.75, but is also influenced by numerous behavioral and environmental factors. Aspects of the built environment (e.g., environmental walkability) are hypothesized to influence obesity by directly affecting BMI, by facilitating or inhibiting behaviors such as physical activity that are related to BMI, or by suppressing genetic tendencies toward higher BMI. The present study investigated relative influences of physical activity and walkability on variance in BMI using 5,079 same-sex adult twin pairs (70% monozygotic, 65% female). High activity and walkability levels independently suppressed genetic variance in BMI. Estimating their effects simultaneously, however, suggested that the walkability effect was mediated by activity. The suppressive effect of activity on variance in BMI was present even with a tendency for low-BMI individuals to select into environments that require higher activity levels. Overall, our results point to community- or macro-level interventions that facilitate individual-level behaviors as a plausible approach to addressing the obesity epidemic among U.S. adults. PMID:25894925

  8. Posttraumatic Stress Disorder and Incidence of Coronary Heart Disease: A Twin Study

    PubMed Central

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

    2013-01-01

    Objectives To determine whether posttraumatic stress disorder (PTSD) is associated with coronary heart disease (CHD) using a prospective twin study design and objective measures of CHD. Background It has long been hypothesized that PTSD increases the risk of CHD but empirical evidence using objective measures is limited. Methods 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 [N13] positron emission tomography, including a stress total severity score (STSS) and coronary flow reserve (CFR). Results A total of 562 twins (281 pairs) were included with mean age of 42.6 yrs at baseline. The incidence of CHD was more than double in twins with PTSD (22.6%) than those without PTSD (8.9%; p<0.001). The association remained robust after adjusting for lifestyle factors, other CHD risk factors and major depression (OR=2.2, 95% confidence interval, 1.2-4.1). STSS was significantly higher (+ 95%, p=0.001) and CFR lower (−0.21, p=0.02) in twins with PTSD than those without, denoting worse myocardial perfusion. Associations were only mildly attenuated within 117 twin pairs discordant for PTSD. Conclusions Among Vietnam era veterans, PTSD is a risk factor for CHD. PMID:23810885

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

    PubMed

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

    2016-09-01

    Psychotic disorders and major depression, both typically adult-onset conditions, often co-occur. At younger ages psychotic experiences and depressive symptoms are often reported in the community. We used a genetically sensitive longitudinal design to investigate the relationship between psychotic experiences and depressive symptoms in adolescence. A representative community sample of twins from England and Wales was employed. Self-rated depressive symptoms, paranoia, hallucinations, cognitive disorganization, grandiosity, anhedonia, and parent-rated negative symptoms were collected when the twins were age 16 (N = 9618) and again on a representative subsample 9 months later (N = 2873). Direction and aetiology of associations were assessed using genetically informative cross-lagged models. Depressive symptoms were moderately correlated with paranoia, hallucinations, and cognitive disorganization. Lower correlations were observed between depression and anhedonia, and depression and parent-rated negative symptoms. Nonsignificant correlations were observed between depression and grandiosity. Largely the same genetic effects influenced depression and paranoia, depression and hallucinations, and depression and cognitive disorganization. Modest overlap in environmental influences also played a role in the associations. Significant bi-directional longitudinal associations were observed between depression and paranoia. Hallucinations and cognitive disorganization during adolescence were found to impact later depression, even after controlling for earlier levels of depression. Our study shows that psychotic experiences and depression, as traits in the community, have a high genetic overlap in mid-adolescence. Future research should test the prediction stemming from our longitudinal results, namely that reducing or ameliorating positive and cognitive psychotic experiences in adolescence would decrease later depressive symptoms. PMID:26994398

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

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  11. Associations between Sexual Abstinence Ideals, Religiosity, and Alcohol Abstinence: A Longitudinal Study of Finnish Twins

    PubMed Central

    Winter, Torsten; Karvonen, Sakari; Rose, Richard J.

    2016-01-01

    We analyzed prevalence and stability of attitudes endorsing sexual abstinence ideals from late adolescence into early adulthood and studied associations of these attitudes with religiosity and alcohol abstinence in a sexually liberal Nordic society. Our population-based sample of Finnish twins permitted comparisons of co-twins concordant for religiosity but discordant for drinking to evaluate the association of sexual abstinence ideals with alcohol abstinence, controlling for household environment. From age 17 to 24, endorsement of sexual abstinence as a romantic ideal declined from 25% to 15%. Religiosity and alcohol abstinence correlated, both separately and together, with endorsing sexual abstinence. Abstinence ideals were associated with literal belief in fundamental tenets of the Bible. The association of sexual abstinence ideals with alcohol abstinence was confirmed in within-family comparisons of co-twins discordant for drinking but concordant for religiosity. Alcohol-abstinent twins were significantly more likely than their non-alcohol-abstinent twin siblings to endorse sexual abstinence ideals; that result suggests the association of sexual abstinence ideals with abstaining from alcohol is not explained by unmeasured confounds in familial background and structure. Our longitudinal results and analyses of discordant twins suggest that attitudes toward sexual abstinence ideals are embedded within other conservative attitudes and behaviors. PMID:23301620

  12. The heritability of alcohol use disorders: a meta-analysis of twin and adoption studies

    PubMed Central

    Verhulst, B.; Neale, M. C.; Kendler, K. S.

    2014-01-01

    Background To clarify the role of genetic and environmental risk factors in alcohol use disorders (AUDs), we performed a meta-analysis of twin and adoption studies and explored the impact of sex, assessment method (interview v. hospital/population records), and study design (twin v. adoption study) on heritability estimates. Method The literature was searched for all unique twin and adoption studies of AUD and identified 12 twin and five adoption studies. The data were then reconstructed and analyzed using ordinal data full information maximum likelihood in the OpenMx program. Heterogeneity was tested with likelihood ratio tests by equating the parameters across studies. Results There was no evidence for heterogeneity by study design, sex or assessment method. The best-fit estimate of the heritability of AUD was 0.49 [95% confidence interval (CI) 0.43–0.53], and the proportion of shared environmental variance was 0.10 (95% CI 0.03–0.16). Estimates of unique environmental proportions of variance differed significantly across studies. Conclusions AUD is approximately 50% heritable. The multiple genetically informative studies of this syndrome have produced consistent results that support the validity of this heritability estimate, especially given the different potential methodological weaknesses of twin and adoption designs, and of assessments of AUD based on personal interviews v. official records. We also found evidence for modest shared environmental effects suggesting that environmental factors also contribute to the familial aggregation of AUDs. PMID:25171596

  13. Heritability in Inflammatory Bowel Disease: From the First Twin Study to Genome-Wide Association Studies

    PubMed Central

    Trier Moller, Frederik; Andersen, Vibeke; Harbord, Marcus

    2015-01-01

    Abstract: Since Tysk et al's pioneering analysis of the Swedish twin registry, twin and family studies continue to support a strong genetic basis of the inflammatory bowel diseases. The coefficient of heritability for siblings of inflammatory bowel disease probands is 25 to 42 for Crohn's disease and 4 to 15 for ulcerative colitis. Heritability estimates for Crohn's disease and ulcerative colitis from pooled twin studies are 0.75 and 0.67, respectively. However, this is at odds with the much lower heritability estimates from Genome-Wide Association Studies (GWAS). This “missing heritability” is likely due to shortfalls in both family studies and GWAS. The coefficient of heritability fails to account for familial shared environment. Heritability calculations from twin data are based on Falconer's method, with premises that are increasingly understood to be flawed. GWAS based heritability estimates may underestimate heritability due to incomplete linkage disequilibrium, and because some single nucleotide polypeptides (SNPs) do not reach a level of significance to allow detection. SNPs missed by GWAS include common SNPs with low penetrance and rare SNPs with high penetrance. All methods of heritability estimation regard genetic and environmental variance as separate entities, although it is now understood that there is a complex multidirectional interplay between genetic are environmental factors mediated by the microbiota, the epigenome, and the innate and acquired immune systems. Due to the limitations of heritability estimates, it is unlikely that a true value for heritability will be reached. Further work aimed at quantifying the variance explained across GWAS, epigenome-wide, and microbiota-wide association studies will help to define factors leading to inflammatory bowel disease. PMID:25895112

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

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  15. Analytical study of the twin-jet shielding

    NASA Technical Reports Server (NTRS)

    Gerhold, C. H.

    1983-01-01

    The development of the analytical model of twin-jet shielding is summarized. The models consist of a point noise source impinging on a cylinder of heated flow in which the temperature and flow velocity are uniform cross the cross section. In the formulation of the model, the wave equations are written for the regions outside the flow and within the flow cylinder. The solutions to the wave equations are matched at the jet boundary under the conditions of continuity of pressure and continuity of the vortex sheet. The solution reduces to an indefinite integral involving Bessel functions. The integral is solved approximately using a saddle point method.

  16. The Beijing Twin Study (BeTwiSt): a longitudinal study of child and adolescent development.

    PubMed

    Chen, Jie; Li, Xinying; Zhang, Jianxin; Natsuaki, Misaki N; Leve, Leslie D; Harold, Gordon T; Chen, Zhiyan; Yang, Xiaodong; Guo, Fei; Zhang, Jie; Ge, Xiaojia

    2013-02-01

    Rates of emotional and behavioral problems among children and adolescents in China are increasing and represent a major public health concern. To investigate the etiology of such problems, including the effects and interplay of genes and environment, the Beijing Twin Study (BeTwiSt) was established. A representative sample of adolescent twins in Beijing (N = 1,387 pairs of adolescent twins, mostly between the ages of 10 and 18 years) was recruited and assessed longitudinally. Data collection included the following: emotional and behavioral problems (e.g., depressive symptoms, anxiety, delinquency, drinking, and smoking); family, peer, and school environments; stress; social and academic competence; cognitive traits (e.g., emotion suppression, rumination, and effortful control); and saliva samples for DNA genotyping and sequencing. The combination of quantitative and molecular genetic approaches and the timeliness of the project, with the sample residing in a region with a rapidly changing economic and cultural climate, are particular strengths of this study. Findings from this study are expected to help understanding of the etiological mechanisms underlying child and adolescent normal and abnormal development in regions undergoing substantial social, cultural, and economic changes. PMID:23177327

  17. The Host Genotype and Environment Affect Strain Types of Bifidobacterium longum subsp. longum Inhabiting the Intestinal Tracts of Twins

    PubMed Central

    Zhang, Min; Hang, Xiaomin; Tan, Jing

    2015-01-01

    To investigate the influences of host genotype and environment on Bifidobacterium longum subsp. longum inhabiting human intestines at the strain level, six pairs of twins, divided into two groups (children and adults), were recruited. Each group consisted of two monozygotic (MZ) twin pairs and one dizygotic (DZ) twin pair. Child twins had been living together from birth, while adult twins had been living separately for 5 to 10 years. A total of 345 B. longum subsp. longum isolates obtained from 60 fecal samples from these twins were analyzed by multilocus sequence typing (MLST), and 35 sequence types (STs) were finally acquired. Comparison of strains within and between the twin pairs showed that no strains with identical STs were observed between unrelated individuals or within adult DZ twin pairs. Eight STs were found to be monophyletic, existing within MZ twins and child DZ twins. The similarity of strain types within child cotwins was significantly higher than that within adult cotwins, which indicated that environment was one of the important determinants in B. longum subsp. longum strain types inhabiting human intestines. However, although these differences between MZ and DZ twins were observed, it is still difficult to reach an exact conclusion about the impact of host genotype. This is mainly because of the limited number of subjects tested in the present study and the lack of strain types tracing in the same twin pairs from birth until adulthood. PMID:25956768

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

    PubMed

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

    2013-02-01

    This update on the Southern Illinois Twins and Siblings Study (SITSS) documents some of the follow-up studies that have been conducted and results that have been obtained from this sample. At the current time, 283 twin pairs, 8 triplet families, 98 non-twin sibling pairs, and 287 singletons have been enrolled in SITSS. Twins and triplets are tested as young as 1 year of age and then every year on their birthday through age 5 years. A variety of follow-up studies have been conducted for SITSS children through age 20. Results thus far have demonstrated significant genetic influences on social behaviors such as aggression, victimization, and attention toward facial expressions. Interesting interactions have been documented between the dopamine receptor D4 gene (DRD4) and the social environment (parental sensitivity or peer aggression) as they predict children's aggressive behaviors. In addition, increased difficulty with social interactions has been noted for twins versus singletons. Thus, this multi-trait, multi-method behavior genetic data set contributes to our understanding of the etiology of social behaviors in preschoolers and to predictors of similar behaviors through adolescence. PMID:23046641

  19. A twin study of differences in the response of plasma ghrelin to a milkshake preload in restrained eaters

    PubMed Central

    Myhre, Rachel; Kratz, Mario; Goldberg, Jack; Polivy, Janet; Melhorn, Susan; Buchwald, Dedra; Cummings, David E.; Schur, Ellen A.

    2014-01-01

    Background Genetic, physiological, and psychological factors can affect food intake, but twin studies can distinguish inherited from environmental contributors. We examined the influence of attempted cognitive control of eating (“restrained eating”) on levels of appetite-regulating hormones. Methods Sixteen female, monozygotic twin pairs, discordant for Restraint Scale score (i.e., one twin a restrained eater with score > 15 whereas the co-twin was unrestrained), were selected from the University of Washington Twin Registry. Serial plasma ghrelin concentrations were monitored during meals and a preload study paradigm involving intake of a milkshake followed by an ad libitum ice cream “taste test.” Results Body weight, body mass index, resting energy expenditure, and fasting leptin levels were very similar between restrained and unrestrained twins. In a preload study, twins ate similar amounts of ice cream shortly after drinking identical milkshakes (mean ±SD; restrained 239 ±158 vs. unrestrained 228 ±132 kilocalories; P = 0.83). However, ghrelin concentrations during the preload study were significantly higher (P = 0.03) in restrained twins than in their unrestrained co-twins. Regardless of restraint status, ghrelin levels prior to the preload study were prospectively and positively associated with ice cream intake (P = 0.001). Conclusions Compared to their unrestrained co-twins, restrained twins had higher endogenous ghrelin levels during a preload study, but ate similar amounts. This finding is consistent with exertion of cognitive control relative to the state of physiologic appetite stimulation. Moreover, these findings in twins suggest that higher ghrelin levels result from restrained eating behavior and not from genetic predisposition. PMID:24534168

  20. Genetic control of ethanol action on the central nervous system. An EEG study in twins.

    PubMed

    Propping, P

    1977-03-14

    The purpose of the investigation is to claify the genetic contribution to the interindividual variability of ethanol action on the central nervous system. The 52 adult male healthy twin pairs (26 MZ, 26 DZ) got 1.2 ml/kg ethanol p.o. under standardized conditions; furthermore, 13 non-twin subjects were repeatedly subjected to the same procedure in order to test the intraindividual variability. The EEG was recorded before and 60, 120, 180, and 240 min after alcohol intake. The EEGs were off-line analyzed by means of a computer program for time domain analysis. As was already known, on the average alcohol led to a better synchronisation of the EEG, i.e., the number of beta-waves decreased whereas the number of alpha- and theta-waves increased. The extent of the alcohol effect on the EEG varied enormously between individuals; however, the EEGs of MZ twins proved to react indentically to alcohol loading, whereas the EEGs of DZ twins became mor dissimilar during the course of the experiment. The low-voltage EEG presumably is resistant to alchohol; furthermore, it is supposed that there exists a special beta-prone EEG-type which is also genetic in origin. The identical EEG reaction of MZ twins to alcohol loading could not be attributed to more similar blood alcohol concentrations. It is hypothesized that the differences in the extent of the alcohol effect on the EEG between individuals might reflect differences in the sensitivity of the ascending reticular activating system. In the literature it has frequently been reported that alcoholics have preferentially brain wave patterns which are poorly synchronized. These findings are discussed in the light of the present results. PMID:557449

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

    PubMed

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

    2002-01-01

    The twin hook has been developed as an alternative to the conventional lag screw to be combined with a barrelled side-plate in the treatment of trochanteric hip fractures. With two oppositely directed apical hooks introduced into the subchondral bone of the femoral head, the twin hook provides different stabilising properties to the lag screw. The femoral head purchase of the twin hook and the lag screw were compared in a biomechanical study using artificial cancellous bone, and responses to axial and torsional loading was determined. A distinct yield point in load and torque was noted for the lag screw, representing failure of the laminas supporting the threads. For the twin hook, gradual increase of load and torque occurred during impaction of the bone supporting the hooks. The peak loads and torques were higher for the lag screw, but were similar for both devices after 8 mm deformation. The stiffness was higher for the lag screw, but in counter-clockwise rotation the stiffness for the lag screw was negligible. The twin hook appeared to provide fixation stability comparable to that offered by the lag screw, but with conceivable advantages in terms of a deformation response involving bone impaction and gradually increasing stability. PMID:12466867

  2. Genetic and Environmental Influences on the Mental Health of Children: A Twin Study.

    PubMed

    Yin, Ping; Hou, Xiao; Qin, Qing; Deng, Wei; Hu, Hua; Luo, Qinghua; Du, Lian; Qiu, Haitang; Qiu, Tian; Fu, Yixiao; Meng, Huaqing; Li, Tao

    2016-08-01

    The current study explored the influences of genetic and environmental factors on the mental health of twins between ages 6 and 16. A total of 41 monozygotic (MZ) twins and 35 dizygotic twins were recruited. The psychological attributes and environmental information of children were evaluated. A significant correlation was found between twins in the diagnostic categories of any psychiatric disorder and attention deficit/hyperactivity disorder (ADHD)/hyperkinesis based on the Strengths and Difficulties Questionnaire scale in MZ twins. Furthermore, fathers' authoritarian parenting style was positively correlated with the probability of any psychiatric disorders and oppositional/conduct disorders, whereas mothers' authoritative parenting style was negatively correlated with the probability of any psychiatric disorders and ADHD/hyperkinesis. The probability of emotional disorders was negatively correlated with scores on the Stressful Life Events Scale. These results collectively suggest that genetic and environmental elements, such as parental rearing style and stressful life events, may influence children's mental health. [Journal of Psychosocial Nursing and Mental Health Services, 54(8), 29-34.]. PMID:27479477

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

    PubMed

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

    2016-03-01

    In epidemiological and twin populations, prior interview studies have identified an externalizing spectrum of disorders. Could this be detected utilizing objective registry data? In 20,603 twin pairs from the Swedish Twin Registry, we obtained information from national medical, criminal and pharmacy records on drug abuse (DA), criminal behavior (CB) and alcohol use disorders (AUD). Multivariate twin modeling was performed with the OpenMx package. A common pathway model with quantitative but not qualitative sex effects fit best with twin resemblance for the latent liability to externalizing syndromes due to both genetic and shared environmental factors. Heritability of the liability was higher in females (76 vs. 62%) while shared environmental influences were considerably stronger in males (23 vs. 3%). In both sexes, this latent liability was most strongly indexed by DA and least by CB. All three syndromes had specific genetic influences (especially CB and AUD in males, and CB in females) and specific shared environmental effects (especially DA and CB in males, and AUD in females). For DA, CB and AUD in men, and DA and AUD in women, at least 75% of the genetic risk arose through the common factor. The best fit model assumed that genetic and environmental influences on these externalizing syndromes in males and females were the same. We identified, in registry data, a highly heritable externalizing spectrum. DA, CB and AUD share substantial genetic and modest to moderate shared environmental influences. The nature of the externalizing spectrum differed meaningfully between the sexes. PMID:26494460

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

    PubMed Central

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

    2015-01-01

    Applied creativity involves bringing innovation to real-life activities. The first reared-apart twin study assessing genetic and environmental origins of applied creativity, via Draw-a-House (DAH) and Draw-a-Person (DAP) tasks, is presented. Participants included 69 MZA and 53 DZA twin pairs from the Minnesota Study of Twins Reared Apart. Drawings were evaluated by four artists and four non-artists. Genetic effects were demonstrated for the DAP (.38–.47), but not for the DAH. Creative personality showed genetic effects (.50), and modest, but significant correlations with scores on the two drawings (rs = .17–.26). Both genetic and nonshared environmental influences underlie variance in applied creativity. Individuals concerned with enhancing creativity among students and others may better understand individual differences in performance and training. PMID:26366030

  5. Patterns and sources of continuity and change of energetic and temporal aspects of temperament in adulthood: A longitudinal twin study of self- and peer reports.

    PubMed

    Kandler, Christian; Riemann, Rainer; Angleitner, Alois

    2013-09-01

    This study investigated the mean-level and individual-level trends as well as the genetic and environmental sources of rank-order continuity and change in temperament traits (Briskness, Perseveration, Sensory Sensitivity, Emotional Reactivity, Endurance, and Activity). We analyzed self-reports and peer ratings from 2 adult age groups of twins, aged 15-30 (n = 348; 113 monozygotic and 61 dizygotic twin pairs) and 31-67 (n = 352; 110 monozygotic and 66 dizygotic twin pairs), captured at 2 different points of time 13 years apart. Temperament traits were fairly stable accompanying high levels of heritability. However, they also undergo mean-level, individual-level, and rank-order changes. In young adulthood, rank-order change was due to both genetic and environmental factors, whereas in older adult years, rank-order change was predominantly attributable to environmental effects. Phenotypic rank-order continuity was larger for older adults due to higher genetic as well as environmental continuity. For specific temperament traits (e.g., Activity), environmental variance proportionally increased across adulthood compared with genetic variance resulting in decreasing levels of heritability, whereas the reverse was found for other traits (e.g., Endurance). Specifics regarding the traits studied were discussed. The results indicate a complex interplay between genetic and environmental sources resulting in continuity and change of temperament across adulthood. PMID:23148934

  6. Twin Lakes studies: a characterization of the Twin Lakes fishery via creel census with an evaluation of potential effects of pump-storage power generation

    SciTech Connect

    Nesler, T.P.

    1981-11-01

    Creel census studies were conducted at Twin Lakes, Colo. from 1972 to 1979 to characterize the fishery, and to provide a basis for the evaluation of potential impacts upon the fishery resulting from the construction and operation of the Mt. Elbert Pumped-Storage Powerplant located on the lower lake. In this report, creel census data are presented for the period December 1976 to September 1979. Creel census has resulted in characterization of the Twin Lakes fishery with a precision adequate for analyses of pumped-storage effects upon the major components of the fishery. Potential powerplant impacts, such as increased mortality to rainbow trout, daily and seasonal water-level fluctuations, and shoreline turbidity may have adverse effects on the Twin Lakes shore fishery for rainbow trout. Large-scale impacts probably will be necessary to demonstrate effects upon the boat fishery and the lake trout harvest.

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

    PubMed Central

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

    2010-01-01

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

  8. Association between Posttraumatic Stress Disorder and Inflammation: A Twin Study

    PubMed Central

    Plantinga, Laura; Bremner, J. Douglas; Miller, Andrew A.; Jones, Dean P.; Veledar, Emir; Goldberg, Jack; Vaccarino, Viola

    2013-01-01

    The association of posttraumatic stress disorder (PTSD) with cardiovascular disease risk may be mediated by inflammation. Our objective was to examine the association between PTSD and measures of inflammation and to determine whether these associations are due to shared familial or genetic factors. We measured lifetime history of PTSD using the Structured Clinical Interview for DSM-IV in 238 male middle-aged military veteran twin pairs (476 individuals), selected from the Vietnam Era Twins Registry, who were free of cardiovascular disease at baseline. We assessed inflammation using levels of high-sensitivity C-reactive protein (hsCRP), interleukin 6 (IL-6), fibrinogen, white blood cells, vascular cell adhesion molecule-1, and intercellular adhesion molecule-1 (ICAM-1). Geometric mean levels and percent differences by PTSD were obtained from mixed-model linear regression analyses with adjustment for potential confounders. Within-pair analysis was conducted to adjust for shared family environment and genetics (monozygotic pairs). Overall, 12.4% of participants had a lifetime history of PTSD. Adjusted mean levels of hsCRP and ICAM-1 were significantly higher among those with vs. without PTSD [hsCRP: 1.75 vs. 1.31 mg/l (33% difference); ICAM-1: 319 vs. 293 ng/ml (9% difference)]. Adjustment for depression rendered the association of PTSD with hsCRP non-statistically significant. For IL-6, no consistent association was seen. Within-pair analysis produced associations that were similar in direction for all three markers but lesser in magnitude for hsCRP and IL-6. There was no evidence of interaction by zygosity. Elevated hsCRP and ICAM-1 are associated with PTSD, and these associations may be confounded by shared non-genetic, antecedent familial and environmental factors. PMID:23379997

  9. Twinship as a resource: zygosity- and gender-based comparison of twins' attitudes toward twinship.

    PubMed

    Hegedűs, Rita; Pári, András; Drjenovszky, Zsófia; Kónya, Hanna

    2014-10-01

    Aiming to perform the first sociological survey of Hungarian twins, our main question was whether being a twin has positive consequences on one's life. Adult twins completed our questionnaire at three Hungarian summer twin festivals, in hospitals during medical twin studies, and on some websites online. Data represent 140 twin pairs (mean age: 38.2 ± 14.6 years). We employed some indices for measuring the resource nature of twinship. Three main types of benefits were distinguished: profit of attraction, as 'material capital'; the easier obtainability of cultural goods when twins take part in it, as 'cultural capital'; and positive aspects of an a priori existing dyadic relation, as 'relational capital'. We were interested in the difference among types of twins regarding advantages. We paid special attention to the five groups of twins derived from gender and zygosity (i.e., monozygotic females, monozygotic males, dizygotic females, dizygotic males, opposite-sex pairs). Our analysis showed that Hungarian twins involved in our research basically enjoy their twinship; during their lives they used and still make use of different benefits given by it. In our twin samples, women had more advantages from being a twin than men. Significant differences could be observed on all indicators between monozygotic and dizygotic twins. PMID:25111726

  10. Sources of Human Psychological Differences: The Minnesota Study of Twins Reared Apart.

    ERIC Educational Resources Information Center

    Bouchard, Thomas J., Jr.; And Others

    1990-01-01

    Described is an ongoing study of monozygotic and dizygotic twins, separated in infancy and reared apart. Discussed are the procedures and results of this study with interpretations of the results. The effects of parenting, education, and other interventions are considered. (CW)

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

    PubMed

    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. PMID:22877999

  12. A Study of the Conjoint Drawings of Identical and Fraternal Twins: A Pilot Study.

    ERIC Educational Resources Information Center

    Rehmann, Jacqueline T.

    Drawings designed by three identical and three fraternal, normal, 6- and 7-year-old twin pairs are inspected for signs of a struggle for individual identity. Each twin must go through the process of becoming aware of him/herself as separate from the mother and must individuate from his/her twin as well. Interdependence may retard maturation. In…

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

    ERIC Educational Resources Information Center

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

    2013-01-01

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

  14. Asymmetric twin Dark Matter

    SciTech Connect

    Farina, Marco

    2015-11-09

    We study a natural implementation of Asymmetric Dark Matter in Twin Higgs models. The mirroring of the Standard Model strong sector suggests that a twin baryon with mass around 5 GeV is a natural Dark Matter candidate once a twin baryon number asymmetry comparable to the SM asymmetry is generated. We explore twin baryon Dark Matter in two different scenarios, one with minimal content in the twin sector and one with a complete copy of the SM, including a light twin photon. The essential requirements for successful thermal history are presented, and in doing so we address some of the cosmological issues common to many Twin Higgs models. The required interactions we introduce predict signatures at direct detection experiments and at the LHC.

  15. Genetic Influence on the Variance in Coincidence Timing and Its Covariance with IQ: A Twin Study.

    ERIC Educational Resources Information Center

    Wright, Margaret J.; Smith, Glen A.; Geffen, Gina M.; Geffen, Laurie B.; Martin, Nicholas G.

    2000-01-01

    Studied whether genetic variability explained some of the variance in coincidence timing and whether common genetic factors accounted for the association with intellectual functioning using 55 pairs of 16-year-old twins. Results suggest that the genetic influence operating on coincidence timing skills was of similar magnitude to that of response…

  16. Social Experiences in Kindergarten and Academic Achievement in Grade 1: A Monozygotic Twin Difference Study

    ERIC Educational Resources Information Center

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

    2012-01-01

    The goal of this study was to examine how different types of social experiences in kindergarten relate to Grade 1 academic achievement, while controlling for possible genetic and shared environmental influences through the use of the monozygotic (MZ) twin difference method. Social experiences in kindergarten included relationship quality with the…

  17. Relationship between Symptom Domains in Autism Spectrum Disorders: A Population Based Twin Study

    ERIC Educational Resources Information Center

    Dworzynski, Katharina; Happe, Francesca; Bolton, Patrick; Ronald, Angelica

    2009-01-01

    Factor structure and relationship between core features of autism (social impairments, communication difficulties, and restricted, repetitive behaviours or interests (RRBIs)) were explored in 189 children from the Twins Early Development Study, diagnosed with autistic spectrum disorders (ASDs) using the Development and Wellbeing Assessment (DAWBA;…

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

    ERIC Educational Resources Information Center

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

    2014-01-01

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

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

    ERIC Educational Resources Information Center

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

    2005-01-01

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

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

    PubMed

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

    2015-11-01

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

  1. Genetic and Environmental Influences on Rapid Naming and Reading Ability: A Twin Study.

    ERIC Educational Resources Information Center

    Davis, Chayna J.; Knopik, Valerie S.; Olson, Richard K.; Wadsworth, Sally J.; DeFries, John C.

    2001-01-01

    A study assessed genetic and environmental etiologies of reading, rapid naming (RN), and their covariation using data from 587 twin pairs (ages 7-20) in which one student had reading difficulties and from 360 control pairs. Correlation between reading and RN performances for subjects was significantly higher than that of controls. (Contains…

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

    PubMed Central

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

    2016-01-01

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

  3. The Genetic and Environmental Etiology of Decision-Making: A Longitudinal Twin Study

    ERIC Educational Resources Information Center

    Tuvblad, Catherine; Gao, Yu; Wang, Pan; Raine, Adrian; Botwick, Theodore; Baker, Laura A.

    2013-01-01

    The present study examined the genetic and environmental etiology of decision-making (Iowa Gambling Task; Bechara, Damasio, Damasio, & Anderson, 1994), in a sample of twins at ages 11-13, 14-15, and 16-18 years. The variance across five 20-trial blocks could be explained by a latent "decision-making" factor within each of the three times of IGT…

  4. The Effect of Classroom Environment on Problem Behaviors: A Twin Study

    ERIC Educational Resources Information Center

    DiLalla, Lisabeth Fisher; Mullineaux, Paula Y.

    2008-01-01

    Children's behavior problems, both internalizing and externalizing, are a function of both genetic and environmental influences. One potentially important environmental influence is the classroom environment. This study of 1941 monozygotic twin pairs examined whether children whose parents rated them as similarly high or low on a number of problem…

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

    ERIC Educational Resources Information Center

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

    2006-01-01

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

  6. Study of unsteady performance of a twin-entry mixed flow turbine

    NASA Astrophysics Data System (ADS)

    Bencherif, M. M.; Hamidou, M. K.; Hamel, M.; Abidat, M.

    2016-03-01

    The aim of this investigation is to study the performance of a twin-entry turbine under pulsed flow conditions. The ANSYS-CFX code is used to solve three-dimensional compressible turbulent flow equations. The computational results are compared with those of a one-dimensional model and experimental data, and good agreement is found.

  7. A twin study of breastfeeding with a preliminary genome wide association scan

    PubMed Central

    Colodro-Conde, L.; Zhu, G.; Power, R. A.; Henders, A.; Heath, A.C.; Madden, P.A.F.; Montgomery, G.W.; Medland, S. E.; Ordoñana, J.R.; Martin, N.G.

    2015-01-01

    Breastfeeding has been an important survival trait during human history, though it has long been recognised that individuals differ in their exact breastfeeding behaviour. Here our aims were, first, to explore to what extent genetic and environmental influences contributed to the individual differences in breastfeeding behaviour; second, to detect possible genetic variants related to breastfeeding; and lastly, to test if the genetic variants associated with breastfeeding have been previously found to be related with breast size. Data were collected from a large community-based cohort of Australian twins, with 3,364 women for the twin modelling analyses and 1,521 of them included in the genome wide association study. Monozygotic twin correlations (rMZ = .52, 95% CI .46 – .57) were larger than dizygotic twin correlations (rDZ = .35, 95% CI .25 – .43) and the best-fitting model was the one composed by additive genetics and unique environmental factors, explaining 53% and 47% of the variance in breastfeeding behaviour, respectively. No breastfeeding-related genetic variants reached genome-wide significance. The polygenic risk score analyses showed no significant results, suggesting breast size does not influence breastfeeding. This study confers a replication of a previous one exploring the sources of variance of breastfeeding and, to our knowledge, is the first one to conduct a Genome-Wide Association Study on breastfeeding and look at the overlap with variants for breast size. PMID:25475840

  8. Ageing, genes, environment and epigenetics: what twin studies tell us now, and in the future.

    PubMed

    Steves, Claire Joanne; Spector, Timothy D; Jackson, Stephen H D

    2012-09-01

    Compared with younger people, older people are much more variable in their organ function, and these large individual differences contribute to the complexity of geriatric medicine. What determines this variability? Is it due to the accumulation of different life experiences, or because of the variation in the genes we are born with, or an interaction of both? This paper reviews key findings from ageing twin cohorts probing these questions. Twin studies are the perfect natural experiment to dissect out genes and life experiences. We discuss the paradox that ageing is strongly determined by heritable factors (an influence that often gets stronger with time), yet longevity and lifespan seem not to be so heritable. We then focus on the intriguing question of why DNA sequence-identical twins might age differently. Animal studies are increasingly showing that epigenetic modifications occurring in early development and adulthood, might be key to ageing phenomena but this is difficult to investigate longitudinally in human populations, due to ethical problems of intervention and long lifespan. We propose that identical twin studies using new and existing cohorts may be useful human models in which to investigate the interaction between the environment and genetics, mediated by epigenetic modifications. PMID:22826292

  9. Twin-to-twin transfusion syndrome

    MedlinePlus

    Twin-to-twin transfusion syndrome is a rare condition that occurs only in identical twins while they are in the womb. ... Twin-to-twin transfusion syndrome (TTTS) occurs when the blood supply of 1 twin moves to the ...

  10. Examining Associations Among ADHD, Homework Behavior, and Reading Comprehension: A Twin Study.

    PubMed

    Little, Callie W; Hart, Sara A; Schatschneider, Christopher; Taylor, Jeanette

    2016-07-01

    Previous literature has indicated an important association between reading comprehension and both attention-deficit/hyperactivity disorder (ADHD) and homework habits. This investigation sought to extend previous knowledge by providing information about how ADHD and homework behavior (i.e., completing homework regularly) may jointly influence reading comprehension. Using a genetically sensitive design, this study examined the genetic and environmental influences on and between ADHD, homework behavior and reading comprehension. Participants for this study included 691 twin pairs (351 monozygotic, 340 same-sex dizygotic) from the Florida Twin Project on Behavior and Environment (FTP-BE) and 2647 twin pairs (865 monozygotic, 1782 dizygotic) from the larger Florida Twin Project on Reading (FTP-R) in Grades 3 through 7. Three separate models, each representing a different definition of ADHD (full ADHD, inattention only, and hyperactivity/impulsivity only), showed similar patterns of results; therefore, results of the full ADHD model are discussed. Overlapping genetic influences were found between ADHD, homework behavior, and reading comprehension, but no shared environmental influences among all three. However, shared environmental influences overlapped between homework behavior and reading comprehension. Although the sources of this environmental overlap are unknown, these results have implications for improving homework practices and their subsequent influence on literacy skills through homework environments. PMID:25349092

  11. Improving fluid registration through white matter segmentation in a twin study design

    NASA Astrophysics Data System (ADS)

    Chou, Yi-Yu; Lepore, Natasha; Brun, Caroline; Barysheva, Marina; McMahon, Katie; de Zubicaray, Greig I.; Wright, Margaret J.; Toga, Arthur W.; Thompson, Paul M.

    2010-03-01

    Robust and automatic non-rigid registration depends on many parameters that have not yet been systematically explored. Here we determined how tissue classification influences non-linear fluid registration of brain MRI. Twin data is ideal for studying this question, as volumetric correlations between corresponding brain regions that are under genetic control should be higher in monozygotic twins (MZ) who share 100% of their genes when compared to dizygotic twins (DZ) who share half their genes on average. When these substructure volumes are quantified using tensor-based morphometry, improved registration can be defined based on which method gives higher MZ twin correlations when compared to DZs, as registration errors tend to deplete these correlations. In a study of 92 subjects, higher effect sizes were found in cumulative distribution functions derived from statistical maps when performing tissue classification before fluid registration, versus fluidly registering the raw images. This gives empirical evidence in favor of pre-segmenting images for tensor-based morphometry.

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

    PubMed

    Condon, Julianne; Shaw, Joanne E; Luciano, Michelle; Kyvik, Kirsten O; Martin, Nicholas G; Duffy, David L

    2008-02-01

    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 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. Weight differences between affected and unaffected cotwins from monozygotic (MZ) discordant pairs were large for T2D and GD, but much larger again for discordant dizygotic (DZ) pairs. The bivariate genetic analysis (under the multifactorial threshold model) estimated the genetic correlation between body mass index (BMI) and T2D to be 0.46, and the environmental correlation at only 0.06. PMID:18251672

  13. Perineal Distensibility Using Epi-no in Twin Pregnancies: Comparative Study with Singleton Pregnancies

    PubMed Central

    Kubotani, Juliana Sayuri; Moron, Antonio Fernandes; Zanetti, Miriam Raquel Diniz; Soares, Vanessa Cardoso Marques; Elito Júnior, Julio

    2014-01-01

    The aims of this study were to compare perineal distensibility between women with twin and singleton pregnancies and to correlate these women's perineal distensibility with anthropometric data. This prospective cross-sectional case-control study was conducted among nulliparous women, of whom 20 were pregnant with twins and 23 with a single fetus. Perineal distensibility was evaluated in the third trimester by means of Epi-no, which was introduced into the vagina and inflated up to the maximum tolerable limit. It was then withdrawn while inflated and its circumference was measured. The unpaired Student's t-test was used to compare perineal distensibility in the two groups and Pearson's correlation coefficient (r) was used to correlate the pregnant women's perineal distensibility with their anthropometric data. There was no difference in perineal distensibility between the twin group (16.51 ± 2.05 cm) and singleton group (16.13 ± 1.67 cm) (P = 0.50). There was a positive correlation between perineal distensibility and abdominal circumference (r = 0.36; P = 0.01). The greater the abdominal circumference was, the greater the perineal distensibility was, regardless of whether the pregnancy was twin or singleton. PMID:25006476

  14. Exaggerated Activation of Dorsal Anterior Cingulate Cortex During Cognitive Interference: A Monozygotic Twin Study of Posttraumatic Stress Disorder

    PubMed Central

    Shin, Lisa M.; Bush, George; Milad, Mohammed R.; Lasko, Natasha B.; Brohawn, Kathryn Handwerger; Hughes, Katherine C.; Macklin, Michael L.; Gold, Andrea L.; Karpf, Rachel D.; Orr, Scott P.; Rauch, Scott L.; Pitman, Roger K.

    2013-01-01

    Objective Neuroimaging studies have revealed functional abnormalities in the anterior cingulate cortex in posttraumatic stress disorder (PTSD). The goal of the current research was to determine whether hyperresponsivity of the dorsal anterior cingulate in PTSD is an acquired characteristic or familial risk factor. Method Using a case-control twin design, we studied combat-exposed veterans with PTSD (n=12) and their identical combat-unexposed co-twins (n=12), as well as combat-exposed veterans without PTSD (n=14) and their identical combat-unexposed co-twins (n=14). Participants underwent functional magnetic resonance imaging during completion of the Multi-Source Interference Task, which reliably activates the dorsal anterior cingulate. Results Combat veterans with PTSD and their co-twins had significantly greater activation in the dorsal anterior cingulate and tended to have larger response time difference scores, as compared to non-PTSD veterans and their co-twins. Dorsal anterior cingulate activation in the exposed twins was positively correlated with their PTSD symptom severity. Dorsal anterior cingulate activation in the unexposed twins was positively correlated with their combat-exposed co-twins’ PTSD symptom severity, but not with depression or alcohol use severity in the combat-exposed co-twins. Conclusions Hyperresponsivity in the dorsal anterior cingulate appears to be a familial risk factor for the development of PTSD following psychological trauma. PMID:21724666

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

    PubMed Central

    Kaprio, Jaakko

    2014-01-01

    The aim of the study was to investigate the effects of age, sex, and body mass index (BMI) on total sitting time among the Finnish twin cohort. Also, heritability and environmental factors were analysed. The final sample included 6713 twin individuals 53–67 years of age (46% men). Among them there were 1940 complete twin pairs (732 monozygotic [MZ] and 1208 dizygotic [DZ] twin pairs). Sedentary behaviour was queried with a self-reported questionnaire with multiple-choice questions about sitting time at different domains. The mean total sitting time per day was 6 hours 41 minutes (standard deviation: 2 hours 41 minutes). The total sitting time was less in women than in men (P = 0.002). Older age was associated with less total sitting time (P < 0.001). Those with higher body mass index had higher total sitting time in age and sex adjusted analysis (P < 0.001). MZ pairs were more similar for sitting time than DZ pairs, with initial estimates of heritability for the total sitting time of 35%.The influence of shared environmental factors was negligible (1%), while most (64%) of the variation could be ascribed to unique environmental factors, the latter including measurement error. PMID:24822182

  16. Early fetal reduction of dichorionic triplets to dichorionic twin or singleton pregnancies: a retrospective study.

    PubMed

    Lin, Haiyan; Wen, Ya; Li, Yu; Chen, Xiaoli; Yang, Dongzi; Zhang, Qingxue

    2016-05-01

    A retrospective study conducted in an academic reproductive medicine centre evaluated the feasibility and safety of early fetal reduction in dichorionic triplets to dichorionic twin or singleton pregnancies. Thirty-three dichorionic triplets that underwent early transvaginal fetal reduction mechanically between 2002 and 2013 were included, of which 21 patients underwent fetal reduction to dichorionic twins (Group A) and 12 patients underwent fetal reduction to a singleton pregnancy (Group B). A further 84 patients with trichorionic triplets reduced to twins were included as the control group (Group C). The main outcome measures were live birth and preterm labour rates. Both early and late spontaneous abortion rates, were similar in group A compared with groups B and C. Gestational age at delivery was significantly lower in group C versus group A (P = 0.02). The preterm labour rate in group A, which was comparable with that in group C, was greater than in group B, but not significantly. Neonatal birth weight, low birth weight rate and neonatal body height were similar among groups. Small for gestational age rates were comparable. Live birth rates were similar among the groups. Early transvaginal fetal reduction for dichorionic triplets to dichorionic twins may be feasible and safe. PMID:26997475

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

    PubMed

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

    2014-06-01

    Neurodevelopmental disorders affect a substantial minority of the general population. Their origins are still largely unknown, but a complex interplay of genetic and environmental factors causing disturbances of the central nervous system's maturation and a variety of higher cognitive skills is presumed. Only limited research of rather small sample size and narrow scope has been conducted in neurodevelopmental disorders using a twin-differences design. The Roots of Autism and ADHD Twin Study in Sweden (RATSS) is an ongoing project targeting monozygotic twins discordant for categorical or dimensional autistic and inattentive/hyperactive-impulsive phenotypes as well as other neurodevelopmental disorders, and typically developing twin controls. Included pairs are 9 years of age or older, and comprehensively assessed for psychopathology, medical history, neuropsychology, and dysmorphology, as well as structural, functional, and molecular brain imaging. Specimens are collected for induced pluripotent (iPS) and neuroepithelial stem cells, genetic, gut bacteria, protein-/monoamine, and electron microscopy analyses. RATSS's objective is to generate a launch pad for novel surveys to understand the complexity of genotype-environment-phenotype interactions in autism spectrum disorder and attention-deficit hyperactivity disorder (ADHD). By October 2013, RATSS had collected data from 55 twin pairs, among them 10 monozygotic pairs discordant for autism spectrum disorder, seven for ADHD, and four for other neurodevelopmental disorders. This article describes the design, recruitment, data collection, measures, collected pairs' characteristics, as well as ongoing and planned analyses in RATSS. Potential gains of the study comprise the identification of environmentally mediated biomarkers, the emergence of candidates for drug development, translational modeling, and new leads for prevention of incapacitating outcomes. PMID:24735654

  18. Genetic Regulation of Acquired Immune Responses to Antigens of Mycobacterium tuberculosis: a Study of Twins in West Africa

    PubMed Central

    Jepson, Annette; Fowler, Amanda; Banya, Winston; Singh, Mahavir; Bennett, Steve; Whittle, Hilton; Hill, Adrian V. S.

    2001-01-01

    The role of genetic factors in clinical tuberculosis is increasingly recognized; how such factors regulate the immune response to Mycobacterium tuberculosis in healthy individuals is unclear. In this study of 255 adult twin pairs residing in The Gambia, West Africa, it is apparent that memory T-cell responses to secreted mycobacterial antigens (85-kDa antigen complex, “short-term culture filtrate,” and peptides from the ESAT-6 protein), as well as to the 65-kDa heat shock protein, are subject to effective genetic regulation. The delayed hypersensitivity response to intradermal tuberculin also demonstrates significant genetic variance, while quantitative T-cell and antibody responses to the 38-kDa cell membrane protein appear to be determined largely by environmental factors. Such findings have implications for vaccine development. PMID:11349068

  19. Alloparenting for chimpanzee twins

    PubMed Central

    Kishimoto, Takeshi; Ando, Juko; Tatara, Seiki; Yamada, Nobuhiro; Konishi, Katsuya; Kimura, Natsuko; Fukumori, Akira; Tomonaga, Masaki

    2014-01-01

    In April 2009, a female chimpanzee named Sango, living in a captive group at the Noichi Zoo, Japan, gave birth to dizygotic male-female twin chimpanzees (male: Daiya, female: Sakura). The extent to which adult group members cared for the twins was investigated using a focal animal sampling method targeting six adults (one male) when the twin chimpanzees were two years old. Data were collected for an average of 6.78 h (SD = 0.79) per focal participant. An unaffiliated female adult of Sango was engaged in parenting Sakura as much as Sango. Given that Sakura was in lesser proximity to Sango than Daiya, Sakura's departures from her mother and her ability to gesture requests might have enabled non-kin adults to provide her care. PMID:25200656

  20. Longitudinal Stability of Genetic and Environmental Influences on the Association between Diurnal Preference and Sleep Quality in Young Adult Twins and Siblings.

    PubMed

    Barclay, Nicola L; Rowe, Richard; O'Leary, Rachael; Bream, Danielle; Gregory, Alice M

    2016-08-01

    Overlapping genetic influences have been implicated in diurnal preference and subjective sleep quality. Our overall aim was to examine overlapping concurrent and longitudinal genetic and environmental effects on diurnal preference and sleep quality over ~5 years. Behavioral genetic analyses were performed on data from the longitudinal British G1219 study of young adult twins and nontwin siblings. A total of 1556 twins and siblings provided data on diurnal preference (Morningness-Eveningness Questionnaire) and sleep quality (Pittsburgh Sleep Quality Index) at time 1 (mean age = 20.30 years, SD = 1.76; 62% female), and 862 participated at time 2 (mean age = 25.30 years, SD = 1.81; 66% female). Preference for eveningness was associated with poorer sleep quality at both time points (r = 0.25 [95% confidence intervals {CIs} = 0.20-0.30] and r = 0.21 [CI = 0.15-0.28]). There was substantial overlap in the genetic influences on diurnal preference and sleep quality individually, across time (genetic correlations [rAs]: 0.64 [95% CI = 0.59-0.67] and 0.48 [95% CI = 0.42-.053]). There were moderate genetic correlations between diurnal preference and sleep quality concurrently and longitudinally (rAs = 0.29-0.60). Nonshared environmental overlap was substantially smaller for all cross-phenotype associations (nonshared environmental correlations (rEs) = -0.02 to 0.08). All concurrent and longitudinal associations within and between phenotypes were largely accounted for by genetic factors (explaining between 60% and 100% of the associations). All shared environmental effects were nonsignificant. Nonshared environmental influences played a smaller role on the associations between phenotypes (explaining between -0.06% and 40% of the associations). These results suggest that to some extent, similar genes contribute to the stability of diurnal preference and sleep quality throughout young adulthood but also that different genes play a part over this relatively short time frame

  1. Body Mass Index and Depressive Symptoms: Testing for Adverse and Protective Associations in Two Twin Cohort Studies.

    PubMed

    Jokela, Markus; Berg, Venla; Silventoinen, Karri; Batty, G David; Singh-Manoux, Archana; Kaprio, Jaakko; Davey Smith, George; Kivimäki, Mika

    2016-08-01

    Studies have suggested both adverse and protective associations of obesity with depressive symptoms. We examined the contribution of environmental and heritable factors in this association. Participants were same-sex twin pairs from two population-based twin cohort studies, the Older Finnish Twin Cohort (n = 8,215; mean age = 44.1) and the US Midlife Development in the United States (MIDUS; n = 1,105; mean age = 45.1). Body mass index (BMI) was calculated from self-reported height and weight. Depressive symptoms were assessed using Beck's Depression Inventory (BDI; Finnish Twin Cohort), and by negative and positive affect scales (MIDUS). In the Finnish Twin Cohort, higher BMI was associated with higher depressive symptoms in monozygotic (MZ) twins (B = 2.01, 95% CI = 1.0, 3.0) and dizygotic (DZ) twins (B = 1.17, 0.5, 1.9) with BMI >22. This association was observed in within-pair analysis in DZ twins (B = 1.47, CI = 0.4, 2.6) but not in within-pair analysis of MZ twins (B = 0.03, CI = -1.9, 2.0). Consistent with the latter result, a bivariate genetic model indicated that the association between higher BMI and higher depressive symptoms was largely mediated by genetic factors. The results of twin-pair analysis and bivariate genetic model were replicated in the MIDUS sample. These findings suggest an association between obesity and higher depressive symptoms, which is largely explained by shared heritable biological mechanisms. PMID:27055784

  2. Longitudinal Investigation into Genetics in the Conservation of Metabolic Phenotypes in Danish and Chinese Twins.

    PubMed

    Li, Shuxia; Kyvik, Kirsten Ohm; Duan, Haiping; Zhang, Dongfeng; Pang, Zengchang; Hjelmborg, Jacob; Tan, Qihua; Kruse, Torben; Dalgård, Christine

    2016-01-01

    Longitudinal twin studies on long term conservation of individual metabolic phenotypes can help to explore the genetic and environmental basis in maintaining metabolic homeostasis and metabolic health. We performed a longitudinal twin study on 12 metabolic phenotypes from Danish twins followed up for 12 years and Chinese twins traced for 7 years. The study covered a relatively large sample of 502 pairs of Danish adult twins with a mean age at intake of 38 years and a total of 181 Chinese adult twin pairs with a mean baseline age of 39.5 years. Bivariate twin models were fitted to the longitudinal measurements taken at two time points (at baseline and follow-up) to estimate the genetic and environmental contributions to phenotype variation and correlation at and between the two time points. High genetic components in the regulation of intra-individual phenotype correlation or stability over time were estimated in both Danish (h2>0.75 except fasting blood glucose) and Chinese (h2>0.72 except blood pressure) twins; moderate to high genetic contribution to phenotype variation at the two time points were also estimated except for the low genetic regulation on glucose in Danish and on blood pressure in Chinese twins. Meanwhile the bivariate twin models estimated shared environmental contributions to the variance and covariance in fasting blood glucose in Danish twins, and in systolic and diastolic blood pressure, low and high density lipoprotein cholesterol in Chinese twins. Overall, our longitudinal twin study on long-term stability of metabolic phenotypes in Danish and Chinese twins identified a common pattern of high genetic control over phenotype conservation, and at the same time revealed population-specific patterns of genetic and common environmental regulation on the variance as well as covariance of glucose and blood pressure. PMID:27618179

  3. Why Aren't Identical Twins Linguistically Identical? Genetic, Prenatal and Postnatal Factors

    ERIC Educational Resources Information Center

    Stromswold, Karin

    2006-01-01

    Results of twin studies clearly demonstrate that genetic factors play an important role in the rate of language acquisition and linguistic proficiency attained by normal and impaired children and adults [see Stromswold, K. (2001). The heritability of language: A review and meta-analysis of twin, adoption and linkage studies. "Language," 77,…

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

    SciTech Connect

    Duffy, D.L.; Healey, S.C.; Martin, N.G.

    1994-09-01

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

  5. Longitudinal associations between social anxiety disorder and avoidant personality disorder: A twin study.

    PubMed

    Torvik, Fartein Ask; Welander-Vatn, Audun; Ystrom, Eivind; Knudsen, Gun Peggy; Czajkowski, Nikolai; Kendler, Kenneth S; Reichborn-Kjennerud, Ted

    2016-01-01

    Social anxiety disorder (SAD) and avoidant personality disorder (AvPD) are frequently co-occurring psychiatric disorders with symptomatology related to fear of social situations. It is uncertain to what degree the 2 disorders reflect the same genetic and environmental risk factors. The current study addresses the stability and co-occurrence of SAD and AvPD, the factor structure of the diagnostic criteria, and genetic and environmental factors underlying the disorders at 2 time points. SAD and AvPD were assessed in 1,761 young adult female twins at baseline and 1,471 of these approximately 10 years later. Biometric models were fitted to dimensional representations of SAD and AvPD. SAD and AvPD were moderately and approximately equally stable from young to middle adulthood, with increasing co-occurrence driven by environmental factors. At the first wave, approximately 1 in 3 individuals with AvPD had SAD, increasing to 1 in 2 at follow-up. The diagnostic criteria for SAD and AvPD had a two-factor structure with low cross-loadings. The relationship between SAD and AvPD was best accounted for by a model with separate, although highly correlated (r = .76), and highly heritable (.66 and .71) risk factors for each disorder. Their genetic and environmental components correlated .84 and .59, respectively. The finding of partially distinct risk factors indicates qualitative differences in the etiology of SAD and AvPD. Genetic factors represented the strongest time-invariant influences, whereas environmental factors were most important at the specific points in time. PMID:26569037

  6. Development of the brain's structural network efficiency in early adolescence: A longitudinal DTI twin study.

    PubMed

    Koenis, Marinka M G; Brouwer, Rachel M; van den Heuvel, Martijn P; Mandl, René C W; van Soelen, Inge L C; Kahn, René S; Boomsma, Dorret I; Hulshoff Pol, Hilleke E

    2015-12-01

    The brain is a network and our intelligence depends in part on the efficiency of this network. The network of adolescents differs from that of adults suggesting developmental changes. However, whether the network changes over time at the individual level and, if so, how this relates to intelligence, is unresolved in adolescence. In addition, the influence of genetic factors in the developing network is not known. Therefore, in a longitudinal study of 162 healthy adolescent twins and their siblings (mean age at baseline 9.9 [range 9.0-15.0] years), we mapped local and global structural network efficiency of cerebral fiber pathways (weighted with mean FA and streamline count) and assessed intelligence over a three-year interval. We find that the efficiency of the brain's structural network is highly heritable (locally up to 74%). FA-based local and global efficiency increases during early adolescence. Streamline count based local efficiency both increases and decreases, and global efficiency reorganizes to a net decrease. Local FA-based efficiency was correlated to IQ. Moreover, increases in FA-based network efficiency (global and local) and decreases in streamline count based local efficiency are related to increases in intellectual functioning. Individual changes in intelligence and local FA-based efficiency appear to go hand in hand in frontal and temporal areas. More widespread local decreases in streamline count based efficiency (frontal cingulate and occipital) are correlated with increases in intelligence. We conclude that the teenage brain is a network in progress in which individual differences in maturation relate to level of intellectual functioning. PMID:26368846

  7. Twin supergravities

    NASA Astrophysics Data System (ADS)

    Roest, Diederik; Samtleben, Henning

    2009-08-01

    We study the phenomenon that pairs of supergravities can have identical bosonic field content but different fermionic extensions. Such twin theories are classified and shown to originate as truncations of a common theory with more supersymmetry. Moreover, we discuss the possible gaugings and scalar potentials of twin theories. This allows us to pinpoint to which extent these structures are determined by the purely bosonic structure of the underlying Kac-Moody algebras and where supersymmetry comes to play its role. As an example, we analyse the gaugings of the six-dimensional {\\cal N}=(0,1) and {\\cal N}=(2,1) theories with an identical bosonic sector and explicitly work out their scalar potentials. The discrepancy between the potentials finds a natural explanation within maximal supergravity, in which both theories may be embedded.

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

    ERIC Educational Resources Information Center

    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…

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

    ERIC Educational Resources Information Center

    Van den Daele, Leland D.

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

  10. Heredity and Environment: Major Findings from Twin Studies of Ability, Personality and Interests.

    ERIC Educational Resources Information Center

    Nichols, Robert C.

    A review of the twin literature and analyses of two large twin samples found identical twin correlations higher than fraternal twin correlations by about .20 for a variety of traits of ability, personality and interests. This was interpreted as indicating that about half of the variation among people in a broad spectrum of psychological traits is…

  11. Genetic and environmental influences on antisocial behavior: a meta-analysis of twin and adoption studies.

    PubMed

    Rhee, Soo Hyun; Waldman, Irwin D

    2002-05-01

    A meta-analysis of 51 twin and adoption studies was conducted to estimate the magnitude of genetic and environmental influences on antisocial behavior. The best fitting model included moderate proportions of variance due to additive genetic influences (.32), nonadditive genetic influences (.09), shared environmental influences (.16), and nonshared environmental influences (.43). The magnitude of familial influences (i.e., both genetic and shared environmental influences) was lower in parent-offspring adoption studies than in both twin studies and sibling adoption studies. Operationalization, assessment method, zygosity determination method, and age were significant moderators of the magnitude of genetic and environmental influences on antisocial behavior, but there were no significant differences in the magnitude of genetic and environmental influences for males and females. PMID:12002699

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

    PubMed Central

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

    2013-01-01

    We address leadership emergence and the possibility that there is a partially innate predisposition to occupy a leadership role. Employing twin design methods on data from the National Longitudinal Study of Adolescent Health, we estimate the heritability of leadership role occupancy at 24%. Twin studies do not point to specific genes or neurological processes that might be involved. We therefore also conduct association analysis on the available genetic markers. The results show that leadership role occupancy is associated with rs4950, a single nucleotide polymorphism (SNP) residing on a neuronal acetylcholine receptor gene (CHRNB3). We replicate this family-based genetic association result on an independent sample in the Framingham Heart Study. This is the first study to identify a specific genotype associated with the tendency to occupy a leadership position. The results suggest that what determines whether an individual occupies a leadership position is the complex product of genetic and environmental influences; with a particular role for rs4950. PMID:23459689

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

    PubMed

    Muñoz-Silva, Alicia; Sánchez-García, Manuel

    2004-01-01

    The authors apply descriptive and sequential analyses to a mother's distancing strategies toward her 3-year-old twin sons in puzzle assembly and book reading tasks. One boy had normal hearing and the other a mild hearing loss (threshold: 30 dB). The results show that the mother used more distancing behaviors with the son with a hearing loss, and thus gave greater encouragement to this son's cognitive development. These results differ from those of previous studies of deaf or hard of hearing children, whose participants generally had severe or profound hearing loss. In those studies, parents of deaf children used more low-level distancing than parents of normally hearing children. The results of the present study are discussed in terms of their implications for the parenting of twins and of children with mild hearing loss. PMID:15646940

  14. The contribution of twin studies to the understanding of the aetiology of asthma and atopic diseases

    PubMed Central

    Thomsen, Simon F.

    2015-01-01

    The prevalence of asthma and other atopic diseases has increased markedly during the past decades and the reasons for this are not fully understood. Asthma is still increasing in many parts of the world, notably in developing countries, and this emphasizes the importance of continuing research aimed at studying the aetiological factors of the disease and the causes of its increase in prevalence. Twin studies enable investigations into the genetic and environmental causes of individual variation in multifactorial diseases such as asthma. Thorough insight into these causes is important as this will ultimately guide the development of preventive strategies and targeted therapies. This review explores the contribution of twin studies to the understanding of the aetiology of asthma and atopic diseases. PMID:26672957

  15. Genetic impact dominates over environmental effects in development of carotid artery stiffness: a twin study.

    PubMed

    Horváth, Tamás; Osztovits, János; Pintér, Alexandra; Littvay, Levente; Cseh, Domonkos; Tárnoki, Adám D; Tárnoki, Dávid L; Jermendy, Adám L; Steinbach, Rita; Métneki, Júlia; Schillaci, Giuseppe; Kollai, Márk; Jermendy, György

    2014-01-01

    Arterial stiffness is an independent predictor of cardiovascular, cerebrovascular and all-cause mortality. Quantifying the genetic influence on the stiff arterial phenotype allows us to better predict the development of arterial stiffness. In this study, we aimed to determine the heritability of carotid artery stiffness in healthy twins. We studied 98 twin pairs of both sexes. We determined carotid artery stiffness locally using echo tracking and applanation tonometry. We estimated the heritability of stiffness parameters using structural equation modeling. The carotid distensibility coefficient showed the highest heritability (64%, 95% confidence interval 45-77%). The incremental elastic modulus, compliance and stiffness index β also showed substantial heritability (62%, 61% and 58%, respectively). The remaining 36-42% phenotypic variance was attributed to unshared environmental effects. Genetic influence appears to dominate over environmental factors in the development of carotid artery stiffness. Environmental factors may have an important role in favorably influencing the genetic predisposition for accelerated arterial stiffening. PMID:24089266

  16. Mental Representations of Attachment in Identical Female Twins with and without Conduct Problems

    ERIC Educational Resources Information Center

    Constantino, John N.; Chackes, Laura M.; Wartner, Ulrike G.; Gross, Maggie; Brophy, Susan L.; Vitale, Josie; Heath, Andrew C.

    2006-01-01

    Insecure mental representations of attachment, a nearly invariant feature of cluster B personality disorders, have never previously been studied in twins. We conducted the Adult Attachment Interview (AAI) on 33 pairs of monozygotic (MZ) female twins reared together as an initial exploration of causal influences on mental representations of…

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

    PubMed

    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. PMID:26538243

  18. Associations Between Sleep-Wake Consolidation and Language Development in Early Childhood: A Longitudinal Twin Study

    PubMed Central

    Dionne, Ginette; Touchette, Evelyne; Forget-Dubois, Nadine; Petit, Dominique; Tremblay, Richard E.; Montplaisir, Jacques Y.; Boivin, Michel

    2011-01-01

    Study Objectives: The objectives were (1) to assess associations between sleep consolidation at 6, 18 and 30 months and language skills at 18, 30, and 60 months; and (2) to investigate the genetic/environmental etiology of these associations. Design: Longitudinal study of a population-based twin cohort. Participants: 1029 twins from the Quebec Newborn Twin Study. Measurements and Results: Sleep consolidation was derived from parental reports of day/night consecutive sleeping durations. Language skills were assessed with the MacArthur Communicative Development Inventory at 18 and 30 months and the Peabody Picture Vocabulary Test at 60 months. The day/night sleep ratio decreased significantly from 6 to 30 months. The 6- and 18-month ratios were negatively correlated with subsequent language skills. Children with language delays at 60 months had less mature sleep consolidation at both 6 and 18 months than children without delays and those with transient early delays. Genetic and regression analyses revealed that the sleep ratio at 6 months was highly heritable (64%) and predicted 18-month (B = −0.06) and 30-month language (B = −0.11) mainly through additive genetic influences (RGs = 0.32 and 0.33, respectively). By contrast, the sleep ratio at 18 months was mainly due to shared environment influences (58%) and predicted 60-month language (B = −0.08) through shared environment influences (RCs = 0.24). Conclusions: Poor sleep consolidation during the first 2 years of life may be a risk factor for language learning, whereas good sleep consolidation may foster language learning through successive genetic and environmental influences. Citation: Dionne G; Touchette E; Forget-Dubois N; Petit D; Tremblay RE; Montplaisir JY; Boivin M. Associations between sleep-wake consolidation and language development in early childhood: a longitudinal twin study. SLEEP 2011;34(8):987-995. PMID:21804661

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed Central

    Zhao, J; Goldberg, J; Vaccarino, V

    2013-01-01

    Objective: Epigenetic mechanisms are increasingly being recognized as an important factor for obesity. The serotonin transporter gene (SLC6A4) has a critical role in regulating food intake, body weight and energy balance. This study examines the potential association between SLC6A4 promoter methylation and obesity measures in a monozygotic (MZ) twin sample. Methods: We studied 84 MZ twin pairs drawn from the Vietnam Era Twin Registry. Obesity measures include body mass index (BMI), body weight, waist circumference (WC) and waist-hip ratio (WHR). The SLC6A4 promoter methylation profile in peripheral blood leukocytes was quantified by bisulfite pyrosequencing. The association between methylation variation and obesity parameters was examined by mixed-model regression and matched pair analysis, adjusting for age, smoking, alcohol consumption, physical activity and total daily energy intake. Multiple testing was controlled using the adjusted false discovery rate (q-value). Results: Mean methylation level was positively correlated with BMI (r=0.29; P=0.0002), body weight (r=0.31; P<0.0001) and WC (r=0.20; P=0.009), but not WHR. Intra-pair differences in mean methylation were significantly correlated with intra-pair differences in BMI, body weight and WC, but not WHR. On average, a 1% increase in mean methylation was associated with 0.33 kg m−2 increase in BMI (95% CI: 0.02–0.65; P=0.03), 1.16 kg increase in body weight (95% CI, 0.16–2.16; P=0.02) and 0.78 cm increase in WC (95% CI, 0.05–1.50; P=0.03) after controlling for potential confounders. Conclusions: SLC6A4 promoter hypermethylation is significantly associated with an increased prevalence of obesity within a MZ twin study. PMID:22290534

  1. A twin-study of sleep difficulties in school-aged children.

    PubMed

    Gregory, Alice M; Rijsdijk, Frühling V; Eley, Thalia C

    2006-01-01

    This study examines frequency, overlap, and genetic and environmental influences on sleep difficulties, which are understudied in school-aged children. The Sleep Self Report and the Children's Sleep Habits Questionnaire were completed by 300 twin pairs (aged 8 years) and their parents. Child report suggested more frequent sleep problems than parent report (e.g., regular sleep onset delay was reported by 45% of children and 17% of parents). Associations between most of the sleep difficulties were small but significant (e.g., r(s)=.16 for parent report of bedtime resistance and sleep onset delay). Twin correlations based on parent reports suggest greater genetic influence (M=50%) than those based on child self-report (M=18%). Possible rater effects should be considered when evaluating children's sleep problems. PMID:17107453

  2. “Teacher Effects” in Early Literacy Development: Evidence from a Study of Twins

    PubMed Central

    Byrne, Brian; Coventry, William L.; Olson, Richard K.; Wadsworth, Sally J.; Samuelsson, Stefan; Petrill, Stephen A.; Willcutt, Erik G.; Corley, Robin

    2009-01-01

    It is often assumed that differences in teacher characteristics are a major source of variability in children’s educational achievements. We examine this assumption for early literacy achievement by calculating the correlations between pairs of twin children who either share or do not share a teacher in kindergarten, Grade 1, and Grade 2. Teacher effects, or more strictly classroom effects, would show up as higher correlations for same- than different-class twin pairs. Same-class correlations were generally higher than different-class correlations, though not significantly so on most occasions. On the basis of the results we estimate that the maximum variance accounted for by being assigned to same or different classrooms is 8%. This is an upper-bound figure for a teacher effect because factors other than teachers may contribute to variation attributable to classroom assignment. We discuss the limitations of the study and draw out some of its educational implications. PMID:20204169

  3. Tribute to dr louis keith: twin and physician extraordinaire/twin research reports: influences on asthma severity; chimerism revisited; DNA strand break repair/media reports: twins born apart; elevated twin frequencies; celebrity father of twins; conjoined twinning.

    PubMed

    Segal, Nancy L

    2014-10-01

    The International Society for Twin Studies has lost a valued friend and colleague. Dr Louis Keith, Emeritus Professor of Obstetrics and Gynecology at Northwestern University, in Chicago, passed away on Sunday, July 6, 2014. His life and work with twins will be acknowledged at the November 2014 International Twin Congress in Budapest, Hungary. Next, twin research reports on the severity of asthma symptoms, a case of chimerism, and factors affecting DNA breakage and repair mechanisms are reviewed. Media reports cover twins born apart, elevated twin frequencies, a celebrity father of twins, and a family's decision to keep conjoined twins together. PMID:25213730

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

    PubMed

    Montag, Christian; Hahn, Elisabeth; Reuter, Martin; Spinath, Frank M; Davis, Ken; Panksepp, Jaak

    2016-01-01

    The present study investigated for the first time the relative importance of genetics and environment on individual differences in primary emotionality as measured with the Affective Neuroscience Personality Scales (ANPS) by means of a twin-sibling study design. In N = 795 participants (n = 303 monozygotic twins, n = 172 dizygotic twins and n = 267 non-twin full siblings), moderate to strong influences of genetics on individual differences in these emotional systems are observed. Lowest heritability estimates are presented for the SEEKING system (33%) and highest for the PLAY system (69%). Further, multivariate genetic modeling was applied to the data showing that associations among the six ANPS scales were influences by both, a genetic as well as an environmental overlap between them. In sum, the study underlines the usefulness of the ANPS for biologically oriented personality psychology research. PMID:26999649

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

    PubMed Central

    Reuter, Martin; Spinath, Frank M.; Davis, Ken; Panksepp, Jaak

    2016-01-01

    The present study investigated for the first time the relative importance of genetics and environment on individual differences in primary emotionality as measured with the Affective Neuroscience Personality Scales (ANPS) by means of a twin-sibling study design. In N = 795 participants (n = 303 monozygotic twins, n = 172 dizygotic twins and n = 267 non-twin full siblings), moderate to strong influences of genetics on individual differences in these emotional systems are observed. Lowest heritability estimates are presented for the SEEKING system (33%) and highest for the PLAY system (69%). Further, multivariate genetic modeling was applied to the data showing that associations among the six ANPS scales were influences by both, a genetic as well as an environmental overlap between them. In sum, the study underlines the usefulness of the ANPS for biologically oriented personality psychology research. PMID:26999649

  6. Heritability of Pain Catastrophizing and Associations with Experimental Pain Outcomes: A Twin Study

    PubMed Central

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

    2014-01-01

    The current study employed a twin paradigm to examine the genetic and environmental contributions to pain catastrophizing as well as the observed association between pain catastrophizing and cold pressor task (CPT) outcomes. Male and female monozygotic (n=206) and dizygotic twins (n=194) from the University of Washington Twin Registry completed a measure of pain catastrophizing and performed a CPT challenge. As expected, pain catastrophizing emerged as a significant predictor of several CPT outcomes, including cold pressor immersion tolerance, pain tolerance, and delayed pain rating. The heritability estimate for pain catastrophizing was found to be 37% with the remaining 63% of variance attributable to unique environmental influence. Additionally, the observed associations between pain catastrophizing and CPT outcomes were not found attributable to shared genetics or environmental exposure, suggesting a direct relationship between catastrophizing and experimental pain outcomes. This study is the first to examine the heritability of pain catastrophizing and potential processes by which pain catastrophizing is related to experimental pain response. PMID:25599234

  7. Noninvasive high-intensity focused ultrasound treatment of twin-twin transfusion syndrome: A preliminary in vivo study.

    PubMed

    Shaw, Caroline J; Civale, John; Botting, Kimberley J; Niu, Youguo; Ter Haar, Gail; Rivens, Ian; Giussani, Dino A; Lees, Christoph C

    2016-07-13

    We investigated the efficacy, maternofetal responses, and safety of using high-intensity focused ultrasound (HIFU) for noninvasive occlusion of placental vasculature compared to sham treatment in anesthetized pregnant sheep. This technique for noninvasive occlusion of placental vasculature may be translatable to the treatment of conditions arising from abnormal placental vasculature, such as twin-twin transfusion syndrome (TTTS). Eleven pregnant sheep were instrumented with maternal and fetal arterial catheters and time-transit flow probes to monitor cardiovascular, acid-base, and metabolic status, and then exposed to HIFU (n = 5) or sham (n = 6) ablation of placental vasculature through the exposed uterine surface. Placental vascular flow was occluded in 28 of 30 targets, and histological examination confirmed occlusion in 24 of 30 targets. In both HIFU and sham exposures, uterine contact reduced maternal uterine artery flow, but delivery of oxygen and glucose to the fetal brain remained normal. HIFU can consistently occlude in vivo placental vessels and ablate blood flow in a pregnant sheep model. Cardiovascular and metabolic fetal responses suggest that the technique is safe in the short term and potentially translatable to human pregnancy. PMID:27412787

  8. Leukotriene A4 Hydrolase Haplotype, Diet and Atherosclerosis: A Twin Study

    PubMed Central

    Zhao, Jinying; Goldberg, Jack; Vaccarino, Viola

    2012-01-01

    Objective Atherosclerosis is an inflammatory process resulting from the interaction between genetic and environmental factors. Leukotrienes are inflammatory mediators generated from arachidonic acid, and genetic polymorphisms involved in leukotriene metabolism are implicated in atherosclerosis. The objectives of this study are to examine whether genetic variants in key leukotriene enzymes are associated with atherosclerosis, and whether dietary intake of competing leukotriene substrates modifies the effect of leukotriene variants on atherosclerosis. Methods Atherosclerosis was assessed by common carotid intima-media thickness (IMT) using ultrasound. Sequence variants within arachidonate 5-lipoxygenase activating protein (ALOX5AP) and leukotriene A4 hydrolase (LTA4H) genes were analyzed with 32 single nucleotide polymorphisms (SNPs) in 169 Caucasian twin pairs from the Vietnam Era Twin Registry. The associations between genetic polymorphisms and carotid atherosclerosis, and gene × diet interactions were examined by generalized estimating equation controlling for potential confounders. Results A six-SNP haplotype in LTA4H, designated HapE, was significantly associated with carotid IMT after adjusting for known coronary risk factors. Twins carrying HapE had a much lower IMT compared to twins not carrying (695 μm vs. 750 μm, p=0.0007). Moreover, dietary intake of polyunsaturated fatty acids strongly augmented the cardioprotective effect of HapE among those with this haplotype but not those without, suggesting a haplotype × diet interaction (Interaction PHapE × n-3 = 0.03, PHapE × n-6 = 0.015). Conclusion We identified a novel leukotriene haplotype that appears to be protective towards subclinical atherosclerosis. This association is modified by dietary intake of polyunsaturated fatty acids. PMID:23153620

  9. Common Etiological Sources of Anxiety, Depression, and Somatic Complaints in Adolescents: A Multiple Rater twin Study.

    PubMed

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

    2016-01-01

    Somatic complaints in children and adolescents may be considered part of a broader spectrum of internalizing disorders that include anxiety and depression. Previous research on the topic has focused mainly on the relationship between anxiety and depression without investigating how common somatic symptoms relate to an underlying factor and its etiology. Based on the classical twin design with monozygotic and dizygotic twins reared together, our study aimed to explore the extent to which the covariation between three phenotypes in adolescent girls and boys can be represented by a latent internalizing factor, with a focus on both common and specific etiological sources. A population-based sample of twins aged 12-18 years and their mothers and fathers (N = 1394 families) responded to questionnaire items measuring the three phenotypes. Informants' ratings were collapsed using full information maximum likelihood estimated factor scores. Multivariate genetic analyses were conducted to examine the etiological structure of concurrent symptoms. The best fitting model was an ACE common pathway model without sex limitation and with one substantially heritable (44%) latent factor shared by the phenotypes. Concurrent symptoms also resulted from shared (25%) and non-shared (31%) environments. The factor loaded most on depression symptoms and least on somatic complaints. Trait-specific influences explained 44% of depression variance, 59% of anxiety variance, and 65% of somatic variance. Our results suggest the presence of a general internalizing factor along which somatic complaints and mental distress can be modeled. However, specific influences make the symptom types distinguishable. PMID:25619928

  10. Parapagus conjoined twin calf: a case study - focused on CT and cardiac abnormalities.

    PubMed

    Schneevoigt, J; Bahramsoltani, M; Gerlach, K; Gericke, A; Fersterra, M; Brehm, W; Seeger, J

    2014-02-01

    Congenital duplication anomalies occasionally occur in both humans and animals. Although various forms of classification of these conjoined twins exist, each case should be considered as an individual. In the case study presented a Holstein Frisian calf, born alive after 281 days of normal gravidity was investigated by computed tomography (CT) and subsequent dissection. The calf could be classified as a parapagus dicephalus tetrabrachius. It exhibited two heads each of them with a complete cervical spine leading to a complete thoracic and lumbar spine and separate tails. Looking at the point of fusion, the twin was conjoined in the ventrolateral thoracic part of the body. The calf had two thoraces with four forelimbs and two pelvic limbs on a single pelvis. As two heads and thoraces were present, beginning at the oral cavity, two intestinal systems were observable leading to a fusion point at the ascending part of the duodenum been continued caudally as a single system. Within each thorax, two lungs and a heart were present. However, only the heart in the left thorax was normal shape, exhibiting a strong myocardium and increased size. In contrast, the heart within the right thorax was considerably smaller, round shaped, and it appeared to be spongy and not fully developed during the foetal period. Commonly, classification of conjoined twins is only based on the appearance of the skeletal system. However, in the case presented, the point of fusion of the skeletal system did not allow conclusions regarding the intestinal or cardiovascular system. PMID:23731024

  11. DISTINCT ETIOLOGICAL INFLUENCES ON OBSESSIVE-COMPULSIVE SYMPTOM DIMENSIONS: A MULTIVARIATE TWIN STUDY

    PubMed Central

    López-Solà, Clara; Fontenelle, Leonardo F.; Verhulst, Brad; Neale, Michael C.; Menchón, José M.; Alonso, Pino; Harrison, Ben J.

    2016-01-01

    Background Obsessive-compulsive disorder (OCD) is characterized by five major dimensions, including contamination/washing, harm/checking, symmetry/ordering, hoarding, and forbidden thoughts. How these dimensions may relate etiologically to the symptoms of other obsessive-compulsive related disorders (OCRDs) and anxiety disorders (ADs) is not well known. The aim of this study was to examine the genetic and environmental overlap between each major obsessive-compulsive dimension with the symptoms of other OCRDs and ADs. Methods Two thousand four hundred ninety-five twins of both sexes, aged between 18 and 45 years, were recruited from the Australian Twin Registry. Measures used scores on four dimensions (obsessing (forbidden thoughts), washing, checking, and ordering) of the Obsessive-Compulsive Inventory-Revised, Dysmorphic Concerns Questionnaire, Hoarding Rating Scale, Anxiety Sensitivity Index, Social Phobia Inventory, and Stress subscale of the Depression, Anxiety, and Stress Scale. Multivariate twin modeling methods using continuous and categorized variables were performed, also controlling for age and gender. Results Our findings suggested that forbidden thoughts and washing demonstrated the strongest genetic overlap with other AD symptoms, while ordering was genetically related to OCRD symptoms. Common genetic influences on checking symptoms were best estimated when modeling OCRDs together with AD symptoms. Common environmental factors of ordering and checking were shared with AD symptoms. Conclusions Important shared genetic and environmental risk factors exist between OCD, OCRDs, and ADs, but which vary alongside the expression of its major dimensions. PMID:26630089

  12. Causes and consequences of obesity: the contribution of recent twin studies.

    PubMed

    Naukkarinen, J; Rissanen, A; Kaprio, J; Pietiläinen, K H

    2012-08-01

    Obesity is a genetically complex disorder that produces a myriad of health problems. Most of the recognized complications of obesity are not only strongly influenced by lifestyle factors, but also present with independent genetic predispositions that are notoriously difficult to disentangle in humans. Most studies on the causes and consequences of acquired obesity are encumbered by the incomplete ability to control for genetic influences. However, utilizing a unique experiment of nature, namely monozygotic twins (MZ) discordant for obesity as 'clonal controls' of obese and non-obese individuals has enabled the fine characterization of the effects and possible antecedents of acquired obesity while controlling for the genetic background, as well as pointed to novel obesity predisposing candidate genes. This review is a distillation of the findings from more than 10 years of research done in an exceptionally well-characterized collection of MZ and dizygotic (DZ) twins, based on the Finnish Twin Cohorts. Topics covered include the nature of development of obesity from the childhood onwards, the role of exercise in modifying the genetic susceptibility, the resulting inflammatory, prediabetic and preatherosclerotic changes in whole body and adipose tissue physiology, as well as the newest insights provided by the omics revolution. PMID:21986704

  13. Regional Cortical Surface Area in Adolescents: A Preliminary MRI Twin Study of Genetic and Environmental Contributions.

    PubMed

    Ma, Xingshun; Eyler, Lisa T; Hu, Xiaomei; Hou, Xiao; Deng, Wei; Zhang, Xiaowei; Lin, Yin; Lei, Wei; Li, Mingli; Kang, Line; Huang, Yongfeng; Wang, Na; Qiu, Tian; Li, Xiao; He, Qian; Fu, Yixiao; Meng, Huaqing; Li, Tao

    2016-03-01

    Cortical surface area (CSA) has particular relevance for understanding development, behavior, and the connection between brain structure and function. Little is known about genetic and environmental determinants of CSA during development. We utilized bivariate twin methods to identify global and regionally specific genetic factors which influence CSA in a preliminary sample of typically-developing adolescents, with hypotheses based on findings in middle-aged adults. Similar to previous findings, we observed high heritability for total CSA. There was also significant evidence for genetic influences on regional CSA, particularly when these were not adjusted for total CSA, with highest heritability in frontal cortex and relatively fewer genetic contributions to medial temporal cortical structures. Adjustment for total CSA reduced regional CSA heritability dramatically, but a moderate influence of genetic factors remained in some regions. Both global and regionally-specific genetic factors influence regional CSA during adolescence. PMID:26519369

  14. Twin Studies and Their Implications for Molecular Genetic Studies: Endophenotypes Integrate Quantitative and Molecular Genetics in ADHD Research

    ERIC Educational Resources Information Center

    Wood, Alexis C.; Neale, Michael C.

    2010-01-01

    Objective: To describe the utility of twin studies for attention-deficit/hyperactivity disorder (ADHD) research and demonstrate their potential for the identification of alternative phenotypes suitable for genomewide association, developmental risk assessment, treatment response, and intervention targets. Method: Brief descriptions of the classic…

  15. Adult Development and Adult Beginning Reading Behaviors: An Exploratory Study.

    ERIC Educational Resources Information Center

    Schumacher, Sally

    An ethnographic study investigated four adult beginning reading (ABR) classes in several adult learning centers in order to determine the effect of an adult's age and developmental phase on his or her behavior and attitudes in the learning-to-read process. For 9 months, a four-member research team conducted on-site observations, compiled extensive…

  16. Study Circle Guide: Adult Student Persistence

    ERIC Educational Resources Information Center

    National Center for the Study of Adult Learning and Literacy (NCSALL), 2006

    2006-01-01

    This study circle was created by the National Center for the Study of Adult Learning and Literacy (NCSALL). The study circle is part of NCSALL's efforts to help connect research and practice in the field of adult basic education and adult literacy. The Adult Student Persistence Study Circle is one of a series of study circles that NCSALL has…

  17. Mesial temporal lobe epilepsy with hippocampal sclerosis in two pairs of identical twins.

    PubMed

    Karatas, H; Dericioglu, N; Saygi, S

    2012-01-01

    The most common pathology in adult patients with temporal lobe epilepsy is hippocampal sclerosis (HS), the etiology of which is not clear. There is a conflicting evidence in literature regarding whether HS is genetic or acquired. Twin studies can help to clarify the mechanisms of HS, but limited numbers of twins have been studied. We describe two monozygotic pairs, in whom the affected twin had mesial temporal lobe epilepsy and HS. The unaffected twin remained seizure free on long-term follow-up. HS was confirmed pathologically in one of the affected twins. Our data and other limited twin studies indicate that HS occurs as a consequence of prolonged repeated seizures or other events during childhood. In other words, some acquired factors may be more important than genetic ones in the etiology of HS (Fig. 2, Ref. 16). PMID:22794520

  18. Academic performance of opposite-sex and same-sex twins in adolescence: A Danish national cohort study.

    PubMed

    Ahrenfeldt, Linda; Petersen, Inge; Johnson, Wendy; Christensen, Kaare

    2015-03-01

    Testosterone is an important hormone in the sexual differentiation of the brain, contributing to differences in cognitive abilities between males and females. For instance, studies in clinical populations such as females with congenital adrenal hyperplasia (CAH) who are exposed to high levels of androgens in utero support arguments for prenatal testosterone effects on characteristics such as visuospatial cognition and behaviour. The comparison of opposite-sex (OS) and same-sex (SS) twin pairs can be used to help establish the role of prenatal testosterone. However, although some twin studies confirm a masculinizing effect of a male co-twin regarding for instance perception and cognition it remains unclear whether intra-uterine hormone transfer exists in humans. Our aim was to test the potential influences of testosterone on academic performance in OS twins. We compared ninth-grade test scores and teacher ratings of OS (n=1812) and SS (n=4054) twins as well as of twins and singletons (n=13,900) in mathematics, physics/chemistry, Danish, and English. We found that males had significantly higher test scores in mathematics than females (.06-.15 SD), whereas females performed better in Danish (.33-.49 SD), English (.20 SD), and neatness (.45-.64 SD). However, we did not find that OS females performed better in mathematics than SS and singleton females, nor did they perform worse either in Danish or English. Scores for OS and SS males were similar in all topics. In conclusion, this study did not provide evidence for a masculinization of female twins with male co-twins with regard to academic performance in adolescence. PMID:25655669

  19. Academic performance of opposite-sex and same-sex twins in adolescence: A Danish national cohort study

    PubMed Central

    Petersen, Inge; Johnson, Wendy; Christensen, Kaare

    2015-01-01

    Testosterone is an important hormone in the sexual differentiation of the brain, contributing to differences in cognitive abilities between males and females. For instance, studies in clinical populations such as females with congenital adrenal hyperplasia (CAH) who are exposed to high levels of androgens in utero support arguments for prenatal testosterone effects on characteristics such as visuospatial cognition and behaviour. The comparison of opposite-sex (OS) and same-sex (SS) twin pairs can be used to help establish the role of prenatal testosterone. However, although some twin studies confirm a masculinizing effect of a male co-twin regarding for instance perception and cognition it remains unclear whether intra-uterine hormone transfer exists in humans. Our aim was to test the potential influences of testosterone on academic performance in OS twins. We compared ninth-grade test scores and teacher ratings of OS (n = 1812) and SS (n = 4054) twins as well as of twins and singletons (n = 13,900) in mathematics, physics/chemistry, Danish, and English. We found that males had significantly higher test scores in mathematics than females (.06–.15 SD), whereas females performed better in Danish (.33–.49 SD), English (.20 SD), and neatness (.45–.64 SD). However, we did not find that OS females performed better in mathematics than SS and singleton females, nor did they perform worse either in Danish or English. Scores for OS and SS males were similar in all topics. In conclusion, this study did not provide evidence for a masculinization of female twins with male co-twins with regard to academic performance in adolescence. PMID:25655669

  20. Infant Temperament and Genetics: An Objective Twin Study of Motor Activity Level.

    ERIC Educational Resources Information Center

    Saudino, Kimberly J.; Eaton, Warren O.

    1991-01-01

    The activity level of 60 pairs of infant twins was measured for 2 days. Differences in activity level for monozygotic and dizygotic twins, as indicated by motion recorders and parent ratings, showed evidence of genetic influences. (BC)

  1. Study of the Mechanical Behavior of Radially Grown Fivefold Twinned Nanowires on the Atomic Scale.

    PubMed

    Yue, Yonghai; Zhang, Qi; Yang, Zhenyu; Gong, Qihua; Guo, Lin

    2016-07-01

    In situ bending tests and dynamic modeling simulations are for the first time revealing the mechanical behavior of copper nanowires (NW) with radially grown fivefold twin structures on the atomic scale. Combining the simulations with the experimental results it is shown that both the twin boundaries (TBs) and the twin center act as dislocation sources. TB migration and L-locks are readily observed in these types of radially grown fivefold-twin structures. PMID:27231215

  2. High Risk of Unexpected Late Fetal Death in Monochorionic Twins Despite Intensive Ultrasound Surveillance: A Cohort Study

    PubMed Central

    2005-01-01

    Background The rationale for fetal surveillance in monochorionic twin pregnancies is timely intervention to prevent the increased fetal/perinatal morbidity and mortality attributed to twin–twin transfusion syndrome and intrauterine growth restriction. We investigated the residual risk of fetal death after viability in otherwise uncomplicated monochorionic diamniotic twin pregnancies. Methods and Findings We searched an electronic database of 480 completed monochorionic pregnancies that underwent fortnightly ultrasound surveillance in our tertiary referral fetal medicine service between 1992 and 2004. After excluding pregnancies with twin–twin transfusion syndrome, growth restriction, structural abnormalities, or twin reversed arterial perfusion sequence, and monoamniotic and high-order multiple pregnancies, we identified 151 uncomplicated monochorionic diamniotic twin pregnancies with normal growth, normal liquor volume, and normal Doppler studies on fortnightly ultrasound scans. Ten unexpected intrauterine deaths occurred in seven (4.6%) of 151 previously uncomplicated monochorionic diamniotic pregnancies, within 2 wk of a normal scan, at a median gestational age of 34+1 wk (weeks+days; range 28+0 to 36+3). Two of the five cases that underwent autopsy had features suggestive of acute late onset twin–twin transfusion syndrome, but no antenatal indicators of transfusional imbalance or growth restriction, either empirically or in a 1:3 gestation-matched case–control comparison. The prospective risk of unexpected antepartum stillbirth after 32 wk was 1/23 monochorionic diamniotic pregnancies (95% confidence interval 1/11 to 1/63). Conclusion Despite intensive fetal surveillance, structurally normal monochorionic diamniotic twin pregnancies without TTTS or IUGR are complicated by a high rate of unexpected intrauterine death. This prospective risk of fetal death in otherwise uncomplicated monochorionic diamniotic pregnancies after 32 wk of gestation might be

  3. Zygosity Differences in Height and Body Mass Index of Twins From Infancy to Old Age: A Study of the CODATwins Project.

    PubMed

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

    2015-10-01

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

  4. A Computational Discriminability Analysis on Twin Fingerprints

    NASA Astrophysics Data System (ADS)

    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.

  5. The Genetic Relationship between Indentical Twins.

    ERIC Educational Resources Information Center

    Herman, Rosemary

    1984-01-01

    Reviews current research on a woman's chances of bearing twins and the genetic relationship, prenatal competition, and personality similarities between twins. In addition, the nature/nurture controversy is discussed in terms of evidence from studies of identical twins reared apart. Future studies are suggested to discover the ways twinning might…

  6. Genome-wide methylation study on depression: differential methylation and variable methylation in monozygotic twins

    PubMed Central

    Córdova-Palomera, A; Fatjó-Vilas, M; Gastó, C; Navarro, V; Krebs, M-O; Fañanás, L

    2015-01-01

    Depressive disorders have been shown to be highly influenced by environmental pathogenic factors, some of which are believed to exert stress on human brain functioning via epigenetic modifications. Previous genome-wide methylomic studies on depression have suggested that, along with differential DNA methylation, affected co-twins of monozygotic (MZ) pairs have increased DNA methylation variability, probably in line with theories of epigenetic stochasticity. Nevertheless, the potential biological roots of this variability remain largely unexplored. The current study aimed to evaluate whether DNA methylation differences within MZ twin pairs were related to differences in their psychopathological status. Data from the Illumina Infinium HumanMethylation450 Beadchip was used to evaluate peripheral blood DNA methylation of 34 twins (17 MZ pairs). Two analytical strategies were used to identify (a) differentially methylated probes (DMPs) and (b) variably methylated probes (VMPs). Most DMPs were located in genes previously related to neuropsychiatric phenotypes. Remarkably, one of these DMPs (cg01122889) was located in the WDR26 gene, the DNA sequence of which has been implicated in major depressive disorder from genome-wide association studies. Expression of WDR26 has also been proposed as a biomarker of depression in human blood. Complementarily, VMPs were located in genes such as CACNA1C, IGF2 and the p38 MAP kinase MAPK11, showing enrichment for biological processes such as glucocorticoid signaling. These results expand on previous research to indicate that both differential methylation and differential variability have a role in the etiology and clinical manifestation of depression, and provide clues on specific genomic loci of potential interest in the epigenetics of depression. PMID:25918994

  7. The Heritability of Insomnia Progression during Childhood/Adolescence: Results from a Longitudinal Twin Study

    PubMed Central

    Barclay, Nicola L.; Gehrman, Philip R.; Gregory, Alice M.; Eaves, Lindon J.; Silberg, Judy L.

    2015-01-01

    Study Objectives: To determine prevalence and heritability of insomnia during middle/late childhood and adolescence; examine longitudinal associations in insomnia over time; and assess the extent to which genetic and environmental factors on insomnia remain stable, or whether new factors come into play, across this developmental period. Design: Longitudinal twin study. Setting: Academic medical center. Patients or Participants: There were 739 complete monozygotic twin pairs (52%) and 672 complete dizygotic twin pairs (48%) initially enrolled and were followed up at three additional time points (waves). Mode ages at each wave were 8, 10, 14, and 15 y (ages ranged from 8–18 y). Interventions: None. Measurements and Results: Clinical ratings of insomnia symptoms were assessed using the Child and Adolescent Psychiatric Assessment (CAPA) by trained clinicians, and rated according to Diagnostic and Statistical Manual of Mental Disorders, 3rd Edition—Revised criteria for presence of “clinically significant insomnia,” over four sequential waves. Insomnia symptoms were prevalent but significantly decreased across the four waves (ranging from 16.6% to 31.2%). “Clinically significant insomnia” was moderately heritable at all waves (h2 range = 14% to 38%), and the remaining source of variance was the nonshared environment. Multivariate models indicated that genetic influences at wave 1 contributed to insomnia at all subsequent waves, and that new genetic influences came into play at wave 2, which further contributed to stability of symptoms. Nonshared environmental influences were time-specific. Conclusion: Insomnia is prevalent in childhood and adolescence, and is moderately heritable. The progression of insomnia across this developmental time period is influenced by stable as well as new genetic factors that come into play at wave 2 (modal age 10 y). Molecular genetic studies should now identify genes related to insomnia progression during childhood and

  8. Atomic-scale studies on the effect of boundary coherency on stability in twinned Cu

    SciTech Connect

    Niu, Rongmei; Han, Ke Su, Yi-Feng; Salters, Vincent J.

    2014-01-06

    The stored energy and hardness of nanotwinned (NT) Cu are related to interaction between dislocations and (111)-twin boundaries (TBs) studied at atomic scales by high-angle annular dark-field scanning transmission electron microscope. Lack of mobile dislocations at coherent TBs (CTBs) provides as-deposited NT Cu a rare combination of stability and hardness. The introduction of numerous incoherent TBs (ITBs) reduces both the stability and hardness. While storing more energy in their ITBs than in the CTBs, deformed NT Cu also exhibits high dislocation density and TB mobility and therefore has increased the driving force for recovery, coarsening, and recrystallization.

  9. Association Between Promoter Methylation of Serotonin Transporter Gene and Depressive Symptoms: A Monozygotic Twin Study

    PubMed Central

    Zhao, Jinying; Goldberg, Jack; Bremner, James D.; Vaccarino, Viola

    2013-01-01

    Objective Epigenetic mechanisms have been implicated in the pathogenesis of psychiatric disorders. The serotonin transporter gene (SLC6A4) is a key candidate gene for depression. We examined the association between SLC6A4 promoter methylation variation and depressive symptoms using 84 monozygotic twin pairs. Methods DNA methylation level in the SLC6A4 promoter region was quantified by bisulfite pyrosequencing using genomic DNA isolated from peripheral blood leukocytes. The number of current depressive symptoms was assessed using the Beck Depressive Inventory II (BDI-II). The association between methylation variation and depressive symptoms was examined using matched twin-pair analyses, adjusting for body mass index, smoking, physical activity, and alcohol consumption. Multiple testing was controlled by adjusted false discovery rate (q value). Results Intrapair difference in DNA methylation variation at 10 of the 20 studied CpG sites is significantly correlated with intrapair difference in BDI scores. Linear regression using intrapair differences demonstrates that intrapair difference in BDI score was significantly associated with intrapair differences in DNA methylation variation after adjusting for potential confounders and correction for multiple testing. On average, a 10% increase in the difference in mean DNA methylation level was associated with 4.4 increase in the difference in BDI score (95% confidence interval = 0.9–7.9, p = .01). Conclusions This study provides evidence that variation in methylation level within the promoter region of the serotonin transporter gene is associated with variation in depressive symptoms in a large sample of monozygotic twin pairs. This relationship is not confounded by genetic and shared environment. The 5-HTTLPR genotype also does not modulate this association. PMID:23766378

  10. Population based study of prevalence of islet cell autoantibodies in monozygotic and dizygotic Danish twin pairs with insulin dependent diabetes mellitus.

    PubMed Central

    Petersen, J. S.; Kyvik, K. O.; Bingley, P. J.; Gale, E. A.; Green, A.; Dyrberg, T.; Beck-Nielsen, H.

    1997-01-01

    OBJECTIVE: To study the comparative importance of environment and genes in the development of islet cell autoimmunity associated with insulin dependent diabetes mellitus. DESIGN: Population based study of diabetic twins. SETTING: Danish population. SUBJECTS: 18 monozygotic and 36 dizygotic twin pairs with one or both partners having insulin dependent diabetes. MAIN OUTCOME MEASURES: Presence of islet cell antibodies, insulin autoantibodies, and autoantibodies to glutamic acid decarboxylase (GAD65) in serum samples from twin pairs 10 years (range 0-30 years) and 9.5 years (2-30 years) after onset of disease. RESULTS: In those with diabetes the prevalence of islet cell antibodies, insulin autoantibodies, and autoantibodies to glutamic acid decarboxylase in the 26 monozygotic twins was 38%, 85%, and 92%, respectively, and in the dizygotic twins was 57%, 70%, and 57%, respectively. In those without diabetes the proportions were 20%, 50%, and 40% in the 10 monozygotic twins and 26%, 49%, and 40% in the 35 dizygotic twins. CONCLUSION: There is no difference between the prevalence of islet cell autoantibodies in dizygotic and monozygotic twins without diabetes, suggesting that islet cell autoimmunity is environmentally rather than genetically determined. Furthermore, the prevalence of islet cell antibodies was higher in the non-diabetic twins than in other first degree relatives of patients with insulin dependent diabetes. This implies that the prenatal or early postnatal period during which twins are exposed to the same environment, in contrast with that experienced by first degree relatives, is of aetiological importance. PMID:9169400

  11. Comparing the biological and cultural inheritance of personality and social attitudes in the Virginia 30,000 study of twins and their relatives.

    PubMed

    Eaves, L; Heath, A; Martin, N; Maes, H; Neale, M; Kendler, K; Kirk, K; Corey, L

    1999-06-01

    Measures of four dimensions of personality (Psychoticism, Extraversion, Neuroticism, and Lie scores) and six aspects of social attitudes (to sex, taxation, militarism, politics, religion and a general conservatism scale) were obtained by mailed questionnaire from 29,691 US subjects including adult twins (n = 14,761) their parents (n = 2360), their spouses (n = 4391), siblings (n = 3184) and adult children (n = 4800). After correction for the average effects of age, sex and source of sample, familial correlations were computed for 80 distinct biological and social relationships. The data allow for the estimation of the additive and non-additive effects of genes, assortative mating, vertical cultural inheritance and other non-parental effects of the shared environment on differences in personality and social attitudes. The interaction of genetic and environmental effects with sex may also be analyzed. Model-fitting analyses show that personality and social attitude measures differ markedly in major features of family resemblance. Additive and dominant genetic effects contribute to differences in both personality and attitudes, but the effects of the family environment, including vertical cultural transmission from parent to child, are much more marked for social attitudes than for personality. There is substantial assortative mating for social attitudes and almost none for personality. The causes of family resemblance depend significantly on sex for almost every variable studied. These findings clarify and extend the more tentative findings derived from previous twin, family and adoption studies. PMID:10480741

  12. Impact of hip fracture on mortality: a cohort study in hip fracture discordant identical twins.

    PubMed

    Michaëlsson, Karl; Nordström, Peter; Nordström, Anna; Garmo, Hans; Byberg, Liisa; Pedersen, Nancy L; Melhus, Håkan

    2014-02-01

    Several studies have shown a long-lasting higher mortality after hip fracture, but the reasons for the excess risk are not well understood. We aimed to determine whether a higher mortality after hip fracture exists when controlling for genetic constitution, shared environment, comorbidity, and lifestyle by use of a nationwide cohort study in hip fracture discordant monozygotic twins. All 286 identical Swedish twin pairs discordant for hip fracture (1972 to 2010) were identified. Comorbidity and lifestyle information was retrieved by registers and questionnaire information. We used intrapair Cox regression to compute multivariable-adjusted hazard ratios (HRs) for death. During follow-up, 143 twins with a hip fracture died (50%) compared with 101 twins (35%) without a hip fracture. Through the first year after hip fracture, the rate of death increased fourfold in women (HR = 3.71; 95% confidence interval [CI] 1.32-10.40) and sevenfold in men (HR = 6.67; 95% CI 1.47-30.13). The increased rate in women only persisted during the first year after hip fracture (HR after 1 year = 0.99; 95% CI 0.66-1.50), whereas the corresponding HR in men was 2.58 (95% CI 1.02-6.62). The higher risk in men after the hip fracture event was successively attenuated during follow-up. After 5 years, the hazard ratio in men with a hip fracture was 1.19 (95% CI 0.29-4.90). On average, the hip fracture contributed to 0.9 years of life lost in women (95% CI 0.06-1.7) and 2.7 years in men (95% CI 1.7-3.7). The potential years of life lost associated with the hip fracture was especially pronounced in older men (>75 years), with an average loss of 47% (95% CI 31-61) of the expected remaining lifetime. We conclude that both women and men display a higher mortality after hip fracture independent of genes, comorbidity, and lifestyle. PMID:23821464

  13. Some Features of Dialogue between Twins

    ERIC Educational Resources Information Center

    Savic, Svenka; Jocic, Mirjana

    1975-01-01

    Dialogues of sets of socially similar twins are studied. The opinion that twins have slower syntactic development than non-twins is seriously questioned. Dialogues with twins saying the same utterance together, correcting each other, quarreling, playing verbal games, etc. are analyzed in their deep structure. (SCC)

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

    PubMed

    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. PMID:10813800

  15. Cigarette smoking behavior in conjoined twins.

    PubMed

    Jarvik, M E; Gritz, E R; Rose, J E

    1983-01-01

    A study of cigarette smoking was undertaken in a pair of craniopagus twins to determine how a transfer of products of smoking is occurring between the twins. Alternately and independently, one twin smoked a nicotine-free cigarette, then the second twin smoked a nicotine-containing cigarette. The procedure enabled the investigators to study the migration of nicotine and carbon monoxide from one twin to the other. Salivary determination provided a noninvasive method of measuring cross circulation in conjoined twins. Measurements of salivary nicotine, however, indicated that, although the nicotine levels rose following smoking, there was relatively little transfer from one twin to the other through the circulation. PMID:6673459

  16. Psychopathic Personality and Negative Parent-to-Child Affect: A Longitudinal Cross-lag Twin Study

    PubMed Central

    Tuvblad, Catherine; Bezdjian, Serena; Raine, Adrian; Baker, Laura A.

    2013-01-01

    Purpose Previous studies that have explored the relationship between parenting style and children’s antisocial behavior have generally found significant bidirectional effects, whereby parenting behaviors influence their child’s antisocial outcomes, but a child’s behaviors also lead to changes in parenting style. Methods The present study investigated the genetic and environmental underpinnings of the longitudinal relationship between negative parent-to-child affect and psychopathic personality in a sample of 1,562 twins. Using a biometrical cross-lag analysis, bidirectional effects were investigated across two waves of assessment when the twins were ages 9–10 and 14–15, utilizing both caregiver and youth self-reports. Results Results demonstrated that negative parental affects observed at ages 9–10 influenced the child’s later psychopathic personality at ages 14–15, based on both caregiver and youth self-reports. For these ‘parent-driven effects’, both genetic and non-shared environmental factors were important in the development of later psychopathic personality during adolescence. There were additional ‘child-driven effects’ such that children’s psychopathic personality at ages 9–10 influenced negative parent-to-child affect at ages 14–15, but only within caregiver reports. Conclusions Thus, children’s genetically influenced psychopathic personality seemed to evoke parental negativity at ages 14–15, highlighting the importance of investigating bidirectional effects in parent-child relationships to understand the development of these traits. PMID:24223446

  17. Differential susceptibility to the environment: Are developmental models compatible with the evidence from twin studies?

    PubMed

    Del Giudice, Marco

    2016-08-01

    According to models of differential susceptibility, the same neurobiological and temperamental traits that determine increased sensitivity to stress and adversity also confer enhanced responsivity to the positive aspects of the environment. Differential susceptibility models have expanded to include complex developmental processes in which genetic variation interacts with exposure to early environmental factors, such as prenatal stress hormones and family conflict. In this study I employed a simulation approach to explore whether, and under what conditions, developmental models of differential susceptibility are compatible with the cumulative findings from twin studies of personality and behavior, which consistently show sizable effects of genetic and nonshared environmental factors and small to negligible effects of the shared environment. Simulation results showed that, to a first approximation, current alternative models of differential susceptibility are all equally compatible with the evidence from twin research; that sizable interaction effects involving individual differences in plasticity are plausible, but only if direct environmental effects are correspondingly weak; and that a major role of shared environmental factors is plausible in early development (consistent with the developmental mechanisms postulated in the differential susceptibility literature) but not in later development. These results support the general plausibility of differential susceptibility models and suggest some realistic constraints on their assumptions. (PsycINFO Database Record PMID:27455408

  18. Associations between motor timing, music practice, and intelligence studied in a large sample of twins.

    PubMed

    Ullén, Fredrik; Mosing, Miriam A; Madison, Guy

    2015-03-01

    Music performance depends critically on precise processing of time. A common model behavior in studies of motor timing is isochronous serial interval production (ISIP), that is, hand/finger movements with a regular beat. ISIP accuracy is related to both music practice and intelligence. Here we present a study of these associations in a large twin cohort, demonstrating that the effects of music practice and intelligence on motor timing are additive, with no significant multiplicative (interaction) effect. Furthermore, the association between music practice and motor timing was analyzed with the use of a co-twin control design using intrapair differences. These analyses revealed that the phenotypic association disappeared when all genetic and common environmental factors were controlled. This suggests that the observed association may not reflect a causal effect of music practice on ISIP performance but rather reflect common influences (e.g., genetic effects) on both outcomes. The relevance of these findings for models of practice and expert performance is discussed. PMID:25773626

  19. Genetic and Environmental Influences on Eating Behavior - A Study of Twin Pairs Reared Apart or Reared Together

    PubMed Central

    Elder, Sonya J.; Neale, Michael C.; Fuss, Paul J.; Lichtenstein, Alice H.; Greenberg, Andrew S.; McCrory, Megan A.; Bouchard, Thomas J.; Saltzman, Edward; Roberts, Susan B.

    2014-01-01

    This study examined the relative influence of genetic versus environmental factors on specific aspects of eating behavior. Adult monozygotic twins (22 pairs and 3 singleton reared apart, 38 pairs and 9 singleton reared together, age 18–76 years, BMI 17–43 kg/m2) completed the Three Factor Eating Questionnaire. Genetic and environmental variance components were determined for the three eating behavior constructs and their subscales using model-fitting univariate and multivariate analyses. Unique environmental factors had a substantial influence on all eating behavior variables (explaining 45–71% of variance), and most strongly influenced external locus for hunger and strategic dieting behavior of restraint (explaining 71% and 69% of variance, respectively). Genetic factors had a statistically significant influence on only 4 variables: restraint, emotional susceptibility to disinhibition, situational susceptibility to disinhibition, and internal locus for hunger (heritabilities were 52%, 55%, 38% and 50%, respectively). Common environmental factors did not statistically significantly influence any variable assessed in this study. In addition, multivariate analyses showed that disinhibition and hunger share a common influence, while restraint appears to be a distinct construct. These findings suggest that the majority of variation in eating behavior variables is associated with unique environmental factors, and highlights the importance of the environment in facilitating specific eating behaviors that may promote excess weight gain. PMID:25067963

  20. Genetic and Environmental Influences on Eating Behavior - A Study of Twin Pairs Reared Apart or Reared Together.

    PubMed

    Elder, Sonya J; Neale, Michael C; Fuss, Paul J; Lichtenstein, Alice H; Greenberg, Andrew S; McCrory, Megan A; Bouchard, Thomas J; Saltzman, Edward; Roberts, Susan B

    2012-04-01

    This study examined the relative influence of genetic versus environmental factors on specific aspects of eating behavior. Adult monozygotic twins (22 pairs and 3 singleton reared apart, 38 pairs and 9 singleton reared together, age 18-76 years, BMI 17-43 kg/m(2)) completed the Three Factor Eating Questionnaire. Genetic and environmental variance components were determined for the three eating behavior constructs and their subscales using model-fitting univariate and multivariate analyses. Unique environmental factors had a substantial influence on all eating behavior variables (explaining 45-71% of variance), and most strongly influenced external locus for hunger and strategic dieting behavior of restraint (explaining 71% and 69% of variance, respectively). Genetic factors had a statistically significant influence on only 4 variables: restraint, emotional susceptibility to disinhibition, situational susceptibility to disinhibition, and internal locus for hunger (heritabilities were 52%, 55%, 38% and 50%, respectively). Common environmental factors did not statistically significantly influence any variable assessed in this study. In addition, multivariate analyses showed that disinhibition and hunger share a common influence, while restraint appears to be a distinct construct. These findings suggest that the majority of variation in eating behavior variables is associated with unique environmental factors, and highlights the importance of the environment in facilitating specific eating behaviors that may promote excess weight gain. PMID:25067963

  1. Twin Higgs WIMP dark matter

    NASA Astrophysics Data System (ADS)

    García García, Isabel; Lasenby, Robert; March-Russell, John

    2015-09-01

    Dark matter (DM) without a matter asymmetry is studied in the context of twin Higgs (TH) theories in which the LHC naturalness problem is addressed. These possess a twin sector related to the Standard Model (SM) by a (broken) Z2 symmetry, and interacting with the SM via a specific Higgs portal. We focus on the minimal realization of the TH mechanism, the fraternal twin Higgs, with only a single generation of twin quarks and leptons, and the S U (3 )'×S U (2 )' gauge group. We show that a variety of natural twin-WIMP DM candidates are present (directly linked to the weak scale by naturalness), the simplest and most attractive being the τ' lepton with a mass mτ'>mHiggs/2 , although spin-1 W'± DM and multicomponent DM are also possible (twin baryons are strongly disfavored by tuning). We consider in detail the dynamics of the possibly (meta)stable glueballs in the twin sector, the nature of the twin QCD phase transition, and possible new contributions to the number of relativistic degrees of freedom, Δ Neff . Direct detection signals are below current bounds but accessible in near-future experiments. Indirect detection phenomenology is rich and requires detailed studies of twin hadronization and fragmentation to twin glueballs and quarkonia and their subsequent decay to SM, and possible light twin sector states.

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

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

  3. Double ovulation and occurrence of twinning in alpacas (Vicugna pacos).

    PubMed

    Campbell, A J; Pearson, L K; Spencer, T E; Tibary, A

    2015-08-01

    Twin births are rare in alpacas despite the high incidence of double ovulation and are undesirable because they contribute to early and late pregnancy loss, abortion, and birth of nonviable neonates. The objective of the present study was to determine the incidence and outcome of twin pregnancy in double-ovulating alpacas by retrospective and prospective analysis. Data from double-ovulating females (N = 41) presented for pregnancy diagnosis were analyzed to determine pregnancy status at three stages after mating (14-16, 25-30, and 45-53 days). In a prospective study, adult reproductively sound alpacas (n = 21) were examined by ultrasonography to determine the incidence of multiple ovulations. A subset of those alpacas (n = 10) were euthanized either at 9 days (n = 5) or 14 days (n = 5) after a single mating and administration of GnRH to determine presence and number of embryos. A total of 31 cycles were included in the study to determine the incidence of multiple ovulations. In the retrospective study, twin pregnancies were identified between 25 and 30 days in 47.1% of double-ovulating females. There were more twins from bilateral ovulations (62.5%) than from unilateral ovulations (37.5%). Twin pregnancies were either reduced to a singleton (62.5%) or lost completely (37.5%). One set of twins remained viable until Day 52. In the prospective study, double ovulation occurred in 18.8% of the cycles. Two embryos were collected from two of the four double-ovulating females. In conclusion, twin conception is not rare in alpacas. A high rate of spontaneous reduction of twin pregnancies occurs before Day 45. However, a significant proportion of twin pregnancy may result in loss of both embryos. Determination of the number of ovulations (CL) at the time of early pregnancy diagnosis (14-16 days) should be an integral part of any pregnancy evaluation. PMID:25963129

  4. Twin's Birth-Order Differences in Height and Body Mass Index From Birth to Old Age: A Pooled Study of 26 Twin Cohorts Participating in the CODATwins Project.

    PubMed

    Yokoyama, Yoshie; Jelenkovic, Aline; Sund, Reijo; Sung, Joohon; Hopper, John L; Ooki, Syuichi; Heikkilä, Kauko; Aaltonen, Sari; Tarnoki, Adam D; Tarnoki, David L; Willemsen, Gonneke; Bartels, Meike; van Beijsterveldt, Toos C E M; Saudino, Kimberly J; Cutler, Tessa L; Nelson, Tracy L; Whitfield, Keith E; Wardle, Jane; Llewellyn, Clare H; Fisher, Abigail; He, Mingguang; Ding, Xiaohu; Bjerregaard-Andersen, Morten; Beck-Nielsen, Henning; Sodemann, Morten; Song, Yun-Mi; Yang, Sarah; Lee, Kayoung; Jeong, Hoe-Uk; Knafo-Noam, Ariel; Mankuta, David; Abramson, Lior; Burt, S Alexandra; Klump, Kelly L; Ordoñana, Juan R; Sánchez-Romera, Juan F; Colodro-Conde, Lucia; Harris, Jennifer R; Brandt, Ingunn; Nilsen, Thomas Sevenius; Craig, Jeffrey M; Saffery, Richard; Ji, Fuling; Ning, Feng; Pang, Zengchang; Dubois, Lise; Boivin, Michel; Brendgen, Mara; Dionne, Ginette; Vitaro, Frank; Martin, Nicholas G; Medland, Sarah E; Montgomery, Grant W; Magnusson, Patrik K E; Pedersen, Nancy L; Aslan, Anna K Dahl; Tynelius, Per; Haworth, Claire M A; Plomin, Robert; Rebato, Esther; Rose, Richard J; Goldberg, Jack H; Rasmussen, Finn; Hur, Yoon-Mi; Sørensen, Thorkild I A; Boomsma, Dorret I; Kaprio, Jaakko; Silventoinen, Karri

    2016-04-01

    We analyzed birth order differences in means and variances of height and body mass index (BMI) in monozygotic (MZ) and dizygotic (DZ) twins from infancy to old age. The data were derived from the international CODATwins database. The total number of height and BMI measures from 0.5 to 79.5 years of age was 397,466. As expected, first-born twins had greater birth weight than second-born twins. With respect to height, first-born twins were slightly taller than second-born twins in childhood. After adjusting the results for birth weight, the birth order differences decreased and were no longer statistically significant. First-born twins had greater BMI than the second-born twins over childhood and adolescence. After adjusting the results for birth weight, birth order was still associated with BMI until 12 years of age. No interaction effect between birth order and zygosity was found. Only limited evidence was found that birth order influenced variances of height or BMI. The results were similar among boys and girls and also in MZ and DZ twins. Overall, the differences in height and BMI between first- and second-born twins were modest even in early childhood, while adjustment for birth weight reduced the birth order differences but did not remove them for BMI. PMID:26996222

  5. Mineral resources of the Devils Playground and Twin Buttes Wilderness study areas, Sweetwater County, Wyoming

    SciTech Connect

    Van Loenen, R.E.; Bryant, W.A. ); Lane, M.E. )

    1991-01-01

    The Devils Playground and Twin Buttes Wilderness Study Areas are contiguous, covering an area totalling 26,800 acres in Southwest Wyoming. The study areas have been withdrawn from mining claim location because of the rich oil shale deposits in the region. In addition, Minerals management Service considers the areas to have moderate development potential for sodium (trona), with as much as 1.2 billion tons of inferred resources. The study areas are classic sites for vertebrate fossils, yielding many thousands of specimens now in museums. Chert beds are common, and it is prized by collectors for its banded appearance. The study area shave a high resource potential for undiscovered natural gas. The study areas have a moderate potential for zeolites. A low potential exists for coal resources (coal is present at great depths) and for undiscovered metallic minerals.

  6. Design and implementation of a twin-family database for behavior genetics and genomics studies.

    PubMed

    Boomsma, Dorret I; Willemsen, Gonneke; Vink, Jacqueline M; Bartels, Meike; Groot, Paul; Hottenga, Jouke Jan; van Beijsterveldt, C E M Toos; Stroet, Therese; van Dijk, Rob; Wertheim, Rien; Visser, Marco; van der Kleij, Frank

    2008-06-01

    In this article we describe the design and implementation of a database for extended twin families. The database does not focus on probands or on index twins, as this approach becomes problematic when larger multigenerational families are included, when more than one set of multiples is present within a family, or when families turn out to be part of a larger pedigree. Instead, we present an alternative approach that uses a highly flexible notion of persons and relations. The relations among the subjects in the database have a one-to-many structure, are user-definable and extendible and support arbitrarily complicated pedigrees. Some additional characteristics of the database are highlighted, such as the storage of historical data, predefined expressions for advanced queries, output facilities for individuals and relations among individuals and an easy-to-use multi-step wizard for contacting participants. This solution presents a flexible approach to accommodate pedigrees of arbitrary size, multiple biological and nonbiological relationships among participants and dynamic changes in these relations that occur over time, which can be implemented for any type of multigenerational family study. PMID:18498212

  7. Genetic and environmental bases of childhood antisocial behavior: a multi-informant twin study.

    PubMed

    Baker, Laura A; Jacobson, Kristen C; Raine, Adrian; Lozano, Dora Isabel; Bezdjian, Serena

    2007-05-01

    Genetic and environmental influences on childhood antisocial and aggressive behavior (ASB) during childhood were examined in 9- to 10-year-old twins, using a multi-informant approach. The sample (605 families of twins or triplets) was socioeconomically and ethnically diverse, representative of the culturally diverse urban population in Southern California. Measures of ASB included symptom counts for conduct disorder, ratings of aggression, delinquency, and psychopathic traits obtained through child self-reports, teacher, and caregiver ratings. Multivariate analysis revealed a common ASB factor across informants that was strongly heritable (heritability was .96), highlighting the importance of a broad, general measure obtained from multiple sources as a plausible construct for future investigations of specific genetic mechanisms in ASB. The best fitting multivariate model required informant-specific genetic, environmental, and rater effects for variation in observed ASB measures. The results suggest that parents, children, and teachers have only a partly "shared view" and that the additional factors that influence the "rater-specific" view of the child's antisocial behavior vary for different informants. This is the first study to demonstrate strong heritable effects on ASB in ethnically and economically diverse samples. PMID:17516756

  8. Genetic and Environmental Bases of Childhood Antisocial Behavior: A Multi-Informant Twin Study

    PubMed Central

    Baker, Laura A.; Jacobson, Kristen C.; Raine, Adrian; Lozano, Dora Isabel; Bezdjian, Serena

    2007-01-01

    Genetic and environmental influences on childhood antisocial and aggressive behavior (ASB) during childhood were examined in 9- to 10-year-old twins, using a multi-informant approach. The sample (605 families of twins or triplets) was socioeconomically and ethnically diverse, representative of the culturally diverse urban population in Southern California. Measures of ASB included symptom counts for conduct disorder, ratings of aggression, delinquency, and psychopathic traits obtained through child self-reports, teacher, and caregiver ratings. Multivariate analysis revealed a common ASB factor across informants that was strongly heritable (heritability was .96), highlighting the importance of a broad, general measure obtained from multiple sources as a plausible construct for future investigations of specific genetic mechanisms in ASB. The best fitting multivariate model required informant-specific genetic, environmental, and rater effects for variation in observed ASB measures. The results suggest that parent, children, and teachers have only a partly “shared view” and that the additional factors that influence the “rater-specific” view of the child's antisocial behavior vary for different informants. This is the first study to demonstrate strong heritable effects on ASB in ethnically and economically diverse samples. PMID:17516756

  9. Heritability of Face Shape in Twins: A Preliminary Study using 3D Stereophotogrammetry and Geometric Morphometrics

    PubMed Central

    Weinberg, Seth M.; Parsons, Trish E.; Marazita, Mary L.; Maher, Brion S.

    2014-01-01

    Introduction Previous research suggests that aspects of facial surface morphology are heritable. Traditionally, heritability studies have used a limited set of linear distances to quantify facial morphology and often employ statistical methods poorly designed to deal with biological shape. In this preliminary report, we use a combination of 3D photogrammetry and landmark-based morphometrics to explore which aspects of face shape show the strongest evidence of heritability in a sample of twins. Methods 3D surface images were obtained from 21 twin pairs (10 monozygotic, 11 same-sex dizygotic). Thirteen 3D landmarks were collected from each facial surface and their coordinates subjected to geometric morphometric analysis. This involved superimposing the individual landmark configurations and then subjecting the resulting shape coordinates to a principal components analysis. The resulting PC scores were then used to calculate rough narrow-sense heritability estimates. Results Three principal components displayed evidence of moderate to high heritability and were associated with variation in the breadth of orbital and nasal structures, upper lip height and projection, and the vertical and forward projection of the root of the nose due to variation in the position of nasion. Conclusions Aspects of facial shape, primarily related to variation in length and breadth of central midfacial structures, were shown to demonstrate evidence of strong heritability. An improved understanding of which facial features are under strong genetic control is an important step in the identification of specific genes that underlie normal facial variation. PMID:24501696

  10. Rearrangement of twin variants in ferromagnetic shape memory alloy polyurethane composites studied by stroboscopic neutron diffraction

    NASA Astrophysics Data System (ADS)

    Feuchtwanger, J.; Lázpita, P.; Vidal, N.; Barandiaran, J. M.; Gutiérrez, J.; Hansen, T.; Peel, M.; Mondelli, C.; O'Handley, R. C.; Allen, S. M.

    2008-03-01

    The use of ferromagnetic shape memory alloy (FSMA) particles as fillers in polymeric matrix composites has been proposed for vibration damping. The large pseudo-plastic recoverable deformation of the FSMA particles due to the rearrangement of twin variants can dissipate a large amount of energy, both under compression and tension. The composites studied are made by mixing particles of NiMnGa with a polyurethane matrix. A magnetic field is applied to the composite while the matrix sets, to achieve a strong [112] texture in the field direction. In situ strobed neutron diffraction measurements were carried out while the composites were subjected to a cyclic deformation. They show that the intensity of certain peaks varies during the deformation cycle. All the peaks that show this behavior can be grouped into pairs that stem from a single austenitic peak. The (020) and (112) martensite peaks correspond to the splitting of the (220) austenite peak, and the intensity of one increases as that of the other decreases. The neutron measurements show directly that there is a change in the texture of the composite during the stress cycle applied to the composite and confirm that the large mechanical loss observed in the stress-strain cycles is in good part due to the rearrangement of twin variants in the FSMA filler used in the composites.

  11. Brain Activation during Memory Encoding in Type 2 Diabetes Mellitus: A Discordant Twin Pair Study.

    PubMed

    Wood, Amanda G; Chen, Jian; Moran, Christopher; Phan, Thanh; Beare, Richard; Cooper, Kimberley; Litras, Stacey; Srikanth, Velandai

    2016-01-01

    Type 2 diabetes mellitus increases the risk of dementia and neuronal dysfunction may occur years before perceptible cognitive decline. We aimed to study the impact of type 2 diabetes on brain activation during memory encoding in middle-aged people, controlling for age, sex, genes, and early-shared environment. Twenty-two twin pairs discordant for type 2 diabetes mellitus (mean age 60.9 years) without neurological disease were recruited from the Australian Twin Registry (ATR) and underwent functional magnetic resonance imaging (fMRI) during a memory encoding task, cognitive tests, and structural MRI. Type 2 diabetes was associated with significantly reduced activation in left hemisphere temporoparietal regions including angular gyrus, supramarginal gyrus, and middle temporal gyrus and significantly increased activation in bilateral posteriorly distributed regions. These findings were present in the absence of within-pair differences in standard cognitive test scores, brain volumes, or vascular lesion load. Differences in activation were more pronounced among monozygotic (MZ) pairs, with MZ individuals with diabetes also displaying greater frontal activation. These results provide evidence for preclinical memory-related neuronal dysfunction in type 2 diabetes. They support the search for modifiable later-life environmental factors or epigenetic mechanisms linking type 2 diabetes and cognitive decline. PMID:27314047

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  13. Brain Activation during Memory Encoding in Type 2 Diabetes Mellitus: A Discordant Twin Pair Study

    PubMed Central

    Wood, Amanda G.; Chen, Jian; Moran, Christopher; Phan, Thanh; Beare, Richard; Cooper, Kimberley; Litras, Stacey; Srikanth, Velandai

    2016-01-01

    Type 2 diabetes mellitus increases the risk of dementia and neuronal dysfunction may occur years before perceptible cognitive decline. We aimed to study the impact of type 2 diabetes on brain activation during memory encoding in middle-aged people, controlling for age, sex, genes, and early-shared environment. Twenty-two twin pairs discordant for type 2 diabetes mellitus (mean age 60.9 years) without neurological disease were recruited from the Australian Twin Registry (ATR) and underwent functional magnetic resonance imaging (fMRI) during a memory encoding task, cognitive tests, and structural MRI. Type 2 diabetes was associated with significantly reduced activation in left hemisphere temporoparietal regions including angular gyrus, supramarginal gyrus, and middle temporal gyrus and significantly increased activation in bilateral posteriorly distributed regions. These findings were present in the absence of within-pair differences in standard cognitive test scores, brain volumes, or vascular lesion load. Differences in activation were more pronounced among monozygotic (MZ) pairs, with MZ individuals with diabetes also displaying greater frontal activation. These results provide evidence for preclinical memory-related neuronal dysfunction in type 2 diabetes. They support the search for modifiable later-life environmental factors or epigenetic mechanisms linking type 2 diabetes and cognitive decline. PMID:27314047

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  15. Insights on Solar Twins

    NASA Astrophysics Data System (ADS)

    Sousa Duarte, Tharcisyo Sa e.; Soares da Costa, Jefferson; Dias do Nascimento Júnior, José

    2015-08-01

    The question about how to define a real solar twin are still active. Cayrel de Strobe et al. (1981) defined a solar twin like a star having at the same time the physical parameters, Teff, gravity, bolometric magnitude, microturbulent velocity, and chemical composition. We presented the more extensive sample of solar twins known to date. From these targets we will study the behavior of the solar twins as a function of fundamentals stellar parameters, effective temperature, luminosity, age, convective envelope mass deepening (1 - M*/M⊙), lithium abundance and rotation period. We selected the solar twins from observations with the spectropolarimeters ESPaDOnS at CFHT and the Narval at TBL and also on literature. All objects have high resolution and high signal to noise. Analyze this sample of solar twins will help us to understand how these stars whether located around of the Sun's place. Our preliminary results show that the lithium abundance presents one clear correlation with stellar age. The (1 - M*/M⊙) values obtained through our method provided good agreement with the solar value. The rotation periods allow us to assess the solar twins as a function of gyrochronology.

  16. Siamese twins--prenatal diagnosis in the first trimester of pregnancy. Case study and review.

    PubMed

    Krawczyk, Józef; Borowski, Dariusz; Węgrzyn, Piotr; Drews, Krzysztof

    2015-06-01

    Conjoined twins are a unique type of monozygotic twins. All monozygotic twins should be thoroughly evaluated for incomplete separation and, if incomplete separation is diagnosed, the extent of internal organ connection and the presence of additional developmental anomalies of the foetuses should be assessed. Common heart of foetuses is particularly difficult to diagnose and crucial for prognosis. We present an example of female thoracoomohalopagus twins with a common triventricular heart, connate livers, and joined hepatic vessels, diagnosed in week 12 of pregnancy Due to the high complexity of foetal connection, separation was not possible and following interdisciplinary consultation, the pregnancy was aborted upon the patient's request in week 16. PMID:26255459

  17. Is human mating adventitious or the result of lawful choice? A twin study of mate selection.

    PubMed

    Lykken, D T; Tellegen, A

    1993-07-01

    Pairs of middle-aged twins and their spouses provided data on 74 mainly psychological variables. Neither spousal similarity nor idiosyncratic criteria could account for specific mate selection in these 738 couples. Of the twins (and their spouses), 547 independently rated their initial attraction to their twin's mate (or to their spouse's twin): Findings suggest that characteristics both of the chooser and the chosen constrain mate selection only weakly. This article proposes that it is romantic infatuation that commonly determines the final choice from a broad field of potential eligibles and that this phenomenon is inherently random, in the same sense as is imprinting in precocial birds. PMID:8355143

  18. Psychiatric Morbidity is Linked to Problem Drinking in Midlife Among Alcohol-Dependent Men: A Co-Twin Control Study

    PubMed Central

    Blonigen, Daniel M.; Burroughs, Thomas; Haber, Jon Randolph; Jacob, Theodore

    2013-01-01

    Objective: Prior research on predictors of problem drinking has been limited because of an inability to attribute an unambiguous environmental explanation to observed findings. Using a prospective co-twin control design, we examined the extent to which a history of psychiatric symptoms exerts an environmental influence on problem drinking in midlife that is unconfounded by genetic underpinnings. Method: Participants were 367 complete male twin pairs (208 monozygotic, 159 dizygotic) from the Vietnam Era Twin Registry who were assessed in midlife as part of the Family Twin Study (Mage = 51.4 years, SD = 2.8). Twin pairs who were concordant for a lifetime diagnosis of an alcohol use disorder (AUD) in 1992 were selected for participation and were reinterviewed in 2001 to measure symptoms of AUD (i.e., problem drinking) since the prior assessment (past 10 years). Results: Within-pair differences in lifetime symptom counts of several psychiatric disorders measured in 1992 (i.e., major depression, dysthymia, generalized anxiety disorder, panic disorder, antisocial personality, mania, and posttraumatic stress disorder) were significantly associated with within-pair differences in AUD symptoms in the subsequent 10 years. Conclusions: A history of psychiatric problems, particularly one marked by internalizing symptoms, appears to be linked to problem drinking in midlife above and beyond the confounding influence of genetic effects and underscores the potential value of integrated interventions for comorbidity to address problem drinking among individuals during this period of the life course. PMID:23200159

  19. A multivariate twin study of hippocampal volume, self-esteem and well-being in middle-aged men.

    PubMed

    Kubarych, T S; Prom-Wormley, E C; Franz, C E; Panizzon, M S; Dale, A M; Fischl, B; Eyler, L T; Fennema-Notestine, C; Grant, M D; Hauger, R L; Hellhammer, D H; Jak, A J; Jernigan, T L; Lupien, S J; Lyons, M J; Mendoza, S P; Neale, M C; Seidman, L J; Tsuang, M T; Kremen, W S

    2012-07-01

    Self-esteem and well-being are important for successful aging, and some evidence suggests that self-esteem and well-being are associated with hippocampal volume, cognition and stress responsivity. Whereas most of this evidence is based on studies on older adults, we investigated self-esteem, well-being and hippocampal volume in 474 male middle-aged twins. Self-esteem was significantly positively correlated with hippocampal volume (0.09, P = 0.03 for left hippocampus, 0.10, P = 0.04 for right). Correlations for well-being were not significant (Ps > 0.05). There were strong phenotypic correlations between self-esteem and well-being (0.72, P < 0.001) and between left and right hippocampal volume (0.72, P < 0.001). In multivariate genetic analyses, a two-factor additive genetic and unique environmental (AE) model with well-being and self-esteem on one factor and left and right hippocampal volumes on the other factor fits the data better than Cholesky, independent pathway or common pathway models. The correlation between the two genetic factors was 0.12 (P = 0.03); the correlation between the environmental factors was 0.09 (P > 0.05). Our results indicate that largely different genetic and environmental factors underlie self-esteem and well-being on one hand and hippocampal volume on the other. PMID:22471516

  20. A Multivariate Twin Study of Hippocampal Volume, Self-Esteem and Well-Being in Middle Aged Men

    PubMed Central

    Kubarych, Thomas S.; Prom-Wormley, Elizabeth C.; Franz, Carol E.; Panizzon, Matthew S.; Dale, Anders M.; Fischl, Bruce; Eyler, Lisa T.; Fennema-Notestine, Christine; Grant, Michael D.; Hauger, Richard L.; Hellhammer, Dirk H.; Jak, Amy J.; Jernigan, Terry L.; Lupien, Sonia J.; Lyons, Michael J.; Mendoza, Sally P.; Neale, Michael C.; Seidman, Larry J.; Tsuang, Ming T.; Kremen, William S.

    2012-01-01

    Self-esteem and well-being are important for successful aging, and some evidence suggests that self-esteem and well-being are associated with hippocampal volume, cognition, and stress responsivity. Whereas most of this evidence is based on studies of older adults, we investigated self-esteem, well-being and hippocampal volume in 474 male middle-age twins. Self-esteem was significantly positively correlated with hippocampal volume (.09, p=.03 for left hippocampus, .10, p=.04 for right). Correlations for well-being were not significant (ps ≫.05). There were strong phenotypic correlations between self-esteem and well-being (.72, p<.001) and between left and right hippocampal volume (.72, p<.001). In multivariate genetic analyses, a 2-factor AE model with well-being and self-esteem on one factor and left and right hippocampal volumes on the other factor fit the data better than Cholesky, independent pathway or common pathway models. The correlation between the two genetic factors was .12 (p=.03); the correlation between the environmental factors was .09 (p>05). Our results indicate that largely different genetic and environmental factors underlie self-esteem and well-being on the one hand and hippocampal volume on the other. PMID:22471516

  1. Adult Multiple Intelligences. NCSALL Study Circle Guide

    ERIC Educational Resources Information Center

    Parrella, A.; Hofer, J.; Bubp, S.; Finn-Miller, S.; Graves, N.; Meador, P.

    2004-01-01

    This Study Circle guide was created by the National Center for the Study of Adult Learning and Literacy (NCSALL) as part of the Practitioner Dissemination and Research Network (PDRN). The guide is part of NCSALL's effort to help connect research and practice in the field of adult basic education and adult literacy. The purpose of the study circle…

  2. Interview Schedule for Studying Why Adults Learn.

    ERIC Educational Resources Information Center

    Tough, Allen

    Designed for use in a 1968 study of why adults learn, this interview schedule contains situation-description and question sheets for use by the interviewer and subject for examining thirteen reasons why adults begin and why they continue a learning project. (The study, "Why Adults Learn: A Study of the Major Reasons for Beginning and Continuing a…

  3. A Taguchi experimental design study of twin-wire electric arc sprayed aluminum coatings

    SciTech Connect

    Steeper, T.J.; Varacalle, D.J. Jr.; Wilson, G.C.; Johnson, R.W.; Irons, G.; Kratochvil, W.R.; Riggs, W.L. II

    1992-08-01

    An experimental study was conducted on the twin-wire electric arc spraying of aluminum coatings. This aluminum wire system is being used to fabricate heater tubes that emulate nuclear fuel tubes for use in thermal-hydraulic experiments. Experiments were conducted using a Taguchi fractional-factorial design parametric study. Operating parameters were varied around the typical process parameters in a systematic design of experiments in order to display the range of processing conditions and their effect on the resultant coating. The coatings were characterized by hardness tests, optical metallography, and image analysis. The paper discusses coating qualities with respect to hardness, roughness, deposition efficiency, and microstructure. The study attempts to correlate the features of the coatings with the changes in operating parameters. A numerical model of the process is presented including gas, droplet, and coating dynamics.

  4. A Taguchi experimental design study of twin-wire electric arc sprayed aluminum coatings

    SciTech Connect

    Steeper, T.J. ); Varacalle, D.J. Jr.; Wilson, G.C.; Johnson, R.W. ); Irons, G.; Kratochvil, W.R. ); Riggs, W.L. II )

    1992-01-01

    An experimental study was conducted on the twin-wire electric arc spraying of aluminum coatings. This aluminum wire system is being used to fabricate heater tubes that emulate nuclear fuel tubes for use in thermal-hydraulic experiments. Experiments were conducted using a Taguchi fractional-factorial design parametric study. Operating parameters were varied around the typical process parameters in a systematic design of experiments in order to display the range of processing conditions and their effect on the resultant coating. The coatings were characterized by hardness tests, optical metallography, and image analysis. The paper discusses coating qualities with respect to hardness, roughness, deposition efficiency, and microstructure. The study attempts to correlate the features of the coatings with the changes in operating parameters. A numerical model of the process is presented including gas, droplet, and coating dynamics.

  5. First-principles study of dislocations in hcp metals through the investigation of the (1121) twin boundary

    SciTech Connect

    Lane, Nina J.; Barsoum, Michel W.; Simak, Sergei I.; Mikhaylushkin, Arkady S.; Abrikosov, Igor A.; Hultman, Lars

    2011-11-01

    Herein, we use first principles calculations to study the energy of the (1121) twin boundary in Zr, Zn, Mg, Ti, and Be. This boundary is important for understanding the microyielding and damping of hexagonal close-packed metals. The (1121) twin boundary is unique in that it is composed of--and can form by the glide of--basal dislocations nucleating at every c lattice parameter. The effect of the number of atoms between boundaries on the boundary energy, and the resulting lattice strains of the relaxed structures are quantified. It is shown that the energies obtained converge within 32-64 atoms/supercell. The structures with a higher second-order elastic constant term, c{sub 44}, also have higher boundary energies. It is further shown that the critical resolved shear stresses of the basal dislocations at 0 K, which make up the (1121) twin, are so low as to be below the threshold of the first principles calculations.

  6. A Chaotic Home Environment Accounts for the Association between Respect for Rules Disposition and Reading Comprehension: A Twin Study.

    PubMed

    Taylor, Jeanette; Hart, Sara A

    2014-10-01

    This study examined the association between socioemotional dispositions from the developmental propensity model and reading comprehension and whether those associations could be accounted for by level of chaos in the home. Data from 342 monozygotic and 333 same-sex dizygotic twin pairs age 7-13 years were used. A parent rated the twins on sympathy, respect for rules, negative emotionality, and daring and level of chaos in the twins' home. Reading comprehension was measured using a state-wide school assessment. Only respect for rules significantly and uniquely predicted reading comprehension. Biometric models indicated that respect for rules was positively associated with reading comprehension via the shared environment and home chaos accounted for a significant amount of that shared environmental variance even after controlling for family income. Children with higher respect for rules have better reading comprehension scores in school and this relationship owes partly to the level of chaos in the family home. PMID:25328362

  7. Genome-wide association study on detailed profiles of smoking behavior and nicotine dependence in a twin sample

    PubMed Central

    Loukola, Anu; Wedenoja, Juho; Keskitalo-Vuokko, Kaisu; Broms, Ulla; Korhonen, Tellervo; Ripatti, Samuli; Sarin, Antti-Pekka; Pitkäniemi, Janne; He, Liang; Häppölä, Anja; Heikkilä, Kauko; Chou, Yi-Ling; Pergadia, Michele L; Heath, Andrew C; Montgomery, Grant W; Martin, Nicholas G; Madden, Pamela AF; Kaprio, Jaakko

    2013-01-01

    Smoking is a major risk factor for several somatic diseases, and is also emerging as a causal factor for neuropsychiatric disorders. Genome-wide association (GWA) and candidate gene studies for smoking behavior and nicotine dependence (ND) have disclosed too few predisposing variants to account for the high estimated heritability. Prior large-scale GWA studies have had very limited phenotypic definitions of relevance to smoking-related behavior, which has likely impeded the discovery of genetic effects. We performed genome-wide association analyses on 1114 adult twins ascertained for ever smoking from the population-based Finnish Twin Cohort study. The availability of 17 smoking-related phenotypes allowed us to comprehensively portray the dimensions of smoking behavior, clustered into the domains of smoking initiation, amount smoked, and ND. Our results highlight a locus on 16p12.3, with several SNPs in the vicinity of CLEC19A showing association (P<1×10−6) with smoking quantity. Interestingly, CLEC19A is located close to a previously reported attention deficit hyperactivity disorder (ADHD) linkage locus and an evident link between ADHD and smoking has been established. Intriguing preliminary association (P<1×10−5) was detected between DSM-IV ND diagnosis and several SNPs in ERBB4, coding for a Neuregulin receptor, on 2q33. The association between ERBB4 and DSM-IV ND diagnosis was replicated in an independent Australian sample. Interestingly, in the paper by Turner et al., significant increase in ErbB4 and Neuregulin 3 (Nrg3) expression was revealed following chronic nicotine exposure and withdrawal in mice. Turner et al. also detected an association between NRG3 SNPs and smoking cessation success in a clinical trial. ERBB4 has previously been associated with schizophrenia; further, it is located within an established schizophrenia linkage locus and within a linkage locus for a smoker phenotype identified in this sample. As a conclusion, we disclose novel

  8. Geographic Variation in Maternal Smoking during Pregnancy in the Missouri Adolescent Female Twin Study (MOAFTS)

    PubMed Central

    Lian, Min; Madden, Pamela A.; Lynskey, Michael T.; Colditz, Graham A.; Lessov-Schlaggar, Christina N.; Schootman, Mario; Heath, Andrew C.

    2016-01-01

    Objective Despite well-known adverse health effects of maternal smoking during pregnancy (MSP), it is still unclear if MSP varies geographically and if neighborhood socioeconomic deprivation (SED) plays an important role in MSP. This study aims to investigate small-area geographic variation in MSP and examine the association of SED with MSP. Methods The Missouri Adolescent Female Twin Study (MOAFTS) is a cohort study of female like-sex twins born in Missouri to Missouri-resident parents during 1975–1985. Biological mothers completed a baseline interview in 1995–1998 and reported MSP with the twins. Residential address of the mother at birth was geocoded. We developed a census tract-level SED index using a common factor approach based on 21 area-level socioeconomic variables from the 1980 Census data. Multilevel logistic regressions estimated geographic heterogeneity (random effect) in MSP and the odds ratios (ORs, fixed effects) of neighborhood SED associated with MSP. Results Of 1658 MOAFTS mothers, 35.2% reported any MSP and 21.9% reported MSP beyond the first trimester. Neighborhood SED was associated with any MSP (the highest vs. the lowest quartile: OR = 1.90, 95% confidence interval [CI] = 1.40–2.57, Ptrend<0.001) and MSP beyond the first trimester (OR = 1.98, 95% CI = 1.38–2.85, Ptrend = 0.002) in unadjusted analyses. After adjusting for individual covariates (demographics, socioeconomic conditions, alcohol use, and parents’ cohabitation), neighborhood SED was not associated with MSP, but geographic variation still persisted in MSP (variance = 0.41, P = 0.003) and in MSP beyond the first trimester (variance = 0.82, P<0.001). Conclusions Neighborhood SED was associated with MSP in unadjusted analyses but this association could be explained by individual socioeconomic conditions. Nonetheless, significant geographic variation in MSP persisted and was not accounted for by differences in neighborhood SED. To develop effective interventions to reduce MSP

  9. Stability and Change in Executive Function Abilities from Late Adolescence to Early Adulthood: A Longitudinal Twin Study

    ERIC Educational Resources Information Center

    Friedman, Naomi P.; Miyake, Akira; Altamirano, Lee J.; Corley, Robin P.; Young, Susan E.; Rhea, Sally Ann; Hewitt, John K.

    2016-01-01

    Executive functions (EFs)--the higher level cognitive abilities that enable us to control our own thoughts and actions--continue to develop into early adulthood, yet no longitudinal study has examined their stability during the important life transition from late adolescence to young adulthood. In this twin study (total N = 840 individuals from…

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

    ERIC Educational Resources Information Center

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

    2006-01-01

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

  11. Do Different Measures Tap the Same Genetic Influences? A Multi-Method Study of Activity Level in Young Twins

    ERIC Educational Resources Information Center

    Saudino, Kimberly J.

    2009-01-01

    Activity level (AL) is a highly salient feature of child behaviour that has been linked to developmental outcome. Twin studies of parent-rated, observer-rated and mechanically assessed AL in childhood find that AL is genetically influenced. Few studies, however, consider whether different methods of assessing AL have a shared genetic etiology.…

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

    ERIC Educational Resources Information Center

    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.

  13. Genetic Influences on Reading Difficulties in Boys and Girls: The Colorado Twin Study

    ERIC Educational Resources Information Center

    Hawke, Jesse L.; Wadsworth, Sally J.; DeFries, John C.

    2006-01-01

    To test the hypothesis that the genetic etiology for reading disability may differ in males and females, data from identical and fraternal twin pairs were analysed using both concordance and multiple regression methods. The sample included 264 identical (129 male, 135 female) and 214 same-sex fraternal (121 male, 93 female) twin pairs in which at…

  14. Unraveling Genetic and Environmental Components of Early Literacy: A Twin Study

    ERIC Educational Resources Information Center

    Bus, A. G.; Out, D.

    2009-01-01

    Even though the acquisition of early literacy skills obviously depends on stimuli and incentives in children's environment we may expect that genes define the constraints for acquiring some or all early literacy skills. Therefore behavior genetic analyses were carried out on twin data including 27 identical and 39 same sex dizygotic twins, 4 years…

  15. Temperament, Emotion, and Cognition at Fourteen Months: The MacArthur Longitudinal Twin Study.

    ERIC Educational Resources Information Center

    Emde, Robert N.; And Others

    1992-01-01

    Assessments of temperament, emotion, cognition, and language acquisition were obtained for 200 pairs of 14-month-old twins. Comparisons between the assessment correlations for identical and fraternal twins indicated an influence of genetics on inhibition, activity, temperament, empathy, negative emotion, spatial memory, categorization skills, and…

  16. Origins of Familial Similarity in Parenting: A Study of Twins and Adoptive Siblings.

    ERIC Educational Resources Information Center

    Losoya, Sandra H.; Callor, Suzanne; Rowe, David C.; Goldsmith, H. Hill

    1997-01-01

    Parents who were identical twins, fraternal twins, or adopted siblings completed questionnaires assessing attitudes toward parenting and specific parenting practices, the emotional atmosphere of the home, and parental personality. Model-fitting results implicated modest genetic effects on affect-related aspects of parenting, such as parental…

  17. A Twin-Sibling Study of Observed Parent-Adolescent Interactions.

    ERIC Educational Resources Information Center

    O'Connor, Thomas G.; And Others

    1995-01-01

    The mother, father, and adolescent siblings from 675 families were observed interacting in problem-solving sessions. Siblings were monozygotic twins, dyzygotic twins, or full siblings in nondivorced families and full, half, and unrelated siblings in stepfamilies. Results suggested a greater genetic component to adolescent behavior than to parent…

  18. A twin study of heritable and shared environmental contributions to autism.

    PubMed

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

    2014-08-01

    The present study examined genetic and shared environment contributions to quantitatively-measured autism symptoms and categorically-defined autism spectrum disorders (ASD). Participants included 568 twins from the Interactive Autism Network. Autism symptoms were obtained using the Social Communication Questionnaire and Social Responsiveness Scale. Categorically-defined ASD was based on clinical diagnoses. DeFries-Fulker and liability threshold models examined etiologic influences. Very high heritability was observed for extreme autism symptom levels ([Formula: see text]). Extreme levels of social and repetitive behavior symptoms were strongly influenced by common genetic factors. Heritability of categorically-defined ASD diagnosis was comparatively low (.21, 95 % CI 0.15-0.28). High heritability of extreme autism symptom levels confirms previous observations of strong genetic influences on autism. Future studies will require large, carefully ascertained family pedigrees and quantitative symptom measurements. PMID:24604525

  19. Fuzzy Controller Design Using Evolutionary Techniques for Twin Rotor MIMO System: A Comparative Study

    PubMed Central

    Hashim, H. A.; Abido, M. A.

    2015-01-01

    This paper presents a comparative study of fuzzy controller design for the twin rotor multi-input multioutput (MIMO) system (TRMS) considering most promising evolutionary techniques. These are gravitational search algorithm (GSA), particle swarm optimization (PSO), artificial bee colony (ABC), and differential evolution (DE). In this study, the gains of four fuzzy proportional derivative (PD) controllers for TRMS have been optimized using the considered techniques. The optimization techniques are developed to identify the optimal control parameters for system stability enhancement, to cancel high nonlinearities in the model, to reduce the coupling effect, and to drive TRMS pitch and yaw angles into the desired tracking trajectory efficiently and accurately. The most effective technique in terms of system response due to different disturbances has been investigated. In this work, it is observed that GSA is the most effective technique in terms of solution quality and convergence speed. PMID:25960738

  20. Fuzzy Controller Design Using Evolutionary Techniques for Twin Rotor MIMO System: A Comparative Study.

    PubMed

    Hashim, H A; Abido, M A

    2015-01-01

    This paper presents a comparative study of fuzzy controller design for the twin rotor multi-input multioutput (MIMO) system (TRMS) considering most promising evolutionary techniques. These are gravitational search algorithm (GSA), particle swarm optimization (PSO), artificial bee colony (ABC), and differential evolution (DE). In this study, the gains of four fuzzy proportional derivative (PD) controllers for TRMS have been optimized using the considered techniques. The optimization techniques are developed to identify the optimal control parameters for system stability enhancement, to cancel high nonlinearities in the model, to reduce the coupling effect, and to drive TRMS pitch and yaw angles into the desired tracking trajectory efficiently and accurately. The most effective technique in terms of system response due to different disturbances has been investigated. In this work, it is observed that GSA is the most effective technique in terms of solution quality and convergence speed. PMID:25960738

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

    PubMed

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

    2016-02-01

    Marijuana is one of the most commonly used drugs in the United States, and use during adolescence--when the brain is still developing--has been proposed as a cause of poorer neurocognitive outcome. Nonetheless, research on this topic is scarce and often shows conflicting results, with some studies showing detrimental effects of marijuana use on cognitive functioning and others showing no significant long-term effects. The purpose of the present study was to examine the associations of marijuana use with changes in intellectual performance in two longitudinal studies of adolescent twins (n = 789 and n = 2,277). We used a quasiexperimental approach to adjust for participants' family background characteristics and genetic propensities, helping us to assess the causal nature of any potential associations. Standardized measures of intelligence were administered at ages 9-12 y, before marijuana involvement, and again at ages 17-20 y. Marijuana use was self-reported at the time of each cognitive assessment as well as during the intervening period. Marijuana users had lower test scores relative to nonusers and showed a significant decline in crystallized intelligence between preadolescence and late adolescence. However, there was no evidence of a dose-response relationship between frequency of use and intelligence quotient (IQ) change. Furthermore, marijuana-using twins failed to show significantly greater IQ decline relative to their abstinent siblings. Evidence from these two samples suggests that observed declines in measured IQ may not be a direct result of marijuana exposure but rather attributable to familial factors that underlie both marijuana initiation and low intellectual attainment. PMID:26787878

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

    PubMed Central

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

    2016-01-01

    Marijuana is one of the most commonly used drugs in the United States, and use during adolescence—when the brain is still developing—has been proposed as a cause of poorer neurocognitive outcome. Nonetheless, research on this topic is scarce and often shows conflicting results, with some studies showing detrimental effects of marijuana use on cognitive functioning and others showing no significant long-term effects. The purpose of the present study was to examine the associations of marijuana use with changes in intellectual performance in two longitudinal studies of adolescent twins (n = 789 and n = 2,277). We used a quasiexperimental approach to adjust for participants’ family background characteristics and genetic propensities, helping us to assess the causal nature of any potential associations. Standardized measures of intelligence were administered at ages 9–12 y, before marijuana involvement, and again at ages 17–20 y. Marijuana use was self-reported at the time of each cognitive assessment as well as during the intervening period. Marijuana users had lower test scores relative to nonusers and showed a significant decline in crystallized intelligence between preadolescence and late adolescence. However, there was no evidence of a dose–response relationship between frequency of use and intelligence quotient (IQ) change. Furthermore, marijuana-using twins failed to show significantly greater IQ decline relative to their abstinent siblings. Evidence from these two samples suggests that observed declines in measured IQ may not be a direct result of marijuana exposure but rather attributable to familial factors that underlie both marijuana initiation and low intellectual attainment. PMID:26787878

  3. Association of Smoking in Adolescence With Abdominal Obesity in Adulthood: A Follow-Up Study of 5 Birth Cohorts of Finnish Twins

    PubMed Central

    Pietiläinen, Kirsi; Kantonen, Suvi; Rissanen, Aila; Kaprio, Jaakko

    2009-01-01

    Objectives. We studied the association of adolescent smoking with overweight and abdominal obesity in adulthood. Methods. We used the FinnTwin16, a prospective, population-based questionnaire study of 5 consecutive and complete birth cohorts of Finnish twins born between 1975 and 1979 (N = 4296) and studied at four points between the ages of 16 and 27 years to analyze the effect of adolescent smoking on abdominal obesity and overweight in early adulthood. Results. Smoking at least 10 cigarettes daily when aged 16 to 18 years increased the risk of adult abdominal obesity (odds ratio [OR]=1.77; 95% confidence interval [CI] = 1.39, 2.26). After we adjusted for confounders, the OR was 1.44 (95% CI = 1.11, 1.88), and after further adjustment for current body mass index (BMI), the OR was 1.34 (95% CI = 0.95, 1.88). Adolescent smoking significantly increased the risk of becoming overweight among women even after adjustment for possible confounders, including baseline BMI (OR = 1.74; 95% CI = 1.06, 2.88). Conclusions. Smoking is a risk factor for abdominal obesity among both genders and for overweight in women. The prevention of smoking during adolescence may play an important role in promoting healthy weight and in decreasing the morbidity related to abdominal obesity. PMID:19059868

  4. Nature-nurture and intelligence: the twin and adoption studies agree.

    PubMed

    Horn, J M; Loehlin, J C; Willerman, L

    1976-01-01

    A large-scale adoption study is underway at the University of Texas where IQ test scores are available for over 1200 women who gave up their children for adoption immediately following delivery. The adopted children and their adoptive families are now being located and tested and, if current trends continue, complete data should eventually be available on over 400 families. About half of these families will contain two or more adopted children or both adopted and natural children. At present, data are available for 89 families. The results are consistent with twin data and support a genetic hypothesis. The biological mother-adopted child correlation is 0.37 whereas the adoptive mother-adopted child and adoptive father-adopted child correlations are only 0.22 and 0.04 respectively. There are 59 pairs of unrelated children reared together in this sample and the IQ correlation for these children is only 0.13. PMID:1036363

  5. Discordant Growth of Monozygotic Twins Starts at the Blastocyst Stage: A Case Study

    PubMed Central

    Noli, Laila; Capalbo, Antonio; Ogilvie, Caroline; Khalaf, Yacoub; Ilic, Dusko

    2015-01-01

    Summary Discordant growth is a common complication of monochorionic/diamniotic pregnancies; in approximately 50% of cases, the cause is unknown. The case presented here suggests that discordant growth of monozygotic twins could start during preimplantation development. Two inner cell masses (ICMs) within the same blastocyst may originate in uneven splitting of a single “parental” ICM, or the two ICMs may be formed independently de novo. We studied the transcriptomes of two morphologically distinct ICMs within a single blastocyst using high-resolution RNA sequencing. The data indicated that the two ICM were at different stages of development; one was in the earliest stages of lineage commitment, while the other had already differentiated into epiblast and primitive endoderm. IGF1-mediated signaling is likely to play a key role in ICM growth and to be the major driver behind these differences. PMID:26584541

  6. Birth Weight, Working Memory and Epigenetic Signatures in IGF2 and Related Genes: A MZ Twin Study

    PubMed Central

    Córdova-Palomera, Aldo; Alemany, Silvia; Fatjó-Vilas, Mar; Goldberg, Ximena; Leza, Juan Carlos; González-Pinto, Ana; Nenadic, Igor; Fañanás, Lourdes

    2014-01-01

    Neurodevelopmental disruptions caused by obstetric complications play a role in the etiology of several phenotypes associated with neuropsychiatric diseases and cognitive dysfunctions. Importantly, it has been noticed that epigenetic processes occurring early in life may mediate these associations. Here, DNA methylation signatures at IGF2 (insulin-like growth factor 2) and IGF2BP1-3 (IGF2-binding proteins 1-3) were examined in a sample consisting of 34 adult monozygotic (MZ) twins informative for obstetric complications and cognitive performance. Multivariate linear regression analysis of twin data was implemented to test for associations between methylation levels and both birth weight (BW) and adult working memory (WM) performance. Familial and unique environmental factors underlying these potential relationships were evaluated. A link was detected between DNA methylation levels of two CpG sites in the IGF2BP1 gene and both BW and adult WM performance. The BW-IGF2BP1 methylation association seemed due to non-shared environmental factors influencing BW, whereas the WM-IGF2BP1 methylation relationship seemed mediated by both genes and environment. Our data is in agreement with previous evidence indicating that DNA methylation status may be related to prenatal stress and later neurocognitive phenotypes. While former reports independently detected associations between DNA methylation and either BW or WM, current results suggest that these relationships are not confounded by each other. PMID:25171170

  7. The Syntactic Abilities of Identical Twins, Fraternal Twins, and Their Siblings

    ERIC Educational Resources Information Center

    Munsinger, Harry; Douglass, Arthur, II

    1976-01-01

    The language development of monozygotic twins, same-sex dizygotic twins, siblings of monozygotic twins, and siblings of dizygotic twins, ages 3-17, was studied to estimate how much of the individual variation in children's language skills results from genetic factors and how much from environmental experience. (BRT)

  8. Impact of Twin-to-Twin Transfusion Syndrome, Preterm Birth, and Vision Loss on Development

    ERIC Educational Resources Information Center

    Celeste, Marie

    2005-01-01

    This study compared the developmental outcomes of twin boys (one who is blind and one who is sighted) who were born prematurely and diagnosed with twin-to-twin transfusion syndrome (TTTS) at age 24 months. The results indicate a disparity in the developmental outcomes of the twins. Although the medical risk factors that are associated with TTTS…

  9. Dogs discriminate identical twins.

    PubMed

    Pinc, Ludvík; Bartoš, Luděk; Reslová, Alice; Kotrba, Radim

    2011-01-01

    Earlier studies have shown variation among experimental attempts to establish whether human monozygotic twins that are genetically identical also have identical individual scents. In none of the cases were the dogs able to distinguish all the individual scents of monozygotic twins living in the same environment if the scents were presented to them separately. Ten specially trained police German Shepherd dogs of three Czech Republic Police Regional Headquarters were used for scent identification in our study. The dogs were supposed to match scents of two monozygotic pairs (5 and 7 years old) and two dizygotic twin pairs (8 and 13 years old). Scents were collected on cotton squares stored in glass jars. Dog handlers were blind to the experiment details. In each trial (line-up), one scent was used as a starting scent and the dog was then sent to determine if any of the 7 presented glass jars contained a matching scent. Scents of children of similar ages were used as distractors. In the matching procedure, the dogs matched correctly the scent of one twin with the other, as well as two scents collected from every single identical and non-identical twin to prove their efficacy and likewise, the presence of the matching twin scent in any given glass jar. All dogs in all trials distinguished correctly the scents of identical as well as non-identical twins. All dogs similarly matched positively two scents collected from the same individuals. Our findings indicated that specially trained German Shepherd dogs are able to distinguish individual scents of identical twins despite the fact that they live in the same environment, eat the same food and even if the scents are not presented to them simultaneously. PMID:21698282

  10. Dogs Discriminate Identical Twins

    PubMed Central

    Pinc, Ludvík; Bartoš, Luděk; Reslová, Alice; Kotrba, Radim

    2011-01-01

    Earlier studies have shown variation among experimental attempts to establish whether human monozygotic twins that are genetically identical also have identical individual scents. In none of the cases were the dogs able to distinguish all the individual scents of monozygotic twins living in the same environment if the scents were presented to them separately. Ten specially trained police German Shepherd dogs of three Czech Republic Police Regional Headquarters were used for scent identification in our study. The dogs were supposed to match scents of two monozygotic pairs (5 and 7 years old) and two dizygotic twin pairs (8 and 13 years old). Scents were collected on cotton squares stored in glass jars. Dog handlers were blind to the experiment details. In each trial (line-up), one scent was used as a starting scent and the dog was then sent to determine if any of the 7 presented glass jars contained a matching scent. Scents of children of similar ages were used as distractors. In the matching procedure, the dogs matched correctly the scent of one twin with the other, as well as two scents collected from every single identical and non-identical twin to prove their efficacy and likewise, the presence of the matching twin scent in any given glass jar. All dogs in all trials distinguished correctly the scents of identical as well as non-identical twins. All dogs similarly matched positively two scents collected from the same individuals. Our findings indicated that specially trained German Shepherd dogs are able to distinguish individual scents of identical twins despite the fact that they live in the same environment, eat the same food and even if the scents are not presented to them simultaneously. PMID:21698282

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

    PubMed

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

    2012-02-01

    There has been almost no overlap between behavior genetics and consumer behavior research, despite each field's importance in understanding society. In particular, both have neglected to study genetic influences on consumer adoption and usage of new technologies -- even technologies as important as the mobile phone, now used by 5.8 out of 7.0 billion people on earth. To start filling this gap, we analyzed self-reported mobile phone use, intelligence, and personality traits in two samples of Australian teenaged twins (mean ages 14.2 and 15.6 years), totaling 1,036 individuals. ACE modeling using Mx software showed substantial heritabilities for how often teens make voice calls (.60 and .34 in samples 1 and 2, respectively) and for how often they send text messages (.53 and. 50). Shared family environment - including neighborhood, social class, parental education, and parental income (i.e., the generosity of calling plans that parents can afford for their teens) -- had much weaker effects. Multivariate modeling based on cross-twin, cross-trait correlations showed negative genetic correlations between talking/texting frequency and intelligence (around -.17), and positive genetic correlations between talking/texting frequency and extraversion (about .20 to .40). Our results have implications for assessing the risks of mobile phone use such as radiofrequency field (RF) exposure and driving accidents, for studying adoption and use of other emerging technologies, for understanding the genetic architecture of the cognitive and personality traits that predict consumer behavior, and for challenging the common assumption that consumer behavior is shaped entirely by culture, media, and family environment. PMID:22784459

  12. The Colorado Longitudinal Twin Study of Reading Difficulties and ADHD: Etiologies of Comorbidity and Stability.

    PubMed

    Wadsworth, Sally J; DeFries, John C; Willcutt, Erik G; Pennington, Bruce F; Olson, Richard K

    2015-12-01

    Approximately 60% of children with reading difficulties (RD) meet criteria for at least one co-occurring disorder. The most common of these, attention deficit-hyperactivity disorder (ADHD), occurs in 20-40% of individuals with RD. Recent studies have suggested that genetic influences are responsible. To assess the genetic etiologies of RD and the comorbidity of RD and two ADHD symptom dimensions -- inattention (IN) and hyperactivity/impulsivity (H/I) -- we are conducting the first longitudinal twin study of RD and ADHD. Data from twin pairs in which at least one member of the pair met criteria for proband status for RD at initial assessment, and were reassessed 5 years later, were subjected to DeFries-Fulker (DF) analysis. Analyses of reading composite data indicated that over 60% of the proband deficit at initial assessment was due to genetic influences, and that reading deficits at follow-up were due substantially to the same genetic influences. When a bivariate DF model was fitted to reading performance and IN data, genetic influences accounted for 60% of contemporaneous comorbidity and over 60% of the longitudinal relationship. In contrast, analysis of the comorbidity between reading performance and H/I indicated that common genetic influences accounted for only about 20% of the contemporaneous and about 10% of the longitudinal relationships. Results indicate that (1) genetic influences on RD are substantial and highly stable; (2) the comorbidity between RD and IN is due largely to genetic influences, both contemporaneously and longitudinally; and (3) genetic influences contribute significantly less to the comorbidity between RD and H/I. PMID:26537134

  13. Identical, Fraternal, or Separated at Birth: A Case Study of Educator Teams within American-Israeli School Twinning

    ERIC Educational Resources Information Center

    Chertok, Fern; Mittelberg, David; Laron, Dinah; Koren, Annette

    2013-01-01

    School-to-school collaboration has emerged as a key paradigm for fostering personal and institutional connections between Israeli and Diaspora youth, educators, and schools. Using the findings of a multi-year case study of a high school level twinning initiative, this article describes the challenges to this form of transnational collaboration and…

  14. A Study of Southeast Asian Refugee Youth in the Twin Cities of Minneapolis and St. Paul, Minnesota. Final Report.

    ERIC Educational Resources Information Center

    Baizerman, Michael; Hendricks, Glenn

    Presented is a report on a comparative study of the educational and occupational aspirations and expectations of Cambodian, Hmong, Laotian, and Vietnamese adolescents and youth in the Minneapolis-St.Paul (Twin Cities), Minnesota, metropolitan area. Data were culled from interviews with about 160 informants using a "story" approach as a data…

  15. A Twin and Adoption Study of Reading Achievement: Exploration of Shared-Environmental and Gene-Environment-Interaction Effects

    ERIC Educational Resources Information Center

    Kirkpatrick, Robert M.; Legrand, Lisa N.; Iacono, William G.; McGue, Matt

    2011-01-01

    Existing behavior-genetic research implicates substantial influence of heredity and modest influence of shared environment on reading achievement and reading disability. Applying DeFries-Fulker analysis to a combined sample of twins and adoptees (N = 4886, including 266 reading-disabled probands), the present study replicates prior findings of…

  16. Severe Developmental Language Disorder--Reading and Spelling. A Longitudinal Study of Two Non-Identical Twins.

    ERIC Educational Resources Information Center

    Sahlen, Birgitta; And Others

    1990-01-01

    Studies two nonidentical twin boys with severe, specific developmental language disorders with respect to their linguistic, neurolinguistic and pragmatic development. Finds that, in spite of poor linguistic awareness, the boys acquired normal reading/spelling skills; however, the boys differed considerably in some aspects of reading and spelling…

  17. The Association between Persistent Disruptive Childhood Behaviour and the Psychopathic Personality Constellation in Adolescence: A Twin Study

    ERIC Educational Resources Information Center

    Forsman, Mats; Larsson, Henrik; Andershed, Henrik; Lichtenstein, Paul

    2007-01-01

    This study tested if persistent externalizing behaviour and symptoms of Attention Deficit Hyperactivity Disorder (ADHD) in childhood are associated with personality and behavioural aspects of the psychopathic personality constellation in adolescence. The target sample consisted of all 1,480 twin pairs born in Sweden between 1985 and 1986.…

  18. Shorter adult stature increases the impact of risk factors for cognitive impairment: a comparison of two Nordic twin cohorts.

    PubMed

    Laitala, Venla S; Hjelmborg, Jacob; Koskenvuo, Markku; Räihä, Ismo; Rinne, Juha O; Christensen, Kaare; Kaprio, Jaakko; Silventoinen, Karri

    2011-12-01

    We analyzed the association between mean height and old age cognition in two Nordic twin cohorts with different childhood living conditions. The cognitive performance of 4720 twin individuals from Denmark (mean age 81.6 years, SD = 4.59) and Finland (mean age 74.4 years, SD = 5.26) was measured using validated cognitive screens. Taller height was associated with better cognitive performance in Finland (beta-estimates 0.18 SD/10cm, p value < .001, for men and 0.13 SD, p = .008, for women), but this association was not significant in Denmark (beta-estimates 0.0093 SD, p value = .16, for men and 0.0075 SD, p value = .016, for women) when adjusted for age and education/social class. Among Finnish participants higher variability of cognitive performance within shorter height quintiles was observed. Analysis using gene-environment interaction models showed that environmental factors exerted a greater impact on cognitive performance in shorter participants, whereas in taller participants' it was explained mainly by genetic factors. Our results suggest that shorter participants with childhood adversity are more vulnerable to environmental risk factors for cognitive impairment. PMID:22506310

  19. Associations of Mother's and Father's Parenting Practices with Children's Observed Social Reticence in a Competitive Situation: A Monozygotic Twin Difference Study

    ERIC Educational Resources Information Center

    Guimond, Fanny-Alexandra; Brendgen, Mara; Forget-Dubois, Nadine; Dionne, Ginette; Vitaro, Frank; Tremblay, Richard E.; Boivin, Michel

    2012-01-01

    This study used the monozygotic (MZ) twin difference method to examine whether the unique environmental effects of maternal and paternal overprotection and hostility at the age of 30 months predict twins' observed social reticence in a competitive situation in kindergarten, while controlling for the effect of family-wide influences, including…

  20. Exploring the Relationship between Autistic-Like Traits and ADHD Behaviors in Early Childhood: Findings from a Community Twin Study of 2-Year-Olds

    ERIC Educational Resources Information Center

    Ronald, Angelica; Edelson, Lisa R.; Asherson, Philip; Saudino, Kimberly J.

    2010-01-01

    Behaviors characteristic of autism and ADHD emerge in early childhood, yet research investigating their comorbidity has focused on older children. This study aimed to explore the nature of the relationship between autistic-like traits and ADHD behaviors in a community sample of 2-year-olds. Twins from the Boston University Twin Project (N = 312…

  1. Increased serotonin transporter gene (SERT) DNA methylation is associated with bullying victimization and blunted cortisol response to stress in childhood: a longitudinal study of discordant monozygotic twins

    PubMed Central

    Ouellet-Morin, I.; Wong, C. C. Y.; Danese, A.; Pariante, C. M.; Papadopoulos, A. S.; Mill, J.; Arseneault, L.

    2014-01-01

    Background Childhood adverse experiences are known to induce persistent changes in the hypothalamic–pituitary–adrenal (HPA) axis reactivity to stress. However, the mechanisms by which these experiences shape the neuroendocrine response to stress remain unclear. Method We tested whether bullying victimization influenced serotonin transporter gene (SERT) DNA methylation using a discordant monozygotic (MZ) twin design. A subsample of 28 MZ twin pairs discordant for bullying victimization, with data on cortisol and DNA methylation, were identified in the Environmental Risk (E-Risk) Longitudinal Twin Study, a nationally representative 1994–1995 cohort of families with twins. Results Bullied twins had higher SERT DNA methylation at the age of 10 years compared with their non-bullied MZ co-twins. This group difference cannot be attributed to the children’s genetic makeup or their shared familial environments because of the study design. Bullied twins also showed increasing methylation levels between the age of 5 years, prior to bullying victimization, and the age of 10 years whereas no such increase was detected in non-bullied twins across time. Moreover, children with higher SERT methylation levels had blunted cortisol responses to stress. Conclusions Our study extends findings drawn from animal models, supports the hypothesis that early-life stress modifies DNA methylation at a specific cytosine–phosphate–guanine (CpG) site in the SERT promoter and HPA functioning and suggests that these two systems may be functionally associated. PMID:23217646

  2. Adult Skills Training Center: Feasibility Study.

    ERIC Educational Resources Information Center

    Skalski, John M.; Baratta, Anthony N.

    A 4-phase project, this study was conducted to determine the feasibility of a bilingual vocational skill training program for out-of-school youth and adults of the Perth Amboy Hispanic community. Sampled were 494 out-of-school youth and adults in the area. Findings include: (1) There is a significant need for an adult vocational skills training…

  3. Postmenopausal hormone replacement therapy modifies skeletal muscle composition and function: a study with monozygotic twin pairs.

    PubMed

    Ronkainen, Paula H A; Kovanen, Vuokko; Alén, Markku; Pöllänen, Eija; Palonen, Eeva-Maija; Ankarberg-Lindgren, Carina; Hämäläinen, Esa; Turpeinen, Ursula; Kujala, Urho M; Puolakka, Jukka; Kaprio, Jaakko; Sipilä, Sarianna

    2009-07-01

    We investigated whether long-term hormone replacement therapy (HRT) is associated with mobility and lower limb muscle performance and composition in postmenopausal women. Fifteen 54- to 62-yr-old monozygotic female twin pairs discordant for HRT were recruited from the Finnish Twin Cohort. Habitual (HWS) and maximal (MWS) walking speeds over 10 m, thigh muscle composition, lower body muscle power assessed as vertical jumping height, and maximal isometric hand grip and knee extension strengths were measured. Intrapair differences (IPD%) with 95% confidence intervals (CI) were calculated. The mean duration of HRT use was 6.9 +/- 4.1 yr. MWS was on average 7% (0.9 to 13.1%, P = 0.019) and muscle power 16% (-0.8 to 32.8%, P = 0.023) greater in HRT users than in their cotwins. Thigh muscle cross-sectional area tended to be larger (IPD% = 6%, 95% CI: -0.07 to 12.1%, P = 0.065), relative muscle area greater (IPD% = 8%, CI: 0.8 to 15.0%, P = 0.047), and relative fat area smaller (IPD% = -5%, CI: -11.3 to 1.2%, P = 0.047) in HRT users than in their sisters. There were no significant differences in maximal isometric strengths or HWS between users and nonusers. Subgroup analyses revealed that estrogen-containing therapies (11 pairs) significantly decreased total body and thigh fat content, whereas tibolone (4 pairs) tended to increase muscle cross-sectional area. This study showed that long-term HRT was associated with better mobility, greater muscle power, and favorable body and muscle composition among 54- to 62-yr-old women. The results indicate that HRT is a potential agent in preventing muscle weakness and mobility limitation in older women. PMID:19246654

  4. Clonal origins of ETV6-RUNX1⁺ acute lymphoblastic leukemia: studies in monozygotic twins.

    PubMed

    Alpar, D; Wren, D; Ermini, L; Mansur, M B; van Delft, F W; Bateman, C M; Titley, I; Kearney, L; Szczepanski, T; Gonzalez, D; Ford, A M; Potter, N E; Greaves, M

    2015-04-01

    Studies on twins with concordant acute lymphoblastic leukemia (ALL) have revealed that ETV6-RUNX1 gene fusion is a common, prenatal genetic event with other driver aberrations occurring subclonally and probably postnatally. The fetal cell type that is transformed by ETV6-RUNX1 is not identified by such studies or by the analysis of early B-cell lineage phenotype of derived progeny. Ongoing, clonal immunoglobulin (IG) and cross-lineage T-cell receptor (TCR) gene rearrangements are features of B-cell precursor leukemia and commence at the pro-B-cell stage of normal B-cell lineage development. We reasoned that shared clonal rearrangements of IG or TCR genes by concordant ALL in twins would be informative about the fetal cell type in which clonal advantage is elicited by ETV6-RUNX1. Five pairs of twins were analyzed for all varieties of IG and TCR gene rearrangements. All pairs showed identical incomplete or complete variable-diversity-joining junctions coupled with substantial, subclonal and divergent rearrangements. This pattern was endorsed by single-cell genetic scrutiny in one twin pair. Our data suggest that the pre-leukemic initiating function of ETV6-RUNX1 fusion is associated with clonal expansion early in the fetal B-cell lineage. PMID:25388957

  5. Vitamin D Status and Coronary Flow Reserve Measured by Positron Emission Tomography: A Co-Twin Control Study

    PubMed Central

    Karohl, Cristina; Vaccarino, Viola; Veledar, Emir; Goldberg, Jack; Tangpricha, Vin; Bellasi, Antonio

    2013-01-01

    Context: Vitamin D insufficiency is associated with increased cardiovascular events in the general population. Additionally, low serum 25-hydroxyvitamin D [25(OH)D] is associated with endothelial dysfunction and arterial stiffness. However, little is known about the association between serum 25(OH)D level and myocardial blood flow. Objective: Our objective was to examine the association between serum 25(OH)D levels and coronary flow reserve (CFR) measured by 13N-positron emission tomography in asymptomatic middle-aged male twins. Design: The Emory Twin Study is a cross-sectional study of soldiers from the Vietnam Era Registry. Setting: The study was conducted at the General Clinical Research Center, Emory University, Atlanta, GA. Participants: A total of 368 middle-aged male twins were enrolled for the study. Serum 25(OH)D levels were measured in all subjects and classified as vitamin D insufficiency [25(OH)D <30 ng/ml] or sufficiency [25(OH)D ≥30 ng/ml]. Positron emission tomography with [13N]ammonia was used to evaluate myocardial blood flow at rest and after adenosine stress. CFR was measured as the ratio of maximum to rest myocardial blood flow. Main Outcome Measure: Primary outcome was CFR measurement. Results: Mean overall serum 25(OH)D concentration was 37.0 ± 21.4 ng/ml; 167 twins (45%) were vitamin D insufficient. CFR was significantly lower in subjects with vitamin D insufficiency compared with subjects with vitamin D sufficiency (2.41 vs. 2.64; P = 0.007), even after adjustment for traditional cardiovascular risk factors, serum PTH, calcium, and phosphorus levels, and season. An abnormal CFR (CFR <2) was more prevalent in subjects with vitamin D insufficiency than with vitamin D sufficiency (31 vs. 20%; P = 0.03). In addition, in vitamin D status-discordant twin pairs, CFR was significantly lower in the vitamin D-insufficient twin than in the vitamin D-sufficient co-twin (2.35 vs. 2.58; P = 0.037). Conclusion: Vitamin D insufficiency is associated

  6. Observations of the Atomic Structure of Tensile and Compressive Twin Boundaries and Twin-Twin Interactions in Zirconium

    NASA Astrophysics Data System (ADS)

    Morrow, Benjamin M.; McCabe, Rodney J.; Cerreta, Ellen K.; Tomé, Carlos N.

    2014-12-01

    The boundary structures of twins in the hexagonal close-packed metal zirconium were studied. High-resolution transmission electron microscopy was used to characterize the boundary structure of (T1), (T2), and (C1) twins on the atomic level. Basal-prismatic (B-P) plane faceting is observed along the T1 twin boundaries, matching previous observations of T1 twins in magnesium. C1 twins are observed to form basal-pyramidal (B-Py) facets along otherwise perfect twin planes. T2 twins exhibit faceting that aligns prism planes with second-order pyramidal planes across the boundary (P-Py facets). As a function of the crystallography, T2 twins appear less likely to accommodate large deviations from perfect twin planes by P-Py faceting alone, and may rely on small dislocation-accommodated facets to achieve arbitrary boundary planes. The structure of these boundaries, specifically the modes by which faceting is permitted, has a direct impact on boundary mobility. In addition, the boundary structure of two C1 twins during a twin-twin interaction event is observed, and is compared to previous observations of tensile twin-twin interactions in magnesium.

  7. Increased physical activity decreases hepatic free fatty acid uptake: a study in human monozygotic twins.

    PubMed

    Hannukainen, Jarna C; Nuutila, Pirjo; Borra, Ronald; Ronald, Borra; Kaprio, Jaakko; Kujala, Urho M; Janatuinen, Tuula; Heinonen, Olli J; Kapanen, Jukka; Viljanen, Tapio; Haaparanta, Merja; Rönnemaa, Tapani; Parkkola, Riitta; Knuuti, Juhani; Kalliokoski, Kari K

    2007-01-01

    Exercise is considered to be beneficial for free fatty acid (FFA) metabolism, although reports of the effects of increased physical activity on FFA uptake and oxidation in different tissues in vivo in humans have been inconsistent. To investigate the heredity-independent effects of physical activity and fitness on FFA uptake in skeletal muscle, the myocardium, and liver we used positron emission tomography (PET) in nine healthy young male monozygotic twin pairs discordant for physical activity and fitness. The cotwins with higher physical activity constituting the more active group had a similar body mass index but less body fat and 18 +/- 10% higher (P < 0.001) compared to the less active brothers with lower physical activity. Low-intensity knee-extension exercise increased skeletal muscle FFA and oxygen uptake six to 10 times compared to resting values but no differences were observed between the groups at rest or during exercise. At rest the more active group had lower hepatic FFA uptake compared to the less active group (5.5 +/- 4.3 versus 9.0 +/- 6.1 micromol (100 ml)(-1) min(-1), P = 0.04). Hepatic FFA uptake associated significantly with body fat percentage (P = 0.05). Myocardial FFA uptake was similar between the groups. In conclusion, in the absence of the confounding effects of genetic factors, moderately increased physical activity and aerobic fitness decrease body adiposity even in normal-weighted healthy young adult men. Further, increased physical activity together with decreased intra-abdominal adiposity seems to decrease hepatic FFA uptake but has no effects on skeletal muscle or myocardial FFA uptake. PMID:17053033

  8. Genetic Influences on Alcohol Use Behaviors Have Diverging Developmental Trajectories: A Prospective Study among Male and Female Twins

    PubMed Central

    Meyers, Jacquelyn L.; Salvatore, Jessica E.; Vuoksimaa, Eero; Korhonen, Tellervo; Pulkkinen, Lea; Rose, Richard J.; Kaprio, Jaakko; Dick, Danielle M.

    2014-01-01

    Background Both alcohol-specific genetic factors and genetic factors related to externalizing behavior influence problematic alcohol use. Little is known, however, about the etiologic role of these two components of genetic risk on alcohol-related behaviors across development. Prior studies conducted in a male cohort of twins suggest that externalizing genetic factors are important for predicting heavy alcohol use in adolescence, whereas alcohol-specific genetic factors increase in importance during the transition to adulthood. In this report, we studied twin brothers and sisters and brother-sister twin pairs to examine such developmental trajectories and investigate whether sex and co-twin sex effects modify these genetic influences. Methods We used prospective, longitudinal twin data collected between ages 12 and 22 within the population-based FinnTwin12 cohort study (analytic n=1,864). Our dependent measures of alcohol use behaviors included alcohol initiation (age 12), intoxication frequency (ages 14 and 17), and alcohol dependence criteria (age 22). Each individual’s genetic risk for alcohol use disorders (AUD-GR) was indexed by his/her parents’ and co-twin’s DSM-IV Alcohol Dependence (AD) criterion counts. Likewise, each individual’s genetic risk for externalizing disorders (EXT-GR) was indexed with a composite measure of parents’ and co-twin’s DSM-IV Conduct Disorder and Antisocial Personality Disorder criterion counts. Results EXT-GR was most strongly related to alcohol use behaviors during adolescence while AUD-GR was most strongly related to alcohol problems in young adulthood. Further, sex of the twin and sex of the co-twin significantly moderated the associations between genetic risk and alcohol use behaviors across development: AUD-GR influenced early adolescent alcohol use behaviors in females more than in males, and EXT-GR influenced age 22 AD more in males than in females. In addition, the associations of AUD-GR and EXT-GR with

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

    PubMed Central

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

    2016-01-01

    To study the effect of twin boundaries on thermal transmission, thermal conductivities of twinned diamond with different twin thicknesses have been studied by NEMD simulation. Results indicate that twin boundaries show a weak phonon scattering effect on thermal transmission, which is only caused by the additional twin boundaries’ thermal resistance. Moreover, according to phonon kinetic theory, this weak phonon scattering effect of twin boundaries is mainly caused by a slightly reduced average group velocity. PMID:26822675

  10. STOPPIT Baby Follow-Up Study: The Effect of Prophylactic Progesterone in Twin Pregnancy on Childhood Outcome

    PubMed Central

    McNamara, Helen Christine; Wood, Rachael; Chalmers, James; Marlow, Neil; Norrie, John; MacLennan, Graeme; McPherson, Gladys; Boachie, Charles; Norman, Jane Elizabeth

    2015-01-01

    Objectives To determine the long-term effects of in utero progesterone exposure in twin children. Methods This study evaluated the health and developmental outcomes of all surviving children born to mothers who participated in a double-blind, placebo-controlled trial of progesterone given for the prevention of preterm birth in twin pregnancies (STOPPIT, ISRCTN35782581). Follow-up was performed via record linkage and two parent-completed validated questionnaires, the Child Development Inventory and the Health Utilities Index. Results Record linkage was successfully performed on at least one record in 759/781 (97%) children eligible for follow-up. There were no differences between progesterone-exposed and placebo-exposed twins with respect to incidence of death, congenital anomalies and hospitalisation, nor on routine national child health assessments. Questionnaire responses were received for 324/738 (44%) children. The mean age at questionnaire follow-up was 55.5 months. Delay in at least one developmental domain on the Child Development Inventory was observed in 107/324 (33%) children, with no evidence of difference between progesterone-exposed and placebo-exposed twins. There was no evidence of difference between the progesterone and placebo groups in global health status assessed using the Health Utilities Index: 89% of children were rated as having ‘excellent’ health and a further 8% as having ‘very good’ health. Conclusions In this cohort of twin children there was no evidence of a detrimental or beneficial impact on health and developmental outcomes at three to six years of age due to in utero exposure to progesterone. PMID:25881289

  11. Twin Valve Caval Stent for Functional Replacement of Incompetent Tricuspid Valve: A Feasibility Animal Study

    SciTech Connect

    Sochman, Jan; Peregrin, Jan H.; Pavcnik, Dusan Uchida, Barry T. Timmermans, Hans A.; Shimohira, Masashi; Choi, Young Ho; Keller, Frederick S. Roesch, Josef

    2011-02-15

    Objective: To evaluate feasibility of a twin valve caval stent (TVCS) for functional replacement of an incompetent tricuspid valve (TV) in an acute animal study. Methods: One swine and three sheep were used in the study. TVCS placement was tested in a swine with a normal TV. TVCS function was tested in three sheep with TV regurgitation created by papillary muscle avulsion. Cardiac angiograms and pressure measurements were used to evaluate TVCS function. Two sheep were studied after fluid overload. Results: TVCS was percutaneously placed properly at the central portions of the superior vena cava (SVC) and inferior vena cava (IVC) in the swine. Papillary muscle avulsion in three sheep caused significant tricuspid regurgitation with massive reflux into the right atrium (RA) and partial reflux into the SVC and IVC. TVCS placement eliminated reflux into the SVC and IVC. After fluid overload, there was enlargement of the right ventricle and RA and significant increase in right ventricle, RA, SVC, and IVC pressures, but no reflux into the IVC and SVC. Conclusion: The results of this feasibility study justify detailed evaluation of TVCS insertion for functional chronic replacement of incompetent TV.

  12. The Texas Twin Project

    PubMed Central

    Harden, K. Paige; Tucker-Drob, Elliot M.; Tackett, Jennifer L.

    2013-01-01

    Socioeconomic position, racial/ethnic minority status, and other characteristics of the macro-environment may be important moderators of genetic influence on a wide array of psychosocial outcomes. Designed to maximize representation of low socioeconomic status families and racial/ethnic minorities, the Texas Twin Project is an on-going study of school-age twins (preschool through 12th grade) enrolled in public schools in the Austin, Texas and Houston, Texas metropolitan areas. School rosters are used to identify twin families from a target population with sizable populations of African-American (18%), Hispanic / Latino (48%), and non-Hispanic White (27%) children and adolescents, over half of whom meet U.S. guidelines for classification as economically disadvantaged. Initial efforts have focused on a large-scale, family-based survey study involving both parent and child reports of personality, psychopathology, physical health, academic interests, parent-child relationships, and aspects of the home environment. In addition, the Texas Twin Project is the basis for an in-laboratory study of adolescent decision-making, delinquency, and substance use. Future directions include geographic expansion of the sample to the entire state of Texas (with a population of over 25 million people) and genotyping of participating twins. PMID:23111007

  13. Traveling magnetospheric convection twin vortices: Another case study, global characteristics, and a model

    SciTech Connect

    Glassmeier, K.H. ); Heppner, C. )

    1992-04-01

    A case study of a transient geomagnetic field variation event associated with a traveling magnetospheric convection twin vortex is presented. The characteristics of this event are different from those of other presented cases, as the sense of rotation of the associated ionospheric current system is reversed, that is, it exhibits upward (downward) field-aligned currents in the tailward (dayside) part of the vortex structure. In particular, a clear tailward motion at high latitudes can be deduced from local as well as global magnetic field observations. At low dayside latitudes, magnetic field variations similar to sudden impulse (SI) variations are recorded. Almost simultaneous onset and no westward propagation are observed, too. As possible source mechanisms of such transient events, localized magnetic field reconnection as well as pressure pulses at the dayside magnetopause are discussed. If the switch-on of magnetic reconnection can be regarded as equivalent to an equivalent current flowing against the existing magnetopause current and if this countercurrent is spatially localized, an Alfven wave is generated with downward (upward) field-aligned current flow in the tailward (dayside) par of the wave, as observed for some of the reported transients. However, the SI-like behavior of the event studied in this paper, its reversed sense of rotation, and the vortex associated field-aligned current density excludes such localized magnetic reconnection as a possible source mechanism and argues in favor of the existence of pressure pulses at the magnetopause.

  14. Etiology of obsessions and compulsions: a meta-analysis and narrative review of twin studies.

    PubMed

    Taylor, Steven

    2011-12-01

    The relative importance of genetic and environmental factors in the etiology of obsessive-compulsive (OC) symptoms is unclear. Cognitive-behavioral models propose that shared environment (e.g., parenting style) is important. Family segregation studies suggest that nonadditive genetic factors may be involved. To investigate the etiology of OC symptoms, a meta-analysis was conducted of 37 twin samples from 14 studies, supplemented by a narrative review. Results indicated that in terms of mean effect sizes, (a) additive genetic effects and nonshared environment accounted for most of the variance in OC symptoms, (b) shared environment and nonadditive genetic effects made little or no contribution; (c) these findings did not vary with sex or symptom severity; (d) variance due to nonshared environment increased with age; (e) gene-environment interactions play an etiologic role; (f) OC symptoms are shaped by etiologic factors common to all types of OC symptoms but also have symptom-specific etiologies; and (g) OC symptoms are also shaped by very general etiologic factors (e.g., those influencing negative emotionality). Overall, the findings indicate that OC symptoms have a complex etiologic architecture that is not adequately explained by contemporary etiological models. PMID:22024245

  15. Probing interactions of neurotransmitters with twin tailed anionic surfactant: A detailed physicochemical study.

    PubMed

    Kaur, Rajwinder; Sanan, Reshu; Mahajan, Rakesh Kumar

    2016-05-01

    Keeping in view the role of neurotransmitters (NTs) in central nervous system diseases and in controlling various physiological processes, present study is aimed to study the binding of neurotransmitters (NTs) such as norepinephrine hydrochloride (NE) and serotonin hydrochloride (5-HT) with twin tailed surfactant sodium bis(2-ethylhexyl)sulfosuccinate (AOT). Spectroscopic and electrochemical measurements combined with microcalorimetric measurements were used to characterize the interactions between AOT and NTs. Meteoric modifications to emission profile and absorption spectra of NTs upon addition of AOT are indicative of the binding of NTs with AOT. Distinct interactional states such as formation of ion-pairs, induced and regular micelles with adsorbed NTs molecules have been observed in different concentration regimes of AOT. The formation of ion-pairs from oppositely charged NTs and AOT is confirmed by the reduced absorbance, quenched fluorescence intensity and decrease in peak current (ipa) as well as shifts in peak potential (Epa) values. The stoichiometry and formation of the NTs-AOT complexes has been judged and the extent of interactions is quantitatively discussed in terms of binding constant (K) and free energy of binding (ΔG°). The enthalpy (ΔH°mic) and free energy of micellization (ΔG°mic) for AOT in presence and absence of NTs are determined from the enthalpy curves. PMID:26866888

  16. Heritability of the spatial distribution and peak density of macular pigment: a classical twin study

    PubMed Central

    Hogg, R E; Ong, E L; Chamberlain, M; Dirani, M; Baird, P N; Guymer, R H; Fitzke, F

    2012-01-01

    Purpose To elucidate the heritability of peak density and spatial width of macular pigment (MP) using a Classical Twin Study. Methods Fundus autofluorescence images were obtained at 488 nm from 86 subjects or 43 twin pairs (21 monozygotic (MZ) and 22 dizygotic (DZ)) (27 male, 59 female) aged from 55 to 76 years (mean 62.2±5.3 years). The relative topographic distribution of MP was measured using a grey scale of intensity (0–255 units) in a 7° eccentricity around the fovea. Relative peak MP density (rPMPD) and relative spatial distribution of MP (rSDMP) were used as the main outcome measure in the statistical analysis. Results A significantly higher correlation was found within MZ pairs as compared with that within DZ pairs for rPMPD, (r=0.99, 95% confidence interval (95% CI) 0.93 to 1.00) and 0.22, 95% CI −0.34 to 0.71), respectively, suggesting strong heritability of this trait. When rSDMP was compared, there was no significant difference between the correlations within MZ pairs (r=0.48, 95% CI −0.02 to 0.83) and DZ pairs (r=0.63, 95% CI 0.32 to 0.83), thus rSDMP is unlikely to have a considerable heritable component. In addition, there was no difference between any MP parameter when normal maculae were compared with early age-related macular degeneration (AMD) (rPMPD 0.36 vs 0.34, t=1.18 P=0.243, rSDMP 1.75 vs 1.75, t=0.028 P=0.977). Conclusions rPMPD is a strongly heritable trait whereas rSDMP has minimal genetic influence and a greater influence by environmental factors. The presence of macular changes associated with early AMD did not appear to influence any of these pigment parameters. PMID:22744384

  17. Twin-to-Twin Transfusion Syndrome

    PubMed Central

    Mahieu-Caputo, Dominique; Dommergues, Marc; Delezoide, Anne-Lise; Lacoste, Mireille; Cai, Yi; Narcy, Françoise; Jolly, Dominique; Gonzales, Marie; Dumez, Yves; Gubler, Marie-Claire

    2000-01-01

    The twin-to-twin transfusion syndrome (TTS) results from an unbalanced blood supply through placental anastomoses in monochorionic twins. It induces growth restriction, renal tubular dysgenesis, and oliguria in the donor and visceromegaly and polyuria in the recipient. A better understanding of its pathophysiology could contribute to improving the management of TTS, which still carries a high perinatal mortality in both twins. As well as several other candidates, the renin-angiotensin system might be involved in TTS. To evaluate its role in the pathogenesis of the syndrome, we studied the kidneys of 21 twin pairs who died from TTS at 19 to 30 weeks, compared with 39 individuals in a control group, using light microscopy, immunohistochemistry, and in situ hybridization. The overexpression of the renin protein and transcript with frequent evidence of renin synthesis by mesangial cells was observed in the donor kidneys, presumably as a consequence of chronic renal hypoperfusion. This upregulation of renin synthesis might be beneficial to restore euvolemia. In severe cases of TTS, however, angiotensin-II-induced vasoconstriction acts as an additional deleterious factor by further reducing the renal blood flow in donors. In recipients, renin expression was virtually absent, possibly because it was down-regulated by hypervolemia. However, in addition to congestion and hemorrhagic infarction, there were severe glomerular and arterial lesions resembling those observed in polycythemia- or hypertension-induced microangiopathy. We speculate that fetal hypertension in the recipient might be partly mediated by the transfer of circulating renin produced by the donor, through the placental vascular shunts. PMID:10666392

  18. Morphological study of cephalothoracopagus deradelphus type conjoined twins. A case report.

    PubMed

    Cîrstoiu, Monica Mihaela; Filipoiu, Florin Mihail; Brătilă, Elvira; Berceanu, Costin; Cîrstoiu, Florin Cătălin; Budu, Vlad Andrei; Bulescu, Ioan Alexandru; Munteanu, Octavian

    2016-01-01

    Cephalopagus is a rare variety of conjoined twins. They are fused with their heads, thoracic and upper abdominal cavities. The exact mechanism for development of conjoined twins cannot be clearly explained. It appears that there is an alteration in the normal developmental process of monozygotic twins, which fail to separate from each other. We present the morphology of a cephalothoracopagus, revealed through anatomical dissection, emphasizing the arrangement of the viscera in the thoracic and abdominal cavities. They are fused with their heads, thoracic and upper abdominal cavities. The lower abdomen and pelvic cavities are free. Each twin has two upper and lower limbs, normally shaped. Each twin has a heart and two lungs. There is a single pharynx, esophagus and stomach, but normal lower abdominal systems. The genital and urinary systems are apparently normal. Due to the fusion of the heads and abnormal arrangement of the superior central nervous system, surgery is not attempted in these cases, the prognosis being very poor. PMID:27151716

  19. Electrical responses and photopigments of twin cones in the retina of the walleye.

    PubMed Central

    Burkhardt, D A; Hassin, G; Levine, J S; MacNichol, E F

    1980-01-01

    1. The properties of twin and single cones in the retina of the walleye (Stizostedion vitreum vitreum) were studied by intracellular recording, dye injection and microspectrophotometry. 2. Twin cones generate hyperpolarizing responses to central illumination, can receive depolarizing influences (feed-back) from the receptive field surround, and show no detectable dye coupling when injected with Procion yellow. In seventeen of eighteen dye-injected cones, fluorescence was intense in the inner segment and undetectable or weak in the cone pedicle. 3. Both members of the twin cone contain the same photopigment in their outer segments. It absorbs maximally at about 605 nm. 4. A 533 nm green-sensitive photopigment was found in single cones. No blue-sensitive cones have been found. 5. With the exception of a modest discrepancy in the violet, the absorptance spectrum of the 605 nm photopigment of twin cones agrees closely with the action spectrum measured by intracellular recording. 6. The spectral properties established by the twin cone's photopigment are not detectably altered by the hyperpolarizing influences arising from nearby cones or by the depolarizing influences arising from the receptive field surround. 7. The twin cones of the walleye retina are thus "identical twins', both photochemically and physiologically, and seem designed to function as long-wave, spectrally univariant receptor units for colour vision. 8. The available evidence suggests that identical twin cones differ functionally from double cones and non-identical twin cones. 9. Although they outnumber single cones by about three to one in adults, identifiable twin cones were rarely observed in the cone population of retinas examined 3-5 days after birth. If walleye twin cones develop by fusion of single cones this process apparently occurs only for cones containing the 605 nm photopigment. Images Plate 1 PMID:7252864

  20. Frequent Extreme Cold Exposure and Brown Fat and Cold-Induced Thermogenesis: A Study in a Monozygotic Twin

    PubMed Central

    Vosselman, Maarten J.; Vijgen, Guy H. E. J.; Kingma, Boris R. M.; Brans, Boudewijn; van Marken Lichtenbelt, Wouter D.

    2014-01-01

    Introduction Mild cold acclimation is known to increase brown adipose tissue (BAT) activity and cold-induced thermogenesis (CIT) in humans. We here tested the effect of a lifestyle with frequent exposure to extreme cold on BAT and CIT in a Dutch man known as ‘the Iceman’, who has multiple world records in withstanding extreme cold challenges. Furthermore, his monozygotic twin brother who has a ‘normal’ sedentary lifestyle without extreme cold exposures was measured. Methods The Iceman (subject A) and his brother (subject B) were studied during mild cold (13°C) and thermoneutral conditions (31°C). Measurements included BAT activity and respiratory muscle activity by [18F]FDG-PET/CT imaging and energy expenditure through indirect calorimetry. In addition, body temperatures, cardiovascular parameters, skin perfusion, and thermal sensation and comfort were measured. Finally, we determined polymorphisms for uncoupling protein-1 and β3-adrenergic receptor. Results Subjects had comparable BAT activity (A: 1144 SUVtotal and B: 1325 SUVtotal), within the range previously observed in young adult men. They were genotyped with the polymorphism for uncoupling protein-1 (G/G). CIT was relatively high (A: 40.1% and B: 41.9%), but unlike during our previous cold exposure tests in young adult men, here both subjects practiced a g-Tummo like breathing technique, which involves vigorous respiratory muscle activity. This was confirmed by high [18F]FDG-uptake in respiratory muscle. Conclusion No significant differences were found between the two subjects, indicating that a lifestyle with frequent exposures to extreme cold does not seem to affect BAT activity and CIT. In both subjects, BAT was not higher compared to earlier observations, whereas CIT was very high, suggesting that g-Tummo like breathing during cold exposure may cause additional heat production by vigorous isometric respiratory muscle contraction. The results must be interpreted with caution given the low

  1. Case Studies in Australian Adult Education.

    ERIC Educational Resources Information Center

    Clark, Ralph J., Ed.; Rooth, S. John, Ed.

    This publication contains the following 24 case studies of adult education in Australia: "NSW Department of Agriculture Home Study Programme" (O'Neill); "Self-Help Adult Education: The University of the Third Age at the Brisbane CAE" (Swindell); "Marriage Enrichment Programme" (D. Kerr, C. Kerr); "Carringbush Library: A Place to Be" (Letcher);…

  2. Lipoprotein(a) in women twins: Heritability and relationship to apolipoprotein(a) phenotypes

    SciTech Connect

    Austin, M.A. ); Sandholzer, C.; Utermann, G. ); Selby, J.V. ); Newman, B. ); Krauss, R.M. )

    1992-10-01

    Lp(a) is a unique lipoprotein consisting of an LDL-like particle and a characteristic protein, apo(a). Increased levels of Lp(a) constitute a risk factor for coronary heart disease. Variation in the size of the apo(a) protein is a phenotype controlled by the apo(a) gene on chromosome 6 and is related to Lp(a) plasma levels. Based on 169 MZ and 125 DZ adult female twin pairs, this study's purpose was to estimate the proportion of the variation in Lp(a) levels that is due to genetic influences and to determine the extent to which the apo(a) locus explains this heritability. Lp(a) levels were significantly more similar in MZ twins than in DZ twins: mean co-twin differences were 3.9 [+-] 5.7 mg/dl and 16.0 [+-] 19.9 mg/dl (P < .001), respectively. Intraclass correlations were .94 in MZ twins and .32 in DZ twins, resulting in a heritability estimate of .94 (P < .001). Heritability was then calculated using only co-twins with the same apo(a) phenotype: the heritability estimate decreased to .45 but was still highly significant (P < .001). Therefore, on the basis of heritability analysis of women twins, Lp(a) levels are almost entirely genetically controlled. Variation at the apo(a) locus contributes to this heritability, although other genetic factors could be involved. 66 refs., 2 figs., 4 tabs.

  3. Association between major depression and type 2 diabetes in mid-life: Findings from the Screening Across the Lifespan Twin Study

    PubMed Central

    Mezuk, Briana; Heh, Victor; Prom-Wormley, Elizabeth; Kendler, Kenneth S.; Pedersen, Nancy L.

    2015-01-01

    Objective Cohort studies suggest that the relationship between major depression (MD) and type 2 diabetes (T2DM) is bi-directional. However, this association may be confounded by shared genetic or environmental factors. The objective of this study was to use a twin design to investigate the association between MD andT2DM. Methods Data come from the Screening Across the Lifespan Twin Study, a sample of monozygotic and dizygotic twins aged ≥40 sampled from the Swedish Twin Registry (N=37,043). MD was assessed using the Composite International Diagnostic Inventory. Structural equation twin modeling and Cox proportional hazards modeling were used to assess the relationship between MD and T2DM. Results Approximately 19% of respondents had a history of MD and 5% had a history of T2DM. MD was associated with 32% increased likelihood of T2DM (95% Confidence Interval: 1.00 – 1.80) among twins aged 40 – 55 even after accounting for genetic risk, but was not associated with T2DM among twins >55 years. T2DM was associated with 33% increased likelihood of MD (95% CI: 1.02 – 1.72) among younger, but not older twins. Cholesky decomposition twin modeling indicated that common unique environmental factors contribute to the association between MD and T2DM. Conclusions Environmental factors that are unique to individuals (e.g., not shared within families), but common to both MD and T2DM contribute to their co-occurrence in mid-life. However, we cannot exclude the possibility of bi-directional causation as an alternate explanation. It is likely that multiple processes are operating to affect the relation between psychological and medical conditions in mid-life. PMID:25967355

  4. Simulator study of vortex encounters by a twin-engine, commercial, jet transport airplane

    NASA Technical Reports Server (NTRS)

    Hastings, E. C., Jr.; Keyser, G. L., Jr.

    1982-01-01

    A simulator study of vortex encounters was conducted for a twin-engine, commercial, jet transport airplane encountering the vortex flow field of a heavy, four-engine, commercial, jet transport airplane in the final-approach configuration. The encounters were conducted with fixed controls and with a pilot using a state-of-the-art, manual-control system. Piloted encounters with the base-line vortex flow field out of ground effect (unattenuated) resulted in initial bank-angle excursions greater than 40 deg, coupled with initial sideslip-angle excursions greater than 10 deg. The severity of these initial upsets was significantly reduced when the vortex center was moved laterally or vertically away from the flight path of the encountering airplane. Smaller reductions occurred when the flow field was attenuated by the flight spoilers on the generating airplane. The largest reduction in the severity of the initial upsets, however, was from aging in ground effect. The severity of the initial upsets of the following airplane was relatively unaffected by the approach speed. Increasing the lift coefficient of the generating airplane resulted in an increase in the severity of the initial upsets.

  5. Stability and Change in Personality Traits From Late Adolescence to Early Adulthood: A Longitudinal Twin Study

    PubMed Central

    Blonigen, Daniel M.; Carlson, Marie D.; Hicks, Brian M.; Krueger, Robert F.; Iacono, William G.

    2008-01-01

    We conducted a longitudinal-biometric study examining stability and change in personality from ages 17 to 24 in a community sample of male and female twins. Using Tellegen's (in press) Multidimensional Personality Questionnaire (MPQ), facets of Negative Emotionality (NEM) declined substantially at the mean and individual levels, whereas facets of Constraint (CON) increased over time. Furthermore, individuals in late adolescence who were lowest on NEM and highest on CON remained the most stable over time, whereas those exhibiting the inverse profile (higher NEM, lower CON) changed the most in a direction towards growth and maturity. Analyses of gender differences yielded greater mean-level increases over time for women as compared to men on facets of CON and greater mean-level increases for men than women on facets of Agentic Positive Emotionality (PEM). Biometric analyses revealed rank-order stability in personality to be largely genetic, with rank-order change mediated by both the nonshared environment (and error) as well as genes. Findings correspond with prior evidence of a normative trend toward growth and maturity in personality during emerging adulthood. PMID:18331280

  6. Topological studies on the twin-arginine translocase component TatC.

    PubMed

    Behrendt, Jana; Standar, Kerstin; Lindenstrauss, Ute; Brüser, Thomas

    2004-05-15

    The twin-arginine translocation (Tat) system can translocate folded proteins across biological membranes. Among the known Tat-system components in Escherichia coli, TatC is the only protein with multiple trans-membrane domains. TatC is important for translocon interactions with Tat substrates. The knowledge of its membrane topology is therefore crucial for the understanding of substrate binding and translocon function. Recently, based on active PhoA reporter fusions to the second predicted cytoplasmic loop of TatC, a topology with four trans-membrane domains has been suggested, calling in silico predictions of six trans-membrane domains into question. Here we report studies with translational fusions of TatC to the topological marker enzymes PhoA and LacZ which provide strong evidence for a six-trans-membrane domain topology. The stop transfer capacity of the fourth trans-membrane domain was found to be strongly influenced by the succeeding cytoplasmic domain. The presence of linker sequences at PhoA-fusion sites of the cytoplasmic domain induced PhoA leakage. In the case of one tested fusion (S185-PhoA), the stop-transfer efficiency was already low due to the negative charge in the center of the fourth trans-membrane domain (E170). The results point to the importance of cytoplasmic loops for the stabilization of stop-transfer sequences and revoke evidence for only four trans-membrane domains of TatC. PMID:15135537

  7. Parametric Study of Magnetospheric Ion Temperatures Using TWINS ENA Data and BATS-R-US Simulations

    NASA Astrophysics Data System (ADS)

    Elfritz, J. G.; Keesee, A. M.; Scime, E. E.

    2013-12-01

    We present results from our continued parametric study into how the spatial distribution of inner magnetospheric ion temperatures varies as a function of solar wind parameters. We have taken 2+ years of ACE solar wind data and binned by (1) Bz polarity, (2) dynamic pressure: low and high, (3) IMF clock angle polarity, and (4) solar wind flow angle polarity. Average magnetospheric ion temperatures over the given time interval are determined for each parametric bin by applying the methods described in Scime, et al. [2002; 2005] and Keesee, et al. [2008; 2011] to energetic neutral atom (ENA) data collected by the TWINS I and II spacecraft. Here we present results showing global and local features in ion temperature maps in an Earth-centered 40 RE x 40 RE region, and we compare these results with magnetospheric ion temperatures simulated using the BATS-R-US global MHD code. The BATS-R-US simulations are driven by solar wind conditions averaged over the times associated with each parametric bin.

  8. Internalizing behavior in adolescent girls affects parental emotional overinvolvement: a cross-lagged twin study.

    PubMed

    Moberg, Therese; Lichtenstein, Paul; Forsman, Mats; Larsson, Henrik

    2011-03-01

    The aim of this study was to examine the direction and the etiology of the association between different parenting styles (parental emotional overinvolvement [EOI] and parental criticism) and internalizing behavior from adolescence to early adulthood. A longitudinal genetically informative cross-lagged design was applied to a population-based sample of Swedish twins contacted at age 16-17 (n = 2369) and at age 19-20 (n = 1705). Sex-limitation modelling revealed different effects for boys and girls. For girls, genetic influences on internalizing problems at age 16-17 independently explained 2.7% of the heritability in parental EOI at age 19-20. These results suggest that emotionally overinvolved and self-sacrificing parental behavior stems in part from daughters (but not sons) genetic predisposition for internalizing behavior. These findings highlight the importance of genetically influenced child-driven effects underlying the parenting-internalizing association, and clarify that the role of such effects may differ depending on sex, type of parenting and developmental period. PMID:20680431

  9. Molecular Dynamics Study on the Distributed Plasticity of Penta-twinned Silver Nanowires

    NASA Astrophysics Data System (ADS)

    Lee, Sangryun; Ryu, Seunghwa

    2015-08-01

    The distributed plasticity of pentatwinned silver nanowires has been revealed in recent computational and experimental studies. However, the molecular dynamics (MD) simulations have not considered the imperfections seen in experiments, such as irregular surface undulations, the high aspect ratio of nanowires, and the stiffness of loading devices. In this work, we report the effect of such inherent imperfections on the distributed plasticity of penta-twinned silver nanowires in MD simulations. We find that the distributed plasticity occurs for nanowires having undulations that are less than 5% of the nanowire diameter. The elastic stress field induced by a stacking fault promotes the nucleation of successive stacking fault decahedrons (SFDs) at long distance, making it hard for necking to occur. By comparing the tensile simulation using the steered molecular dynamics (SMD) method with the tensile simulation with periodic boundary condition (PBC), we show that a sufficiently long nanowire must be used in the constant strain rate simulations with PBC, because the plastic displacement burst caused by the SFD formation induces compressive stress, promoting the removal of other SFDs. Our finding can serve as a guidance for the molecular dynamics simulation of crystalline materials with large plastic deformation, and in the design of mechanically reliable devices based on silver nanowires.

  10. Retrospective reports of parental physical affection and parenting style: a study of Finnish twins.

    PubMed

    Harlaar, Nicole; Santtila, Pekka; Björklund, Johanna; Alanko, Katarina; Jern, Patrick; Varjonen, Markus; von der Pahlen, Bettina; Sandnabba, Kenneth

    2008-08-01

    Individual differences in parenting behaviors are due, in part, to genetic factors. In the present study, the authors sought to determine whether the degree of genetic influence varied according to the type of parental behavior under consideration. A population-based sample of 2,334 pairs of Finnish twins provided ratings on the physical affection, control, abusiveness, and indifference shown by their father and mother during childhood. Genetic influences, shared environmental influences, and nonshared environmental influences accounted for a small-to-medium proportion (17%-30%), a small-to-large proportion (22%-44%), and a medium-to-large proportion (37%-55%) of the variance in each parenting measure, respectively. There were no significant differences in effect sizes for mothers and fathers or across the 4 types of parental behavior. The genetic results may reflect characteristic styles with which parents respond to genetically influenced behaviors of individuals (gene-environment correlations) or individual perceptions of this relationship (gene-person correlation processes). The findings have implications for intervention and prevention work with families and for interpretation of evidence for interactions between genes and parenting behaviors. PMID:18729674

  11. Is Chronic Low Back Pain Associated with the Prevalence of Coronary Heart Disease when Genetic Susceptibility Is Considered? A Co-Twin Control Study of Spanish Twins

    PubMed Central

    Fernandez, Matt; Ordoñana, Juan R.; Hartvigsen, Jan; Ferreira, Manuela L.; Refshauge, Kathryn M.; Sánchez-Romera, Juan F.; Pinheiro, Marina B.; Simpson, Stephen J.; Hopper, John L.; Ferreira, Paulo H.

    2016-01-01

    Objective To investigate the chronic low back pain and coronary heart disease relationship, after adjusting for relevant confounders, including genetics. Methods In a cross-sectional design, 2148 twins were recruited from the Murcia Twin Registry, Spain. The exposure was chronic LBP and the outcomes were myocardial infarction and other coronary heart diseases—lifetime and in the last 2 years–based on standardized health-related questionnaires. First, logistic regression analysis investigated associations of the total sample followed by a matched co-twin control analyses, with all complete twin pairs discordant for chronic LBP utilised, separated for zygosity—dizygotic (DZ) and monozygotic (MZ) pairs, which adjusted for shared familial factors, including genetics. Results Chronic LBP pain is associated with lifetime myocardial infarction [odds ratio (OR) = 2.69, 95% confidence interval (CI) = 1.35–5.36], other coronary heart diseases over a lifetime (OR = 2.58, 95% CI: 1.69–3.93) and in the last two years (OR = 2.19, 95% CI: 1.33–3.60), while there was a borderline association with myocardial infarction in the last 2 years (OR = 2.64, 95% CI: 0.98–7.12). Although the magnitude of the association remained or increased in the co-twin control analyses, none reached statistical significance. Conclusion Chronic LBP is associated with a higher prevalence of myocardial infarction and coronary heart disease. It is possible that this association remains even when controlling for genetics and early shared environment, although this should be investigated with larger samples of twins discordant for LBP. PMID:27171210

  12. Speech and Language Delays in Identical Twins.

    ERIC Educational Resources Information Center

    Bentley, Pat

    Following a literature review on speech and language development of twins, case studies are presented of six sets of identical twins screened for entrance into kindergarten. Five sets of the twins and one boy from the sixth set failed to pass the screening test, particularly the speech and language section, and were referred for therapy to correct…

  13. An OSSE study using the GFDL ensemble coupled data assimilation system: Biased twin experiment for deep Argo array

    NASA Astrophysics Data System (ADS)

    Chang, Y. S.; Zhang, S.; Rosati, A.; Vecchi, G. A.; Yang, X.

    2014-12-01

    A "biased" twin experiment of coupled data assimilation with two CGCMs is designed to address two questions: 1) given atmospheric and oceanic observations and a biased numerical climate system, how to obtain balanced climate estimation? 2) Within the steady and coherent climate estimation framework, what is the impact of deep ocean Argo profiles? Based on the modern Argo observing system and artificial extension to the full depth, "observations" drawn from one CGCM are assimilated into the other. Our results show that the simultaneous atmospheric and oceanic constraints play a significant role for preventing the deep ocean drift. Within the bias magnitude in the twin experiment, the Argo extension to the full depth does not significantly improve the quality of climate estimation. More studies based on different assimilation models with improved spatial and temporal scales of the deep Argo array are demanding for further understanding the impact of deep Argo array.

  14. First-principles study of the electronic properties of wurtzite, zinc-blende, and twinned InP nanowires

    SciTech Connect

    Li, Dengfeng; Wang, Zhiguo; Gao, Fei

    2010-12-17

    The electronic properties of zinc blende, wurtzite, and rotationally twinned InP nanowires were studied using first-principles calculations. The results show that all the simulated nanowires exhibit a semiconducting character, and the band gap decreases with increasing the nanowire size. The band gap difference between the zinc blende, wurtzite, and twinned InP nanowires and a bulk InP can be described by several formulas proportional to the diameter of nanowires. The valence band maximum (VBM) and conduction band minimum (CBM) originate mainly from the p-orbitals of the P atoms and s-orbitals of the In atoms at the core regions of the nanowires, respectively. The hexagonal (2H) stacking inside the cubic (3C) stacking has no effect on the electronic properties of thin InP nanowires.

  15. A Chaotic Home Environment Accounts for the Association between Respect for Rules Disposition and Reading Comprehension: A Twin Study

    PubMed Central

    Taylor, Jeanette; Hart, Sara A.

    2014-01-01

    This study examined the association between socioemotional dispositions from the developmental propensity model and reading comprehension and whether those associations could be accounted for by level of chaos in the home. Data from 342 monozygotic and 333 same-sex dizygotic twin pairs age 7-13 years were used. A parent rated the twins on sympathy, respect for rules, negative emotionality, and daring and level of chaos in the twins’ home. Reading comprehension was measured using a state-wide school assessment. Only respect for rules significantly and uniquely predicted reading comprehension. Biometric models indicated that respect for rules was positively associated with reading comprehension via the shared environment and home chaos accounted for a significant amount of that shared environmental variance even after controlling for family income. Children with higher respect for rules have better reading comprehension scores in school and this relationship owes partly to the level of chaos in the family home. PMID:25328362

  16. Dialysis for twins

    PubMed Central

    Gramkow, Ann-Maria; Aarup, Michael; Andersen, Lise Lotte Torvin; Tepel, Martin

    2014-01-01

    A 32-year-old woman with known stage-4 chronic kidney disease due to lupus nephritis presented with twin pregnancy after in vitro fertilization at a gestational age of 24 weeks + 3 days because of imminent preterm labour. Repeated ultrasound evaluations confirmed intrauterine growth restriction in both twins and polyhydramnios as the cause of imminent preterm labour. After initiation of haemodialysis treatment, ultrasound evaluation showed a significant decrease in amniotic fluids, and also reduction in blood urea nitrogen and in clinical complaints could be observed. At a gestational age of 28 weeks + 4 days, delivery was performed by Caesarean section. This case study shows that effective treatment of elevated uraemic toxins significantly reduced the morbidity risks of the twins. PMID:25859352

  17. A twin association study of nicotine dependence with markers in the CHRNA3 and CHRNA5 genes.

    PubMed

    Maes, Hermine H; Neale, Michael C; Chen, Xiangning; Chen, Jingchun; Prescott, Carol A; Kendler, Kenneth S

    2011-09-01

    Twin and family studies have provided overwhelming evidence for the genetic basis of individual differences in tobacco initiation (TI), regular smoking (RS) and nicotine dependence (ND). However, only a few genes have been reliably associated with ND. We used a finite mixture distribution model to examine the significance and effect size of the association of previously identified and replicated specific variants in the CHRNA5 and CHRNA3 receptor genes with ND, against the background of genetic and environmental risk factors for ND. We hypothesize that additional phenotypic information in relatives who have not been genotyped can be used to increase the power of detecting the genetic variant. The nicotine measures were assessed by personal interview in female, male and opposite sex twin pairs (N = 4,153) from the population-based Virginia Twin Registry. Three SNPs in the CHRNA5 and CHRNA3 receptor genes, previously shown to be significantly associated with ND in this sample, were replicated in the augmented analyses; they accounted for less than one percent of the genetic variance in liability to ND, which is estimated to be over 50% of the phenotypic variance. The significance of these effects was increased by adding twins with phenotype but without genotype data, but gains are limited and variable. The SNPs associated with ND did not show a significant association with either TI or RS and appear to be specific to the addictive stage of ND, characterized by current smoking and smoking a large amount of cigarettes per day. Furthermore, these SNPs did not appear to be associated with the remaining items comprising the FTND scale. This study confirmed a significant contribution of the CHRNA receptor on different forms of tobacco dependence. However, the genetic variant only accounted for little of the total genetic variance for liability to ND. Including phenotypic data on ungenotyped relatives can improve the statistical power to detect the effects of genetic

  18. Labor patterns in twin gestations

    PubMed Central

    Leftwich, Heidi K.; Zaki, Mary N.; Wilkins, Isabelle; Hibbard, Judith U.

    2014-01-01

    Objective To compare labor progression in twin vs singleton gestations. Study Design Retrospective review of electronic database created by Consortium on Safe Labor, reflecting labor and delivery information from 12 clinical centers 2002-2008. Women with twin gestations, cephalic presentation of presenting twin, gestational age ≥34 weeks, with ≥2 cervical examinations were included. Exclusion criteria were fetal anomalies or demise. Singleton controls were selected by the same criteria. Categorical variables were analyzed by χ2; continuous by Student t test. Interval censored regression was used to determine distribution for time of cervical dilation in centimeters, or “traverse times,” and controlled for confounding factors. Repeated-measures analysis constructed mean labor curves by parity and number of fetuses. Results A total of 891 twin gestations were compared with 100,513 singleton controls. Twin gestations were more often older, white or African American, earlier gestational age, increased prepregnancy body mass index, and with lower birthweight. There was no difference in number of prior cesarean deliveries, induction, or augmentation, or epidural use. Median traverse times increased at every centimeter interval in nulliparous twins, in both unadjusted and adjusted analysis (P < .01). A similar pattern was noted for multiparas in both analyses. Labor curves demonstrated a delayed inflection point in the labor pattern for nulliparous and multiparous twin gestations. Conclusion Both nulliparous and multiparous women have slower progression of active phase labor with twins even when controlling for confounding factors. PMID:23871795

  19. The Charles Perkins Centre's Twins Research Node.

    PubMed

    Ferreira, Lucas C; Craig, Jeffrey M; Hopper, John L; Carrick, Susan E

    2016-08-01

    Twins can help researchers disentangle the roles of genes from those of the environment on human traits, health, and diseases. To realize this potential, the Australian Twin Registry (ATR), University of Melbourne, and the Charles Perkins Centre (CPC), University of Sydney, established a collaboration to form the Twins Research Node, a highly interconnected research facility dedicated specifically to research involving twins. This collaboration aims to foster the adoption of twin designs as important tools for research in a range of health-related domains. The CPC hosted their Twins Research Node's launch seminar entitled 'Double the power of your research with twin studies', in which experienced twin researchers described how twin studies are supporting scientific discoveries and careers. The launch also featured twin pairs who have actively participated in research through the ATR. Researchers at the CPC were surveyed before the event to gauge their level of understanding and interest in utilizing twin research. This article describes the new Twins Research Node, discusses the survey's main results and reports on the launch seminar. PMID:27302367

  20. Longitudinal Twin Study of Early Reading Development in Three Countries: Preliminary Results.

    ERIC Educational Resources Information Center

    Byrne, Brian; Delaland, Cara; Fielding-Barnsley, Ruth; Quain, Peter; Samuelsson, Stefan; Hoien, Torleiv; Corley, Robin; DeFries, John C.; Wadsworth, Sally; Willcutt, Erik; Olson, Richard K.

    2002-01-01

    Preliminary results from data on 146 Australian, 284 American, and 70 Norwegian preschool twins indicate reliable genetic influences on phonological awareness and memory and learning. Vocabulary, grammar, and morphology showed significant shared environment and negligible genetic effects. A print knowledge composite showed genetic and shared…

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

    ERIC Educational Resources Information Center

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

    2016-01-01

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

  2. Longitudinal Twin Study of Early Literacy Development: Preschool and Kindergarten Phases

    ERIC Educational Resources Information Center

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

    2005-01-01

    We conducted behavior?genetic analyses of kindergarten reading, spelling, phonological awareness, rapid naming, and spoken sentence processing in 172 pairs of monozygotic and 153 pairs of same-sex dizygotic twin kindergarten children sampled in the United States and Australia. We also modeled progress from preschool to kindergarten in…

  3. A Twin Study of Spatial and Non-Spatial Delayed Response Performance in Middle Age

    ERIC Educational Resources Information Center

    Kremen, William S.; Mai, Tuan; Panizzon, Matthew S.; Franz, Carol E.; Blankfeld, Howard M.; Xian, Hong; Eisen, Seth A.; Tsuang, Ming T.; Lyons, Michael J.

    2011-01-01

    Delayed alternation and object alternation are classic spatial and non-spatial delayed response tasks. We tested 632 middle-aged male veteran twins on variants of these tasks in order to compare test difficulty, measure their inter-correlation, test order effects, and estimate heritabilities (proportion of observed variance due to genetic…

  4. Measuring Puberty and Understanding Its Impact: A Longitudinal Study of Adolescent Twins.

    ERIC Educational Resources Information Center

    Dick, Danielle M.; Rose, Richard J.; Pulkkinen, Lea; Kaprio, Jaakko

    2001-01-01

    Established normative data on the Pubertal Development Scale (PDS) (A. Petersen and others, 1988) of two population-based birth cohorts of Finnish twin boys and girls assessed at ages 11-12 and 14 years (complete data for 664 boys and 681 girls). Also reports longitudinal analyses of the associations between pubertal development and substance use.…

  5. Analysis and Interpretation of Twin Studies Including Measures of the Shared Environment

    ERIC Educational Resources Information Center

    Turkheimer, Eric; D'Onofrio, Brian M.; Maes, Hermine H.; Eaves, Lindon J.

    2005-01-01

    Recent reports using a classical behavior genetic research design in which twin data are combined with a measured characteristic of their shared family environment have made striking claims about estimating environmental influences on behavior with genetic effects controlled. Such claims are overstated for two related reasons. First, when a…

  6. The Development of Inhibitory Control in Early Childhood: A Twin Study from 2-3 Years

    ERIC Educational Resources Information Center

    Gagne, Jeffrey R.; Saudino, Kimberly J.

    2016-01-01

    Parent- and lab-based observer ratings were employed to examine genetic and environmental influences on continuity and change in inhibitory control (IC) in over 300 twin-pairs assessed longitudinally at 2 and 3 years of age. Genetic influences accounted for approximately 60% of the variance in parent-rated IC at both ages. Although many of the…

  7. Nature, Nurture and Academic Achievement: A Twin Study of Teacher Assessments of 7-year-olds

    ERIC Educational Resources Information Center

    Walker, Sheila O.; Petrill, Stephen A.; Spinath, Frank M.; Plomin, Robert

    2004-01-01

    Background: Twin research has consistently shown substantial genetic influence on individual differences in cognitive ability; however, much less is known about the genetic and environmental aetiologies of school achievement. Aims: Our goal is to test the hypotheses that teacher-assessed achievement in the early school years shows substantial…

  8. The Influence of Social Relations on Mortality in Later Life: A Study on Elderly Danish Twins

    ERIC Educational Resources Information Center

    Rasulo, Domenica; Christensen, Kaare; Tomassini, Cecilia

    2005-01-01

    Purpose: We examined whether the presence of a spouse and the frequency of interaction with children, relatives, and friends significantly influence the risk of dying in late life. We assessed these effects separately by gender, controlling for self-reported health. In addition, we examined whether interaction with the co-twin has a different…

  9. A Case Study of Phonological Development in Language Delayed Twins Not Enrolled in Therapy.

    ERIC Educational Resources Information Center

    Watson, Marie May; And Others

    1993-01-01

    This report documents phonological changes in a pair of identical twin boys diagnosed as language delayed. The boys were evaluated four times between the ages of three and four. Speech samples were analyzed for phonetic inventories, phonological process use, and syllabic shapes. Observed changes in their speech generally followed normal…

  10. Environmental and Genetic Influence on Dimensions of Perceived Parenting: A Twin Study.

    ERIC Educational Resources Information Center

    Rowe, David C.

    Determinants of Schaefer's (1965) three dimensions of perceived parenting (Acceptance vs. Rejection, Psychological Control vs. Psychological Autonomy, and Firm vs. Lax Control) were investigated by administering a shortened Children's Reports of Parental Behavior Inventory to adolescent twins. The sample consisted of 46 pairs of identical twins…

  11. Nonshared Environmental Influences on Individual Differences in Early Behavioral Development: A Monozygotic Twin Differences Study.

    ERIC Educational Resources Information Center

    Asbury, Kathryn; Dunn, Judith F.; Pike, Alison; Plomin, Robert

    2003-01-01

    Examined nonshared environmental (NSE) influences on twin preschoolers' behavior independent of genetics. Found that within-pair parenting differences correlated with monozygotic differences in behavior. For the extreme 10 percent of the parenting-discordant and behavior-discordant distributions, average NSE effect size was 11 percent, suggesting…

  12. A Monozygotic Twin Differences Study of Nonshared Environmental Influence on Adolescent Depressive Symptoms

    ERIC Educational Resources Information Center

    Liang, Holan; Eley, Thalia C.

    2005-01-01

    The monozygotic (MZ) twin differences method was used to examine nonshared environmental aspects of the association of parenting (punitive and constructive discipline), negative life events (independent and dependent), and peers (antisocial and prosocial) with adolescent depressive symptoms in terms of sequelae, risk, and maintaining factors. Two…

  13. Parent Interactions with Twins Who Are Developmentally Different: A Case Study

    ERIC Educational Resources Information Center

    Graham, Teresa K.; Scudder, Rosalind R.

    2007-01-01

    Language and social interactions were examined between a father and mother and their twin children, one with Down syndrome and one developing typically. Systematic observations were made of videotaped segments and coded in real time using a computerized behavior coding program. Codes for the parents' interactions consisted of total vocalizations,…

  14. Maternal Distancing Strategies toward Twin Sons, One with Mild Hearing Loss: A Case Study

    ERIC Educational Resources Information Center

    Munoz-Silva, Alicia; Sanchez-Garcia, Manuel

    2004-01-01

    The authors apply descriptive and sequential analyses to a mother's distancing strategies toward her 3-year-old twin sons in puzzle assembly and book reading tasks. One boy had normal hearing and the other a mild hearing loss (threshold: 30 dB). The results show that the mother used more distancing behaviors with the son with a hearing loss, and…

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

    PubMed

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

    2016-08-01

    Inefficient response to oxidative stress has been associated with ageing and health risk. Metals are known to inhibit DNA repair and may modify the antioxidant response. How genetic variability and lifestyle factors modulate the response to oxidative stress is poorly explored. Our study aims to disentangle the contribution of genetics and environmental exposures to oxidative stress response using data from twin pairs. The non-enzymatic antioxidant capacity (NEAC), the repair capacity of 8-oxo-7,8-dihydroguanine (OGG activity) and the levels of 12 metals were measured in blood of 64 monozygotic and 31 dizygotic twin pairs. The contributions of genetic and environmental effects were assessed using standard univariate twin modelling. NEAC and OGG activity significantly decreased with age. Gender-, age- and body mass index-associated differences were identified for some metals. Principal Component Analysis identified two groups of metals whose levels in blood were highly correlated: As, Hg, Pb, Se, Zn and Al, Co, Cr, Mn, Ni. The environmental influence was predominant on OGG activity and NEAC variance whereas for most metals the best-fitting model incorporated additive genetic and unique environmental sources of variance. NEAC and OGG activity were both inversely correlated with blood levels of various metals. The inhibition of OGG activity by Cd was largely explained by smoking. Our data show a substantial role of environmental factors in NEAC and OGG activity variance that is not explained by twins' age. Exogenous environmental factors such as metals contribute to oxidative stress by decreasing NEAC and inhibiting repair of oxidatively-induced DNA damage. PMID:27264237

  16. Twin and family studies reveal strong environmental and weaker genetic cues explaining heritability of eosinophilic esophagitis

    PubMed Central

    Alexander, Eileen S.; Martin, Lisa J.; Collins, Margaret H.; Kottyan, Leah; Sucharew, Heidi; He, Hua; Mukkada, Vincent A.; Succop, Paul A.; Abonia, J. Pablo; Foote, Heather; Eby, Michael D.; Grotjan, Tommie M.; Greenler, Alexandria J.; Dellon, Evan S.; Demain, Jeffrey G.; Furuta, Glenn T.; Gurian, Larry E.; Harley, John B.; Hopp, Russell J.; Kaul, Ajay; Nadeau, Kari C.; Noel, Richard J.; Putnam, Philip E.; von Tiehl, Karl F.; Rothenberg, Marc E.

    2014-01-01

    Background Eosinophilic esophagitis (EoE) is a chronic antigen-driven allergic inflammatory disease, likely involving the interplay of genetic and environmental factors, yet their respective contributions to heritability are unknown. Objective To quantify risk associated with genes and environment on familial clustering of EoE. Methods Family history was obtained from a hospital-based cohort of 914 EoE probands, (n=2192 first-degree “Nuclear-Family” relatives) and the new international registry of monozygotic and dizygotic twins/triplets (n=63 EoE “Twins” probands). Frequencies, recurrence risk ratios (RRRs), heritability and twin concordance were estimated. Environmental exposures were preliminarily examined. Results Analysis of the Nuclear-Family–based cohort revealed that the rate of EoE, in first-degree relatives of a proband, was 1.8% (unadjusted) and 2.3% (sex-adjusted). RRRs ranged from 10–64, depending on the family relationship, and were higher in brothers (64.0; p=0.04), fathers (42.9; p=0.004) and males (50.7; p<0.001) compared to sisters, mothers and females, respectively. Risk of EoE for other siblings was 2.4%. In the Nuclear-Families, combined gene and common environment heritability (hgc2) was 72.0±2.7% (p<0.001). In the Twins cohort, genetic heritability was 14.5±4.0% (p<0.001), and common family environment contributed 81.0±4% (p<0.001) to phenotypic variance. Proband-wise concordance in MZ co-twins was 57.9±9.5% compared to 36.4±9.3% in DZ (p=0.11). Greater birth-weight difference between twins (p=0.01), breastfeeding (p=0.15) and Fall birth season (p=0.02) were associated with twin discordance in disease status. Conclusions EoE recurrence risk ratios are increased 10–64-fold compared with the general population. EoE in relatives is 1.8–2.4%, depending upon relationship and sex. Nuclear-Family heritability appeared to be high (72.0%). However, Twins cohort analysis revealed a powerful role for common environment (81

  17. Dentoskeletal effects of Class II malocclusion treatment with the Twin Block appliance in a Brazilian sample: A prospective study

    PubMed Central

    Saikoski, Luciano Zilio; Cançado, Rodrigo Hermont; Valarelli, Fabrício Pinelli; de Freitas, Karina Maria Salvatore

    2014-01-01

    Objective The aim of this study was to assess the dentoskeletal effects of Class II malocclusion treatment performed with the Twin Block appliance. Methods The experimental group comprised 20 individuals with initial mean age of 11.76 years and was treated for a period of 1.13 years. The control group comprised 25 individuals with initial mean age of 11.39 years and a follow-up period of 1.07 years. Lateral cephalograms were taken at treatment onset and completion to assess treatment outcomes. Intergroup comparison was performed by means of the chi-square and independent t tests. Results The Twin Block appliance did not show significant effects on the maxillary component. The mandibular component showed a statistically significant increase in the effective mandibular length (Co-Gn) and significant improvement in the maxillomandibular relationship. The maxillary and mandibular dentoalveolar components presented a significant inclination of anterior teeth in both arches. The maxillary incisors were lingually tipped and retruded, while the mandibular incisors were labially tipped and protruded. Conclusions The Twin Block appliance has great effectiveness for correction of skeletal Class II malocclusion in individuals with growth potential. Most changes are of dentoalveolar nature with a large component of tooth inclination associated with a significant skeletal effect on the mandible. PMID:24713558

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

    PubMed Central

    Pedersen, Nancy L.

    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. PMID:25544932

  19. Physical activity and risk for breast cancer a prospective cohort study among Swedish twins.

    PubMed

    Moradi, Tahereh; Adami, Hans-Olov; Ekbom, Anders; Wedrén, Sara; Terry, Paul; Floderus, Birgitta; Lichtenstein, Paul

    2002-07-01

    The epidemiologic association between physical activity and breast cancer has been corroborated in many studies. Some inconsistencies remain, possibly due to variation in life periods for exposure assessment, confounding and undetected effect modification. In our cohort study, we address some of these questions by taking into account physical activity in different periods of life and by investigating effect modification by birth cohort and body mass index (BMI). Altogether 9,539 same-sex twin women aged 42-70 years who answered a questionnaire about their work and leisure-time physical exercise from ages 25 to 50 during 1967 and 1970 were included in our cohort. During follow-up, 506 breast cancer cases occurred through 1997. We used multivariate Cox models to estimate relative risk (RR) with 95% confidence interval (CI). We found no associations between physical activity and breast cancer overall. Women born between 1901 and 1917 (aged 51-70 at baseline) who reported regular leisure-time activity had a borderline significant 40% lower risk compared with those who reported no activity (RR 0.6; 95% CI 0.4-1.0; test for trend, p = 0.07). This association appeared to be confined to women with a low BMI after the age of 50 and to women with a high BMI during the premenopausal period. We found no evidence that work activity reduces risk for breast cancer. The importance of physical activity for breast cancer risk seems to depend on birth cohort. The association may be limited to normal-weight postmenopausal women and overweight premenopausal women. PMID:12115590

  20. Environmental geophysics and sequential air photo study at Sunfish Lake Twin Cities Army Ammunition Plant

    SciTech Connect

    Padar, C.A.; McGinnis, L.D.; Thompson, M.D.; Anderson, A.W.

    1996-11-01

    Geophysical and air photo studies at the Twin Cities Army Ammunition Plant (TCAAP), Minnesota, were conducted to establish a chronology of dumping and waste disposal. This study was undertaken to aid in the assessment of the amount of remediation needed to reclaim a wetland area. An integrated analysis of electromagnetic, magnetic and ground-penetrating RADAR (GPR) measurements over a 25-acre site, provided the information necessary to define waste disposal events. These events are observed on a sequence of aerial photos taken between 1940 and 1993. The former southwestern embayment of the lake, filled in during the original construction of the base, has been clearly defined. Two burn cages and their surrounding debris have been delineated. The areal extent of another waste site has been defined along the northern shoreline. Depth estimates determined from EM-61 analysis, and depths to original lake bottom, derived from GPR, have yielded volumetric estimates of the amount of material that would need removal if excavation is required. Magnetic and electromagnetic data have pinpointed the locations of mounds, observed from historical air photos. Except for these areas along the Northwestern shore, there is no evidence of waste disposal along the shoreline or within the present-day lake margins. The ability to date the anomalous regions is significant, in that different production demands upon TCAAP, during the time periods of WWII, The Korean War, and The Vietnam Conflict, have resulted in different types of waste. The ability to categorize areas with distinct time periods of operation and waste disposal can greatly aid the environmental cleanup effort with regard to the type of contaminants that might be expected at these poorly documented disposal sites.

  1. Heredity-Environment Influences on Growth and Development During Adolescence. A Longitudinal Study of Twins. Studies in Education and Psychology 4.

    ERIC Educational Resources Information Center

    Fischbein, Siv

    A summary and discussion of a series of studies considered the dilemma that equal educational treatment of all children in public schools appears likely to increase the spread of differences among them in educational achievement. Longitudinal studies of pairs of identical and of fraternal twins in Sweden from 10 to 18 years of age considered the…

  2. Similarity of Monozygotic and Dizygotic Twins in Level and Lability of Subclinically Depressed Mood.

    ERIC Educational Resources Information Center

    Wierzbicki, Michael

    1986-01-01

    Ninety-two adult twin-pairs were recruited. Twin zygosity was determined by self-report inventory. Monozygotic twins resembled one another more than dizygotic twins in most measures of both level and lability of mood, which provides modest evidence for a genetic influence on subclinical levels of depression. (Author/ABB)

  3. The Influence of Chorion Type on Health Measures at Birth and Dental Development in Australian and Dutch Twins: A Comparative Study.

    PubMed

    Mihailidis, Suzanna; Bockmann, Michelle; McConnell, Elise; Hughes, Toby; van Beijsterveldt, Toos C E M; Boomsma, Dorret I; McMaster, Minni; Townsend, Grant

    2015-08-01

    Chorion type may significantly influence the prenatal environment of twins. This study explored the associations between chorion type and gestational age, birth weight, birth length, and the timing of emergence of the first primary tooth in two populations of twins, Australian and Dutch. Additionally, we investigated the relationship between chorion type and birth weight discordance (BWD) in order to determine whether a significant relationship existed between discordance in birth weight and discordance in the timing of emergence of the first primary tooth. The two study samples consisted of 409 Australian twin pairs and 301 Dutch twin pairs, all of European ancestry. Data were collected through a combination of questionnaires and recording charts administered to the parents and through linkage with biological databases. In the Australian sample, monozygotic monochorionic (MZMC) twins experienced the shortest mean gestation time (35 weeks), the lowest mean birth length (46 cm) and the lowest mean birth weight (2.3 kg) compared with other twin groups. For the same variables in the Dutch sample, these trends with MZMC twinning were not observed. Chorion type did not significantly affect the mean timing of emergence of the first primary tooth in either sample. Monochorionicity was found to be significantly associated with BWD in both samples, but there was a significant association between BWD in MZMC twin pairs and timing of emergence of the first primary tooth only in the Australian sample. Results from this study support previous findings that the timing of emergence of the first primary tooth is influenced strongly by genetic factors and is well protected from environmental disturbances. PMID:26227835

  4. Investigations on the mechanical behavior of nanowires with twin boundaries by atomistic simulations

    SciTech Connect

    Tian, Xia

    2015-03-10

    Atomistic simulations are used to study the deformation behavior of twinned Cu nanowires with a <111> growth orientation under tension. Due to the existence of the twin boundaries, the strength of the twinned nanowires is higher than that of the twin-free nanowire and the yielding stress of twinned nanowires is inversely proportional to the spacings of the twin boundaries. Moreover, The ductility of the twin-free nanowire is the highest of all and it grows with the increasing spacings of the twin boundaries for twinned nanowires. Besides, we find that the twin boundaries can be served as dislocation sources as well as the free surfaces and grain boundaries.

  5. Comparative Study on Statistical-Variation Tolerance Between Complementary Crossbar and Twin Crossbar of Binary Nano-scale Memristors for Pattern Recognition.

    PubMed

    Truong, Son Ngoc; Shin, SangHak; Byeon, Sang-Don; Song, JaeSang; Mo, Hyun-Sun; Min, Kyeong-Sik

    2015-12-01

    This paper performs a comparative study on the statistical-variation tolerance between two crossbar architectures which are the complementary and twin architectures. In this comparative study, 10 greyscale images and 26 black-and-white alphabet characters are tested using the circuit simulator to compare the recognition rate with varying statistical variation and correlation parameters.As with the simulation results of 10 greyscale image recognitions, the twin crossbar shows better recognition rate by 4 % on average than the complementary one, when the inter-array correlation = 1 and intra-array correlation = 0. When the inter-array correlation = 1 and intra-array correlation = 1, the twin architecture can recognize better by 5.6 % on average than the complementary one.Similarly, when the inter-array correlation = 1 and intra-array correlation = 0, the twin architecture can recognize 26 alphabet characters better by 4.5 % on average than the complementary one. When the inter-array correlation = 1 and intra-array correlation = 1, the twin architecture is better by 6 % on average than the complementary one. By summary, we can conclude that the twin crossbar is more robust than the complementary one under the same amounts of statistical variation and correlation. PMID:26474886

  6. Genetic and Environmental Contributions to Behavioral Stability and Change in Children 6-36 months of Age Using Louisville Twin Study Data.

    PubMed

    Davis, Deborah Winders; Finkel, Deborah; Turkheimer, Eric; Dickens, William

    2015-11-01

    The Infant Behavior Record (IBR) from the Bayley Scales of Infant Development has been used to study behavioral development since the 1960s. Matheny (1983) examined behavioral development at 6, 12, 18, and 24 months from the Louisville Twin Study (LTS). The extracted temperament scales included Task Orientation, Affect-Extraversion, and Activity. He concluded that monozygotic twins were more similar than same-sex dizygotic twins on these dimensions. Since this seminal work was published, a larger LTS sample and more advanced analytical methods are available. In the current analyses, Choleksy decomposition was applied to behavioral data (n = 1231) from twins 6-36 months. Different patterns of genetic continuity vs genetic innovations were identified for each IBR scale. Single common genetic and shared environmental factors explained cross-age twin similarity in the Activity scale. Multiple shared environmental factors and a single genetic factor coming on line at age 18 months contributed to Affect-Extraversion. A single shared environmental factor and multiple genetic factors explained cross-age twin similarity in Task Orientation. PMID:26477572

  7. Alternative techniques in trochanteric hip fracture surgery. Clinical and biomechanical studies on the Medoff sliding plate and the Twin hook.

    PubMed

    Olsson, O

    2000-10-01

    In allowing compression along the femoral shaft (uniaxial dynamization) and optional compression along the femoral neck (biaxial dynamization), the Medoff sliding plate (MSP) represents a new principle in the fixation of trochanteric hip fractures. The Twin hook with 2 apical hooks was designed as an alternative to the lag screw. In 3 prospective consecutive case series and 1 prospective randomized study together comprising 342 trochanteric fractures, these alternative techniques were investigated. 3 postoperative fixation failures occurred in the unstable intertrochanteric fractures treated with biaxial dynamization with the MSP (n = 194), and 5 in those treated with the sliding hip screw (n = 62) (p = 0.04). A mean femoral shortening of 15 mm with the MSP and 11 mm with the sliding hip screw was found (p = 0.03). More medialization of the femoral shaft occurred with the sliding hip screw (26%) than with the MSP (12%) in patients with marked femoral shortening (p = 0.03). 3 postoperative fixation failures occurred in subtrochanteric fractures treated with uniaxial dynamization (n = 29) and 2 in those treated with biaxial dynamization (n = 19). Medialization of the femoral shaft occurred in 9 of the 19 biaxially dynamized fractures. The Twin hook was used in 50 patients and appeared to provide similar fixation stability as the lag screw. Biomechanical tests confirmed improved stress transmission over the fracture area with the MSP compared to the sliding hip screw in intertrochanteric fractures, and similar fixation stability with the MSP and the Intramedullary Hip Screw in subtrochanteric fractures. In axial and torsional loading, the Twin hook demonstrated gradually increasing resistance to migration. With the lag screw, the peak load was higher, but after migration with failure of the support by the threads, the loads were similar. Biaxial dynamization with the MSP appears to control fracture impaction effectively and minimizes the rate of postoperative fixation

  8. The genetic and environmental foundations of political, psychological, social, and economic behaviors: a panel study of twins and families.

    PubMed

    Hatemi, Peter K; Smith, Kevin; Alford, John R; Martin, Nicholas G; Hibbing, John R

    2015-06-01

    Here we introduce the Genetic and Environmental Foundations of Political and Economic Behaviors: A Panel Study of Twins and Families (PIs Alford, Hatemi, Hibbing, Martin, and Smith). This study was designed to explore the genetic and environmental influences on social, economic, and political behaviors and attitudes. It involves identifying the psychological mechanisms that operate on these traits, the heritability of complex economic and political traits under varying conditions, and specific genetic correlates of attitudes and behaviors. In addition to describing the study, we conduct novel analyses on the data, estimating the heritability of two traits so far unexplored in the extant literature: Machiavellianism and Baron-Cohen's Empathizing Quotient. PMID:25994545

  9. Monozygotic twin sisters discordant for familial hemiplegic migraine

    PubMed Central

    2013-01-01

    Background The high concordance rate of migraine in monozygotic twin pairs has long been recognised. In the current study, we present a monozygotic twin pair discordant for familial hemiplegic migraine (FHM). Case presentations We evaluated 12 adult family members in 2012. The twin pair was separately examined by neurologists at different time points. Mutation screening was performed for known FHM-related genes. The monozygosity of the twins was verified. Eleven individuals had a history of migraine or paroxysmal neurological symptoms, including four patients with motor aura. No mutations were detected in the CACNA1A, ATP1A2, SCN1A, PRRT2 or NOTCH3 genes. The monozygotic twin sisters, aged 52, were discordant for age of onset, motor aura and neuropsychological aura (forced thinking). Overall, the family members presented a wide range of phenotypical features. Conclusions Familial hemiplegic migraine is a monogenic disorder that is distinct from migraine with typical aura. However, in certain families with motor aura, such as this one, it is possible that the most severe phenotype is caused by an unlikely combination of polygenic traits and non-genetic factors. In these kindreds, we propose that hemiplegic aura is only a severe and complex form of typical aura. PMID:24041236

  10. Twinning of dodecanedicarboxylic acid

    NASA Technical Reports Server (NTRS)

    Sen, R.; Wilcox, W. R.

    1986-01-01

    Twinning of 1,10-dodecanedicarboxyl acid (DDA) was observed in 0.1 mm thick films with a polarizing microscope. Twins originated from polycrystalline regions which tended to nucleate on twin faces, and terminated by intersection gone another. Twinning increased dramatically with addition of organic compounds with a similar molecular size and shape. Increasing the freezing rate, increasing the temperature gradient, and addition of silica particles increased twinning. It is proposed that twins nucleate with polycrystals and sometimes anneal out before they become observable. The impurities may enhance twinning either by lowering the twin energy or by adsorbing on growing faces.

  11. Childhood EEG frontal alpha power as a predictor of adolescent antisocial behavior: A twin heritability study

    PubMed Central

    Niv, Sharon; Ashrafulla, Syed; Tuvblad, Catherine; Joshi, Anand; Raine, Adrian; Leahy, Richard; Baker, Laura A.

    2015-01-01

    High EEG frontal alpha power (FAP) is thought to represent a state of low arousal in the brain, which has been related in past research to antisocial behavior (ASB). We investigated a longitudinal sample of 900 twins in two assessments in late childhood and mid-adolescence to verify whether relationships exist between FAP and both aggressive and nonaggressive ASB. ASB was measured by the Child Behavioral Checklist, and FAP was calculated using connectivity analysis methods that used principal components analysis to derive power of the most dominant frontal activation. Significant positive predictive relationships emerged in males between childhood FAP and adolescent aggressive ASB using multilevel mixed modeling. No concurrent relationships were found. Using bivariate biometric twin modeling analysis, the relationship between childhood FAP and adolescent aggressive ASB in males was found to be entirely due to genetic factors, which were correlated r = 0.22. PMID:25456277

  12. Chronic Fatigue and Personality: A Twin Study of Causal Pathways and Shared Liabilities

    PubMed Central

    Poeschla, Brian; Strachan, Eric; Dansie, Elizabeth; Buchwald, Dedra S.; Afari, Niloofar

    2013-01-01

    Background The etiology of chronic fatigue syndrome (CFS) remains unknown. Personality traits influence well-being and may play a role in CFS and unexplained chronic fatigue. Purpose To examine the association of emotional instability and extraversion with chronic fatigue and CFS in a genetically informative sample. Methods We evaluated 245 twin pairs for two definitions of chronic fatigue. They completed the Neuroticism and Extraversion subscales of the NEO-FFI. Using a co-twin control design, we examined the association between personality and chronic fatigue. Results Higher emotional instability was associated with both definitions of chronic fatigue and was confounded by shared genetics. Lower extraversion was also associated with both definitions of fatigue, but was not confounded by familial factors. Conclusions Both emotional instability and extraversion are related to chronic fatigue and CFS. Whereas emotional instability and chronic fatigue are linked by shared genetic mechanisms, the relationship with extraversion may be causal and bi-directional. PMID:23361410

  13. Examining electrodermal hyporeactivity as a marker of externalizing psychopathology: a twin study.

    PubMed

    Isen, Joshua D; Iacono, William G; Malone, Stephen M; McGue, Matt

    2012-08-01

    Literature suggests that reduced electrodermal reactivity (EDR) is related to externalizing problems. However, the genetic and environmental etiology of this association is unknown. Using a standard habituation paradigm, we measured responses to 15 loud tones in four cohorts of adolescent twins (N = 2,129). We quantified EDR as the average size of elicited responses (amplitude) and by counting the number of skin conductance responses (frequency). Externalizing liability was indexed through a general factor underlying substance-related problems and antisocial behavior. Response frequency, but not mean amplitude, was inversely associated with externalizing liability in each twin cohort. Biometric modeling revealed that most of the overlap between response frequency and externalizing liability was due to genetic influences common to both phenotypes. It is argued that neurological mechanisms involved in habituation may shed light on the etiology of psychopathology. PMID:22646690

  14. Two by two: a twin study of second-language acquisition.

    PubMed

    Dale, Philip S; Harlaar, Nicole; Haworth, Claire M A; Plomin, Robert

    2010-05-01

    In this report, we provide initial results of the first application of the classic twin design to second-language acquisition. The analysis was conducted on assessments teachers made using United Kingdom National Curriculum standards and included 604 pairs of 14-year-old twins. The results demonstrate substantial heritability (.67) and low influence of shared environment (.13) on this measure of second-language acquisition. The heritability of second-language acquisition at 14 years is comparable to the heritability of the two first-language acquisition measures obtained at 12 and 14 years, respectively, and is higher than heritability estimates previously published for first-language acquisition in early childhood. Multivariate behavior genetic analyses suggest very high, but not complete, overlap of genetic influences on first- and second-language acquisition, and less overlap between shared environmental influences on the two domains. PMID:20483839

  15. Childhood EEG frontal alpha power as a predictor of adolescent antisocial behavior: a twin heritability study.

    PubMed

    Niv, Sharon; Ashrafulla, Syed; Tuvblad, Catherine; Joshi, Anand; Raine, Adrian; Leahy, Richard; Baker, Laura A

    2015-02-01

    High EEG frontal alpha power (FAP) is thought to represent a state of low arousal in the brain, which has been related in past research to antisocial behavior (ASB). We investigated a longitudinal sample of 900 twins in two assessments in late childhood and mid-adolescence to verify whether relationships exist between FAP and both aggressive and nonaggressive ASB. ASB was measured by the Child Behavioral Checklist, and FAP was calculated using connectivity analysis methods that used principal components analysis to derive power of the most dominant frontal activation. Significant positive predictive relationships emerged in males between childhood FAP and adolescent aggressive ASB using multilevel mixed modeling. No concurrent relationships were found. Using bivariate biometric twin modeling analysis, the relationship between childhood FAP and adolescent aggressive ASB in males was found to be entirely due to genetic factors, which were correlated r=0.22. PMID:25456277

  16. Ontogenetic de novo copy number variations (CNVs) as a source of genetic individuality: studies on two families with MZD twins for schizophrenia.

    PubMed

    Maiti, Sujit; Kumar, Kiran Halagur Bhoge Gowda; Castellani, Christina A; O'Reilly, Richard; Singh, Shiva M

    2011-01-01

    Genetic individuality is the foundation of personalized medicine, yet its determinants are currently poorly understood. One issue is the difference between monozygotic twins that are assumed identical and have been extensively used in genetic studies for decades. Here, we report genome-wide alterations in two nuclear families each with a pair of monozygotic twins discordant for schizophrenia evaluated by the Affymetrix 6.0 human SNP array. The data analysis includes characterization of copy number variations (CNVs) and single nucleotide polymorphism (SNPs). The results have identified genomic differences between twin pairs and a set of new provisional schizophrenia genes. Samples were found to have between 35 and 65 CNVs per individual. The majority of CNVs (~80%) represented gains. In addition, ~10% of the CNVs were de novo (not present in parents), of these, 30% arose during parental meiosis and 70% arose during developmental mitosis. We also observed SNPs in the twins that were absent from both parents. These constituted 0.12% of all SNPs seen in the twins. In 65% of cases these SNPs arose during meiosis compared to 35% during mitosis. The developmental mitotic origin of most CNVs that may lead to MZ twin discordance may also cause tissue differences within individuals during a single pregnancy and generate a high frequency of mosaics in the population. The results argue for enduring genome-wide changes during cellular transmission, often ignored in most genetic analyses. PMID:21399695

  17. Genetic Influences on Resting-state Functional Networks: A Twin Study

    PubMed Central

    Fu, Yixiao; Ma, Zhiwei; Hamilton, Christina; Liang, Zhifeng; Hou, Xiao; Ma, Xingshun; Hu, Xiaomei; He, Qian; Deng, Wei; Wang, Yingcheng; Zhao, Liansheng; Meng, Huaqing; Li, Tao; Zhang, Nanyin

    2015-01-01

    Alterations in resting-state networks (RSNs) are often associated with psychiatric and neurologic disorders. Given this critical linkage, it has been hypothesized that RSNs can potentially be used as endophenotypes for brain diseases. To validate this notion, a critical step is to show that RSNs exhibit heritability. However, the investigation of the genetic basis of RSNs has only been attempted in the default-mode network at the region-of-interest level, while the genetic control on other RSNs has not been determined yet. Here we examined the genetic and environmental influences on eight well-characterized RSNs by using a twin design. Resting-state functional magnetic resonance imaging data in 56 pairs of twins were collected. The genetic and environmental effects on each RSN were estimated by fitting the functional connectivity covariance of each voxel in the RSN to the classic ACE twin model. The data showed that although environmental effects accounted for the majority of variance in widespread areas, there were specific brain sites that showed significant genetic control for individual RSNs. These results suggest that part of the human brain functional connectome is shaped by genomic constraints. Importantly, this information can be useful for bridging genetic analysis and network-level assessment of brain disorders. PMID:26147340

  18. Mental representations of attachment in identical female twins with and without conduct problems.

    PubMed

    Constantino, John N; Chackes, Laura M; Wartner, Ulrike G; Gross, Maggie; Brophy, Susan L; Vitale, Josie; Heath, Andrew C

    2006-01-01

    Insecure mental representations of attachment, a nearly invariant feature of cluster B personality disorders, have never previously been studied in twins. We conducted the Adult Attachment Interview (AAI) on 33 pairs of monozygotic (MZ) female twins reared together as an initial exploration of causal influences on mental representations of attachment. As predicted by attachment theory, we observed substantial twin-twin concordance for attachment security (odds ratio 13.8; P = 0.001), a similar level of concordance between twins and their non-twin siblings, and an inverse relationship between attachment security and current level of aggression (P = 0.01). These data indicate that there are minimal effects of non-shared environmental influences (or measurement error) on attachment classifications derived from the AAI. In this sample of twins with and without histories of Conduct Disorder, mental representations of attachment appear to be highly familial, i.e., strongly influenced by either shared environmental factors, genetic factors, or both. PMID:16804751

  19. Twin Higgs Asymmetric Dark Matter.

    PubMed

    García García, Isabel; Lasenby, Robert; March-Russell, John

    2015-09-18

    We study asymmetric dark matter (ADM) in the context of the minimal (fraternal) twin Higgs solution to the little hierarchy problem, with a twin sector with gauged SU(3)^{'}×SU(2)^{'}, a twin Higgs doublet, and only third-generation twin fermions. Naturalness requires the QCD^{'} scale Λ_{QCD}^{'}≃0.5-20  GeV, and that t^{'} is heavy. We focus on the light b^{'} quark regime, m_{b^{'}}≲Λ_{QCD}^{'}, where QCD^{'} is characterized by a single scale Λ_{QCD}^{'} with no light pions. A twin baryon number asymmetry leads to a successful dark matter (DM) candidate: the spin-3/2 twin baryon, Δ^{'}∼b^{'}b^{'}b^{'}, with a dynamically determined mass (∼5Λ_{QCD}^{'}) in the preferred range for the DM-to-baryon ratio Ω_{DM}/Ω_{baryon}≃5. Gauging the U(1)^{'} group leads to twin atoms (Δ^{'}-τ^{'}[over ¯] bound states) that are successful ADM candidates in significant regions of parameter space, sometimes with observable changes to DM halo properties. Direct detection signatures satisfy current bounds, at times modified by dark form factors. PMID:26430985

  20. Mechanism of slip and twinning

    NASA Technical Reports Server (NTRS)

    Rastani, Mansur

    1992-01-01

    The objectives are to: (1) demonstrate the mechanisms of deformation in body centered cubic (BCC), face centered cubic (FCC), and hexagonal close-packed (HCP)-structure metals and alloys and in some ceramics as well; (2) examine the deformed microstructures (slip lines and twin boundaries) in different grains of metallic and ceramic specimens; and (3) study visually the deformed macrostructure (slip and twin bands) of metals and alloys. Some of the topics covered include: deformation behavior of materials, mechanisms of plastic deformation, slip bands, twin bands, ductile failure, intergranular fracture, shear failure, slip planes, crystal deformation, and dislocations in ceramics.

  1. Physically active vs. inactive lifestyle, muscle properties, and glucose homeostasis in middle-aged and older twins.

    PubMed

    Leskinen, T; Sipilä, S; Kaprio, J; Kainulainen, H; Alen, M; Kujala, U M

    2013-10-01

    Exercise-induced positive changes in skeletal muscle properties and metabolism decrease the risk for disability, cardiometabolic diseases and mortality. Here, we studied muscle properties and glucose homeostasis in a non-exercise stage in twin pairs with co-twins discordant for physical activity habits for at least 32 years of their adult lives. Isometric knee extension force, MR imaging of midthigh tissue composition and muscle volume, and fasting blood samples were acquired from 16 same-sex (seven monozygotic, nine dizygotic) middle-aged and older twin pairs. The consistently active twins had 20 % higher knee extension forces than their inactive co-twins (p = 0.006) although the active twins had only 4 % higher midthigh muscle cross-sectional areas (p = 0.072). These results were similar in intrapair analysis in which only the seven identical twin pairs were included. The ratio between the area of midthigh fat and muscle tissues was significantly lower among the active twins (0.65 vs. 0.48, p = 0.006). The active twins had also lower fasting plasma glucose levels (5.1 vs 5.6 mmol/l, p = 0.041). The area of midthigh intramuscular (extramyocellular) fat was associated with the markers of glucose homeostasis, especially with glycated hemoglobin, and these associations were emphasized by the diabetic and inactive twins. Regular exercise throughout the adult life retains muscle strength and quality but not necessarily mass. The regular use of muscles also prevents from the accumulation of intramuscular fat which might be related to maintained glucose metabolism and, thus, prevention of metabolic disorders. PMID:23124702

  2. Conceptual and Data-based Investigation of Genetic Influences and Brain Asymmetry: A Twin Study of Multiple Structural Phenotypes

    PubMed Central

    Eyler, Lisa T.; Vuoksimaa, Eero; Panizzon, Matthew S.; Fennema-Notestine, Christine; Neale, Michael C.; Chen, Chi-Hua; Jak, Amy; Franz, Carol E.; Lyons, Michael J.; Thompson, Wesley K.; Spoon, Kelly M.; Fischl, Bruce; Dale, Anders M.; Kremen, William S.

    2014-01-01

    Right–left regional cerebral differences are a feature of the human brain linked to functional abilities, aging, and neuro-developmental and mental disorders. The role of genetic factors in structural asymmetry has been incompletely studied. We analyzed data from 515 individuals (130 monozygotic twin pairs, 97 dizygotic pairs, and 61 unpaired twins) from the Vietnam Era Twin Study of Aging to answer three questions about genetic determinants of brain structural asymmetry: First, does the magnitude of heritability differ for homologous regions in each hemisphere? Despite adequate power to detect regional differences, heritability estimates were not significantly larger in one hemisphere versus the other, except left > right inferior lateral ventricle heritability. Second, do different genetic factors influence left and right hemisphere size in homologous regions? Inter-hemispheric genetic correlations were high and significant; in only two subcortical regions (pallidum and accumbens) did the estimate statistically differ from 1.0. Thus, there was little evidence for different genetic influences on left and right hemisphere regions. Third, to what extent do genetic factors influence variability in left–right size differences? There was no evidence that variation in asymmetry (i.e., the size difference) of left and right homologous regions was genetically determined, except in pallidum and accumbens. Our findings suggest that genetic factors do not play a significant role in determining individual variation in the degree of regional cortical size asymmetries measured with MRI, although they may do so for volume of some subcortical structures. Despite varying interpretations of existing left–right, we view the present results as consistent with previous findings. PMID:24283492

  3. Adult Basic Education Follow-Up Study.

    ERIC Educational Resources Information Center

    Fallon, Ruth

    The Gateway Technical Institute's followup study on former adult basic education (ABE) students is examined in this report, which focuses primarily on the process of the study. Since the Gateway study complemented objective measures of program effectiveness with a perspective that is often missing in program evaluations, namely, former…

  4. Cancer and Longevity—Is There a Trade-off? A Study of Cooccurrence in Danish Twin Pairs Born 1900–1918

    PubMed Central

    Pedersen, Jacob K.; Hjelmborg, Jacob v. B.; Vaupel, James W.; Stevnsner, Tinna; Holm, Niels V.; Skytthe, Axel

    2012-01-01

    Background. Animal models and a few human studies have suggested a complex interaction between cancer risk and longevity indicating a trade-off where low cancer risk is associated with accelerating aging phenotypes and, vice versa, that longevity potential comes with the cost of increased cancer risk. This hypothesis predicts that longevity in one twin is associated with increased cancer risk in the cotwin. Methods. A total of 4,354 twin pairs born 1900–1918 in Denmark were followed for mortality in the Danish Civil Registration System through 2008 and for cancer incidence in the period 1943–2008 through the Danish Cancer Registry. Results. The 8,139 twins who provided risk time for cancer occurrence entered the study between ages 24 and 43 (mean 33 years), and each participant was followed up to death, emigration, or at least 90 years of age. The total follow-up time was 353,410 person-years and, 2,524 cancers were diagnosed. A negative association between age at death of a twin and cancer incidence in the cotwin was found in the overall analyses as well as in the subanalysis stratified on sex, zygosity, and random selection of one twin from each twin pair. Conclusions. This study did not find evidence of a cancer–longevity trade-off in humans. On the contrary, it suggested that longevity in one twin is associated with lower cancer incidence in the cotwin, indicating familial factors associated with both low cancer occurrence and longevity. PMID:22472962

  5. Infant twins' social interactions with caregivers and same-age siblings.

    PubMed

    Aldrich, Naomi J; Brooks, Patricia J; Yuksel-Sokmen, P Ozlem; Ragir, Sonia; Flory, Michael J; Lennon, Elizabeth M; Karmel, Bernard Z; Gardner, Judith M

    2015-11-01

    The study of twin behavior offers the opportunity to study differential patterns of social and communicative interactions in a context where the adult partner and same-age peer are equally familiar. We investigated the development of social engagement, communicative gestures, and imitation in 7- to 25-month-old twins. Twin dyads (N=20 pairs) participated in 10-min, semi-structured play sessions, with the mother seated in a chair completing paperwork for half the session, and on the floor with her children for the other half. Overall, twins engaged more with their mothers than with their siblings: they showed objects and imitated speech and object use more frequently when interacting with their mothers than with their siblings. When the mother was otherwise engaged, the twins played with toys separately, observed each other's toy play, or were unengaged. These results demonstrate that adult scaffolding of social interactions supports increased communicative bids even in a context where both familiar peers and adults are available as communicative partners. PMID:26476957

  6. Subclinical eating disorder, polycystic ovary syndrome- is there any connection between these two conditions through leptin- a twin study.

    PubMed

    Jahanfar, Sh; Maleki, H; Mosavi, A R

    2005-10-01

    The genetic property of subclinical eating behaviour (SEB) and the link between SEB and polycystic ovary syndrome (PCOS) has been studied before but the role of leptin within this connection has never been investigated. The objective of this study was 1). to study the genetic property of SEB. 2). To find a link between leptin, SEB and PCOS. One hundred and fifty four (77 pairs) female-female Iranian twins including 96 MZ individuals (48 pairs) and 58 DZ individuals (29 pairs) participated in the study. Clinical, biochemical and ultrasound tools were used to diagnose polycystic ovary syndrome. BITE questionnaire was filled out for subjects. Eight percent of subjects were diagnosed for subclinical eating disorder. No significant difference was found between intraclass correlation of MZ and DZ (z = 0.57, P = 0.569). Serum leptin level correlated significantly with bulimia score (P < 0.007). The mean (+/-SD) value for bulimia score was found to be higher among PCOS(positive) subjects (3.27 +/- 5.51) in comparison with PCOS(negative) subjects (2.06 +/- 4.48) (P < 0.001). The genetic property of subclinical eating disorder was not confirmed as shared environment might have played a major role in likeliness of DZ twins as well as MZ. Leptin is linked with both subclinical eating disorder and PCOS. PMID:16570705

  7. Etiological overlap between obsessive-compulsive disorder and anorexia nervosa: a longitudinal cohort, multigenerational family and twin study

    PubMed Central

    Cederlöf, Martin; Thornton, Laura M; Baker, Jessica; Lichtenstein, Paul; Larsson, Henrik; Rück, Christian; Bulik, Cynthia M; Mataix-Cols, David

    2015-01-01

    Obsessive-compulsive disorder (OCD) often co-occurs with anorexia nervosa (AN), a comorbid profile that complicates the clinical management of both conditions. This population-based study aimed to examine patterns of comorbidity, longitudinal risks, shared familial risks and shared genetic factors between OCD and AN at the population level. Participants were individuals with a diagnosis of OCD (N=19,814) or AN (N=8,462) in the Swedish National Patient Register between January 1992 and December 2009; their first-, second- and third-degree relatives; and population-matched (1:10 ratio) unaffected comparison individuals and their relatives. Female twins from the population-based Swedish Twin Register (N=8,550) were also included. Females with OCD had a 16-fold increased risk of having a comorbid diagnosis of AN, whereas males with OCD had a 37-fold increased risk. Longitudinal analyses showed that individuals first diagnosed with OCD had an increased risk for a later diagnosis of AN (risk ratio, RR=3.6), whereas individuals first diagnosed with AN had an even greater risk for a later diagnosis of OCD (RR=9.6). These longitudinal risks were about twice as high for males than for females. First- and second-degree relatives of probands with OCD had an increased risk for AN, and the magnitude of this risk tended to increase with the degree of genetic relatedness. Bivariate twin models revealed a moderate but significant degree of genetic overlap between self-reported OCD and AN diagnoses (ra=0.52, 95% CI: 0.26-0.81), but most of the genetic variance was disorder-specific. The moderately high genetic correlation supports the idea that this frequently observed comorbid pattern is at least in part due to shared genetic factors, though disorder-specific factors are more important. These results have implications for current gene-searching efforts and for clinical practice. PMID:26407789

  8. A study of the hot and cold deformation of twin-roll cast magnesium alloy AZ31

    NASA Astrophysics Data System (ADS)

    Askari, Hesam; Young, John; Field, David; Kridli, Ghassan; Li, Dongsheng; Zbib, Hussein

    2014-02-01

    Recent advances in twin-roll casting (TRC) technology of magnesium have demonstrated the feasibility of producing magnesium sheets in the range of widths needed for automotive applications. However, challenges in the areas of manufacturing, material processing and modelling need to be resolved in order to fully utilize magnesium alloys. Despite the limited formability of magnesium alloys at room temperature due to their hexagonal close-packed crystalline structure, studies have shown that the formability of magnesium alloys can be significantly improved by processing the material at elevated temperatures and by modifying their microstructure to increase ductility. Such improvements can potentially be achieved by processes such as superplastic forming along with manufacturing techniques such as TRC. In this work, we investigate the superplastic behaviour of twin-roll cast AZ31 through mechanical testing, microstructure characterization and computational modelling. Validated by the experimental results, a novel continuum dislocation dynamics-based constitutive model is developed and coupled with viscoplastic self-consistent model to simulate the deformation behaviour. The model integrates the main microstructural features such as dislocation densities, grain shape and grain orientations within a self-consistent viscoplasticity theory with internal variables. Simulations of the deformation process at room temperature show large activity of the basal and prismatic systems at the early stages of deformation and increasing activity of pyramidal systems due to twinning at the later stages. The predicted texture at room temperature is consistent with the experimental results. Using appropriate model parameters at high temperatures, the stress-strain relationship can be described accurately over the range of low strain rates.

  9. Etiological overlap between obsessive-compulsive disorder and anorexia nervosa: a longitudinal cohort, multigenerational family and twin study.

    PubMed

    Cederlöf, Martin; Thornton, Laura M; Baker, Jessica; Lichtenstein, Paul; Larsson, Henrik; Rück, Christian; Bulik, Cynthia M; Mataix-Cols, David

    2015-10-01

    Obsessive-compulsive disorder (OCD) often co-occurs with anorexia nervosa (AN), a comorbid profile that complicates the clinical management of both conditions. This population-based study aimed to examine patterns of comorbidity, longitudinal risks, shared familial risks and shared genetic factors between OCD and AN at the population level. Participants were individuals with a diagnosis of OCD (N=19,814) or AN (N=8,462) in the Swedish National Patient Register between January 1992 and December 2009; their first-, second- and third-degree relatives; and population-matched (1:10 ratio) unaffected comparison individuals and their relatives. Female twins from the population-based Swedish Twin Register (N=8,550) were also included. Females with OCD had a 16-fold increased risk of having a comorbid diagnosis of AN, whereas males with OCD had a 37-fold increased risk. Longitudinal analyses showed that individuals first diagnosed with OCD had an increased risk for a later diagnosis of AN (risk ratio, RR=3.6), whereas individuals first diagnosed with AN had an even greater risk for a later diagnosis of OCD (RR=9.6). These longitudinal risks were about twice as high for males than for females. First- and second-degree relatives of probands with OCD had an increased risk for AN, and the magnitude of this risk tended to increase with the degree of genetic relatedness. Bivariate twin models revealed a moderate but significant degree of genetic overlap between self-reported OCD and AN diagnoses (ra =0.52, 95% CI: 0.26-0.81), but most of the genetic variance was disorder-specific. The moderately high genetic correlation supports the idea that this frequently observed comorbid pattern is at least in part due to shared genetic factors, though disorder-specific factors are more important. These results have implications for current gene-searching efforts and for clinical practice. PMID:26407789

  10. Two consecutive singleton pregnancies versus one twins pregnancy as preferred outcome of in vitro fertilization for mothers and infants: a retrospective case-control study.

    PubMed

    La Sala, Giovanni Battista; Morini, Daria; Gizzo, Salvatore; Nicoli, Alessia; Palomba, Stefano

    2016-04-01

    Objective Many infertile couples request a multiple embryo transfer because they desire more than one child. Based on this consideration, the current study aimed to compare the reproductive and perinatal outcomes of two consecutive singleton pregnancies versus one twin pregnancy in a large cohort of in vitro fertilization (IVF) patients. Research design and methods Retrospective analysis of data from patients with clinical twin pregnancy after IVF fresh cycles and from patients with two consecutive IVF fresh cycles and clinical singleton pregnancy. Main outcome measures Miscarriage rate, delivery rate, gestational age at birth, neonatal birth weight, and perinatal complications. A sub-analysis of data according to vanishing twin syndrome (VTS) was also performed. Results A total of 18,703 autologous fresh cycles were analyzed. One hundred seven patients had two consecutive singleton clinical pregnancies, whereas one clinical twin pregnancy occurred in 641 women. In patients who had two consecutive singleton clinical pregnancies the rates of overall pregnancies lost (odds ratio [OR] 4.9, 95% confidence interval [CI] 3.4, 6.9) and live births (OR 0.2, 95% CI 0.1, 0.3) were, respectively, higher and lower when compared to patients who had one clinical twin pregnancy. That data did not change after sub-analysis for VTS. The overall risk of perinatal complications was significantly higher in patients who had one twin delivery rather than patients who had two consecutive singleton deliveries (OR 31.8, 95% CI 14.1, 71.5). No difference between groups was detected in terms of intrauterine/neonatal deaths, perinatal mortality and neonatal intensive care unit admission. Data did not change after adjusting for confounders. Conclusions When compared with two consecutive singleton pregnancies, twin pregnancies are characterized by higher success rates but worse perinatal outcomes irrespectively of VTS. Well designed prospective controlled studies are needed to confirm or rebut

  11. A study of genetic and environmental contributions to structural brain changes over time in twins concordant and discordant for bipolar disorder.

    PubMed

    Bootsman, F; Brouwer, R M; Schnack, H G; Kemner, S M; Hillegers, M H J; Sarkisyan, G; van der Schot, A C; Vonk, R; Hulshoff Pol, H E; Nolen, W A; Kahn, R S; van Haren, N E M

    2016-08-01

    This is the first longitudinal twin study examining genetic and environmental contributions to the association between liability to bipolar disorder (BD) and changes over time in global brain volumes, and global and regional measures of cortical surface area, cortical thickness and cortical volume. A total of 50 twins from pairs discordant or concordant for BD (monozygotic: 8 discordant and 3 concordant pairs, and 1 patient and 3 co-twins from incomplete pairs; dizygotic: 6 discordant and 2 concordant pairs, and 1 patient and 7 co-twins from incomplete pairs) underwent magnetic resonance imaging twice. In addition, 57 twins from healthy twin pairs (15 monozygotic and 10 dizygotic pairs, and 4 monozygotic and 3 dizygotic subjects from incomplete pairs) were also scanned twice. Mean follow-up duration for all twins was 7.5 years (standard deviation: 1.5 years). Data were analyzed using structural equation modeling software OpenMx. The liability to BD was not associated with global or regional structural brain changes over time. Although we observed a subtle increase in cerebral white matter in BD patients, this effect disappeared after correction for multiple comparisons. Heritability of brain changes over time was generally low to moderate. Structural brain changes appear to follow similar trajectories in BD patients and healthy controls. Existing brain abnormalities in BD do not appear to progressively change over time, but this requires additional confirmation. Further study with large cohorts is recommended to assess genetic and environmental influences on structural brain abnormalities in BD, while taking into account the influence of lithium on the brain. PMID:27218817

  12. Association Between Ideal Cardiovascular Health and Carotid Intima‐Media Thickness: A Twin Study

    PubMed Central

    Kulshreshtha, Ambar; Goyal, Abhinav; Veledar, Emir; McClellan, William; Judd, Suzanne; Eufinger, Silvia C.; Bremner, J. Douglas; Goldberg, Jack; Vaccarino, Viola

    2014-01-01

    Background The American Heart Association (AHA) recently developed the Cardiovascular Health Index (CVHI), a health metric consisting of 7 modifiable risk factors. The relationship of the CVHI with preclinical markers, such as carotid intima‐media thickness (CIMT) has not been assessed. Methods We examined 490 male monozygotic and dizygotic twins without overt cardiovascular disease. CIMT was measured using B‐mode ultrasonography. Each of the 7 CVHI components (blood pressure, fasting glucose, total cholesterol, body mass index, physical activity, healthy diet, and smoking) was given a point score of 0, 1, or 2 to represent poor, intermediate, or ideal health, respectively. A CVHI summation score was computed (range 0 to 14) and categorized as inadequate (0 to 4), average (5 to 9), or optimum (10 to 14) cardiovascular health. Mixed‐model regression was used to examine the association of the CVHI with CIMT. Results The mean age of the twins was 55.4 years, and 61% were monozygotic. The mean CIMT was 0.75 (±0.11) mm and the mean CVHI score was 7.7 (±2.1). There was an inverse correlation between CVHI and CIMT (Spearman r=−0.22, P<0.01). For every 5‐unit increase in overall CVHI score (indicating better cardiovascular health category), CIMT decreased by 0.045 mm (P<0.001) after adjusting for demographic variables and other confounders. Within monozygotic twin pairs, a 5‐unit increment in CVHI score was associated with a 0.05 mm lower CIMT (P<0.001). Conclusions The CVHI is independently associated with CIMT and the association is not confounded by shared genetic and other familial factors. PMID:24385450

  13. Special forms in twin pregnancy – asymmetric conjoined twins

    PubMed Central

    Anca, FA; Negru, A; Mihart, AE; Grigoriu, C; Bohîlțea, RE

    2015-01-01

    Twin pregnancies generally represent a high-risk pregnancy. However, monozygous twins are real challenges for obstetricians due to the complications that may occur. Among the particular cases of monozygous twins in the University Emergency Hospital of Bucharest, Department of Obstetrics and Gynecology, a monochorial monoamniotic pregnancy with conjoined twins has been described. These particular medical circumstances require a deeper understanding of the vascular anatomical particularities. An accurate diagnosis implies a most detailed description of the morphological dynamics of the fetuses with the study of the impact of the vascular anomaly on their development so that the maximum chances of survival and the best outcome for the viable fetus can be obtained. The diagnosis of the most frequently associated anomalies is also extremely important. Abbreviations: MRI = Magnetic resonance imaging PMID:26361519

  14. Special forms in twin pregnancy - asymmetric conjoined twins.

    PubMed

    Anca, F A; Negru, A; Mihart, A E; Grigoriu, C; Bohîlțea, R E

    2015-01-01

    Twin pregnancies generally represent a high-risk pregnancy. However, monozygous twins are real challenges for obstetricians due to the complications that may occur. Among the particular cases of monozygous twins in the University Emergency Hospital of Bucharest, Department of Obstetrics and Gynecology, a monochorial monoamniotic pregnancy with conjoined twins has been described. These particular medical circumstances require a deeper understanding of the vascular anatomical particularities. An accurate diagnosis implies a most detailed description of the morphological dynamics of the fetuses with the study of the impact of the vascular anomaly on their development so that the maximum chances of survival and the best outcome for the viable fetus can be obtained. The diagnosis of the most frequently associated anomalies is also extremely important. PMID:26361519

  15. Twin Jet

    NASA Technical Reports Server (NTRS)

    Henderson, Brenda; Bozak, Rick

    2010-01-01

    Many subsonic and supersonic vehicles in the current fleet have multiple engines mounted near one another. Some future vehicle concepts may use innovative propulsion systems such as distributed propulsion which will result in multiple jets mounted in close proximity. Engine configurations with multiple jets have the ability to exploit jet-by-jet shielding which may significantly reduce noise. Jet-by-jet shielding is the ability of one jet to shield noise that is emitted by another jet. The sensitivity of jet-by-jet shielding to jet spacing and simulated flight stream Mach number are not well understood. The current experiment investigates the impact of jet spacing, jet operating condition, and flight stream Mach number on the noise radiated from subsonic and supersonic twin jets.

  16. Synthesis and Raman scattering studies of novel semiconductor nanostructures: silicon, germanium and gallium arsenide twinning superlattice nanowires

    NASA Astrophysics Data System (ADS)

    Adu, Kofi Wi

    This thesis work focuses on synthesis of novel semiconductor nanostructures: nanowires, quantum dots and twinning superlattices by Pulsed Laser Vaporization (PLV) and Thermal Batch Process (TBP) and the studies of their optical properties. We have developed growth and synthesis routes to produce Ge and Si nanowires of diameters ranging from 3nm to 10nm that exhibit quantum confinement effects. The asymmetric Raman lineshape predicted for scattering from confined optical phonon by Richter, and the Fano interference lineshape in n-type Si and Ge are found to be similar. However, the physics of either phenomenon is distinctively different. We performed a series of Raman scattering experiments on Si and Ge nanowires to determine the true origin of the asymmetry. The experiments were conducted under two conditions: high wire density and low wire density, corresponding to poor thermal anchorage and good thermal anchorage on substrate. We identified three physical phenomena that contribute to the lineshape: Phonon confinement, photo-stimulated and thermally induced Fano scattering. We can distinguish each of these processes based on the diameter of the wire and the laser flux dependence of the scattering and the evolution of the lineshape at low laser power with nanowire diameter. Which effect dominates depends on the contact of the Raman sample to the substrate, the substrate thermal properties, and the diameter of the nanowires. We have proposed a coupled phenomenological model which takes the phonon confinement and Fano processes into account that best describe the observed asymmetry in the phonon lineshapes. We are the first to report true phonon confinement in Si and Ge nanowires that shows the evolution of the lineshape asymmetry with diameter (3 nm to 30 nm) first predicted by Richter. We have also investigated the effect of oxide layer, and strain induced by the oxide layer on the first order Raman scattering from Si nanowires. Our data reveal that: (a) one can

  17. Associations of mother's and father's parenting practices with children's observed social reticence in a competitive situation: a monozygotic twin difference study.

    PubMed

    Guimond, Fanny-Alexandra; Brendgen, Mara; Forget-Dubois, Nadine; Dionne, Ginette; Vitaro, Frank; Tremblay, Richard E; Boivin, Michel

    2012-04-01

    This study used the monozygotic (MZ) twin difference method to examine whether the unique environmental effects of maternal and paternal overprotection and hostility at the age of 30 months predict twins' observed social reticence in a competitive situation in kindergarten, while controlling for the effect of family-wide influences, including genetic and shared environmental factors, family socio-economical status and twin's birth weight. It was also examined whether these associations are moderated by parental depressive symptoms. Participants were 137 MZ twin pairs who were part of an ongoing longitudinal study. Hierarchical linear regressions revealed that differences in maternal and paternal overprotection predicted differences in twins' social reticence, albeit only in boys. Differences in paternal hostile parenting predicted differences in girls' reticent behavior, but only when fathers showed high levels of depressive symptoms. Hence, overprotected boys, as well as girls confronted with father's hostility and depressive symptoms, may tend to withdraw rather than face the challenge when experiencing difficult social situations such as competition. The results from the present study suggest that targeting maladaptive maternal as well as paternal child-rearing practices and psychopathology early on may be useful for reducing later internalizing behavior in the offspring. PMID:21947581

  18. Common immune-related exposures/conditions and risk of non-Hodgkin lymphoma: a case-control study of disease-discordant twin pairs.

    PubMed

    Wang, Jun; Mack, Thomas M; Hamilton, Ann S; Hwang, Amie E; Nathwani, Bharat N; Masood, Kamil; Buchanan, Laura H; Bernstein, Leslie; Deapen, Dennis M; Martínez-Maza, Otoniel; Cozen, Wendy

    2015-09-01

    We evaluated the association between common immune system-altering experiences and non-Hodgkin lymphoma (NHL) risk using a case-control study of 162 like-sex twin pairs discordant for NHL, identified from the International Twin Study. Information on medical history and evidence of childhood exposure to microbes was obtained by questionnaire from 1998 to 2002. Conditional logistic regression was used to estimate odds ratios and 95% confidence intervals. Intra-twin-pair agreement between twins on individual exposures was high (76%-97%). A negative association between NHL and seasonal hay fever (odds ratio (OR) = 0.28, 95% confidence interval (CI): 0.10, 0.75) and certain allergies (OR = 0.29, 95% CI: 0.13, 0.68) was observed. The number of atopic diseases was negatively associated with NHL (P for trend = 0.0003). A history of infectious mononucleosis was negatively associated with NHL risk (OR = 0.35, 95% CI: 0.14, 0.90). NHL risk was associated with more frequent childhood exposure to microbes during early life (P for trend = 0.04). No differences in association by NHL subtype were observed, although statistical power for these comparisons was low. These observations support the hypothesis that immune-related exposures, especially atopy, are associated with decreased NHL risk. Use of the within-twin-pair study design mitigates confounding by genome, family structure, and unmeasured characteristics of early childhood factors. PMID:26271116

  19. Simulation study of mechanical properties of bulk metallic glass systems: martensitic inclusions and twinned precipitates

    NASA Astrophysics Data System (ADS)

    Zaheri, A.; Abdeljawad, F.; Haataja, M.

    2014-12-01

    Monolithic bulk metallic glasses (BMGs) exhibit a unique combination of mechanical properties, such as high strength and large elasticity limits, but the lack of ductility is considered the main Achilles' heel of BMG systems. To increase the competitiveness of BMGs vis-à-vis conventional structural materials, the problem of catastrophic failure via intense plastic strain localization (‘shear banding’) has to be addressed. Recent experimental observations suggest that the addition of structural heterogeneities, in the form of crystalline particles, to BMG systems hinders the catastrophic propagation of shear bands and leads to enhanced ductility. These structural heterogeneities can be introduced by either forming BMG composites, where second-phase crystalline particles accommodate applied loads via martensitic transformation mechanisms, or developing glassy alloys that precipitate crystalline particles under deformation, a process by which further deformation can be sustained by twinning mechanisms in the crystalline phase. In this work, we present a non-linear continuum model capable of capturing the structural heterogeneity in the glassy phase and accounting for intrinsic work hardening via martensitic transformations in second-phase reinforcements in BMG composites and deformation twinning in precipitated crystalline particles. Simulation results reveal that in addition to intrinsic work hardening in the crystalline phase, particle size greatly affects the overall mechanical behavior of these BMG systems. The precipitation of crystalline particles in monolithic BMGs yields two-phase microstructures that promote more homogeneous deformation, delay the propagation of incipient shear bands, and ultimately result in improved ductility characteristics.

  20. Studies of the Twin Helix Parametric-resonance Ionization Cooling Channel with COSY INFINITY

    SciTech Connect

    J.A. Maloney, K.B. Beard, R.P. Johnson, A. Afanasev, S.A. Bogacz, Y.S. Derbenev, V.S. Morozov, B. Erdelyi

    2012-07-01

    A primary technical challenge to the design of a high luminosity muon collider is an effective beam cooling system. An epicyclic twin-helix channel utilizing parametric-resonance ionization cooling has been proposed for the final 6D cooling stage. A proposed design of this twin-helix channel is presented that utilizes correlated optics between the horizontal and vertical betatron periods to simultaneously focus transverse motion of the beam in both planes. Parametric resonance is induced in both planes via a system of helical quadrupole harmonics. Ionization cooling is achieved via periodically placed wedges of absorbing material, with intermittent rf cavities restoring longitudinal momentum necessary to maintain stable orbit of the beam. COSY INFINITY is utilized to simulate the theory at first order. The motion of particles around a hyperbolic fixed point is tracked. Comparison is made between the EPIC cooling channel and standard ionization cooling effects. Cooling effects are measured, after including stochastic effects, for both a single particle and a distribution of particles.

  1. Experimental Studies of Active and Passive Flow Control Techniques Applied in a Twin Air-Intake

    PubMed Central

    Joshi, Shrey; Jindal, Aman; Maurya, Shivam P.; Jain, Anuj

    2013-01-01

    The flow control in twin air-intakes is necessary to improve the performance characteristics, since the flow traveling through curved and diffused paths becomes complex, especially after merging. The paper presents a comparison between two well-known techniques of flow control: active and passive. It presents an effective design of a vortex generator jet (VGJ) and a vane-type passive vortex generator (VG) and uses them in twin air-intake duct in different combinations to establish their effectiveness in improving the performance characteristics. The VGJ is designed to insert flow from side wall at pitch angle of 90 degrees and 45 degrees. Corotating (parallel) and counterrotating (V-shape) are the configuration of vane type VG. It is observed that VGJ has the potential to change the flow pattern drastically as compared to vane-type VG. While the VGJ is directed perpendicular to the side walls of the air-intake at a pitch angle of 90 degree, static pressure recovery is increased by 7.8% and total pressure loss is reduced by 40.7%, which is the best among all other cases tested for VGJ. For bigger-sized VG attached to the side walls of the air-intake, static pressure recovery is increased by 5.3%, but total pressure loss is reduced by only 4.5% as compared to all other cases of VG. PMID:23935422

  2. Congenital cytomegalovirus infection in fraternal twins: a longitudinal case study examining neurocognitive and neurobehavioral correlates.

    PubMed

    Llorente, Antolin M; Castillo, Christine L

    2012-01-01

    Cytomegalovirus (CMV) is the most ubiquitous member of the herpes virus family and is the leading cause of congenital (vertical) infection in newborns (Fowler, Stagno, & Pass, 2003; Llorente, Steigmeyer, Cooper, Rivers, & Gazley, 2011; Noyola et al., 2000; Steigmeyer & Llorente, 2010). CMV is related to the group of viruses capable of causing more pernicious infectious diseases, such as chicken pox (Santos de Barona, 1998). Although the virus generally remains dormant, individuals whose symptoms are clinically apparent often are dramatically affected. Common symptomatic characteristics of the virus include microcephaly, jaundice, liver-spleen infections, pneumonia, cardiac anomalies, chorioretinitis, vision loss, sensory-neural hearing loss, mental retardation, and mononucleosis (Demmler, 1991; Kashden, Frison, Fowler, Pass, & Boll, 1998; Noyola et al., 2000; Pass, 2005; Santos de Barona). The prognosis of individuals with CMV is highly variable, and the prognosis of individuals with congenital CMV can usually be determined based on the extent of infection at birth. The purpose of this investigation is to present longitudinal results of neuropsychological evaluation of two dizygotic twin sets (one twin of each set is asymptomatic CMV-positive and the other is uninfected) who were reared in the same environment. In addition, the present findings are discussed within the context of emerging murine and other animal analogues of CMV as well as within the extant CMV literature. PMID:23428280

  3. Methylomic analysis of monozygotic twins discordant for childhood psychotic symptoms

    PubMed Central

    Fisher, Helen L; Murphy, Therese M; Arseneault, Louise; Caspi, Avshalom; Moffitt, Terrie E; Viana, Joana; Hannon, Eilis; Pidsley, Ruth; Burrage, Joe; Dempster, Emma L; Wong, Chloe C Y; Pariante, Carmine M; Mill, Jonathan

    2015-01-01

    Childhood psychotic symptoms are associated with increased rates of schizophrenia, other psychiatric disorders, and suicide attempts in adulthood; thus, elucidating early risk indicators is crucial to target prevention efforts. There is considerable discordance for psychotic symptoms between monozygotic twins, indicating that child-specific non-genetic factors must be involved. Epigenetic processes may constitute one of these factors and have not yet been investigated in relation to childhood psychotic symptoms. Therefore, this study explored whether differences in DNA methylation at age 10 were associated with monozygotic twin discordance for psychotic symptoms at age 12. The Environmental Risk (E-Risk) Longitudinal Twin Study cohort of 2,232 children (1,116 twin pairs) was assessed for age-12 psychotic symptoms and 24 monozygotic twin pairs discordant for symptoms were identified for methylomic comparison. Children provided buccal samples at ages 5 and 10. DNA was bisulfite modified and DNA methylation was quantified using the Infinium HumanMethylation450 array. Differentially methylated positions (DMPs) associated with psychotic symptoms were subsequently tested in post-mortem prefrontal cortex tissue from adult schizophrenia patients and age-matched controls. Site-specific DNA methylation differences were observed at age 10 between monozygotic twins discordant for age-12 psychotic symptoms. Similar DMPs were not found at age 5. The top-ranked psychosis-associated DMP (cg23933044), located in the promoter of the C5ORF42 gene, was also hypomethylated in post-mortem prefrontal cortex brain tissue from schizophrenia patients compared to unaffected controls. These data tentatively suggest that epigenetic variation in peripheral tissue is associated with childhood psychotic symptoms and may indicate susceptibility to schizophrenia and other mental health problems. PMID:26479702

  4. The Impact of Preschool Twins' Physical Difficulties on Parental Perceptions towards Separation, Closeness and Friendship

    ERIC Educational Resources Information Center

    Markodimitraki, Maria; Linardakis, Michalis; Kypriotaki, Maria; Manolitsis, George

    2016-01-01

    The aims of this study were to: (a) provide descriptive data of twins with physical difficulties among 120 Greek twins of preschool age; and (b) to investigate the impact of twins' health condition on parental perceptions towards twins' separation, closeness and friendship. The administration of School Policy for Twins and Higher Multiples…

  5. 4D STUDY OF STRAIN GRADIENTS EVOLUTION IN TWINNED NiMnGa SINGLE CRYSTALS UNDER MAGNETIC FIELD

    SciTech Connect

    Barabash, Rozaliya; Xu, Ruqing; Barabash, Oleg M; Sozinov, Alexei

    2014-01-01

    Time-resolved 3D X-ray microscopy with a submicron beam size was used to follow the evolution of strains in off-stoichiometric NiMnGa twinned crystals near type I (hard) twin boundary under magnetic field. Laminate A/B microstructure was revealed near the twin boundaries in A variant. Large strain gradients are observed in the C variant in the immediate vicinity of the type I twin boundary: the lattice is under large tensile strains ~0.4% along the c- axes within first micron. Distinct a and b lattice parameter evolution with temperature and magnetic field is demonstrated. In an applied magnetic field the strain field was observed at larger distances from the twin boundary and becomes more complex. Stochastic twin boundary motion was observed after the magnetic field reaches a certain critical value.

  6. Fingerprint recognition with identical twin fingerprints.

    PubMed

    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. PMID:22558204

  7. Fingerprint Recognition with Identical Twin Fingerprints

    PubMed Central

    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. PMID:22558204

  8. Twin studies reveal specific imbalances in the mucosa-associated microbiota of patients with ileal Crohn's disease

    SciTech Connect

    Willing, B.; Halfvarson, J.; Dicksved, J.; Rosenquist, M.; Jarnerot, G.; Engstrand, L.; Tysk, C.; Jansson, J. K

    2008-08-15

    Large inter-individual variation in the composition of the intestinal microbiota between unrelated individuals has made it challenging to identify specific aspects of dysbiosis that lead to Crohn's disease. To reduce variations in exposure during establishment of the gut flora and influence of genotype, we studied the mucosaassociated microbiota of monozygotic twin pairs that were discordant (n=6) or concordant (n=4) for Crohn's disease. DNA was extracted from biopsies collected from 5 locations between the ileum and rectum. Bacterial 16S ribosomal RNA genes were amplified and community composition assessed by terminal-restriction fragment length polymorphism, cloning and sequencing and quantitative real-time PCR. The microbial compositions at all biopsy locations for each individual were similar, regardless of disease state, but there were differences between individuals. In particular, individuals with predominantly ileal Crohn's had a dramatically lower abundance (P<0.001) of Faecalibacterium prausnitzii and increased abundance (P<0.03) of Escherichia coli compared to healthy co-twins and those with Crohn's localized in the colon. This dysbiosis was significantly correlated to the disease phenotype rather than genotype. The reduced abundance of F. prausnitzii and increased abundance of E. coli are indicative of an ileal Crohn's disease phenotype, distinct from colonic Crohn's disease and the relative abundances of these specific bacterial populations are promising biomarker candidates for differential diagnosis of Crohn's and eventually customized treatment.

  9. Parkinsonism in a pair of monozygotic CADASIL twins sharing the R1006C mutation: a transcranial sonography study.

    PubMed

    Ragno, Michele; Sanguigni, Sandro; Manca, Antonio; Pianese, Luigi; Paci, Cristina; Berbellini, Alfonso; Cozzolino, Valeria; Gobbato, Roberto; Peluso, Silvio; De Michele, Giuseppe

    2016-06-01

    Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), the most common hereditary cerebral small vessel disease, is caused by mutations in the NOTCH3 gene on chromosome 19. Clinical manifestations of CADASIL include recurrent transient ischemic attacks, strokes, cognitive defects, epilepsy, migraine and psychiatric symptoms. Parkinsonian features have variably been reported in CADASIL patients, but only a few patients showed a clear parkinsonian syndrome. We studied two patients, a pair of monozygotic twins, carrying the R1006C mutation of the NOTCH3 gene and affected by a parkinsonian syndrome. For the first time in CADASIL patients, we used transcranial sonography (TCS) to assess basal ganglia abnormalities. TCS showed a bilateral hyperechogenic pattern of substantia nigra in one twin, and a right hyperechogenic pattern in the other. In both patients, lenticular nuclei showed a bilateral hyperechogenic pattern, and the width of the third ventricle was slightly increased. The TCS pattern found in our CADASIL patients is characteristic neither for Parkinson's disease, nor for vascular parkinsonism and seems to be specific and related to the disease-specific pathological features. PMID:26850715

  10. Heritability and Genome-Wide Association Studies for Hair Color in a Dutch Twin Family Based Sample.

    PubMed

    Lin, Bochao Danae; Mbarek, Hamdi; Willemsen, Gonneke; Dolan, Conor V; Fedko, Iryna O; Abdellaoui, Abdel; de Geus, Eco J; Boomsma, Dorret I; Hottenga, Jouke-Jan

    2015-01-01

    Hair color is one of the most visible and heritable traits in humans. Here, we estimated heritability by structural equation modeling (N = 20,142), and performed a genome wide association (GWA) analysis (N = 7091) and a GCTA study (N = 3340) on hair color within a large cohort of twins, their parents and siblings from the Netherlands Twin Register (NTR). Self-reported hair color was analyzed as five binary phenotypes, namely "blond versus non-blond", "red versus non-red", "brown versus non-brown", "black versus non-black", and "light versus dark". The broad-sense heritability of hair color was estimated between 73% and 99% and the genetic component included non-additive genetic variance. Assortative mating for hair color was significant, except for red and black hair color. From GCTA analyses, at most 24.6% of the additive genetic variance in hair color was explained by 1000G well-imputed SNPs. Genome-wide association analysis for each hair color showed that SNPs in the MC1R region were significantly associated with red, brown and black hair, and also with light versus dark hair color. Five other known genes (HERC2, TPCN2, SLC24A4, IRF4, and KITLG) gave genome-wide significant hits for blond, brown and light versus dark hair color. We did not find and replicate any new loci for hair color. PMID:26184321

  11. Heritability and Genome-Wide Association Studies for Hair Color in a Dutch Twin Family Based Sample

    PubMed Central

    Lin, Bochao Danae; Mbarek, Hamdi; Willemsen, Gonneke; Dolan, Conor V.; Fedko, Iryna O.; Abdellaoui, Abdel; de Geus, Eco J.; Boomsma, Dorret I.; Hottenga, Jouke-Jan

    2015-01-01

    Hair color is one of the most visible and heritable traits in humans. Here, we estimated heritability by structural equation modeling (N = 20,142), and performed a genome wide association (GWA) analysis (N = 7091) and a GCTA study (N = 3340) on hair color within a large cohort of twins, their parents and siblings from the Netherlands Twin Register (NTR). Self-reported hair color was analyzed as five binary phenotypes, namely “blond versus non-blond”, “red versus non-red”, “brown versus non-brown”, “black versus non-black”, and “light versus dark”. The broad-sense heritability of hair color was estimated between 73% and 99% and the genetic component included non-additive genetic variance. Assortative mating for hair color was significant, except for red and black hair color. From GCTA analyses, at most 24.6% of the additive genetic variance in hair color was explained by 1000G well-imputed SNPs. Genome-wide association analysis for each hair color showed that SNPs in the MC1R region were significantly associated with red, brown and black hair, and also with light versus dark hair color. Five other known genes (HERC2, TPCN2, SLC24A4, IRF4, and KITLG) gave genome-wide significant hits for blond, brown and light versus dark hair color. We did not find and replicate any new loci for hair color. PMID:26184321

  12. The value of twins in epigenetic epidemiology.

    PubMed

    Bell, Jordana T; Saffery, Richard

    2012-02-01

    During past decades, twin studies have played an important role in genetic epidemiology studies of complex traits. The strength of twin studies lies in the ability to disentangle genetic and environmental factors that contribute to a phenotype, by comparing genetically identical monozygotic twins to dizygotic twins, who share on average 50% of genetic variants. Twin studies now offer the opportunity to study epigenetic variation across the genome with two aims. First, twin studies can improve our understanding of the factors regulating epigenetic variability by assessing the heritability of epigenetic variants. Secondly, the use of twins in epigenetic research is increasingly recognized as an important approach to help unravel the complexities associated with human development and disease. The strategic use of identical twins discordant for complex disease has revealed the importance of linking epigenetic disruption to the disease-associated risk in humans. Lastly, we also discuss the possibility that epigenetic effects on disease may in part explain some of the missing heritability in genome-wide association studies. The study of human epigenetic factors in twins can inform the role of genetics, as well as in utero and postnatal environments to the establishment, maintenance and functional consequences of human epigenome variation. PMID:22253312

  13. Studies of X inactivation and isodisomy in twins provide further evidence that the X chromosomes is not involved in Rett syndrome

    SciTech Connect

    Migeon, B.R.; Dunn, M.A.; Schmeckpeper, B.J.; Naidu, S.; Thomas, G. |

    1995-03-01

    Rett syndrome (RS), a progressive encephalopathy with onset in infancy, has been attributed to an X-linked mutation, mainly on the basis of its occurrence almost exclusively in females and its concordance in female MZ twins. The underlying mechanisms proposed are an X-linked dominant mutation with male lethality, uniparental disomy of the X chromosome, and/or some disturbance in the process of X inactivation leading to unequal distribution of cells expressing maternal or paternal alleles (referred to as a {open_quotes}nonrandom{close_quotes} or {open_quotes}skewed {close_quotes} inactivation). To determine if the X chromosome is in fact involved in RS, we studied a group of affected females including three pairs of MZ twins, two concordant for RS and one uniquely discordant for RS. Analysis of X-inactivation patterns confirms the frequent nonrandom X inactivation previously observed in MZ twins but indicates that this is independent of RS. Analysis of 29 RS females reveals not one instance of uniparental X disomy, extending the observations previously reported. Therefore, our findings contribute no support for the hypothesis that RS is an X-linked disorder. Furthermore, the concordant phenotype in most MZ females twins with RS, which has not been observed in female twins with known X-linked mutations, argues against an X mutation. 41 refs., 2 figs.

  14. Characterization of Psychotic Experiences in Adolescence Using the Specific Psychotic Experiences Questionnaire: Findings From a Study of 5000 16-Year-Old Twins

    PubMed Central

    Ronald, Angelica; Sieradzka, Dominika; Cardno, Alastair G.; Haworth, Claire M. A.; McGuire, Philip; Freeman, Daniel

    2014-01-01

    We aimed to characterize multiple psychotic experiences, each assessed on a spectrum of severity (ie, quantitatively), in a general population sample of adolescents. Over five thousand 16-year-old twins and their parents completed the newly devised Specific Psychotic Experiences Questionnaire (SPEQ); a subsample repeated it approximately 9 months later. SPEQ was investigated in terms of factor structure, intersubscale correlations, frequency of endorsement and reported distress, reliability and validity, associations with traits of anxiety, depression and personality, and sex differences. Principal component analysis revealed a 6-component solution: paranoia, hallucinations, cognitive disorganization, grandiosity, anhedonia, and parent-rated negative symptoms. These components formed the basis of 6 subscales. Correlations between different experiences were low to moderate. All SPEQ subscales, except Grandiosity, correlated significantly with traits of anxiety, depression, and neuroticism. Scales showed good internal consistency, test-retest reliability, and convergent validity. Girls endorsed more paranoia, hallucinations, and cognitive disorganization; boys reported more grandiosity and anhedonia and had more parent-rated negative symptoms. As in adults at high risk for psychosis and with psychotic disorders, psychotic experiences in adolescents are characterized by multiple components. The study of psychotic experiences as distinct dimensional quantitative traits is likely to prove an important strategy for future research, and the SPEQ is a self- and parent-report questionnaire battery that embodies this approach. PMID:24062593

  15. Twin Higgs Asymmetric Dark Matter

    NASA Astrophysics Data System (ADS)

    García García, Isabel; Lasenby, Robert; March-Russell, John

    2015-09-01

    We study asymmetric dark matter (ADM) in the context of the minimal (fraternal) twin Higgs solution to the little hierarchy problem, with a twin sector with gauged SU(3)'×SU(2)', atwin Higgs doublet, and only third-generation twin fermions. Naturalness requires the QCD' scale ΛQCD'≃0.5 - 20 GeV , and that t' is heavy. We focus on the light b' quark regime, mb'≲ΛQCD', where QCD' is characterized by a single scale ΛQCD' with no light pions. A twin baryon number asymmetry leads to a successful dark matter (DM) candidate: the spin-3 /2 twin baryon, Δ'˜b'b'b', with a dynamically determined mass (˜5 ΛQCD') in the preferred range for the DM-to-baryon ratio ΩDM/Ωbaryon≃5 . Gauging the U (1 )' group leads to twin atoms (Δ'-τ' ¯ bound states) that are successful ADM candidates in significant regions of parameter space, sometimes with observable changes to DM halo properties. Direct detection signatures satisfy current bounds, at times modified by dark form factors.

  16. The development of inhibitory control in early childhood: A twin study from 2-3 years

    PubMed Central

    Gagne, Jeffrey R.; Saudino, Kimberly J.

    2015-01-01

    Parent and lab-based observer ratings were employed to examine genetic and environmental influences on continuity and change in inhibitory control (IC) in over 300 twin-pairs assessed longitudinally at 2 and 3 years of age. Genetic influences accounted for approximately 60% of the variance in parent-rated IC at both ages. Although many of the same genetic effects on parent-rated IC were stable across age, there were also novel genetic effects that emerged at age 3 (i.e., genetic factors contributed to both continuity and change in parent ratings of IC). Observed IC displayed a different developmental pattern. Genetic influences were moderate at age 2 (38%) and nonsignificant at age 3 (6%). Change in observed IC across early childhood was due to shared and nonshared environmental factors. Findings indicate that it is important to consider the measurement of IC when interpreting developmental and etiological findings. PMID:26784384

  17. Identical Twins with Infantile Systemic Hyalinosis: Case study and review of literature

    PubMed Central

    Aggarwal, Maheshwar Lakkireddyl Shagun; Chilakamarri, Vijaykrishna; Chennuri, Vasundhara S; Karra, Madhulatha

    2016-01-01

    Introduction: Infantile Systemic Hyalinosis (ISH) is a rare and fatal genetic disorder with mutations in Capillary morphogenesis gene-2 CMG2 / Human anthrax toxin receptor gene-2 ANTXR2 resulting in spindle cell proliferation, altered collagen metabolism with extensive deposition of amorphous eosinophilic PAS positive hyaline material in the connective tissues of various organs. The common presenting features would be progressive stiffness of multiple joints, skin lesions, multiple episodes of protracted infections, prolonged diarrhoea and failure to thrive. ISH is a rapidly progressive painful disorder of infancy with a very short life expectancy. Case Presentation: 3 months old identical twins born to a 5th degree consanguinous couple were brought with complaints of excessive cry, deformity of all four limbs, recurrent episodes of respiratory tract infections and diarrhoea since birth. Evaluation of both the probands revealed facial dysmorphism with perinasal nodules, gingival hypertrophy, fixed deformities of multiple joints bilaterally, umbilical hernia, fleshy perianal nodules and pigmented patches over knuckles and ankle. A clinical diagnosis of ISH was suspected and confirmed by detection of homozygous c.277_278insATTATTT (or p.L93Yfs*14) in exon 3 of the ANTXR2 gene. The probands were managed symptomatically and parents were counselled regarding prenatal diagnosis in future pregnancies. Conclusion: IHS is commonly misdiagnosed as Arthrogryposis Multiplex Congenita and is often mismanaged with manipulation of the stiff joints and invasive surgical procedures. Prenatal diagnosis by chorionic villus biopsy is possible once causative mutation in a family is identified. Invasive surgical interventions for histopathological analysis can be avoided as clinical features are most often classical and genetic analysis is confirmatory. Management is conservative and symptomatic. We report this case of identical twins with features of ISH in view of its rarity as timely

  18. A longitudinal twin study of the direction of effects between ADHD symptoms and IQ.

    PubMed

    Rommel, Anna Sophie; Rijsdijk, Frühling; Greven, Corina U; Asherson, Philip; Kuntsi, Jonna

    2015-01-01

    While the negative association between ADHD symptoms and IQ is well documented, our knowledge about the direction and aetiology of this association is limited. Here, we examine the association of ADHD symptoms with verbal and performance IQ longitudinally in a population-based sample of twins. In a population-based sample of 4,771 twin pairs, DSM-IV ADHD symptoms were obtained from the Conners' Parent Rating Scale-Revised. Verbal (vocabulary) and performance (Raven's Progressive Matrices) IQ were assessed online. ADHD symptom ratings and IQ scores were obtained at ages 12, 14 and 16 years. Making use of the genetic sensitivity and time-ordered nature of our data, we use a cross-lagged model to examine the direction of effects, while modelling the aetiologies of the association between ADHD symptoms with vocabulary and Raven's scores over time. Although time-specific aetiological influences emerged for each trait at ages 14 and 16 years, the aetiological factors involved in the association between ADHD symptoms and IQ were stable over time. ADHD symptoms and IQ scores significantly predicted each other over time. ADHD symptoms at age 12 years were a significantly stronger predictor of vocabulary and Raven's scores at age 14 years than vice versa, whereas no differential predictive effects emerged from age 14 to 16 years. The results suggest that ADHD symptoms may put adolescents at risk for decreased IQ scores. Persistent genetic influences seem to underlie the association of ADHD symptoms and IQ over time. Early intervention is likely to be key to reducing ADHD symptoms and the associated risk for lower IQ. PMID:25875897

  19. A Longitudinal Twin Study of the Direction of Effects between ADHD Symptoms and IQ

    PubMed Central

    Rommel, Anna Sophie; Rijsdijk, Frühling; Greven, Corina U.; Asherson, Philip; Kuntsi, Jonna

    2015-01-01

    While the negative association between ADHD symptoms and IQ is well documented, our knowledge about the direction and aetiology of this association is limited. Here, we examine the association of ADHD symptoms with verbal and performance IQ longitudinally in a population-based sample of twins. In a population-based sample of 4,771 twin pairs, DSM-IV ADHD symptoms were obtained from the Conners’ Parent Rating Scale-Revised. Verbal (vocabulary) and performance (Raven’s Progressive Matrices) IQ were assessed online. ADHD symptom ratings and IQ scores were obtained at ages 12, 14 and 16 years. Making use of the genetic sensitivity and time-ordered nature of our data, we use a cross-lagged model to examine the direction of effects, while modelling the aetiologies of the association between ADHD symptoms with vocabulary and Raven’s scores over time. Although time-specific aetiological influences emerged for each trait at ages 14 and 16 years, the aetiological factors involved in the association between ADHD symptoms and IQ were stable over time. ADHD symptoms and IQ scores significantly predicted each other over time. ADHD symptoms at age 12 years were a significantly stronger predictor of vocabulary and Raven’s scores at age 14 years than vice versa, whereas no differential predictive effects emerged from age 14 to 16 years. The results suggest that ADHD symptoms may put adolescents at risk for decreased IQ scores. Persistent genetic influences seem to underlie the association of ADHD symptoms and IQ over time. Early intervention is likely to be key to reducing ADHD symptoms and the associated risk for lower IQ. PMID:25875897

  20. Symptoms of autism and ADHD: a Swedish twin study examining their overlap.

    PubMed

    Ronald, Angelica; Larsson, Henrik; Anckarsäter, Henrik; Lichtenstein, Paul

    2014-05-01

    Autism spectrum disorders (ASD) and attention deficit hyperactivity disorder (ADHD) show high comorbidity. The following questions were addressed regarding their specific symptoms: What is the factor structure of ASD and ADHD symptoms, to what degree do different symptom domains cluster together, to what extent are these domains caused by the same genetic and environmental influences, and what is the best model of their co-occurrence? A population-based twin cohort of over 17,000 9- and 12-year-olds were assessed using the Autism-Tics, AD/HD, and other Comorbidities parental interview inventory. Principal component analyses were conducted, and symptom domain clustering was assessed. Four multivariate twin models were compared. Factors split into three ASD (social impairments, communication impairments, and restricted repetitive behaviors and interests), and three ADHD (inattention, hyperactivity, and impulsivity) symptom domains. Some ASD-ADHD symptom domain combinations clustered together often, although others not at all. A two-factor common pathway model fit the data, suggesting that ASD and ADHD symptom domains tap into separate "ASD" and "ADHD" latent factors that showed high genetic overlap. All subdomains also showed significant specific genetic and environmental influences, reflecting the etiological heterogeneity both within and between ASD and ADHD. These findings support the conceptual distinction of ASD and ADHD, and demonstrate the considerable natural co-occurrence of particular ASD/ADHD symptom domains. The results imply that more children with 1 condition show features of the other condition than show complete comorbidity. Emphasis on symptom co-occurrence, rather than complete comorbidity between disorders, may help focus clinical approaches and advance molecular genetic research. PMID:24731073

  1. Genetic Factors of Individual Differences in Decision Making in Economic Behavior: A Japanese Twin Study using the Allais Problem

    PubMed Central

    Shikishima, Chizuru; Hiraishi, Kai; Yamagata, Shinji; Ando, Juko; Okada, Mitsuhiro

    2015-01-01

    Why does decision making differ among individuals? People sometimes make seemingly inconsistent decisions with lower expected (monetary) utility even when objective information of probabilities and reward are provided. It is noteworthy, however, that a certain proportion of people do not provide anomalous responses, choosing the alternatives with higher expected utility, thus appearing to be more “rational.” We investigated the genetic and environmental influences on these types of individual differences in decision making using a classical Allais problem task. Participants were 1,199 Japanese adult twins aged 20–47. Univariate genetic analysis revealed that approximately a third of the Allais problem response variance was explained by genetic factors and the rest by environmental factors unique to individuals and measurement error. The environmental factor shared between families did not contribute to the variance. Subsequent multivariate genetic analysis clarified that decision making using the expected utility theory was associated with general intelligence and that the association was largely mediated by the same genetic factor. We approach the mechanism underlying two types of “rational” decision making from the perspective of genetic correlations with cognitive abilities. PMID:26617546

  2. Genetic Factors of Individual Differences in Decision Making in Economic Behavior: A Japanese Twin Study using the Allais Problem.

    PubMed

    Shikishima, Chizuru; Hiraishi, Kai; Yamagata, Shinji; Ando, Juko; Okada, Mitsuhiro

    2015-01-01

    Why does decision making differ among individuals? People sometimes make seemingly inconsistent decisions with lower expected (monetary) utility even when objective information of probabilities and reward are provided. It is noteworthy, however, that a certain proportion of people do not provide anomalous responses, choosing the alternatives with higher expected utility, thus appearing to be more "rational." We investigated the genetic and environmental influences on these types of individual differences in decision making using a classical Allais problem task. Participants were 1,199 Japanese adult twins aged 20-47. Univariate genetic analysis revealed that approximately a third of the Allais problem response variance was explained by genetic factors and the rest by environmental factors unique to individuals and measurement error. The environmental factor shared between families did not contribute to the variance. Subsequent multivariate genetic analysis clarified that decision making using the expected utility theory was associated with general intelligence and that the association was largely mediated by the same genetic factor. We approach the mechanism underlying two types of "rational" decision making from the perspective of genetic correlations with cognitive abilities. PMID:26617546

  3. Piloted simulation study of an ILS approach of a twin-pusher business/commuter turboprop aircraft configuration

    NASA Technical Reports Server (NTRS)

    Riley, Donald R.; Brandon, Jay M.; Glaab, Louis J.

    1994-01-01

    A six-degree-of-freedom nonlinear simulation of a twin-pusher, turboprop business/commuter aircraft configuration representative of the Cessna ATPTB (Advanced turboprop test bed) was developed for use in piloted studies with the Langley General Aviation Simulator. The math models developed are provided, simulation predictions are compared with with Cessna flight-test data for validation purposes, and results of a handling quality study during simulated ILS (instrument landing system) approaches and missed approaches are presented. Simulated flight trajectories, task performance measures, and pilot evaluations are presented for the ILS approach and missed-approach tasks conducted with the vehicle in the presence of moderate turbulence, varying horizontal winds and engine-out conditions. Six test subjects consisting of two research pilots, a Cessna test pilot, and three general aviation pilots participated in the study. This effort was undertaken in cooperation with the Cessna Aircraft Company.

  4. Effect of process parameters on solidification of Al-33Cu strip in high speed twin roll strip casting- A numerical study

    NASA Astrophysics Data System (ADS)

    Sahoo, Seshadev

    2015-02-01

    In twin roll strip casting process, the solidification behavior in the molten pool affects the process efficiency and the product quality which is influenced by the process parameters. Numerical simulations have been carried out to analyze the fluid flow, heat transfer and solidification in high speed twin roll strip caster at different pouring temperatures and roll gaps and the knowledge of heat flux distribution at the liquid metal-roll interface. In the present study a numerical simulation has been carried out for the solidification of Al-33wt% Cu in the twin-roll strip casting system at different pouring temperatures and roll gaps. FLUENT 6.3.16 was used to model fluid flow, heat transfer and solidification behavior during the casting of Al-33wt. % Cu alloy. From the simulation results, the initial pouring temperature of the liquid metal and the roll gap has been optimized for producing quality strips.

  5. Chemically twinned phases in the Ag 2S-PbS-Bi 2S 3 system.Part I. Electron microscope study

    NASA Astrophysics Data System (ADS)

    Skowron, A.; Tilley, R. J. D.

    1990-04-01

    Phases in the PbS-rich region of the Ag 2S-PbS-Bi 2S 3 system have been studied by high resolution transmission electron microscopy. In samples quenched from the melt or melted and annealed at 773 or 973 K a number of new chemically twinned phases have been found. Their structures contain galena-like slabs four-, five-, seven-, and eight-octahedra wide, joined along twin planes. Ordered phases predominate in the PbS-rich region of the phase diagram, while both ordered and disordered intergrowths occur in the PbS-poor region. The role of Ag in stabilizing slabs of galena-like material five- and eight-octahedra wide and its function in the formation of these twinned phases is discussed.

  6. Common plankton of Twin Lakes, Colorado

    SciTech Connect

    Lieberman, D.M.

    1983-02-01

    A series of studies is being performed to evaluate the effects of the Mt. Elbert Pumped-Storage Powerplant on the ecology of Twin Lakes. Twin Lakes are a pair of connected dimictic lakes, formed as the result of glacial action on alluvial deposits. This report presents a taxonomic species study of the common plankton collected since 1974 from Twin Lakes. A total of 11 zooplankters and 14 phytoplankters were identified from the limnetic zone of Twin Lakes and the associated Mt. Elbert Forebay. The four divisions of zooplankton included four species of Rotifera (rotifer), three species of Copepoda (copepod), three species of Cladocera (cladoceran), and one species of Mysidacea (opossum shrimp).

  7. The Etiology of Variation in Language Skills Changes with Development: A Longitudinal Twin Study of Language from 2 to 12 Years

    ERIC Educational Resources Information Center

    Hayiou-Thomas, Marianna E.; Dale, Philip S.; Plomin, Robert

    2012-01-01

    The present study is the first long-term longitudinal examination of the etiology of individual differences in language from early childhood through to adolescence. We applied a multivariate latent factor genetic model to longitudinal data from the Twins Early Development Study in order to (a) compare the magnitude of genetic and environmental…

  8. Family-Based Treatment of a 17-Year-Old Twin Presenting with Emerging Anorexia Nervosa: A Case Study Using the "Maudsley Method"

    ERIC Educational Resources Information Center

    Loeb, Katharine L.; Hirsch, Alicia M.; Greif, Rebecca; Hildebrandt, Thomas B.

    2009-01-01

    This article describes the successful application of family-based treatment (FBT) for a 17-year-old identical twin presenting with a 4-month history of clinically significant symptoms of anorexia nervosa (AN). FBT is a manualized treatment that has been studied in randomized controlled trials for adolescents with AN. This case study illustrates…

  9. Comparative Study on Statistical-Variation Tolerance Between Complementary Crossbar and Twin Crossbar of Binary Nano-scale Memristors for Pattern Recognition

    NASA Astrophysics Data System (ADS)

    Truong, Son Ngoc; Shin, SangHak; Byeon, Sang-Don; Song, JaeSang; Mo, Hyun-Sun; Min, Kyeong-Sik

    2015-10-01

    This paper performs a comparative study on the statistical-variation tolerance between two crossbar architectures which are the complementary and twin architectures. In this comparative study, 10 greyscale images and 26 black-and-white alphabet characters are tested using the circuit simulator to compare the recognition rate with varying statistical variation and correlation parameters.

  10. [Prognosis of twin deliveries in an African milieu].

    PubMed

    Meye, J F; Zue, A S; Ngou, J P; Engongah-Beka, T

    2001-01-01

    We carried out a retrospective study of 101 multiple pregnancies between January 1st 1997 and June 30 1999, to investigate the prognosis of twin deliveries at the Josephine Bongo Maternity Unit. The frequency of twin deliveries was 2.22%, corresponding to over 1 in 45 deliveries. Mean birth weight was 2,309.6 +/- 369.31 g for the first twin and 2,234.31 +/- 397.58 g for the second twin. The frequency of cesarean section was 11% for the first twin and 18% for the second twin. The neonatal mortality rate was 30 per thousand for the first twin and 50 per thousand for the second twin. The reorganization of mother and child health services would help to improve fetal prognosis in twin deliveries. PMID:11440883

  11. Effects of 32-year leisure time physical activity discordance in twin pairs on health (TWINACTIVE study): aims, design and results for physical fitness.

    PubMed

    Leskinen, Tuija; Waller, Katja; Mutikainen, Sara; Aaltonen, Sari; Ronkainen, Paula H A; Alén, Markku; Sipilä, Sarianna; Kovanen, Vuokko; Perhonen, Merja; Pietiläinen, Kirsi H; Cheng, Sulin; Suominen, Harri; Kainulainen, Heikki; Kaprio, Jaakko; Kujala, Urho M

    2009-02-01

    The physically active lifestyle is associated with low future morbidity and mortality, but the causality between physical activity and health is not always clear. As some inherited biological characteristics and childhood experiences may cause selection bias in observational studies, we sought to take them into account by identifying 16 twin pairs (7 MZ, 9 DZ, mean age 60 years) discordant for leisure time physical activity habits for thirty years. We conducted detailed health-related examinations among these twin pairs. Our main aims were to study the effects of physical activity and genes on fitness and body composition, with special reference to body fat compartments, metabolic syndrome components and related diseases and risk factor levels, status of arteries, structure and function of the heart, bone properties, and muscle and fat tissue-related mechanisms linked to physical activity and chronic disease development. Our physical activity assessments showed that inactive co-twins were on average 8.8 MET hours/day less active than their active co-twins through out their midlife (2.2+/-2.3 vs. 11.0+/-4.1 MET h/day, p< .001). Follow-up fitness tests showed that physically inactive co-twins were less fit than their active co-twins (estimated VO(2peak) 26.4+/-4.9 vs. 32.5+/-5.5 ml/kg/min, p< .001). Similar differences were found in both MZ and DZ pairs. On the basis of earlier epidemiological observations on nonrelated individuals, these physical activity and fitness differences are large enough to cause differences in many mechanisms and risk factors related to the development of chronic diseases and to permit future analyses. PMID:19210186

  12. Selective Reduction Using Intravascular Potassium Chloride Injection after Laser Surgery for Twin-Twin Transfusion Syndrome.

    PubMed

    Chmait, Ramen H; Kontopoulos, Eftichia V; Jackson, Marc; Horenstein, Janet; Timor-Tritsch, Ilan; Quintero, Rubén A

    2016-01-01

    Selective reduction (SR) via intravascular potassium chloride (KCl) injection is contraindicated in monochorionic twins due to the presence of placental vascular communications, which may serve as a conduit for inter-twin passage of KCl or allow exsanguination of the living twin into the demised twin. After successful selective laser photocoagulation of communicating vessels (SLPCV) for twin-twin transfusion syndrome (TTTS), the twins' circulatory systems are rendered independent. Theoretically, intravascular KCl injection into one twin after successful SLPCV should not result in passage of the feticidal agent nor cause hemodynamic alterations in the co-twin. We describe 3 cases of 1,069 patients (0.3%) that underwent SLPCV for TTTS between 2003 and 2013 and subsequent SR. SLPCV was successfully completed at 180, 226, and 230 weeks' gestational age for Quintero stages III, IV, and III TTTS, respectively. SR via intravascular KCl injection was later performed at maternal request due to the risk of neurological compromise in one twin at 226, 254, and 236 weeks' gestational age. All co-twins survived after SR, and no neurological sequelae were suspected after birth. Further study is necessary before SR can be routinely considered after laser surgery for TTTS. PMID:26067899

  13. Math Fluency Is Etiologically Distinct from Untimed Math Performance, Decoding Fluency, and Untimed Reading Performance: Evidence from a Twin Study

    ERIC Educational Resources Information Center

    Petrill, Stephen; Logan, Jessica; Hart, Sara; Vincent, Pamela; Thompson, Lee; Kovas, Yulia; Plomin, Robert

    2012-01-01

    The authors examined whether math fluency was independent from untimed math and from reading using 314 pairs of school-aged twins drawn from the Western Reserve Reading and Math Projects. Twins were assessed through a 90-min home visit at approximately age 10 and were reassessed in their homes approximately 1 year later. Results suggested that the…

  14. The Nature of Covariation between Autistic Traits and Clumsiness: A Twin Study in a General Population Sample

    ERIC Educational Resources Information Center

    Moruzzi, Sara; Ogliari, Anna; Ronald, Angelica; Happe, Francesca; Battaglia, Marco

    2011-01-01

    While social impairment, difficulties with communication, and restricted repetitive behaviors are central features of Autism Spectrum Disorders, physical clumsiness is a commonly co-occurring feature. In a sample of 398 twin pairs (aged 8-17 years) from the Italian Twin Registry we investigated the nature of the co-variation between a psychometric…

  15. Birth Weight and Attention-Deficit/Hyperactivity Symptoms in Childhood and Early Adolescence: A Prospective Swedish Twin Study

    ERIC Educational Resources Information Center

    Hultman, Christina M.; Torrang, Anna; Tuvblad, Catherine; Cnattingius, Sven; Larsson, Jan-Olov; Lichtenstein, Paul

    2007-01-01

    Objective: To determine whether low birth weight increases the risk of attention-deficit/hyperactivity disorder (ADHD) in childhood and early adolescence. Method: In a population-based sample of 1,480 twin pairs born in the period 1985-1986 ascertained from the Swedish Twin Registry, birth weight was collected prospectively through the Medical…

  16. Revisiting the association between reading achievement and antisocial behavior: new evidence of an environmental explanation from a twin study.

    PubMed

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

    2006-01-01

    Previous studies have reported, but not explained, the reason for a robust association between reading achievement and antisocial behavior. This association was investigated using the Environmental Risk (E-Risk) Longitudinal Twin Study, a nationally representative 1994-1995 birth cohort of 5- and 7-year-olds. Results showed that the association resulted primarily from environmental factors common to both reading and antisocial behavior and was stronger in boys. Environmental factors also explained the relation between reading disability and conduct disorder. Leading candidate environmental risk factors weakly mediated the association. For boys the best explanation was a reciprocal causation model: poor reading led to antisocial behavior, and vice versa. In contrast, the relation between reading achievement and attention deficit hyperactivity disorder was best explained by common genetic influences. PMID:16460526

  17. Plasticity and ultra-low stress induced twin boundary migration in nanotwinned Cu by in situ nanoindentation studies

    SciTech Connect

    Liu, Y.; Chen, Y.; Jian, J.; Wang, H.; Zhang, X.

    2014-06-09

    Nanotwinned metals have rare combinations of mechanical strength and ductility. Previous studies have shown that detwinning occurs in plastically deformed nanotwinned metals. Although molecular dynamics simulations have predicted that fine nanotwins can migrate at low stress, there is little in situ evidence to validate such predictions. Also it is unclear if detwinning occurs prior to or succeeding plastic yielding. Here, by using in situ nanoindentation in a transmission electron microscope, we show that a non-elastic detwinning process in nanotwinned Cu occurred at ultra-low indentation stress (0.1 GPa), well before the stress necessary for plastic yielding. Furthermore, the in situ nanoindentation technique allows us to differentiate dislocation-nucleation dominated microscopic yielding preceding macroscopic yielding manifested by dislocation-transmission through twin boundaries. This study thus provides further insights for understanding plasticity in nanotwinned metals at microscopic levels.

  18. Numerical study on mixing performance of glass fiber dispersion in a twin-screw extruder with backward-mixing elements

    NASA Astrophysics Data System (ADS)

    Hirata, Kunihiro; Ishida, Hiroshi; Hiragori, Motohiro; Nakayama, Yasuya; Kajiwara, Toshihisa

    2015-05-01

    In the kneading of glass-fiber-reinforced plastics by twin-screw extrusion, the use of a backward-mixing screw (BMS) element for melt mixing has been found to be effective in dispersing glass-fiber bundles. In this study, we use the computational fluid dynamics (CFD) to study the mechanism of dispersion by a BMS element for glass fiber bundles. The result of CFD for a BMS and a forward kneading disk (FKD) reveals that the melt mixing by a BMS is highly effective to act the required stress on overall resin. In addition, there is a good correlation between the incidence of undispersed glass-fiber bundles measured experimentally and the minimum value of distribution of the time-integrated stress calculated numerically. On the basis of the above results, we propose a method to predict the operating conditions in which the incident probability of undispersed glass-fiber bundles and thermal degradation are controlled.

  19. "The Bell Curve" on Separated Twins.

    ERIC Educational Resources Information Center

    Fancher, Raymond E.

    1995-01-01

    "The Bell Curve" declares that studies of separated identical twins--the "purest" of "direct" methods for estimating IQ heritability--indicate a value of +.75-+.80. But, the main study cited suggests a heritability of "two-thirds" for the middle class, and Herrnstein and Murray neglect to mention numerous complicating factors in twin studies that…

  20. Twinning in multicrystalline silicon for solar cells

    NASA Astrophysics Data System (ADS)

    Stokkan, G.

    2013-12-01

    Twinning in multicrystalline silicon was studied by observing the surface of as-cut wafers and by EBSD. By tracing twin structures downwards to their first point of origin, the conditions at the point of generation were identified. Twins covering the whole width of a grain predominantly originates at junctions between three grain boundaries. Twins also originate at straight grain boundary segments of alternating direction, indicative of faceted grain boundaries. The phenomena are proposed to occur because they reduce grain boundary energy, which is substantiated by pole figure analysis. In addition to the CSL relationship, the orientation of the grain boundary in low energy configurations turned out to be essential.

  1. Genetic effects on serum testosterone and sex hormone-binding globulin in men: a Korean twin and family study

    PubMed Central

    Sung, Joohon; Song, Yun-Mi

    2016-01-01

    We conducted a community-based cross-sectional study to evaluate the role of genetics in determining the individual difference in total testosterone and sex hormone-binding globulin levels. Study participants comprised 730 Korean men consisting of 142 pairs of monozygotic twins, 191 pairs of siblings, and 259 father-offspring pairs from 270 families who participated in the Healthy Twin study. Serum concentration of total testosterone and sex hormone-binding globulin were measured by chemiluminescence immunoassay, and free testosterone and bioavailable testosterone were calculated using Vermeulen's method. Quantitative genetic analysis based on a variance decomposition model showed that the heritability of total testosterone, free testosterone, bioavailable testosterone, and sex hormone-binding globulin were 0.56, 0.45, 0.44, and 0.69, respectively after accounting for age and body mass index. Proportions of variance explained by age and body mass index varied across different traits, from 8% for total testosterone to 31% for sex hormone-binding globulin. Bivariate analysis showed a high degree of additive genetic correlation (ρG = 0.67) and a moderate degree of individual-specific environmental correlation (ρE = 0.42) between total testosterone and sex hormone-binding globulin. The findings confirmed the important role of genetics in determining the individually different levels of testosterone and sex hormone-binding globulin during adulthood in Korean men as found in non-Asian populations, which may suggest that common biologic control for determining testosterone level directly or indirectly through binding protein are largely shared among different populations. PMID:26486061

  2. A twin study of self-regulatory eating in early childhood: Estimates of genetic and environmental influence, and measurement considerations

    PubMed Central

    Faith, Myles S.; Pietrobelli, Angelo; Heo, Moonseong; Johnson, Susan L.; Keller, Kathleen L.; Heymsfield, Steven B.; Allison, David B.

    2016-01-01

    Objective Children differ greatly in their ability to self-regulate food intake for reasons that are poorly understood. This laboratory-based twin study tested genetic and environmental contributions to self-regulatory eating and body fat in early childhood. Methods Sixty-nine 4 to 7 year-old same-sex twin pairs, including 40 monozygotic (MZ) and 29 dizygotic (DZ) pairs, were studied. Self-regulatory eating was operationalized as the percentage compensation index (COMPX%), assessed by a “preload” challenge in which lunch intake was measured following a low- (3 kcal) or high-calorie (159 kcal) drink. Body fat indexes also were measured. The familial association for COMPX% was estimated by an intraclass correlation, and biometric analyses estimated heritability. Results Children ate more at lunch following the low- compared to high-energy preload (p< 0.001), although variability in COMPX% was considerable. Compensation was significantly poorer among African American and Hispanic compared to European American children, and among girls compared to boys. There was a familial association for self-regulatory eating (ρ= 0.23, p= 0.03) but no significant genetic component. Twenty two percent of the variance in COMPX% was due to shared environmental (‘household’) factors, with the remaining variance attributable to child-specific (‘unique’ or ‘random’) environments. Poorer self-regulatory eating was associated with greater percent body fat (r= −0.21, p= 0.04). Conclusions Self-regulatory eating was influenced by environmental factors, especially those differing among siblings. The absence of a significant genetic effect may reflect age of the sample or could be artifactual due to measurement issues that need to be considered in future studies. PMID:22249227

  3. Genetic effects on serum testosterone and sex hormone-binding globulin in men: a Korean twin and family study.

    PubMed

    Sung, Joohon; Song, Yun-Mi

    2016-01-01

    We conducted a community-based cross-sectional study to evaluate the role of genetics in determining the individual difference in total testosterone and sex hormone-binding globulin levels. Study participants comprised 730 Korean men consisting of 142 pairs of monozygotic twins, 191 pairs of siblings, and 259 father-offspring pairs from 270 families who participated in the Healthy Twin study. Serum concentration of total testosterone and sex hormone-binding globulin were measured by chemiluminescence immunoassay, and free testosterone and bioavailable testosterone were calculated using Vermeulen's method. Quantitative genetic analysis based on a variance decomposition model showed that the heritability of total testosterone, free testosterone, bioavailable testosterone, and sex hormone-binding globulin were 0.56, 0.45, 0.44, and 0.69, respectively after accounting for age and body mass index. Proportions of variance explained by age and body mass index varied across different traits, from 8% for total testosterone to 31% for sex hormone-binding globulin. Bivariate analysis showed a high degree of additive genetic correlation (ρG = 0.67) and a moderate degree of individual-specific environmental correlation (ρE = 0.42) between total testosterone and sex hormone-binding globulin. The findings confirmed the important role of genetics in determining the individually different levels of testosterone and sex hormone-binding globulin during adulthood in Korean men as found in non-Asian populations, which may suggest that common biologic control for determining testosterone level directly or indirectly through binding protein are largely shared among different populations. PMID:26486061

  4. Why does parental language input style predict child language development? A twin study of gene–environment correlation

    PubMed Central

    Dale, Philip S.; Tosto, Maria Grazia; Hayiou-Thomas, Marianna E.; Plomin, Robert

    2015-01-01

    There are well-established correlations between parental input style and child language development, which have typically been interpreted as evidence that the input style causes, or influences the rate of, changes in child language. We present evidence from a large twin study (TEDS; 8395 pairs for this report) that there are also likely to be both child-to-parent effects and shared genetic effects on parent and child. Self-reported parental language style at child age 3 and age 4 was aggregated into an ‘informal language stimulation’ factor and a ‘corrective feedback’ factor at each age; the former was positively correlated with child language concurrently and longitudinally at 3, 4, and 4.5 years, whereas the latter was weakly and negatively correlated. Both parental input factors were moderately heritable, as was child language. Longitudinal bivariate analysis showed that the correlation between the language stimulation factor and child language was significantly and moderately due to shared genes. There is some suggestive evidence from longitudinal phenotypic analysis that the prediction from parental language stimulation to child language includes both evocative and passive gene–environment correlation, with the latter playing a larger role. Learning outcomes: The reader will understand why correlations between parental language and rate of child language are by themselves ambiguous, and how twin studies can clarify the relationship. The reader will also understand that, based on the present study, at least two aspects of parental language style – informal language stimulation and corrective feedback – have substantial genetic influence, and that for informal language stimulation, a substantial portion of the prediction to child language represents the effect of shared genes on both parent and child. It will also be appreciated that these basic research findings do not imply that parental language input style is unimportant or that interventions

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

    PubMed Central

    MUTCHINICK, OSVALDO M.; LUNA-MUÑOZ, LEONORA; AMAR, EMMANUELLE; BAKKER, MARIAN K.; CLEMENTI, MAURIZIO; COCCHI, GUIDO; DUTRA, MARIA DA GRAÇA; FELDKAMP, MARCIA L.; LANDAU, DANIELLE; LEONCINI, EMANUELE; LI, ZHU; LOWRY, BRIAN; MARENGO, LISA K.; MARTÍNEZ-FRÍAS, MARÍA-LUISA; MASTROIACOVO, PIERPAOLO; MÉTNEKI, JULIA; MORGAN, MARGERY; PIERINI, ANNA; RISSMAN, ANKE; RITVANEN, ANNUKKA; SCARANO, GIOACCHINO; SIFFEL, CSABA; SZABOVA, ELENA; ARTEAGA-VÁZQUEZ, JAZMÍN

    2015-01-01

    Conjoined twins (CT) are a very rare developmental accident of uncertain etiology. Prevalence has been previously estimated to be 1 in 50,000 to 1 in 100,000 births. The process by which monozygotic twins do not fully separate but form CT is not well understood. The purpose of the present study was to analyze diverse epidemiological aspects of CT, including the different variables listed in the Introduction Section of this issue of the Journal. The study was made possible using the International Clearinghouse for Birth Defects Surveillance and Research (ICBDSR) structure. This multicenter worldwide research includes the largest sample of CT ever studied. A total of 383 carefully reviewed sets of CT obtained from 26,138,837 births reported by 21 Clearinghouse Surveillance Programs (SP) were included in the analysis. Total prevalence was 1.47 per 100,000 births (95% CI: 1.32–1.62). Salient findings including an evident variation in prevalence among SPs: a marked variation in the type of pregnancy outcome, a similarity in the proportion of CT types among programs: a significant female predominance in CT: particularly of the thoracopagus type and a significant male predominance in parapagus and parasitic types: significant differences in prevalence by ethnicity and an apparent increasing prevalence trend in South American countries. No genetic, environmental or demographic significant associated factors were identified. Further work in epidemiology and molecular research is necessary to understand the etiology and pathogenesis involved in the development of this fascinating phenomenon of nature. PMID:22002822

  6. Familial influences on the full range of variability in attention and activity levels during adolescence: A longitudinal twin study.

    PubMed

    Peng, Chun-Zi; Grant, Julia D; Heath, Andrew C; Reiersen, Angela M; Mulligan, Richard C; Anokhin, Andrey P

    2016-05-01

    To investigate familial influences on the full range of variability in attention and activity across adolescence, we collected maternal ratings of 339 twin pairs at ages 12, 14, and 16, and estimated the transmitted and new familial influences on attention and activity as measured by the Strengths and Weaknesses of Attention-Deficit/Hyperactivity Disorder Symptoms and Normal Behavior Scale. Familial influences were substantial for both traits across adolescence: genetic influences accounted for 54%-73% (attention) and 31%-73% (activity) of the total variance, and shared environmental influences accounted for 0%-22% of the attention variance and 13%-57% of the activity variance. The longitudinal stability of individual differences in attention and activity was largely accounted for by familial influences transmitted from previous ages. Innovations over adolescence were also partially attributable to familial influences. Studying the full range of variability in attention and activity may facilitate our understanding of attention-deficit/hyperactivity disorder's etiology and intervention. PMID:26612434

  7. A Twin and Adoption Study of Reading Achievement: Exploration of Shared-Environmental and Gene-Environment-Interaction Effects.

    PubMed

    Kirkpatrick, Robert M; Legrand, Lisa N; Iacono, William G; McGue, Matt

    2011-08-01

    Existing behavior-genetic research implicates substantial influence of heredity and modest influence of shared environment on reading achievement and reading disability. Applying DeFries-Fulker analysis to a combined sample of twins and adoptees (N = 4,886, including 266 reading-disabled probands), the present study replicates prior findings of considerable heritability for both reading achievement and reading disability. A simple biometric model adequately described parent and offspring data (combined N = 9,430 parents and offspring) across differing types of families present in the sample Analyses yielded a high heritability estimate (around 0.70) and a negligible shared-environmentality estimate for both reading achievement and reading disability. No evidence of gene × environment interaction was found for parental reading ability and parental educational attainment, the two moderators analyzed. PMID:21743785

  8. A Twin and Adoption Study of Reading Achievement: Exploration of Shared-Environmental and Gene-Environment-Interaction Effects

    PubMed Central

    Kirkpatrick, Robert M.; Legrand, Lisa N.; Iacono, William G.; McGue, Matt

    2011-01-01

    Existing behavior-genetic research implicates substantial influence of heredity and modest influence of shared environment on reading achievement and reading disability. Applying DeFries-Fulker analysis to a combined sample of twins and adoptees (N = 4,886, including 266 reading-disabled probands), the present study replicates prior findings of considerable heritability for both reading achievement and reading disability. A simple biometric model adequately described parent and offspring data (combined N = 9,430 parents and offspring) across differing types of families present in the sample Analyses yielded a high heritability estimate (around 0.70) and a negligible shared-environmentality estimate for both reading achievement and reading disability. No evidence of gene × environment interaction was found for parental reading ability and parental educational attainment, the two moderators analyzed. PMID:21743785

  9. Comparative Studies in Adult Education--A Review.

    ERIC Educational Resources Information Center

    Charters, Alexander N.

    One of the most important recent developments in comparative adult education (CAE) has been the formation in 1987 of the Committee for Study and Research in Comparative Adult Education (CSRCAE), jointly founded by the International Council of Adult Education and the International Congress of University Adult Education. The Committee continues to…

  10. Employment Placement Data of 1990-91 Occupational Graduates at Minnesota's Twin City Area Community Colleges. Metro Pilot Study Report #1.

    ERIC Educational Resources Information Center

    Taylor, Kenneth E.; Flermoen, Cynthia

    In 1991, followup studies of the employment and educational status of 1990-1991 occupational program graduates were conducted by the seven community colleges in the Twin Cities metro area of Minnesota: Anoka-Ramsey, Cambridge Center, Inver Hills, Lakewood, Minneapolis, North Hennepin, and Normandale. While the colleges used different questionnaire…

  11. Genetic and Environmental Influences on Socio-Emotional Behavior in Toddlers: An Initial Twin Study of the Infant-Toddler Social and Emotional Assessment

    ERIC Educational Resources Information Center

    Van Hulle, C. A.; Lemery-Chalfant, K.; Goldsmith, H. H.

    2007-01-01

    Background: Relatively little is known about the genetic architecture of childhood behavioral disorders in very young children. Method: In this study, parents completed the Infant-Toddler Social and Emotional Assessment, a questionnaire that assesses symptoms of childhood disorders, as well as socio-emotional competencies, for 822 twin pairs…

  12. Nature, Nurture, and Perceptions of the Classroom Environment as They Relate to Teacher-Assessed Academic Achievement: A Twin Study of Nine-Year-Olds

    ERIC Educational Resources Information Center

    Walker, Sheila O.; Plomin, Robert

    2006-01-01

    Although prior research has examined children's perceptions of the classroom environment as related to academic achievement, genetically sensitive designs have not been employed. In the first study of its kind for the primary school classroom environment, data were collected for 3,020 pairs of nine-year-old identical and fraternal twin pairs in…

  13. Attention Interchanges at Story-Time: A Case Study from a Deaf and Hearing Twin Pair Acquiring Swedish Sign Language in Their Deaf Family

    ERIC Educational Resources Information Center

    Cramer-Wolrath, Emelie

    2012-01-01

    This case study longitudinally analyzes and describes the changes of attentional expressions in interchanges between a pair of fraternal twins, 1 deaf and 1 hearing, from the age of 10-40 months, and their Deaf family members. The video-observed attentional expressions of initiating and reestablishing interchange were grouped in 5 functional…

  14. Genetic and Environmental Relationships between Head Circumference Growth in the First Year of Life and Sociocognitive Development in the Second Year: A Longitudinal Twin Study

    ERIC Educational Resources Information Center

    Fujisawa, Keiko K.; Ozaki, Koken; Suzuki, Kunitake; Yamagata, Shinji; Kawahashi, Ikko; Ando, Juko

    2012-01-01

    Although growth in head circumference (HC) during infancy is known to predict later childhood outcomes, the mechanisms underlying this association with later sociocognitive abilities remain undetermined. Thus, using a sample of 241 pairs of normally developing Japanese twins, this study investigated the underpinnings of the association between HC…

  15. Exotic quarks in Twin Higgs models

    DOE PAGESBeta

    Cheng, Hsin -Chia; Jung, Sunghoon; Salvioni, Ennio; Tsai, Yuhsin

    2016-03-14

    The Twin Higgs model provides a natural theory for the electroweak symmetry breaking without the need of new particles carrying the standard model gauge charges below a few TeV. In the low energy theory, the only probe comes from the mixing of the Higgs fields in the standard model and twin sectors. However, an ultraviolet completion is required below ~ 10 TeV to remove residual logarithmic divergences. In non-supersymmetric completions, new exotic fermions charged under both the standard model and twin gauge symmetries have to be present to accompany the top quark, thus providing a high energy probe of themore » model. Some of them carry standard model color, and may therefore be copiously produced at current or future hadron colliders. Once produced, these exotic quarks can decay into a top together with twin sector particles. If the twin sector particles escape the detection, we have the irreducible stop-like signals. On the other hand, some twin sector particles may decay back into the standard model particles with long lifetimes, giving spectacular displaced vertex signals in combination with the prompt top quarks. This happens in the Fraternal Twin Higgs scenario with typical parameters, and sometimes is even necessary for cosmological reasons. We study the potential displaced vertex signals from the decays of the twin bottomonia, twin glueballs, and twin leptons in the Fraternal Twin Higgs scenario. As a result, depending on the details of the twin sector, the exotic quarks may be probed up to ~ 2.5 TeV at the LHC and beyond 10 TeV at a future 100 TeV collider, providing a strong test of this class of ultraviolet completions.« less

  16. Exotic quarks in Twin Higgs models

    NASA Astrophysics Data System (ADS)

    Cheng, Hsin-Chia; Jung, Sunghoon; Salvioni, Ennio; Tsai, Yuhsin

    2016-03-01

    The Twin Higgs model provides a natural theory for the electroweak symmetry breaking without the need of new particles carrying the standard model gauge charges below a few TeV. In the low energy theory, the only probe comes from the mixing of the Higgs fields in the standard model and twin sectors. However, an ultraviolet completion is required below ˜ 10 TeV to remove residual logarithmic divergences. In non-supersymmetric completions, new exotic fermions charged under both the standard model and twin gauge symmetries have to be present to accompany the top quark, thus providing a high energy probe of the model. Some of them carry standard model color, and may therefore be copiously produced at current or future hadron colliders. Once produced, these exotic quarks can decay into a top together with twin sector particles. If the twin sector particles escape the detection, we have the irreducible stop-like signals. On the other hand, some twin sector particles may decay back into the standard model particles with long lifetimes, giving spectacular displaced vertex signals in combination with the prompt top quarks. This happens in the Fraternal Twin Higgs scenario with typical parameters, and sometimes is even necessary for cosmological reasons. We study the potential displaced vertex signals from the decays of the twin bottomonia, twin glueballs, and twin leptons in the Fraternal Twin Higgs scenario. Depending on the details of the twin sector, the exotic quarks may be probed up to ˜ 2.5TeV at the LHC and beyond 10TeV at a future 100TeV collider, providing a strong test of this class of ultraviolet completions.

  17. [Ultrasonography of twin pregnancies].

    PubMed

    Grignon, A; Dubois, J

    2002-12-01

    Sonographers must be familiar with the diagnostic tools available to them for determining twin pregnancy type. During the first trimester, these tools include the number of chorionic sacs, the number of yolk sacs, and the presence of an inter-twin membrane. During the second trimester, sonographers must look for a difference in sex, the presence of two separate placentas, and a thick vs. thin membrane, or the absence of a membrane. Complications are frequent in twin pregnancies and may be maternal or fetal. Measuring cervical length is the only way for sonographers to predict pre-term labour. A cervical length of< or =2.5 cm before 23 weeks is significant. Some fetal anomalies are more frequent in twin pregnancy than in single pregnancy. The more frequent are: esophageal atresia, omphalocele and cardiac anomalies. Some fetal anomalies are peculiar to twin pregnancy: Siamese twins, digestive atresia, craniofacial deformation and club-foot. A significant growth asymmetry is defined as a CRL of 3 or more millimetres and a difference of 20% in weight. The poly-oligo sequence represents a severe level asymmetry of amniotic fluid in monodiamniotic twins where survival rate without sequelae is 13.6%. The twin-twin transfusion syndrome is an event occurring after the apparition of the poly-oligo sequence, which manifests by discordances in weight and hemodynamic changes leading to myocardial repercussion. Twin embolization syndrome follows the in utero death of a co-twin in a monochorionic twin pregnancy; ischemic events must be monitored in such cases. Cord entanglement is unpredictable and is specific to monochorionic monoamniotic twin pregnancies. Finally, an acardius is a parasitic twin that feeds on its co-twin, resulting in the viable twin's death in 50% of cases. PMID:12592152

  18. Twin chamber sample assembly in DAC and HPHT studies on GaN nano-particles

    NASA Astrophysics Data System (ADS)

    Shukla, Balmukund; Shekar, N. V. Chandra; Kumar, N. R. Sanjay; Ravindran, T. R.; Sahoo, P.; Dhara, S.; Sahu, P. Ch

    2012-07-01

    In this paper, we have suggested a novel idea of twin chamber sample assembly for separating ruby from the sample to overcome certain problems during high pressure-high temperature experiments using diamond anvil cell. Two holes of diameter 70μm were drilled symmetrically about the centre of the preindented area (500 μm diameter) in a stainless steel gasket using EDM. Using ruby pressure calibration, good pressure correlation between these two holes was established up to about 15GPa. Also, high pressure - high temperature (HPHT) experiments on the III-V compound semiconductor GaN were performed up to ~ 3GPa and 2000K using the two chamber sample assembly and a laser heated diamond anvil cell facility. NaCl, both hydrous and anhydrous, were used as the pressure transmitting media in two separate experiments. Micro-Raman spectroscopy was used to characterise the HPHT treated samples. While GaN remained stable in its wurtzite phase when heated in anhydrous NaCl medium, it transformed to Ga2O3 with rocksalt structure in the hydrous NaCl medium.

  19. Genetic determination of telomere size in humans: A twin study of three age groups

    SciTech Connect

    Slagboom, P.E.; Droog, S.; Boomsma, D.I.

    1994-11-01

    Reduction of telomere length has been postulated to be a casual factor in cellular aging. Human telomeres terminate in tandemly arranged repeat arrays consisting of the (TTAGGG) motif. The length of these arrays in cells from human mitotic tissues is inversely related to the age of the donor, indicating telomere reduction with age. In addition to telemore length differences between different age cohorts, considerable variation is present among individuals of the same age. To investigate whether this variation can be ascribed to genetic influences, we have measured the size of terminal restriction fragments (TRFs) in HaeIII-digested genomic DNA from 123 human MZ and DZ twin pairs 2-95 years of age. The average rate of telomere shortening was 31 bp/year, which is similar to that observed by others. Statistical analysis in 115 pairs 2-63 years of age indicates a 78% heritability for mean TRF length in this age cohort. The individual differences in mean TRF length in blood, therefore, seem to a large extent to be genetically determined. 24 refs., 4 figs., 2 tabs.

  20. Deformation twins in Hornblende

    USGS Publications Warehouse

    Rooney, T.P.; Riecker, R.E.; Ross, M.

    1970-01-01

    Hornblende deformation twins with twin planes parallel to (101) are produced experimentally in single crystals by compression parallel to the c axis. Twinning occurs at confining pressures from 5 to 15 kilobars and temperatures from 400?? to 600??C (strain rate, 10-5 per second).