Dorret Boomsma

..We explore whether the current change in environmental conditions has influenced the genetic architecture of smoking. This would constitute evidence for Gene × Environment (G×E) interaction...

..The objective of this study is to examine factors associated with birth weight in a large, population-based sample of triplets registered with the Netherlands Twin Register (NTR)...

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..Using structural equation modelling we assessed the heritability of several performance indices derived from those tasks...

..The aim of this study is the identification of functional (non)coding variants underlying cognitive phenotypic variation...

..043). We review evidence for linkage in this region for psychiatric disorders and discuss our findings within this context...

..Because of their design, these registers offer unique opportunities for selected sampling for quantitative trait loci linkage and association studies...

..In contrast, for males, variance in the evening bedtime is so affected by environmental circumstances, that the genetic contribution to the variance becomes negligible...

..Heritability for individual differences in the intercept was estimated at 77%. For the item 'Nobody loves me' no significant trend over age was seen; the heritability of the intercept was estimated at 70%...

..Twin studies of obsessive-compulsive disorder have indicated a significant genetic component to its expression...

..Whether these factors operate in addition to or in interaction with genetic disposition is to be elucidated in future studies...

..In addition to a shared set of genes that influenced all phenotypes, there were also genetic influences specific to the different verbal phenotypes...

..Female jerk and snap, and also female height at birth and height at 2 years of age, are mostly under control of the same additive genetic factor...

..However, the association occurred in the absence of evidence for linkage in this region on chromosome 2...

..In addition, our findings suggest that the association between birth weight and sympathetic activity depends on genetic factors...

..Non-shared environmental effects accounted for the remaining covariance over time...

..At the environmental level, in both age cohorts, environmental factors create differences between these domains...

..The finding of larger mean testis volume in dizygotic twins may be of interest for future research into the mechanisms underlying dizygotic twinning...

..To account for these discrepant findings, we hypothesize that genetic and environmental risk factors differently impact on amygdala functioning...

..A difference between genetical and environmental etiologies may relate to the amount of reduced striatal responsiveness...

..To examine differences in body composition and smoking between mothers of spontaneous monozygotic and dizygotic twins, while taking into account maternal age, gravidity, and educational attainment...

..Twinning is not more familial in women who have their twins at a younger age...

..This result illustrates the relevance of comparative genomics to detect genes that are involved in human behavior...

..As an alternative hypothesis, we suggest that a decrease in cholesterol clearance may play an important role...

..These results indicate that autistic traits have specific characteristics that are substantially genetically independent from other common but related behavioral domains such as social problems and withdrawn behavior...

..To study familial and nonfamilial environmental influences on attention problems and attention-deficit/hyperactivity disorder (ADHD) in monozygotic twins discordant and concordant-high and low for these traits...

..PsycINFO Database Record (c) 2009 APA, all rights reserved)...

..To investigate whether there is an association between catch-up growth and cognitive performance in humans...

..The overall pattern of results suggests that measures related to accuracy are more informative than measures related to speed of responding in refining the cognitive phenotype of ADHD...

..Men scored higher than women and science students higher than non-science students. The Dutch translation of the AQ is a reliable instrument to assess autism spectrum conditions...

..Use of the Contamination dimension could therefore provide a powerful approach for the detection of genetic susceptibility loci that contribute to OCS...

..Heritability was 63% for Attention problems, around 45% for Withdrawn, Social Problems, Aggressive Behavior and Rule Breaking Behavior, and around 30% for Anxious/Depressed, Thought Problems and Somatic Complaints...

..We also briefly mention a few extensions of the model that become naturally available once the model is implemented in such procedures...

..However, after a normalizing transformation, the Jinks and Fulker test performed slightly better. Some possible future extensions of the MML-based test are briefly discussed...

..Mutations in one of these genes (growth differentiation factor 9) are significantly more frequent in mothers of DZ twins. However, the mutations are rare and only account for a small part of the genetic contribution for twinning...

..79 < r < 0.88) of eyes-closed resting-state magnetoencephalogram power, which is insensitive to intervening tissues. These results confirm that brain activity itself is highly heritable...

..Current biological psychiatric models assume that genetic and environmental risk factors for anxiety and depression act on the same brain structures...

..Further replication is needed to establish the relevance of our linkage finding on chromosome 2...

..In this paper we give an update on the YNTR and ANTR phenotyping and on the ongoing ANTR biobank studies...

..21 for systolic blood pressure was observed on chromosome 13q34. These results replicate earlier findings and add to a slowly emerging picture of multiple loci contributing to quantitative blood pressure variation...

..Furthermore, the extent to which there are qualitative and quantitative differences in genetic architecture between men and women with OC symptoms has not been elucidated...

..To explore genetic and environmental influences on individual differences in autistic traits in early adulthood and to test if there is assortative mating (nonrandom partner choice) for autistic traits in the general population...

..To date, no genome-wide linkage study has been conducted to identify the genomic region(s) containing the quantitative trait loci that influence the manifestation of BPD features...

..A twin design was used to test whether the association between exercise behavior and heart rate and the association between exercise behavior and respiratory sinus arrhythmia (RSA) derive from a common genetic factor...

..The substantial impact of genetic factors on nicotine dependence emphasizes the need for further research to localize and identify specific genes and pathways involved in nicotine dependence...

..A twin design was used to assess the relative contribution of genetic and environmental influences on the variation in sports participation of Dutch male and female twins between the ages of 13 and 20 yr...

..The analysis of L-shaped distributed data with normal theory ML results in biased parameter estimates. Unbiased parameter estimates are obtained with categorical data analysis, but the power decreases...

..It offers opportunities for DNA-based and gene expression studies as well as for future metabolomic and proteomic projects...

..These results may help clarify the nature of ADHD, which is characterized by problems with response interference...

..To review the methodology of behavior genetics studies addressing research questions that go beyond simple heritability estimation and illustrate these using representative research on childhood and adolescent anxiety and depression...

..78 > R(G) > .98). These results indicate that head circumference is a highly heritable biometric trait and a valid target for future GWA studies...

..Future studies on adolescent exercise behavior should focus on identification of the generation specific environmental factors...

..2 for hyperactivity was also found. Heritability of inattention, hyperactivity and total ADHD symptoms is lower in adults than in children. Chromosomes 18q and 2p are likely to harbor genes that influence several aspects of adult ADHD...

..This study investigates two models that have been used to explain the agreement and disagreement between mothers and fathers in the ratings of their children...

..The results showed clear familial resemblances on performance. It proved difficult to ascribe these effects to shared genes or to shared environment. An exception was memory search rate, which was clearly heritable...

..12 and .23). Children with a larger amount of child care did not show more behavior problems, therefore it was questioned whether the increased levels of behavior problems could be attributed to quantity of child care...

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..This peak encloses the D1A dopamine receptor gene which is a functional candidate gene for smoking behavior...

..A. Teasdale, R. D, and Box, N. F. (2001). Gene 277:49-62]. Our results demonstrate that comparative measures on relatives can be used in genetic linkage analysis...

..Genetic correlations across time were high, suggesting that the genes that influence variability in attention problems in late adolescence are largely the same as those that influence variability in early adulthood...

..This cortisol awakening response provides a useful endophenotype in the search for genes that may affect hypothalamic-pituitary adrenocortical functioning in children...

..42-.46) and CO (.43-.50) improved. CONCLUSION: Moderate long-term temporal stability is found for individual differences in ambulatory stroke volume and cardiac output measured by impedance cardiography...

..The findings were the same for monozygotic and dizygotic twins...

..Future studies in European and other populations will reveal whether these results are specific to the Dutch population...

..The variance in coffee preference (defined as the proportion of coffee consumption relative to the consumption of coffee and tea in total) was explained by genetic factors (62%) and unique environmental factors (38%)...

..To explain the differential course of anxiety and depression in individuals from childhood to adulthood by examining age-related changes in the genetic and environmental etiology of anxious and depressive symptoms...

..It also suggests that the power of genome-wide association studies to identify the genetic variants contributing to physical activity may be larger in young adult cohorts...

..This poor concordance in LD block structure suggests that large samples are required for robust estimations of local LD block structure in populations...

..To examine whether ceiling effects at long inter beat intervals (IBIs)cause an underestimation of cardiac vagal control in regular exercisers by time and frequency-domain measures of respiratory sinus arrhythmia (RSA)...

..We propose that the DFA method is an important complement to classical spectral analysis in fundamental and clinical research on ongoing oscillations...

..These studies typically used DSM ADHD symptoms collected by telephone or interviews with mothers. The purpose of this study was to test the genetic architecture of ADHD by using the ADHD index from Conners' Rating Scales-Revised...

..To estimate the genetic and environmental contributions to oppositional defiant behavior (ODB) from mother, father, and teacher report using the Conners Revised Short Forms in a large twin sample...

..The new method can be extended to more general pedigrees and multivariate phenotypes in a similar way as the original variance components method...

..This finding of a common genetic factor provides a better target for identifying genes involved in cognition than genes which are unique to specific traits...

..Although sample specific effects are present, we have shown that genes play a major role in determining the variance of apolipoprotein and lipid levels in four independent twin samples from three different countries...

..In conclusion, application of a new meta-analysis approach maximised the power to detect QTLs for lipid levels and improved the precision of their location estimate...

..We conclude that rare mutations in GDF9 may influence twinning, but twinning frequency is not associated with common variation in GDF9...

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..CONCLUSION: In preschoolers, familial resemblances on sustained attention and inhibition were observed...

..Twin studies have also contributed to our understanding of the life course hypothesis, and GenomEUtwin has the potential to add to this...

..Furthermore, they suggest that strategies to identify predisposing genes may benefit from taking into account potential sex specific effects...

..Our results indicate that, in general, there are only minor differences in the genetic architecture of height between affluent Caucasian populations, especially among men...

..Polymorphisms in 5,10-methylenetetrahydrofolate reductase (MTHFR) have been associated with dizygotic (DZ) twinning through pregnancy loss...

..The covariation among the WAIS group factors and the covariation between the group factors and the Raven is predominantly influenced by a second-order genetic factor and strongly support the notion of a biological basis of g...

..Throughout, Rubin's general theory of inference with missing data serves as an integrating framework...

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..For BMI, both the genetic and the environmental variance components were larger in Spanish than in Dutch women...

..There was no evidence of non-random mating for extraversion in the parental generation. Results show that in addition to additive genetic influences, extraversion in adolescents is influenced by non-additive genetic factors...

..The objective of the study was to assess relative maternal and paternal genetic influences on birth timing...

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..Environmental factors affecting height and BMI during growth period are also important, and further studies are needed to identify these factors and test whether they interact with genetic factors...

..The aim of this study was to examine whether the drinking habits of parents, siblings, and friends were related to regular drinking in adolescents and young adults, cross-sectionally as well as longitudinally...

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..Age differences indicated that these risks decreased with age. Irrespective of age, regular drinking of fathers and mothers posed the lowest risk. Findings were generally the same for males and females...

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..Findings suggest that physical activity may be beneficial to both general and selective aspects of cognition, particularly among older adults...

..We previously identified a deletion mutation in GDF9 in sisters with spontaneous dizygotic (DZ) twins, but the prevalence of rare GDF9 variants in twinning families is unknown...

..30% between the Australian and the Netherlands cohorts, a smaller value than between many European groups. We conclude that it is reasonable to combine the Australian and the Netherlands samples for joint genetic analyses...