D I Boomsma

..In contrast to the large number of studies in children, there is little information on the contribution of genetic factors to Attention Deficit Hyperactivity Disorder (ADHD) in adults...

..A simultaneous analysis of all three loci showed that both the apoE and the apoA4 polymorphism did not contribute significantly to Lp(a) variation...

..We detail how these data were used to select families for the QTL study and discuss strategies that may help elucidate the molecular pathways leading from genes to anxious depression...

..Large cohorts of phenotyped family members from the general population are very valuable for genetic epidemiological studies and permit selection of informative families for gene finding studies...

..Taken together, these results confirm and expand the hypothesis that individual differences in plasma levels of noncholesterol sterols are moderately (lathosterol) to highly (plant sterols) heritable...

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..These findings may provide support for why certain family therapeutic approaches are effective in the A/D spectrum of illnesses...

..All resemblance between twin relatives was explained by shared genes, without any suggestion of a contribution of shared environmental factors...

..The purpose of this study is to assess the developmental stability of the CBCL-JBD phenotype across ages 7, 10, and 12 years in a large population-based twin sample and to examine its genetic architecture...

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

..Genome-wide association results are open-access and can be viewed at the dbGAP web portal (http://www.ncbi.nlm.nih.gov). Approved users can download the genotype and phenotype data, which have been made available as of 9 October 2007...

..The resemblances between twins for the Disinhibition scale differ according to their religious upbringing. Receiving a religious upbringing seems to reduce the influence of genetic factors on Disinhibition, especially in males...

..A short description of 16 registries in nine European countries is presented. These registries have access to over 350000 twin pairs and are a major resource for genetic-epidemiological research...

..An advantage of this approach is that, rather than employing phenotypic selection, individuals with extreme genotypes may selected when ascertaining a sample of extreme families...

..The gain in power attributable to the use of factor scores, however, outweighs this observed loss in power. The advantages of using factor scores in selecting sib-pairs are discussed...

..For DBP in males no significant contributions of shared environment were found. The multivariate analyses indicated that the same genetic and environmental influences are expressed during rest and stress conditions...

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..Two homolog genes lie in this region -Dlk1 (delta-like 1 homolog, Drosophila) and Rtl1 (retrotransposon-like 1). Future association studies of these genes are warranted...

..Analyses of data provided by both parents and collected over multiple ages did not result in better prediction of zygosity. Details on the discriminant function are provided...

..Significant age-specific influences were found for all components, indicating that genetic and environmental factors also contributed to changes in problem behavior...

..The effect of genes that influence environmental exposure might be mediated through personality and we therefore also examined the association between life events and personality (neuroticism and extraversion)...

..Overall, there has been no convincing evidence, so far, for a role of genetic variation in these pathways in the development of anxiety and depression...

..We conclude that the connectivity parameters SL, CC, and L in the alpha band show the hallmarks of a good endophenotype for behavior and developmental disorders...

..It is concluded that twin studies provide reliable estimates of heritabilities of intellectual abilities which can be generalised to the singleton population...

..To examine whether regular exercise is associated with anxiety, depression and personality in a large population-based sample as a function of gender and age...

..As a result, functional polymorphisms in (non)coding regulatory sequences may affect spatial and temporal regulation of gene expression underlying normal cognitive variation...

..As the presence of genotype-environment correlation (rGE) can lead to spurious findings of genotype-environment interaction (G × E), we also test whether BPD features increase the likelihood of exposure to life events...

..Again it was not possible to show that the shared factors where either genetic or shared environmental...

..These results suggest that fMRI activation of the LIFG in a verbal emotional memory task may be a useful vulnerability marker for anxiety and depression...

..There was no evidence of a genetic correlation between alpha peak frequency and any of the four WAIS dimensions: Smarter brains do not seem to run faster...

..The implications of these findings are discussed with reference to the clinical setting and in the context of future research...

..Genes in this area (GFRA1, ADORA2L, FGR2, EMX2, and HMX2) can be considered promising positional candidates for genetic association studies of respiratory control during sleep...

..So, co-occurrence in AGG and RB is mainly caused by a common set of genes. Parental disagreement seems to be a combination of so-called rater bias and of parental specific views...

..Our aim was to provide an overview of prospective studies that have addressed the association between attention problems (AP, i.e. symptoms of hyperactivity and inattentiveness) and academic achievement (AA)...

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..We investigated the association between leisure time exercise participation and well-being (i.e., life satisfaction and happiness) and examined the causality underlying this association...

..Evidence for a special twin environment was limited to boredom susceptibility in females...

..Because Attention Problems that are persistent over situations may indicate more serious behavior problems than context dependent Attention Problems, we believe that gene finding strategies should focus on this common phenotype...

..Shared environmental influences were found for aggressive behavior, anxiety problems, dependency, and emotional lability. Rater contrast and/or sibling interaction effects were found for attention problems and physical coordination...

..These extensions can be implemented when parental genotypes are available or unavailable...

..e., high concordant MZ pairs) vs. environmental (i.e., high-low discordant MZ pairs) risk factors. These results provide clues that further our understanding of brain alterations in ADHD...

..We propose that identification of the genes that cause differences in exercise behavior will help resolve the issue of causality...

..Understanding causes of individual differences in external factors may aid in clarifying the intricate nature between genetic and environmental influences on complex traits...

..Environmental factors shared by twin siblings did not influence variation in EEG coherence. These results suggest that individual differences in coherence form a potential candidate for (molecular) genetic studies on brain function...

..We estimated the heritability of individual differences in beta cell function after a mixed meal test designed to assess a wide range of classical and model-derived beta cell function parameters...

..Heritability (obtained from the frailties rather than actual onset times) was estimated as 0.42; this value was highly significant. The highest lod score, a score of 1.9, was found at the end of chromosome 19...

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..This study suggests shared genetic risk factors for neuroticism and MDD on the one hand and for extraversion and BD on the other...

..The phenotypic stability of the P300 amplitude from 16 to 18 years was high in both sexes, and stability could be attributed largely to the same familial factors. There was no evidence that new familial influences emerged at age 18...

..e. including families with twins and one or two additional siblings increases the statistical power to detect sources of variance due to additive and non-additive genetic influences, and common environment...

..The scripts are written to be used with the freely available software package Mx and provide a flexible and uniform approach to the analysis of data from relatives...

..This is in line with the suggestion of increasing heritability of IQ in adulthood...

..The aim of this study was to investigate the relative contribution of genes and environment to individual differences in life satisfaction in a large sample of Dutch twins and their singleton siblings...

..However, the genetic correlation between the generations turned out to be lower than 0.5, suggesting that different genes for morningness-eveningness are expressed in both generations...

..The soundness of these recommendations is subsequently in a number of test cases...

..Whether or not they were raised religiously, the liability to alcohol use initiation in males was moderately influenced by genetic factors (30%) and substantially influenced by shared environmental factors (60%)...

..We are interested in identifying the genes underlying disordered eating behaviour (DEB), and want to know how much of the genetic influence underlying DEB is attributable to genetic influences on body mass index (BMI)...

..66) for SI and on chromosome 3 (LOD=1.98) for NC. Strikingly, on chromosome 10 a peak was found in the same region for both SI (LOD=1.92) and for NC (LOD=2.29) which may partly explain the overlapping etiological factors for SI and NC...

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..For both Externalizing and Internalizing problems, around 30% of the variance was accounted for by the shared environmental factors...

..Larger scale GWA studies and alternative approaches are required for confirmation of KATNAL2 as a novel gene affecting Conscientiousness...

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..84 PIQ points (P=0.0002). Variance in this SNP accounts for 3.4% of the phenotypic variance in PIQ...

..These data support the idea that both genetic and environmental influences play a role in the stability of AGG from age 3 to 12...

..These results are in agreement with earlier findings (Baker et al., Behav Genet 1991;21:351-67; Ho et al., Behav Genet 1988;18:247-61) and support the existence of a common, heritable biological basis underlying the SIP-IQ relationship...

..The high heritability and the limited influence of shared environmental factors may point to gene x environment interactions. Future research should focus on this type of interaction processes...

..This study investigated the effects of sharing a classroom during primary school on cognitive achievement in twins...

..We examined the existence and cause(s) of assortment for obsessive-compulsive (OC), anxious and depressive symptoms in a population-based twin-family sample...

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..This relation was explained by shared genes influencing both EEG and disease risk. Future studies on asymmetry of left and right frontal brain activation should carefully consider the effects of sex and age...

..Stability in subtest performance is due mainly to genetic influences. The shared environment contribution to phenotypic stability is small. The unique environment contributes to age-specific variance only...

..Allelic association between a trait and a marker can be studied in a case-control design, but because of possible problems due to population stratification, within-family designs have been proposed as the optimal test for association...

..Shared environmental influences are responsible for stability as well as change in the development of cognitive abilities, represented by a common factor influencing FSIQ at all ages and age-specific influences, respectively...

..In the present longitudinal twin study, we report on the size of genetic and environmental effects on individual differences in attention problems at ages 3, 7, 10 and 12 years...

..Finally, we tried to identify specific risk factors for burnout...

..The aim of this paper is to evaluate the theory of Gray and McNaughton using the results of genetic epidemiological studies...

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..Common environmental influences other than gestational age accounted for a slightly larger part of the variance not associated with gestational age (17-20%)...

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..Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders among women of reproductive age. There is evidence for a genetic component in PCOS based on familial clustering of cases...

..This was true for both boys and girls as well as for first and secondborn twins. Evidence in support of a biological explanation of the association between maternal age and child behavior problems, is presented...

..Three papers concentrate on emotionality, depression and loneliness and examine chromosomes 2q and 12q. The papers in this issue represent a summary of the first large scale linkage enterprises of human behavioral traits...

..Three of the 10 size 3 and 7 of the 36 size 4 sibships are particularly informative. The results presented concern random (unselective) sampling but do have implications for selective sampling...

..We conclude that across the scalp and most of the frequency spectrum, individual differences in adult EEG are largely determined by genetic factors...

..The phenotypic data was best described by an oblique two-factor model. This model was not mirrored in the factor structures found for either the genetic or environmental covariances...

..Earlier analyses of these data suggested that alcohol metabolism is related to drinking behavior and imply that this QTL may be protective against alcohol dependence...

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..The high heritability estimates that were found indicate that brain volumes may be useful as intermediate phenotypes in behavioral genetic research...

..A genome scan following this modified protocol can be performed using a maximum amount of 2.5 micrograms of genomic DNA per individual, isolated from either blood or from mouth swabs...

..It is concluded that measures of the ability to perform well under conditions of stimulus-response incongruency are viable endophenotypes of cognitive ability...

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..Contributions of common (13%-27%) and unique (16%-31%) environment were small to moderate. There was some evidence of genetic dominance by teacher report for 10-year-old girls...

..We conclude that visual N1 amplitude and latency may serve as endophenotypes to detect genetic variation in susceptibility to psychiatric disorders...

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..Though family history studies of borderline personality disorder indicate genetic influences, there have been very few twin studies and the degree of genetic influence on borderline personality disorder remains unclear...

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..Our findings argue the need for much larger samples than anticipated in genetic association studies and that the biological basis of emotional disorders is extremely complex...

..Improvement of intrauterine nutrition may not lower fibrinogen levels in later life...

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