@article {235, title = {Genome-wide analysis of DNA methylation in buccal cells: a study of monozygotic twins and mQTLs}, journal = {Epigenetics {\&} Chromatin}, volume = {11}, year = {2018}, month = {Sep}, pages = {54}, abstract = {
DNA methylation arrays are widely used in epigenome-wide association studies and methylation quantitative trait locus (mQTL) studies. Here, we performed the first genome-wide analysis of monozygotic (MZ) twin correlations and mQTLs on data obtained with the Illumina MethylationEPIC BeadChip (EPIC array) and compared the performance of the EPIC array to the Illumina HumanMethylation450 BeadChip (HM450 array) for buccal-derived DNA.
}, issn = {1756-8935}, doi = {10.1186/s13072-018-0225-x}, url = {https://doi.org/10.1186/s13072-018-0225-x}, author = {Jenny van Dongen and Ehli, Erik A. and Jansen, Rick and Catharina E. M. van Beijsterveldt and Gonneke Willemsen and Hottenga, Jouke J. and Kallsen, Noah A. and Peyton, Shanna A. and Breeze, Charles E. and Kluft, Cornelis and Bastiaan T. Heijmans and Meike Bartels and Gareth E Davies and Dorret I. Boomsma} } @article {283, title = {Unraveling the Genetic and Environmental Relationship Between Well-Being and Depressive Symptoms Throughout the Lifespan}, journal = {Frontiers in Psychiatry}, volume = {9}, year = {2018}, pages = {261}, abstract = {Whether well-being and depressive symptoms can be considered as two sides of the same coin is widely debated. The aim of this study was to gain insight into the etiology of the association between well-being and depressive symptoms across the lifespan. In a large twin-design, including data from 43,427 twins between age 7 and 99, we estimated the association between well-being and depressive symptoms throughout the lifespan and assessed genetic and environmental contributions to the observed overlap. For both well-being (range 31\% \–47\%) and depressive symptoms (range 50\%-61\%), genetic factors explained a substantial part of the phenotypic variance across the lifespan. Phenotypic correlations between well-being and depressive symptoms across ages ranged from -.34 in childhood to -.49 in adulthood. In children, genetic effects explained 49\% of the phenotypic correlation while in adolescents and young adults, genetic effects explained 60\% to 77\% of the phenotypic correlations. Moderate to high genetic correlations (ranging from -0.60 to -0.66) were observed in adolescence and adulthood, while in childhood environmental correlations were substantial but genetic correlations small. Our results suggest that in childhood genetic and environmental effects are about equally important in explaining the relationship between well-being and depressive symptoms. From adolescence onwards, the role of genetic effects increases compared to environmental effects. These results provided more insights into the etiological underpinnings of well-being and depressive symptoms, possibly allowing to articulate better strategies for health promotion and resource allocation in the future.
}, issn = {1664-0640}, doi = {10.3389/fpsyt.2018.00261}, url = {https://www.frontiersin.org/article/10.3389/fpsyt.2018.00261}, author = {Bart M. L. Baselmans and Willems, Yayouk E. and Catharina E. M. van Beijsterveldt and Lannie Ligthart and Gonneke Willemsen and Conor V Dolan and Dorret I. Boomsma and Meike Bartels} } @article {194, title = {Genetic and environmental influences on conduct and antisocial personality problems in childhood, adolescence, and adulthood}, journal = {European Child {\&} Adolescent Psychiatry}, year = {2017}, month = {Jun}, abstract = {Conduct problems in children and adolescents can predict antisocial personality disorder and related problems, such as crime and conviction. We sought an explanation for such predictions by performing a genetic longitudinal analysis. We estimated the effects of genetic, shared environmental, and unique environmental factors on variation in conduct problems measured at childhood and adolescence and antisocial personality problems measured at adulthood and on the covariation across ages. We also tested whether these estimates differed by sex. Longitudinal data were collected in the Netherlands Twin Register over a period of 27\ years. Age appropriate and comparable measures of conduct and antisocial personality problems, assessed with the Achenbach System of Empirically Based Assessment, were available for 9783 9\–10-year-old, 6839 13\–18-year-old, and 7909 19\–65-year-old twin pairs, respectively; 5114 twins have two or more assessments. At all ages, men scored higher than women. There were no sex differences in the estimates of the genetic and environmental influences. During childhood, genetic and environmental factors shared by children in families explained 43 and 44{\%} of the variance of conduct problems, with the remaining variance due to unique environment. During adolescence and adulthood, genetic and unique environmental factors equally explained the variation. Longitudinal correlations across age varied between 0.20 and 0.38 and were mainly due to stable genetic factors. We conclude that shared environment is mainly of importance during childhood, while genetic factors contribute to variation in conduct and antisocial personality problems at all ages, and also underlie its stability over age.
}, issn = {1435-165X}, doi = {10.1007/s00787-017-1014-y}, url = {https://doi.org/10.1007/s00787-017-1014-y}, author = {Laura W. Wesseldijk and Meike Bartels and Vink, Jacqueline M. and Catharina E. M. van Beijsterveldt and Lannie Ligthart and Dorret I. Boomsma and Christel Middeldorp} } @article {193, title = {Heritability of Behavioral Problems in 7-Year Olds Based on Shared and Unique Aspects of Parental Views}, journal = {Behavior Genetics}, volume = {47}, year = {2017}, month = {Mar}, pages = {152{\textendash}163}, abstract = {In studies of child psychopathology, phenotypes of interest are often obtained by parental ratings. When behavioral ratings are obtained in the context of a twin study, this allows for the decomposition of the phenotypic variance, into a genetic and a non-genetic part. If a phenotype is assessed by a single rater, heritability is based on the child\&$\#$39;s behavior as expressed in the presence of that particular rater, whereas heritability based on assessments by multiple raters allows for the estimation of the heritability of the phenotype based on rater agreement, as well as the heritability of the rater specific view of the behavior. The aim of this twin study was to quantify the rater\ common and rater specific contributions to the variation in children\&$\#$39;s behavioral problems. We estimated the heritability of maternal and paternal ratings of the Child Behavior Checklist (CBCL) 6\–18 empirical emotional and behavioral problem scales in a large sample of 12,310 7-year old Dutch twin pairs. Between 30 and 59{\%} of variation in the part of the phenotype parents agree upon was explained by genetic effects. Common environmental effects that make children in the same family similar explained less variance, ranging between 0 and 32{\%}. For unique views of their children\&$\#$39;s behavioral problems, heritability ranged between 0 and 20{\%} for maternal and between 0 and 22{\%} for paternal views. Between 7 and 24{\%} of the variance was accounted for by common environmental factors specific to mother and father\&$\#$39;s views. The proportion of rater shared and rater specific heritability can be translated into genetic correlations between parental views and inform the design and interpretation of results of molecular genetic studies. Genetic correlations were nearly or above 0.7 for all CBCL based psychopathology scales. Such large genetic correlations suggest two practical guidelines for genome-wide association studies (GWAS): when studies have collected data from either fathers or mothers, the shared genetic aetiology in parental ratings indicates that is possible to analyze paternal and maternal assessments in a single GWAS or meta-analysis. Secondly, if a study has collected information from both parents, a gain in statistical power may be realized in GWAS by the simultaneous analysis of the data.
}, issn = {1573-3297}, doi = {10.1007/s10519-016-9823-1}, url = {https://doi.org/10.1007/s10519-016-9823-1}, author = {Fedko, Iryna O. and Laura W. Wesseldijk and Michel G. Nivard and Hottenga, Jouke-Jan and Catharina E. M. van Beijsterveldt and Christel Middeldorp and Meike Bartels and Dorret I. Boomsma} } @article {102, title = {Longitudinal heritability of childhood aggression.}, journal = {Am J Med Genet B Neuropsychiatr Genet}, year = {2016}, month = {2016 Jan 19}, abstract = {The genetic and environmental contributions to the variation and longitudinal stability in childhood aggressive behavior were assessed in two large twin cohorts, the Netherlands Twin Register (NTR), and the Twins Early Development Study (TEDS; United Kingdom). In NTR, maternal ratings on aggression from the Child Behavior Checklist (CBCL) were available for 10,765 twin pairs at age 7, for 8,557 twin pairs at age 9/10, and for 7,176 twin pairs at age 12. In TEDS, parental ratings of conduct disorder from the Strength and Difficulty Questionnaire (SDQ) were available for 6,897 twin pairs at age 7, for 3,028 twin pairs at age 9 and for 5,716 twin pairs at age 12. In both studies, stability and heritability of aggressive behavioral problems was high. Heritability was on average somewhat, but significantly, lower in TEDS (around 60\%) than in NTR (between 50\% and 80\%) and sex differences were slightly larger in the NTR sample. In both studies, the influence of shared environment was similar: in boys shared environment explained around 20\% of the variation in aggression across all ages while in girls its influence was absent around age 7 and only came into play at later ages. Longitudinal genetic correlations were the main reason for stability of aggressive behavior. Individual differences in CBCL-Aggressive Behavior and SDQ-Conduct disorder throughout childhood are driven by a comparable but significantly different genetic architecture. \© 2016 Wiley Periodicals, Inc.
}, issn = {1552-485X}, doi = {10.1002/ajmg.b.32420}, author = {Porsch, Robert M and Christel Middeldorp and Cherny, Stacey S and Eva Krapohl and Catharina E. M. van Beijsterveldt and Loukola, Anu and Korhonen, Tellervo and Pulkkinen, Lea and Corley, Robin and Rhee, Soo and Kaprio, Jaakko and Rose, Richard R and Hewitt, John K and Sham, Pak and Robert Plomin and Dorret I. Boomsma and Meike Bartels} }