Genome-wide association study identifies 48 common genetic variants associated with handedness.

Handedness has been extensively studied because of its relationship with language and the over-representation of left-handers in some neurodevelopmental disorders. Using data from the UK Biobank, 23andMe and the International Handedness Consortium, we conducted a genome-wide association meta-analysis of handedness (N = 1,766,671). We found 41 loci associated (P < 5 × 10) with left-handedness and 7 associated with ambidexterity.

Definitive Zygosity Scores in the Peas in the Pod Questionnaire is a Sensitive and Accurate Assessment of the Zygosity of Adult Twins.

Twin researchers face the challenge of accurately determining the zygosity of twins for research. As part of the annual questionnaire between 1999 and 2006, 8,307 twins from the TwinsUK registry were asked to complete five questions (independently from their co-twin) to ascertain their self-perceived zygosity during childhood on up to five separate occasions. This questionnaire is known as the 'peas in the pod' questionnaire (PPQ), but there is little evidence of its validation.

Genetic and environmental components of female depression as a function of the severity of the disorder.

Background: Both clinical care and genome-wide studies need to account for levels of severity in the etiology of depression. The purpose of the study is to estimate the genetic and environmental components of female depression as a function of the severity of the disorder.

Methods: A genetic and environmental model analysis of depression incidence was made using the IOP Depression Severity Measure (IDSM).

Shared genetic basis for migraine and ischemic stroke: A genome-wide analysis of common variants.

Objective: To quantify genetic overlap between migraine and ischemic stroke (IS) with respect to common genetic variation.

Methods: We applied 4 different approaches to large-scale meta-analyses of genome-wide data on migraine (23,285 cases and 95,425 controls) and IS (12,389 cases and 62,004 controls). First, we queried known genome-wide significant loci for both disorders, looking for potential overlap of signals.

Evaluating the consent preferences of UK research volunteers for genetic and clinical studies.

Objectives: To establish the views of research volunteers on the consent process; to explore their views on the consent process in different research scenarios; to inform debate on emerging models of consent for participation in research.

Design, Setting And Participants: 2,308 adult volunteers from the TwinsUK Registry (www.twinsuk.

GWAS of 126,559 individuals identifies genetic variants associated with educational attainment.

A genome-wide association study (GWAS) of educational attainment was conducted in a discovery sample of 101,069 individuals and a replication sample of 25,490. Three independent single-nucleotide polymorphisms (SNPs) are genome-wide significant (rs9320913, rs11584700, rs4851266), and all three replicate. Estimated effects sizes are small (coefficient of determination R(2) ≈ 0.

Genome-wide association analysis of eating disorder-related symptoms, behaviors, and personality traits.

Eating disorders (EDs) are common, complex psychiatric disorders thought to be caused by both genetic and environmental factors. They share many symptoms, behaviors, and personality traits, which may have overlapping heritability. The aim of the present study is to perform a genome-wide association scan (GWAS) of six ED phenotypes comprising three symptom traits from the Eating Disorders Inventory 2 [Drive for Thinness (DT), Body Dissatisfaction (BD), and Bulimia], Weight Fluctuation symptom, Breakfast Skipping behavior and Childhood Obsessive-Compulsive Personality Disorder trait (CHIRP).

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

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.

Age differences in genetic and environmental variations in stress-coping during adulthood: a study of female twins.

The way people cope with stressors of day to day living has an important influence on health. The aim of the present study was to explore whether genetic and environmental variations in stress-coping differ over time during adulthood. The brief COPE was mailed to a large sample of the UK female twins (N = 4,736) having a wide range of age (20-87 years).

Evidence for a genetic overlap between body dysmorphic concerns and obsessive-compulsive symptoms in an adult female community twin sample.

Body dysmorphic disorder (BDD) is thought to be etiologically related to obsessive-compulsive disorder (OCD) but the available evidence is incomplete. The current study examined the genetic and environmental sources of covariance between body dysmorphic and obsessive-compulsive symptoms in a community sample of adult twins. A total of 2,148 female twins (1,074 pairs) completed valid and reliable measures of body dysmorphic concerns and obsessive-compulsive symptoms.

Genetic and environmental influences on female sexual orientation, childhood gender typicality and adult gender identity.

Background: Human sexual orientation is influenced by genetic and non-shared environmental factors as are two important psychological correlates--childhood gender typicality (CGT) and adult gender identity (AGI). However, researchers have been unable to resolve the genetic and non-genetic components that contribute to the covariation between these traits, particularly in women.

Methodology/principal Findings: Here we performed a multivariate genetic analysis in a large sample of British female twins (N = 4,426) who completed a questionnaire assessing sexual attraction, CGT and AGI.

A multivariate twin study of obsessive-compulsive symptom dimensions.

Context: Obsessive-compulsive disorder (OCD) is clinically heterogeneous, but it is unclear whether this phenotypic heterogeneity reflects distinct, or partially distinct, etiologic mechanisms.

Objective: To clarify the structure of the genetic and environmental risk factors for the major symptom dimensions of OCD.

Design: Self-report questionnaires and multivariate twin model fitting.

Variance components models for physical activity with age as modifier: a comparative twin study in seven countries.

Physical activity is influenced by genetic factors whose expression may change with age. We employed an extension to the classical twin model that allows a modifier variable, age, to interact with the effects of the latent genetic and environmental factors. The model was applied to self-reported data from twins aged 19 to 50 from seven countries that collaborated in the GenomEUtwin project: Australia, Denmark, Finland, Norway, Netherlands, Sweden and United Kingdom.

A survey of UK public interest in internet-based personal genome testing.

Background: In view of the increasing availability of commercial internet-based Personal Genome Testing (PGT), this study aimed to explore the reasons why people would consider taking such a test and how they would use the genetic risk information provided.

Methodology/principal Findings: A self-completion questionnaire assessing public awareness and interest in PGT and motivational reasons for undergoing PGT was completed by 4,050 unselected adult volunteers from the UK-based TwinsUK register, aged 17 to 91 (response rate 62%). Only 13% of respondents were aware of the existence of PGT.

Replication of psychometric properties of the FSFI and validation of a modified version (FSFI-LL) assessing lifelong sexual function in an unselected sample of females.

Introduction: The 19-item Female Sexual Function Index (FSFI) is an easy-to-administer self-report questionnaire, allowing multidimensional assessment of female sexual function and female sexual dysfunction (FSD) over the past 4 weeks. However, studies aiming to dissect the underlying pathoetiology-especially biophysiological factors-often require assessment of sexual function over a broader time frame.

Aim: The purpose of this study was to develop a modified version of the widely used FSFI which allows assessment of women's lifelong sexual function-the FSFI-LL-and to evaluate the psychometric properties and aptness of this new version.

Genetics, the Big Five, and the tendency to be self-employed.

We applied multivariate genetics techniques to a sample of 3,412 monozygotic and dizygotic twins from the United Kingdom and 1,300 monozygotic and dizygotic twins from the United States to examine whether genetic factors account for part of the covariance between the Big Five personality characteristics and the tendency to be an entrepreneur. We found that common genes influenced the phenotypic correlations between only Extraversion and Openness to Experience and the tendency to be an entrepreneur. Although the phenotypic correlations between the personality characteristics and the tendency to be an entrepreneur were small in size, genetic factors accounted for most of them.

Cerebellar asymmetry in a pair of monozygotic handedness-discordant twins.

Increasing evidence for a cerebellar role in human cognition has accrued with respect to anatomically and functionally distinct lobules. Questions of laterality, however, have been largely overlooked. This study therefore introduced and applied a novel measurement protocol for comparatively bias-free analysis of cerebellar asymmetries.

Exploring genetic and environmental influences on miscarriage rates: a twin study.

Abstract Miscarriage is the most common type of pregnancy loss, occurring in up to 15% of clinically recognized pregnancies. Our understanding of the etiology is still limited but is believed to be multifactorial, including endocrine and anatomical abnormalities, immunologic, genetic and lifestyle factors. The aim of this study was to explore whether genetic variability in miscarriage is under any genetic influence.

Phenotypic and genetic relations between the HEXACO dimensions and trait emotional intelligence.

The present study investigated the location of trait emotional intelligence (trait EI or trait emotional self-efficacy) within the context of the HEXACO model - a more comprehensive personality framework than the conventional Big Five structure. A total of 666 MZ and 526 DZ adult twin pairs from the United Kingdom completed the short form of the Trait Emotional Intelligence Questionnaire (TEIQue-SF) and the short form of the HEXACO Personality Inventory (HEXACO-60). Many significant phenotypic correlations between the TEIQue-SF and the HEXACO-60 were obtained, which were strongest for HEXACO Extraversion, and weakest for HEXACO Honesty-Humility.