Search results for "Dizygotic"
showing 10 items of 77 documents
Harmonizing behavioral outcomes across studies, raters, and countries: application to the genetic analysis of aggression in the ACTION Consortium
2020
BACKGROUND: Aggression in children has genetic and environmental causes. Studies of aggression can pool existing datasets to include more complex models of social effects. Such analyses require large datasets with harmonized outcome measures. Here, we made use of a reference panel for phenotype data to harmonize multiple aggression measures in school-aged children to jointly analyze data from five large twin cohorts.METHODS: Individual level aggression data on 86,559 children (42,468 twin pairs) were available in five European twin cohorts measured by different instruments. A phenotypic reference panel was collected which enabled a model-based phenotype harmonization approach. A bi-factor i…
The Molecular Genetic Architecture of Self-Employment
2013
Economic variables such as income, education, and occupation are known to affect mortality and morbidity, such as cardiovascular disease, and have also been shown to be partly heritable. However, very little is known about which genes influence economic variables, although these genes may have both a direct and an indirect effect on health. We report results from the first large-scale collaboration that studies the molecular genetic architecture of an economic variable-entrepreneurship-that was operationalized using self-employment, a widely-available proxy. Our results suggest that common SNPs when considered jointly explain about half of the narrow-sense heritability of self-employment es…
Changing Environmental Influences on Substance Use Across Development
2007
AbstractIn contrast to many phenotypes that have been studied using twin designs, substance use shows considerable evidence of environmental influence. Accordingly, specifying the relevant environments and understanding the nature of their effects is an important research priority. Twin studies also have demonstrated that the importance of genetic and environmental influences varies across development for a variety of behavioral outcomes, including substance use. Here, we report analyses exploring moderating effects associated with parenting and peer characteristics on adolescent smoking and drinking, measured at ages 14 and 17. We find significant evidence of moderating effects associated …
Genetics of Perceived Family Interaction From 12 to 17 Years of Age
2019
We analyzed how the effects of genetic and environmental factors on the perceptions of family interaction change from early to late adolescence. The data were collected by postal surveys on Finnish twins (N = 4808) at 12, 14 and 17 years of age and analyzed using genetic twin modeling. Additive genetic factors explained a modest share of the variation in perceived relational support (a2 = 0.30 in boys and 0.18 in girls) and relational tensions (a2 = 0.13 and 0.14, respectively) at 12 years of age, with the proportions becoming larger through 17 years of age (a2 = 0.53 in boys and 0.49 in girls for relational support; a2 = 0.35 in boys and 0.33 in girls for relational tensions). Simultaneous…
Genetic and Environmental Influences on the Relationship Between Aggression and Hyperactivity-impulsivity as Rated by Teachers and Parents
2004
This study examined genetic and environmental contributions to the covariance between aggression and hyperactivity-impulsivity as rated by twins' teachers and parents. Sex-differences in these genetic and environmental contributions and rater bias/sibling interaction effects were of interest as well. Part of an ongoing nation-wide twin-family study of behavioral development and health habits, the sample consisted of 1636 Finnish twin pairs ascertained from five consecutive and complete twin birth cohorts. Data were collected at ages 11-12, using teacher and parental rating forms of the Multidimensional Peer Nomination Inventory. Bivariate analyses were performed using structural equation mo…
Externalizing Problem Behaviors and Headache: A Follow-up Study of Adolescent Finnish Twins
2004
Objective.To examine the association of teacher- and parent-rated behavior with headache in a prospective follow-up study of adolescent Finnish twins.Methods.Questionnaire data were collected during 1995–2001 from a nationwide sample of Finnish families of 11-year-old twins who were born 1983–1987 (n = 5393) and again at age of 14. Psychological factors were measured by using parents’ and teachers’ ratings of a 37-item multidimensional rating instrument at the ages of 11 and 14.Results.At age 11, headache frequency (5 categories) was associated with total scales of externalizing and internalizing problem behaviors and adaptive behaviors, assessed by parents, but only with externalizing prob…
Multiple sclerosis in twins from continental Italy and Sardinia: a nationwide study.
2005
Knowledge about the balance between heritable and nonheritable risk in multiple sclerosis (MS) is based on twin studies in high-prevalence areas. In a study that avoided ascertainment limitations and directly compared continental Italy (medium-prevalence) and Sardinia (high-prevalence), we ascertained 216 pairs from 34,549 patients. This gives a twinning rate of 0.62% among MS patients, significantly less than that of the general population. In continental Italy, probandwise concordance was 14.5% (95% confidence interval, 5.1-23.8) for monozygotic and 4.0% (95% confidence interval, 0.8-7.1) for dizygotic twins. Results in Sardinia resemble those in northern populations but in limited number…
Force-time characteristics and fiber composition in human leg extensor muscles
1978
Recording of the force-time (f-t) characteristics of muscular contraction expresses the rate at which tension is developed. To further understand the problems involved in force production during voluntary contraction, the f-t curve was registered during maximal voluntary isometric extension of both legs performed in the sitting position with the knee angle at 107 degrees. 38 athletes representing various sport events, five pairs of monozygous, and ten pairs of dizygous twins were used as subjects. The reference group consisted of eight normal men. The data disclosed that the time to produce certain force levels showed good trial-to-trial and satisfactory day-to-day reproducibility below ten…
Genetic and environmental influences on non-specific neck pain in early adolescence: A classical twin study
2012
Background Prevalence of neck pain has increased among adolescents. The origins of adult chronic neck pain may lie in late childhood, but for early prevention, more information is needed about its aetiology. We investigated the relative roles of genetic and environmental factors in early adolescent neck pain with a classic twin study. Methods Frequency of neck pain was assessed with a validated pain questionnaire in a population‐based sample of nearly 1800 pairs of 11–12‐year‐old Finnish twins. Twin pair similarity for neck pain was quantified by polychoric correlations, and variance components were estimated with biometric structural equation modelling. Results Prevalence of neck pain repo…
Genetic analysis of reaction time variability: room for improvement?
2013
Background. Increased reaction time variability (RTV) on cognitive tasks requiring a speeded response is characteristic of several psychiatric disorders. In attention deficit hyperactivity disorder (ADHD), the association with RT is strong phenotypically and genetically, yet high RTV is not a stable impairment but shows ADHD-sensitive improvement under certain conditions, such as those with rewards. The state regulation theory proposed that the RTV difference score, which captures change from baseline to a rewarded or fast condition, specifically measures ‘state regulation’. By contrast, the interpretation of RTV baseline (slow, unrewarded) scores is debated. We aimed to investigate directl…