-
International Journal of Environmental... Oct 2022Epidemiological studies have suggested the role of multiple genetic and environmental factors in the development of non-neoplastic gastrointestinal (GI) diseases;...
Comparison of Concordance of Peptic Ulcer Disease, Non-Adenomatous Intestinal Polyp, and Gallstone Disease in Korean Monozygotic and Dizygotic Twins: A Cross-Sectional Study.
Epidemiological studies have suggested the role of multiple genetic and environmental factors in the development of non-neoplastic gastrointestinal (GI) diseases; however, little information is available on these factors in the Korean population. Therefore, this cross-sectional study explored the effect of these factors by analyzing the concordance of several benign GI disorders in 525 monozygotic twins compared to that in 122 dizygotic twins aged >20 years from the Healthy Twin Study data of the Korean Genome and Epidemiology Study (2005-2014). Chi-square test, Wilcoxon rank-sum, and binomial and multinomial logistic regression models were used for statistical analysis. There was lack of concordance of gastric/duodenal ulcers and cholelithiasis/cholangitis between monozygotic twins compared to that in dizygotic twins, suggesting that environmental factors may mediate those concordant disease expressions in monozygotic twins. The concordance of intestinal polyps in monozygotic twins was 32% lower than that in dizygotic twins ( = 0.028), indicating that the effect of genetic factors on the risk for intestinal polyp development may be low. In conclusion, the lack or low concordance of several benign GI diseases between monozygotic and dizygotic twin groups suggests the relative importance of environmental factors, indicating that these are preventable diseases.
Topics: Cholelithiasis; Cross-Sectional Studies; Diseases in Twins; Humans; Intestinal Polyps; Peptic Ulcer; Republic of Korea; Twins, Dizygotic; Twins, Monozygotic
PubMed: 36232007
DOI: 10.3390/ijerph191912708 -
Psychological Medicine Nov 2023Are genetic risk factors for current depressive symptoms good proxies for genetic risk factors for syndromal major depression (MD)?
BACKGROUND
Are genetic risk factors for current depressive symptoms good proxies for genetic risk factors for syndromal major depression (MD)?
METHODS
In over 9000 twins from the population-based Virginia Adult Twin Study of Psychiatric and Substance Use Disorders, the occurrence of all nine DSM symptomatic criteria for MD in the last year was assessed at personal interview and then grouped by their temporal co-occurrence. The DSM criteria which occurred outside (OUT) inside of (IN) MD episodes were then separated. We calculated tetrachoric correlations for OUT and IN depressive criteria in monozygotic (MZ) and dizygotic (DZ) pairs and fitted univariate and bivariate ACE twin models using OpenMx.
RESULTS
The mean twin correlations (±95% CIs) for IN depressive criteria were substantially higher than for OUT depressive criteria in both MZ [+0.35 (0.32-0.38) 0.20 (0.17-0.24)] and DZ pairs [0.20 (0.17-0.24) 0.10 (0.04-0.16]. The mean IN-OUT cross-correlation in MZ and DZ pairs was modest [+0.15 (0.07-0.24) and +0.07 (0.03-0.12)]. The mean heritability estimates for the nine In Out depressive criteria was 0.31 (0.22-0.41) and 0.15 (0.08-0.21), in MZ and DZ pairs, respectively. The mean genetic correlation between the nine IN and OUT depressive criteria was +0.07 (-0.07 to 0.21).
CONCLUSIONS
Depressive criteria occurring outside depressive episodes are less heritable than those occurring within. These two ways criteria can manifest are not closely genetically related. Current depressive symptoms - most of which are occurring outside of depressive episodes - are not, for genetic studies, good proxies for MD.
Topics: Adult; Humans; Depressive Disorder, Major; Depression; Twins, Monozygotic; Twins, Dizygotic; Diseases in Twins
PubMed: 37154209
DOI: 10.1017/S0033291723001241 -
Genes, Brain, and Behavior Apr 2021Twin studies of insomnia exhibit heterogeneity in estimates of heritability. This heterogeneity is likely because of sex differences, age of the sample, the reporter and... (Meta-Analysis)
Meta-Analysis
Twin studies of insomnia exhibit heterogeneity in estimates of heritability. This heterogeneity is likely because of sex differences, age of the sample, the reporter and the definition of insomnia. The aim of the present study was to systematically search the literature for twin studies investigating insomnia disorder and insomnia symptoms and to meta-analyse the estimates of heritability derived from these studies to generate an overall estimate of heritability. We further examined whether heritability was moderated by sex, age, reporter and insomnia symptom. A systematic literature search of five online databases was completed on 24 January 2020. Two authors independently screened 5644 abstracts, and 160 complete papers for the inclusion criteria of twin studies from the general population reporting heritability statistics on insomnia or insomnia symptoms, written in English, reporting data from independent studies. We ultimately included 12 papers in the meta-analysis. The meta-analysis focussed on twin intra-class correlations for monozygotic and dizygotic twins. Based on these intra-class correlations, the meta-analytic estimate of heritability was estimated at 40%. Moderator analyses showed stronger heritability in females than males; and for parent-reported insomnia symptoms compared with self-reported insomnia symptoms. There were no other significant moderator effects, although this is likely because of the small number of studies that were comparable across levels of the moderators. Our meta-analysis provides a robust estimate of the heritability of insomnia, which can inform future research aiming to uncover molecular genetic factors involved in insomnia vulnerability.
Topics: Adult; Age Factors; Female; Humans; Male; Self Report; Sex Characteristics; Sleep Initiation and Maintenance Disorders; Twins, Dizygotic; Twins, Monozygotic
PubMed: 33222383
DOI: 10.1111/gbb.12717 -
Journal of Psychiatry & Neuroscience :... May 1994This paper reviews key studies that have addressed genetic and neurobiological aspects in attention deficit hyperactive disorder. Genetic studies can be divided into... (Review)
Review
This paper reviews key studies that have addressed genetic and neurobiological aspects in attention deficit hyperactive disorder. Genetic studies can be divided into three distinct types: twin, adoption, and family studies. Evidence for a particular mode of inheritance and the possible specific genetic abnormalities are also explored. There is strong evidence of genetic involvement in this condition, although a clear-cut mode of inheritance and specific genetic abnormalities are yet to be determined. Neurobiological aspects such as the neuroanatomical and neurochemical evidence of various neurotransmitter system involvement is explored. Frontal lobe and dopamine and norepinephrine neurotransmitter systems appear to be involved in attention deficit hyperactive disorder.
Topics: Adoption; Attention Deficit Disorder with Hyperactivity; Child; Comorbidity; Diseases in Twins; Humans; Models, Genetic; Risk Factors; Social Environment; Synaptic Transmission; Twins, Dizygotic; Twins, Monozygotic
PubMed: 8031743
DOI: No ID Found -
Twin Research and Human Genetics : the... Aug 2009Testis size is an important feature of male pubertal development. The genetic and environmental contributions to variation in human testis size have hardly been studied....
Testis size is an important feature of male pubertal development. The genetic and environmental contributions to variation in human testis size have hardly been studied. We estimated the heritability of human testicular size in a group of mono- and dizygotic twins and their non-twin brothers (145 twins and 20 brothers from 95 families). Participants were 18 years old on average and all had reached Tanner development stage 4 or higher. Dizygotic twins and their siblings had a larger mean testis volume than monozygotic twins and their siblings. There was significant familial resemblance, with higher correlations in monozygotic twin pairs (0.59) than in dizygotic twin and sibling pairs (0.34). Heritability was estimated at 59% (95% CI = 37-75%), but a model that excluded genetic influences and attributed all familial resemblance to shared environment, fitted the data only marginally worse. The finding of larger mean testis volume in dizygotic twins may be of interest for future research into the mechanisms underlying dizygotic twinning.
Topics: Adolescent; Environment; Genetic Predisposition to Disease; Humans; Longitudinal Studies; Male; Organ Size; Phenotype; Siblings; Testis; Twins; Twins, Dizygotic; Twins, Monozygotic
PubMed: 19653835
DOI: 10.1375/twin.12.4.351 -
Psychiatry Research May 1997Various environmental variables are hypothesized to operate differentially within identical and fraternal twin pairs. To the extent that these factors are correlated...
Various environmental variables are hypothesized to operate differentially within identical and fraternal twin pairs. To the extent that these factors are correlated with behavioral outcomes, such as alcohol or drug abuse, traditional twin studies of concordance may be biased. Self-ratings of within-pair emotional closeness, assessed in 169 same-sex twin pairs ascertained through alcohol and drug treatment centers, were used to determine the impact of the twin relationship on concordance for alcohol dependence (N = 130 twin pairs) and other drug abuse and/or dependence (N = 85 twin pairs). In general, identical twin pairs reported significantly closer relationships than fraternal twin pairs, and female twin pairs reported significantly closer relationships than male twin pairs. The data did not indicate an overall effect of closeness on co-twin risk for alcohol dependence. In contrast, closeness was significantly related to co-twin risk for other drug abuse and/or dependence. However, the MZ/DZ concordance difference for other drug abuse and/or dependence remained significant when the effects of within-pair closeness were controlled. Thus, the initial zygosity and sex differences in concordance for substance use disorders cannot be explained solely by differences in twin relationship due to closeness as assessed in this study.
Topics: Adolescent; Adult; Alcoholism; Diseases in Twins; Female; Humans; Illicit Drugs; Male; Middle Aged; Minnesota; Prospective Studies; Psychotropic Drugs; Retrospective Studies; Risk Factors; Sibling Relations; Social Environment; Substance-Related Disorders; Twins, Dizygotic; Twins, Monozygotic
PubMed: 9211577
DOI: 10.1016/s0165-1781(97)03045-x -
Pediatric Allergy and Immunology :... Mar 2022Currently, we cannot predict whether a pre-school child with asthma-like symptoms will have asthma at school age. Whether genetic information can help in this prediction...
BACKGROUND
Currently, we cannot predict whether a pre-school child with asthma-like symptoms will have asthma at school age. Whether genetic information can help in this prediction depends on the role of genetic factors in persistence of pre-school to school-age asthma. We examined to what extent genetic and environmental factors contribute to persistence of asthma-like symptoms at ages 3 to asthma at age 7 using a bivariate genetic model for longitudinal twin data.
METHODS
We performed a cohort study in monozygotic and dizygotic twins from the Netherlands Twin Register (NTR, n = 21,541 twin pairs). Bivariate genetic models were fitted to longitudinal data on asthma-like symptoms reported by parents at age 3 and 7 years to estimate the contribution of genetic and environmental factors.
RESULTS
Bivariate genetic modeling showed a correlation on the liability scale between asthma-like symptoms at age 3 and asthma at age 7 of 0.746 and the contribution of genetics was estimated to be 0.917. The genetic analyses indicated a substantial influence of genetic factors on asthma-like symptoms at ages 3 and 7 (heritability 80% and 90%, respectively); hence, contribution of environmental factors was low. Persistence was explained by a high (rg = 0.807) genetic correlation.
CONCLUSION
Parental-reported asthma-like symptoms at age 3 and asthma at age 7 are highly heritably. The phenotype of asthma-like symptoms at age 3 and 7 was highly correlated and mainly due to heritable factors, indicating high persistence of asthma development over ages 3 and 7.
Topics: Asthma; Child, Preschool; Cohort Studies; Humans; Longitudinal Studies; Parents; Twins, Dizygotic; Twins, Monozygotic
PubMed: 35338742
DOI: 10.1111/pai.13762 -
BMJ (Clinical Research Ed.) Mar 1999To test the hypothesis that non-diabetic dizygotic and monozygotic twin siblings of patients with type 1 diabetes have a similar high prevalence of islet cell...
OBJECTIVE
To test the hypothesis that non-diabetic dizygotic and monozygotic twin siblings of patients with type 1 diabetes have a similar high prevalence of islet cell autoantibodies, thus suggesting that islet cell autoimmunity is mainly environmentally determined.
DESIGN
Prospective twin study.
SETTING
Two specialist centres for diabetes in the United States.
PARTICIPANTS
Non-diabetic monozygotic twin (n=53), dizygotic twin (n=30), and non-twin (n=149) siblings of patients with type 1 diabetes; 101 controls.
MAIN OUTCOME MEASURES
Analysis of progression to diabetes and expression of anti-islet autoantibodies.
RESULTS
Monozygotic twin siblings had a higher risk of progression to diabetes (12/53) than dizygotic twin siblings (0/30; P<0.005). At the last follow up 22 (41.5%) monozygotic twin siblings expressed autoantibodies compared with 6 (20%) dizygotic twin siblings (P<0.05), 16 (10.7%) non-twin siblings (P<0.0001), and 6 (5.9%) controls (P<0.0001). Monozygotic twin siblings expressed multiple (>/=2) antibodies more often than dizygotic twin siblings (10/38 v 1/23; P<0.05). By life table analysis the probability of developing positive autoantibodies was higher among the monozygotic twin siblings bearing the diabetes associated HLA DQ8/DQ2 genotype than in those without this genotype (64.2% (95% confidence interval 32.5% to 96%) v 23.5% (7% to 40%) at 10 years of discordance; P<0.05).
CONCLUSION
Monozygotic and dizygotic twins differ in progression to diabetes and expression of islet cell autoantibodies. Dizygotic twin siblings are similar to non-twin siblings. These two observations suggest that genetic factors play an important part in determination of islet cell autoimmunity, thus rejecting the hypothesis. In addition, there is a high penetrance of islet cell autoimmunity in DQ8/DQ2 monozygotic twin siblings.
Topics: Adolescent; Adult; Aged; Antibody Specificity; Autoantibodies; Child; Child, Preschool; Diabetes Mellitus, Type 1; Disease Progression; Female; Histocompatibility Testing; Humans; Infant; Islets of Langerhans; Male; Middle Aged; Prospective Studies; Sensitivity and Specificity; Twins, Dizygotic; Twins, Monozygotic
PubMed: 10074012
DOI: 10.1136/bmj.318.7185.698 -
Sleep Jan 2016We used quantitative genetic models to assess whether area-level deprivation as indicated by the Singh Index predicts shorter sleep duration and modifies its underlying...
STUDY OBJECTIVES
We used quantitative genetic models to assess whether area-level deprivation as indicated by the Singh Index predicts shorter sleep duration and modifies its underlying genetic and environmental contributions.
METHODS
Participants were 4,218 adult twin pairs (2,377 monozygotic and 1,841 dizygotic) from the University of Washington Twin Registry. Participants self-reported habitual sleep duration. The Singh Index was determined by linking geocoding addresses to 17 indicators at the census-tract level using data from Census of Washington State and Census Tract Cartographic Boundary Files from 2000 and 2010. Data were analyzed using univariate and bivariate genetic decomposition and quantitative genetic interaction models that assessed A (additive genetics), C (common environment), and E (unique environment) main effects of the Singh Index on sleep duration and allowed the magnitude of residual ACE variance components in sleep duration to vary with the Index.
RESULTS
The sample had a mean age of 38.2 y (standard deviation [SD] = 18), and was predominantly female (62%) and Caucasian (91%). Mean sleep duration was 7.38 h (SD = 1.20) and the mean Singh Index score was 0.00 (SD = 0.89). The heritability of sleep duration was 39% and the Singh Index was 12%. The uncontrolled phenotypic regression of sleep duration on the Singh Index showed a significant negative relationship between area-level deprivation and sleep length (b = -0.080, P < 0.001). Every 1 SD in Singh Index was associated with a ∼4.5 min change in sleep duration. For the quasi-causal bivariate model, there was a significant main effect of E (b(0E) = -0.063; standard error [SE] = 0.30; P < 0.05). Residual variance components unique to sleep duration were significant for both A (b(0Au) = 0.734; SE = 0.020; P < 0.001) and E (b(0Eu) = 0.934; SE = 0.013; P < 0.001).
CONCLUSIONS
Area-level deprivation has a quasi-causal association with sleep duration, with greater deprivation being related to shorter sleep. As area-level deprivation increases, unique genetic and nonshared environmental residual variance in sleep duration increases.
Topics: Adult; Censuses; Environment; Female; Gene-Environment Interaction; Humans; Male; Models, Genetic; Registries; Self Report; Sleep; Socioeconomic Factors; Time Factors; Twins, Dizygotic; Twins, Monozygotic; Washington; White People
PubMed: 26285009
DOI: 10.5665/sleep.5320 -
Cerebral Cortex (New York, N.Y. : 1991) Mar 2019Females might possess protective mechanisms regarding autism spectrum disorder (ASD) and require a higher detrimental load, including structural brain alterations,...
Females might possess protective mechanisms regarding autism spectrum disorder (ASD) and require a higher detrimental load, including structural brain alterations, before developing clinically relevant levels of autistic traits. This study examines sex differences in structural brain morphology in autism and autistic traits using a within-twin pair approach. Twin design inherently controls for shared confounders and enables the study of gene-independent neuroanatomical variation. N = 148 twins (62 females) from 49 monozygotic and 25 dizygotic same-sex pairs were included. Participants were distributed along the whole continuum of autism including twin pairs discordant and concordant for clinical ASD. Regional brain volume, surface area, and cortical thickness were computed. Within-twin pair increases in autistic traits were related to decreases in cortical volume and surface area of temporal and frontal regions specifically in female twin pairs, in particular regions involved in social communication, while only two regions were associated with autistic traits in males. The same pattern was detected in the monozygotic twin pairs only. Thus, non-shared environmental factors seem to impact female more than male cerebral architecture associated with autistic traits. Our results are in line with the hypothesis of a female protective effect in autism and highlights the need to study ASD in females separately from males.
Topics: Adolescent; Adult; Autism Spectrum Disorder; Brain; Child; Female; Gene-Environment Interaction; Genetic Predisposition to Disease; Humans; Male; Sex Characteristics; Twins, Dizygotic; Twins, Monozygotic; Young Adult
PubMed: 30566633
DOI: 10.1093/cercor/bhy303