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Twin Registry (twin + registry)
Kinds of Twin Registry Selected AbstractsDepression and obesity: do shared genes explain the relationship?DEPRESSION AND ANXIETY, Issue 9 2010Niloofar Afari Ph.D. Abstract Background: Studies have found a modest association between depression and obesity, especially in women. Given the substantial genetic contribution to both depression and obesity, we sought to determine whether shared genetic influences are responsible for the association between these two conditions. Methods: Data were obtained from 712 monozygotic and 281 dizygotic female twin pairs who are members of the community-based University of Washington Twin Registry. The presence of depression was determined by self-report of doctor-diagnosed depression. Obesity was defined as body mass index of ,30,kg/m2, based on self-reported height and weight. Generalized estimating regression models were used to assess the age-adjusted association between depression and obesity. Univariate and bivariate structural equation models estimated the components of variance attributable to genetic and environmental influences. Results: We found a modest phenotypic association between depression and obesity (odds ratio=1.6, 95% confidence interval=1.2,2.1). Additive genetic effects contributed substantially to depression (57%) and obesity (81%). The best-fitting bivariate model indicated that 12% of the genetic component of depression is shared with obesity. Conclusions: The association between depression and obesity in women may be in part due to shared genetic risk for both conditions. Future studies should examine the genetic, environmental, social, and cultural mechanisms underlying the relationship between this association. Depression and Anxiety, 2010. © 2010 Wiley-Liss, Inc. [source] Genetic aspects of pathological gambling: a complex disorder with shared genetic vulnerabilitiesADDICTION, Issue 9 2009Daniela S. S. Lobo ABSTRACT Aims To summarize and discuss findings from genetic studies conducted on pathological gambling (PG). Methods Searches were conducted on PubMed and PsychInfo databases using the keywords: ,gambling and genes', ,gambling and family' and ,gambling and genetics', yielding 18 original research articles investigating the genetics of PG. Results Twin studies using the Vietnam Era Twin Registry have found that: (i) the heritability of PG is estimated to be 50,60%; (ii) PG and subclinical PG are a continuum of the same disorder; (iii) PG shares genetic vulnerability factors with antisocial behaviours, alcohol dependence and major depressive disorder; (iv) genetic factors underlie the association between exposure to traumatic life-events and PG. Molecular genetic investigations on PG are at an early stage and published studies have reported associations with genes involved in the brain's reward and impulse control systems. Conclusions Despite the paucity of studies in this area, published studies have provided considerable evidence of the influence of genetic factors on PG and its complex interaction with other psychiatric disorders and environmental factors. The next step would be to investigate the association and interaction of these variables in larger molecular genetic studies with subphenotypes that underlie PG. Results from family and genetic investigations corroborate further the importance of understanding the biological underpinnings of PG in the development of more specific treatment and prevention strategies. [source] Timing of first alcohol use and alcohol dependence: evidence of common genetic influencesADDICTION, Issue 9 2009Carolyn E. Sartor ABSTRACT Aims To estimate the magnitude of genetic and environmental influences on timing of first alcohol use and alcohol dependence (AD) and to quantify the overlap in these influences across the two alcohol-related outcomes. Participants The sample consisted of 5382 twins (2691 complete pairs), aged 24,36 years, from the Australian Twin Registry. Measurements History of alcohol use and DSM-IV alcohol dependence were assessed by structured telephone interview. Findings In both sexes, the relationship between age at first alcohol use and risk for AD followed a linear trend, such that the highest rates of AD were observed in individuals who began drinking at an earlier than average age (14 years or younger). Heritability estimates for timing of first alcohol use and AD were 36% and 53%, respectively. Shared environmental factors accounted for 15% of variance in initiation. There was no evidence of shared environmental influences on AD. The genetic correlation between timing of first alcohol use and AD was 0.59. Conclusions Findings highlight the substantial role of genetics in the development of AD and the early manifestation of that genetic risk in the timing of alcohol use initiation which, unlike AD, is also influenced to a modest degree by shared environmental factors. The considerable overlap in heritable influences,and the virtual absence of overlap in individual-specific environmental influences,on initiation of alcohol use and AD indicates that the association between age at first drink and AD is attributable in large part to common genetic sources of variance. [source] Modeling the genetic and environmental association between peer group deviance and cannabis use in male twinsADDICTION, Issue 3 2009Nathan A. Gillespie ABSTRACT Background Peer group deviance (PGD) is linked strongly to liability to drug use, including cannabis. Our aim was to model the genetic and environmental association, including direction of causation, between PGD and cannabis use (CU). Method Results were based on 1736 to 1765 adult males from the Mid-Atlantic Twin Registry with complete CU and PGD data measured retrospectively at three time-intervals between 15 and 25 years using a life-history calendar. Results At all ages, multivariate modeling showed that familial aggregation in PGD was explained by a combination of additive genetic and shared environmental effects. Moreover, the significant PGD,CU association was best explained by a CU,PGD causal model in which large portions of the additive genetic (50,78%) and shared environmental variance (25,73%) in PGD were explained by CU. Conclusions Until recently PGD was assumed to be an environmental, upstream risk factor for CU. Our data are not consistent with this hypothesis. Rather, they suggest that the liability to affiliate with deviant peers is explained more clearly by a combination of genetic and environmental factors that are indexed by CU which sits as a ,risk indicator' in the causal pathway between genetic and environmental risks and the expression of PGD. This is consistent with a process of social selection by which the genetic and environmental risks in CU largely drive the propensity to affiliate with deviant peers. [source] Pathways to cannabis abuse: a multi-stage model from cannabis availability, cannabis initiation and progression to abuseADDICTION, Issue 3 2009Nathan A. Gillespie ABSTRACT Aims Although previous twin studies have modeled the association between drug initiation and abuse, none has included the obvious risk factor of drug availability. Our aim is to determine whether the genetic and environmental risk factors for cannabis availability also generate variation in cannabis initiation and/or progression to DSM-IV symptoms of abuse. Design We used multi-stage modeling, also known as causal-common-contingent (CCC) analysis, to partition the genetic and environmental factors into common and stage-specific components. Participants This report is based on data collected from 1772 adult males from the Mid Atlantic Twin Registry. Measurements The twins participated in two structured interviews which included clinical and non-clinical measures of cannabis abuse as well as retrospective assessments of perceived cannabis availability between ages 8 and 25 years. Findings Cannabis availability explained almost all the shared environmental risks in cannabis initiation and abuse. The influence of availability on the symptoms of abuse was indirect and mediated entirely by cannabis initiation. Conclusion These findings have begun to elucidate the causal processes underlying the liability to drug use and abuse in terms of putative risk factors. Specifically, our results show that the latent shared environmental factors in cannabis initiation and abuse can be explained by measured aspects of the shared environment,those responsible for variation in cannabis availability. [source] Factor and item-response analysis DSM-IV criteria for abuse of and dependence on cannabis, cocaine, hallucinogens, sedatives, stimulants and opioidsADDICTION, Issue 6 2007Nathan A. Gillespie ABSTRACT Aims This paper explored, in a population-based sample of males, the factorial structure of criteria for substance abuse and dependence, and compared qualitatively the performance of these criteria across drug categories using item,response theory (IRT). Design Marginal maximum likelihood was used to explore the factor structure of criteria within drug classes, and a two-parameter IRT model was used to determine how the difficulty and discrimination of individual criteria differ across drug classes. Participants A total of 4234 males born from 1940 to 1974 from the population-based Virginia Twin Registry were approached to participate. Measurements DSM-IV drug use, abuse and dependence criteria for cannabis, sedatives, stimulants, cocaine and opiates. Findings For each drug class, the pattern of endorsement of individual criteria for abuse and dependence, conditioned on initiation and use, could be best explained by a single factor. There were large differences in individual item performance across substances in terms of item difficulty and discrimination. Cocaine users were more likely to have encountered legal, social, physical and psychological consequences. Conclusions The DSM-IV abuse and dependence criteria, within each drug class, are not distinct but best described in terms of a single underlying continuum of risk. Because individual criteria performed very differently across substances in IRT analyses, the assumption that these items are measuring equivalent levels of severity or liability with the same discrimination across different substances is unsustainable. Compared to other drugs, cocaine usage is associated with more detrimental effects and negative consequences, whereas the effects of cannabis and hallucinogens appear to be less harmful. Implications for other drug classes are discussed. [source] Genetic Probes of Three Theories of Maternal Adjustment: II.FAMILY PROCESS, Issue 3 2001Environmental Influences, Genetic This is the first report of the Twin Mom Study, an investigation of three hypotheses concerning influences on maternal adjustment. These hypotheses concern the role of the marital and parent-child relationships in mediating genetic influences on maternal adjustment and on the importance of the mothers' marital partners as a specifiable source of influences on their adjustment not shared with their sisters. The study's sample of 150 monozygotic (MZ) twins and 176 dizygotic (DZ) twins was drawn randomly from the Swedish Twin Registry and is, with some small exceptions, likely to be representative of women in the Swedish population. The sample included the marital partners of these twins and their adolescent children. Self-report and coded videotapes were a source of information about family process. Results reported in this first report focus on comparability of American and Swedish samples on scales measuring psychiatric symptoms, and on an analysis of genetic and environmental influences on nine measures of mothers' adjustment. Results suggest comparability between the US and Sweden. Genetic influences were found for all measures of adjustment, particularly in the psychological manifestations of anxiety and for smoking. The pattern of findings also underscored the importance of influences unique to each sibling within the twin pair, thus focusing attention on the potential role of marital partners in maternal adjustment. Results also suggested that experiences shared by the twin sisters, experiences unrelated to their genetic similarity, may influence their fearfulness and alcohol consumption. Our model did not include these influences and thus must be amended. [source] Lifetime Prevalence and Characteristics of Recurrent Primary Headaches in a Population-Based Sample of Swedish TwinsHEADACHE, Issue 8 2002Dan A. Svensson MSc Objective.,To examine the lifetime prevalence and other characteristics of recurrent primary headaches in twins. Background.,The twin model may provide insights into the role of genetic and environmental influences in headache disorders. However, assumptions as to whether twins are representative of the general population, and whether monozygotic and dizygotic twins are similar have rarely been addressed. Methods.,The study population consisted of a random sample of 17- to 82-year-old twins from the Swedish Twin Registry (n = 1329). Structured interviews on the telephone by lay personnel and the International Headache Society criteria were used for assessment and diagnosis of recurrent primary headaches. Prevalence data of the general population for migraine and tension-type headache was obtained from various published reports. Results.,A total of 372 subjects (29%) had ever had recurrent headaches. In total, 241 recurrent headache sufferers fulfilled the criteria for migraine or tension-type headache, and the lifetime prevalence was 7.1% for migraine without aura, 1.4% for migraine always with aura, 1.9% for migraine occasionally with aura, 9.4% for episodic tension-type headache, and 1.3% for chronic tension-type headache. The lifetime prevalence of all migraine and all tension-type headache, including another 84 subjects fulfilling all but one of the criteria for migraine or tension-type headache, was 13.8% and 13.5%, respectively. The corresponding prevalence risk for women was 2.4 (95% confidence interval [CI] 1.7, 3.4) and 1.5 (95% CI 1.1, 2.1), respectively. Zygosity was not a significant predictor for migraine. In tension-type headache, the prevalence risk for dizygotic twins and unlike-sexed twins as compared with monozygotic twins was 1.9 (95% CI: 1.2, 3.1) and 1.8 (95% CI: 1.1, 2.9), respectively. Conclusion.,There is no twin-singleton or monozygotic-dizygotic difference for the risk of migraine. In tension-type headache, twins seem to have a lower risk than singletons, and this is especially true for monozygotic twins. [source] Use of snus and risk for cardiovascular disease: results from the Swedish Twin RegistryJOURNAL OF INTERNAL MEDICINE, Issue 6 2009J. Hansson Abstract. Objective. To study the association between snus use and the risk for cardiovascular disease, i.e. ischemic heart disease and stroke. Design. Cohort study. Setting. Sweden. Subjects. Sixteen thousand six hundred and forty-two male Swedish twins participating in the Screening Across the Lifespan Twin Study, conducted in 1998,2002, were followed for incident cardiovascular disease. Participants were without a history of cardiovascular disease at baseline and incident cases were identified via the Swedish Cause of Death Register and Hospital Discharge Register. Results. Overall, there was no association between use of snus and risk for cardiovascular disease. Current snus users, without a smoking history, had a relative risk of 1.00 (95% confidence interval 0.69,1.46) for cardiovascular disease as compared to non users. Corresponding relative risks for ischemic heart disease and stroke were 0.85 (95% confidence interval 0.51,1.41) and 1.18 (95% confidence interval 0.67,2.08), respectively. In smoking adjusted models, risk estimates for ischemic heart disease in relation to snus use were all close to unity regardless of timing or intensity of snus use. However, current heavy snus users (consuming more than four cans week,1) had a relative risk for stroke of 1.75 (95% confidence interval 0.95,3.21). Conclusion. These data do not support any strong association between snus use and risk for cardiovascular disease. [source] The Relationship Between Genetic Influences on Alcohol Dependence and on Patterns of Alcohol ConsumptionALCOHOLISM, Issue 6 2010Kenneth S. Kendler Background:, Genetic factors impact substantially both on alcohol consumption (AC) and on the risk for alcohol dependence (AD). However, we know little about the degree to which measures of AC index the genetic risk for AD. Methods:, We assessed a lifetime history of AD by DSM-IV criteria and four measures of AC at the time of heaviest drinking (drink frequency, regular quantity, maximum quantity, and drunk frequency) in 5,073 adult twins from same-sex pairs from the Virginia Twin Registry. Structural models were fitted using Mx. Results:, We found evidence for different genetic structure in the sexes. In women, genetic risk for AD and for the four measures of AC was entirely shared. In men, the AC measures captured 85% of the genetic risk for AD. In women, the genetic relationship with AD was strongest for drunk frequency and in men for both drunk frequency and regular quantity. Conclusions:, In a population-based sample of twins, four relatively simple measures of AC obtained for the time of lifetime heaviest drinking were able to capture all (in women) or a very large proportion (in men) of the genetic risk for the complex multi-dimensional construct of AD. If replicated, these results have practical implications for studies aiming to assess genetic risk for AD. [source] Common Genetic Contributions to Alcohol and Cannabis Use and Dependence SymptomatologyALCOHOLISM, Issue 3 2010Carolyn E. Sartor Background:, Despite mounting evidence that use of and dependence on alcohol and cannabis are influenced by heritable factors, the extent to which heritable influences on these phenotypes overlap across the 2 substances has only rarely been explored. In the current study, we quantified cross-substance overlap in sources of variance and estimated the degree to which within-substance associations between use and dependence measures are attributable to common genetic and environmental factors for alcohol and cannabis. Methods:, The sample was comprised of 6,257 individuals (2,761 complete twin pairs and 735 singletons) from the Australian Twin Registry, aged 24 to 36 years. Alcohol and cannabis use histories were collected via telephone diagnostic interviews and used to derive an alcohol consumption factor, a frequency measure for cannabis use, and DSM-IV alcohol and cannabis dependence symptom counts. Standard genetic analyses were conducted to produce a quadrivariate model that provided estimates of overlap in genetic and environmental influences across the 4 phenotypes. Results:, Over 60% of variance in alcohol consumption, cannabis use, and cannabis dependence symptoms, and just under 50% of variance in alcohol dependence (AD) symptoms were attributable to genetic sources. Shared environmental factors did not contribute significantly to the 4 phenotypes. Nearly complete overlap in heritable influences was observed for within-substance measures of use and dependence symptoms. Genetic correlations across substances were 0.68 and 0.62 for use and dependence symptoms, respectively. Conclusions:, Common heritable influences were evident for alcohol and cannabis use and for AD and cannabis dependence symptomatology, but findings indicate that substance-specific influences account for the majority of the genetic variance in the cannabis use and dependence phenotypes. By contrast, the substantial correlations between alcohol use and AD symptoms and between cannabis use and cannabis dependence symptoms suggest that measures of heaviness of use capture much of the same genetic liability to alcohol- and cannabis-related problems as dependence symptomatology. [source] Juvenile conduct disorder as a risk factor for trauma exposure and posttraumatic stress disorderJOURNAL OF TRAUMATIC STRESS, Issue 1 2005Karestan C. Koenen Juvenile conduct disorder (CD) is a well-documented risk factor for posttraumatic stress disorder (PTSD). This study examines the mechanisms underlying this relationship by using data from 3,315 twin pairs in the Vietnam Era Twin Registry. Results indicate the number of conduct disorder symptoms increased risk of trauma exposure and PTSD in a dose,response fashion. This increased risk was mediated in part by the positive association between CD and lifestyle factors and was not due to confounding by shared genetic or familial vulnerability. The findings suggest CD increases risk for trauma exposure and PTSD among male veterans through direct and indirect mechanisms. Veterans who have a history of CD are at high risk for trauma exposure and development of PTSD. [source] A quantitative genetic analysis of intermediate asthma phenotypesALLERGY, Issue 3 2009S. F. Thomsen Aim:, To study the relative contribution of genetic and environmental factors to the correlation between exhaled nitric oxide (FeNO), airway responsiveness, airway obstruction, and serum total immunoglobulin E (IgE). Methods:, Within a sampling frame of 21 162 twin subjects, 20,49 years of age, from the Danish Twin Registry, a total of 575 subjects (256 intact pairs and 63 single twins) who either themselves and/or their co-twins reported a history of asthma at a nationwide questionnaire survey, were clinically examined. Traits were measured using standard techniques. Latent factor models were fitted to the observed data using maximum likelihood methods. Results:, Additive genetic factors explained 67% of the variation in FeNO, 43% in airway responsiveness, 22% in airway obstruction, and 81% in serum total IgE. In general, traits had genetically and environmentally distinct variance structures. The most substantial genetic similarity was observed between FeNO and serum total IgE, genetic correlation (,A) = 0.37, whereas the strongest environmental resemblance was observed between airway responsiveness and airway obstruction, specific environmental correlation (,E) = ,0.46, and between FeNO and airway responsiveness, ,E = 0.34. Conclusions:, Asthma is a complex disease characterized by a set of etiologically heterogeneous biomarkers, which likely constitute diverse targets of intervention. [source] Heritability of Obesity-related Phenotypes and Association with Adiponectin Gene Polymorphisms in the Chinese National Twin RegistryANNALS OF HUMAN GENETICS, Issue 2 2010Juan Lee Summary The purpose of this study was to estimate the heritability of obesity-related phenotypes and investigate the association of adiponectin gene polymorphisms +45T>G and +276G>T with these measures in Chinese twins. 1260 twin pairs were recruited from two cities through the Chinese National Twin Registry System from 2001 to 2005. Two SNPs at the adiponectin locus (+45T>G and +276G>T) were genotyped. Structural equation modeling (SEM) was used to estimate heritability and the best-fitting variance component model. The regular association among all twins was analysed with generalised estimating equations (GEE). Sib-transmission/disequilibrium test (TDT) within dizygotic (DZ) twin pairs discordant for their genotype was performed using SEM. Additive genetic, common and unique environmental (ACE) model-based heritability of body mass index (BMI) was 61%, while additive genetic and unique environmental (AE)-model-based heritability of waist circumference (WC) and waist-hip ratio (WHR) were 75% and 61%, respectively. There was no association of adiponectin gene +45T>G and +276G>T genotypes with obesity-related phenotypes in all twins or discordant DZ twins. Our twins data did not support that there was an association between adiponectin gene polymorphisms +45T>G and +276G>T and the obesity-related phenotypes. Further studies are required to better understand the role of adiponectin gene polymorphisms in obesity. [source] The occurrence and characteristics of auras in a large epilepsy cohortACTA NEUROLOGICA SCANDINAVICA, Issue 2 2009K. O. Nakken Objectives,,, Despite several studies, estimates of the frequency with which auras occur in conjunction with epilepsy continue to be imprecise. The aim of this study was to assess the occurrence and characteristics of auras in a large population-based epilepsy cohort. Materials and methods,,, Subjects with verified epilepsy were recruited from population-based twin registries in the USA, Denmark and Norway. Using a structured interview in which a list of auras was provided, subjects were asked about the warning symptoms preceding their epileptic attacks. Results,,, 31% of the total sample (n = 1897) and 39% of those with active epilepsy (n = 765) had experienced an aura. Six percent reported more than one type. Non-specified auras were most frequently reported (35%), followed by somatosensory (11%) and vertiginous (11%). While the majority of those reporting auras (59%) had focal epilepsies, auras of a mostly non-specific nature were experienced by 13% of those with generalized epilepsies. Conclusion,,, Auras serve an important purpose in that they may prevent seizure-related injuries and could provide an indication as to where the seizures originate. The occurrence of auras often is underestimated, especially in children and those with learning disabilities. [source] Investigation of quality of the parental relationship as a risk factor for subclinical bulimia nervosaINTERNATIONAL JOURNAL OF EATING DISORDERS, Issue 4 2001Tracey D. Wade Abstract Objective Previous literature suggests a link between the quality of the parental relationship and disordered eating in offspring. We investigated the relationship between offspring pyschopathology and the parental relationship using a population-based twin registry that contained 766 complete twin pairs. Method We used reports of twin lifetime psychopathology from the twins and quality of parental relationship and parental lifetime psychopathology from both parents. Results Poorer quality of the marital relationship predicted the presence of subclinical bulimia nervosa (SBN) using both mother's (odds ratio [OR] = 0.83, 95% confidence interval [CI]: 0.71,0.97) and father's (OR = 0.78, 95% CI: 0.62,0.97) reports. It also predicted the presence of generalized anxiety disorder (GAD) and alcohol dependence. SBN was still strongly predicted by the marital relationship when parental psychopathology was included as a covariate. Discussion These results are supportive of the notion that a conflictual and distant marital relationship can, at least partially, act as an environmental risk factor for SBN. © 2001 by John Wiley & Sons, Inc. Int J Eat Disord 30: 389,400, 2001. [source] Epidemiology of cancer-related fatigue in the Swedish twin registryCANCER, Issue 9 2005M.P.H., Michael J. Forlenza Ph.D. Abstract BACKGROUND Estimates of the prevalence of cancer-related fatigue (CRF) are wide, and data suggest that fatigue is more prevalent among cancer patients than among the general population. However, most studies examining the prevalence of CRF have been hospital-based or clinic-based studies, which often are subject to bias. METHODS Point prevalence and prevalence odds ratios of fatigue were estimated using data from a large, population-based cohort that was screened for fatigue and linked with national registry-based data about cancer. Prevalence odds ratios and 95% confidence intervals were calculated using logistic regression with general estimating equations. RESULTS Approximately 23% of cancer registrants reported abnormal fatigue in the previous 6 months, 19% reported abnormal fatigue that lasted for at least 1 month, 14% reported abnormal fatigue that lasted at least 6 months, and 11% reported abnormal fatigue that lasted at least 6 months and caused significant functional impairment. Individuals who were listed in the cancer registry within the last 5 years were more likely to report experiencing fatigue than individuals who were not listed. There was an elevated prevalence of fatigue among those who were registered with carcinomas of the lung, uterine cervix, colon-rectum, ovaries, and prostate. Both women and men who were listed recently in the cancer registry were more likely to experience any level of fatigue than the comparison group. However, a greater proportion of women experienced fatigue relative to men. CONCLUSIONS A greater proportion of individuals who were listed in a national cancer registry reported experiencing fatigue compared with individuals in the general population. Cancer 2005. © 2005 American Cancer Society. [source] | |||||||||||||