title: Clustering of hypertension, diabetes, and obesity in adult male twins: same genes or same environments?
abstract: We investigated the mediating role of genetic factors in the clustering of hypertension, diabetes, and obesity, using the twin registry maintained by the National Academy of Sciences--National Research Council. The study sample included 2,508 male twin pairs born between 1917 and 1927 who responded to a mailed questionnaire that covered demographic variables, cardiovascular risk factors, and health behaviors. The incidence of hypertension and diabetes in this cohort was ascertained from subjects' self-report of a physician diagnosis and/or the use of prescription medications. The body-mass index calculated from self-reports of height and weight was used as a measure of obesity. Descriptive analyses indicated probandwise concordance rates of 34.0%, 31.2%, and 32.7%, respectively, for the joint occurrences of hypertension and diabetes, hypertension and obesity, and diabetes and obesity in MZ twin pairs. Corresponding concordance rates in DZ twin pairs were 8.1%, 14.9%, and 2.8%. The probandwise concordance for the clustering of all three conditions in the same individuals was 31.6% in MZ pairs and 6.3% in DZ pairs (relative risk 5.0; X2(1) = 2.6; P < .15). Multivariate genetic modeling of the correlation in liabilities to develop these conditions suggested the presence of a common latent factor mediating the clustering of hypertension, diabetes, and obesity in this twin sample. This common factor was influenced by both genetic and environmental effects (59% 8 genetic, 41% environmental). The genetic influences on the common latent factor were due to dominant rather than additive sources; the environmental influences appeared to be specific rather than shared by co-twins.
authors.affiliation: Health Sciences Program, SRI International, Menlo Park, CA 94025.
authors.forename: D
authors.initials: D
authors.lastname: Carmelli
authors.forename: L R
authors.initials: LR
authors.lastname: Cardon
authors.forename: R
authors.initials: R
authors.lastname: Fabsitz
mesh_terms: D000368:Aged; D016009:Chi-Square Distribution; D016000:Cluster Analysis; D015897:Comorbidity; D003920:Diabetes Mellitus / Q000453:epidemiology / Q000235:genetics*; D004200:Diseases in Twins / Q000453:epidemiology / Q000235:genetics*; D004777:Environment; D005799:Genes, Dominant; D014644:Genetic Variation; D006801:Humans; D006973:Hypertension / Q000453:epidemiology / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D008889:Military Personnel; D008957:Models, Genetic; D015999:Multivariate Analysis; D009765:Obesity / Q000453:epidemiology / Q000235:genetics*; D015995:Prevalence; D012306:Risk; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic; D014481:United States / Q000453:epidemiology