Segregation analysis of waist circumference, hip circumference and waist-to-hip ratio in the Korean Nationwide Family Study

AIM: A central distribution of adipose tissue is frequently associated with cardiovascular disease and its risk factors. In this study, we investigated environmental, familial and genetic influences on waist circumference (WC), hip circumference (HC) and waist-to-hip ratio (WHR) in 2507 members of 435 families who had participated in the Korean Nationwide Health Examination Survey. METHOD: Maximum likelihood methods were used to fit several genetic and nongenetic models of inheritance to these data to determine whether an unobserved Mendelian major gene could explain the familial distribution of WC, HC and WHR. Adjustments for age, age(2), body mass index, smoking, alcohol consumption and exercise were carried out separately for males and females by multiple regression procedures for WC, HC and WHR phenotypes prior to segregation analysis. Regression models were used to test genetic and non-genetic models in these 435 families. RESULTS: Segregation analysis did not provide statistical evidence of a major gene controlling either HC or WHR. Mendelian single-locus models with two underlying genotypic distributions were best supported by these data on WC, and this putative major gene explained the 22.4% of variance in adjusted WC. CONCLUSION: Future linkage studies may be worthwhile to further clarify the mechanisms controlling WC.