Sex and genetic effects on upper and lower body fat and associations with diabetes in multigenerational families of African heritage.

Abstract Very few studies have comprehensively defined the genetic and environmental influences on body fat storage in the arms and legs and their association with diabetes, especially in families of African heritage. We analyzed body fat distribution by dual-energy x-ray absorptiometry (percentage total fat, percentage trunk fat, percentage arm fat, and percentage leg fat) and fasting serum glucose in 471 individuals (mean age, 43 years) from 8 multigenerational Afro-Caribbean families (mean family size=51; 3535 relative pairs). Diabetes was inversely associated with percentage leg fat ( P = .009) and, to some extent, positively associated with percentage arm fat independent of age, sex, and body size ( P = .08), but not with anthropometric or dual-energy x-ray absorptiometric measures of total and central adiposity. Furthermore, percentage leg fat was inversely, whereas percentage arm fat was positively, associated with body mass index, waist circumference, and serum glucose ( P P P = .02) in women than in men (h2r values, 58% vs 17%, respectively). Genetic correlation ( ρ G ) between arm and leg fat was −0.61 ( P