Heritability estimates of obesity measures in siblings with and without hypertension

The goal of the present study was to evaluate mean values and heritability estimates of 3 global and 11 regional obesity measures in siblings with (HP T, n=209) or without (non-HPT, n=91) early-onset (age :less than or equal t o 55 years) hypertension who originated from the same families. Sixty-one s ibships, each having at least 2 HPT siblings, were selected from a French-C anadian population with a known founder effect. Comparison of the mean valu es showed that HPT siblings are more obese than non-HPT siblings and that t he body fat of HPT siblings is more centrally distributed. Significant diff erences were observed in all global obesity measures (P=0.009 to 0.0001). A mong the regional measures, the most prominent differences were seen in wai st circumference (P=0.00002), waist/hip ratio (P=0.0001), and suprailiac sk infold (P=0.00008). Comparison of the heritability estimates derived from s ibling/sibling correlations (FCOR program, SAGE) suggested that genetic fac tors play a greater role in HPT (n=357) than in non-HPT (n=93) sib-pairs in determining most obesity measures. Similar to the mean values, these diffe rences were most apparent in global and upper-body measures, with heritabil ities ranging from 40% to 70% (P=0.05 to 0.0006) in HPT siblings and from 0 % to 32% (P=NS) in non-HPT siblings. In summary, the present results sugges t that HPT and non-HPT siblings drawn from the same families differ by the degree and distribution of body fat accumulation and that this difference i s determined, at least in part, by genetic factors cosegregating with hyper tension. This, in turn, suggests that a genetic link exists between obesity and hypertension in these families.