INVESTIGATION OF THE FAMILIAL RESEMBLANCE BETWEEN BODY FAT AND BLOOD LIPIDS 33

The familial resemblance between body fat and blood lipids was investigated using a bivariate familial correlation model assessing both intraindividual(e.g. body fat-lipid correlation within fathers) and interindividual (e.g. father's body fat with his son's blood lipid) cross-trait correlations. Cross-trait familial resemblance between 4 indicators of body fat [body mass index (BMI), sum of 6 skinfolds (SF6)] and fat distribution [the ratio of the trunk to extremity skinfolds adjusted (TER-sf) and unadjusted (TER) for SF6] with 5 blood lipid variables [total cholesterol (CH), triglycerides (TG), cholesterol associated with high-density lipoproteins (HDL), the CH/HDL ratio and the difference between CH and HDL (CH-HDL)], was investigated in 583 parents and 656 of their biological offsprings after adjustment of body fat and lipid data for the effects of age and sex. The results indicate: 1) greater cross-trait familial resemblance between body fat (rather than fat distribution) measures and blood lipids, 2) stronger cross-trait familial resemblance of body fat and regional fat distribution phenotypes with CH/HDL and CH-HDL than with other lipid variables and 3) larger contribution of siblings to the cross-trait familial resemblance. These results suggest that environmental factors unique to each individual rather than common genes explain familial resemblance between body fat and blood lipids.