The relation between ponderosity and coronary risk factors in children and their relatives. The Muscatine Ponderosity Family Study.

A family study was conducted in Muscatine, Iowa in 1984-1985 to evaluate the relation between ponderosity in children and coronary risk factor levels in these children and in their family members, and the genetic contribution to familial clustering of levels of ponderosity (body weight relative to height). Four groups of probands were selected from the 1,783 students who participated in three consecutive biennial school surveys. A random group (n = 70), a random sample of students from the entire pool; a lean group (n = 72), students in the lowest quintile of relative weight on all three surveys; a gain group (n = 70), students who gained at least two quintiles of relative weight over the four-year period; and a heavy group (n = 72), students in the highest quintile of relative weight on all three surveys. The parents, siblings, a related aunt or uncle, and a first cousin of these probands were also examined. The data show that levels of high density lipoprotein (HDL) cholesterol, apolipoproteins A-1 and B, and systolic blood pressure in heavy group probands are consistent with increased coronary risk. This same association exists among the relatives with excess ponderosity. Levels of body mass index in the mothers, fathers, and siblings cluster with the levels in the probands, and genetic differences among persons explain 36-52 per cent of the variability in body mass index across the range of ponderosity represented by the probands and their relatives. While the contribution from genes is strong, these data suggest that the contribution from environmental factors is equally as important.