Familial aggregation of total cholesterol, triglyceride and high-density lipoprotein-cholesterol in an Israeli population sample

An analysis of factors involved in the determination of cholesterol, triglyceride and high-density lipoprotein-cholesterol (HDL-C) variables is presented. The Jerusalem Lipid Clinic tested a population sample of 3,118 youngsters aged 17 to 18 yr and their parents. In 233 of these families, another sibling was examined at age 17 to 18 yr. Analysis was performed after adjustment of fasting lipid variables for age and sex effects. Since the Israeli population is heterogeneous, the families studied were classified by the parents' country of birth into four groups in which both parents had originated from the same country and one group in which each parent had originated from a different continent. Father-mother correlations for plasma lipid variables were relatively high in parents born in the same country and low in those from different continents. This result could be due to common genetic factors or perhaps to environmental factors shared by parents in early life. The midparent-child correlations were higher for cholesterol and HDL-C in all four groups where parents originated from the same country and lower in the heterogeneous group, but these differences were not statistically significant. The parent-child correlations for total cholesterol and HDL-C were between 0.21 and 0.32, and for triglyceride between 0.09 and 0.20. Sib-sib correlations were significantly positive for all three plasma lipids measured. Although mother-child correlations were stronger than those for father-child, this difference was only significant for HDL-C. The estimated heritability coefficients were between 0.30 and 0.54 for cholesterol and HDL-C and lower for triglyceride. These results provide evidence for familial aggregation of plasma cholesterol, triglyceride and HDL-C in an Israeli population, and they indicate that much of the variation in lipid variables can be explained by genetic factors.