GENETIC-ANALYSIS OF SEX AND GENERATION DIFFERENCES IN PLASMA-LIPID, LIPOPROTEIN, AND APOLIPOPROTEIN LEVELS IN ADOLESCENT TWINS AND THEIR PARENTS

In a sample of Dutch families consisting of parents aged 35-65 years a nd their twin offspring aged 14-21 years, a significant difference bet ween generations was observed in phenotypic variances and in genetic h eritabilities for plasma levels of total cholesterol, triglycerides, h igh density lipoprotein (HDL) and low density lipoprotein (LDL) choles terol, and apolipoproteins (ape) A1, A2, B, and E. For all traits pare nts were more variable than their offspring. This increase in phenotyp ic variance was best explained by a genetic model in which individual specific environmental variance increased with increasing age. Genetic variance was the same across generations for nearly all traits except triglycerides and apoE, for which a decrease in genetic variance was observed. This model led to large intergenerational differences in gen etic heritabilities. Heritabilities for children were between 65 and 8 7%, while heritabilities for their parents were between 10 and 50%. No evidence was found for effects of a shared family environment. (C) 19 96 Wiley-Liss, Inc.