Common genetic and environmental effects on lipid phenotypes: The HERITAGE Family Study

Objective: Despite the well known genetic component influencing plasma lipid-lipoprotein levels and the observed correlations among these traits, little is known about pleiotropic heritable determinants among them. Our aim is to investigate pair-wise polygenic and environmental correlations among lipid-lipoprotein levels at baseline and in response to regular exercise in Whites and Blacks. Methods: Common pair-wise genetic and environmental correlations among levels of total cholesterol (TC), LDL-C, ApoB, HDL-C (also HDL₂-C and HDL₃-C), triglycerides (TG, HDL-TG and LDL-TG) and ApoA-1 were investigated at baseline and again after a 20-week endurance exercise program using a variance-components-decomposition. Results: With a few exceptions, all lipid phenotypes were heritable at baseline and for training responses in Blacks and Whites. Strong to high genetic and environmental correlations (0.4 < ρ_g < 0.7) were observed for the majority of the baseline pair-wise traits. For training responses, many of the same patterns were noted, although fewer genetic correlations were significant as compared to the baseline results. Conclusions: Results suggest that the observed phenotypic correlations among many of these traits may be due to in part to pleiotropic genes, in particular between LDL-C and ApoB and between TG and HDL-C. This shared genetic architecture should be considered in follow-up gene finding studies.