Effects of the ApoE Polymorphism on Plasma Lipoproteins in Mexican Americans

PURPOSE: To evaluate the impact of apolipoprotein E (apoE) genotypes on lipoprotein measurements relative to that of other known cardiovascular risk factors in participants of a large population-based family study. METHODS: We measured concentrations of apoE, the major constituents of HDL (cholesterol, apoAI), LDL-C (cholesterol and apoB), and fraction of apoE in lipoprotein size classes in 859 participants of the San Antonio Family Heart Study, and then tested the association between the three common apoE genotypes (epsilon (Porson)2epsilon (Porson)3, epsilon (Porson)3epsilon (Porson)3, and epsilon (Porson)3epsilon (Porson)4) and lipoprotein traits using the measured genotype approach to account for residual familial correlations. RESULTS: Allele frequencies in this population for epsilon (Porson)2, epsilon (Porson)3, and epsilon (Porson)4 were 3.5%, 89.6%, and 6.9%, respectively. As expected, adjusted apoE concentrations were highest in those with epsilon (Porson)2epsilon (Porson)3, intermediate in those with epsilon (Porson)3epsilon (Porson)3, and lowest in those with epsilon (Porson)3epsilon (Porson)4. The concentrations of total cholesterol, LDL-C and apoB were lowest in those with epsilon (Porson)2epsilon (Porson)3, intermediate in those with epsilon (Porson)3epsilon (Porson)3, and highest in those with epsilon (Porson)3epsilon (Porson)4. There was no significant effect of apoE genotypes on triglycerides, HDL-C, or apoAI levels. Compared to subjects with epsilon (Porson)3epsilon (Porson)4, subjects with epsilon (Porson)2epsilon (Porson)3 had relatively less apoE in LDL and HDL1, and relatively more in HDL2 and HDL3 size fractions. The effect of apoE genotypes was significantly greater on apoB in women than in men image. ApoE genotypes accounted for 4.5%, 12.3%, and 4.7% of the total genetic variation in apoB, apoE, and LDL-C, respectively. CONCLUSION: ApoE genotypes account for a modest, albeit significant, proportion of phenotypic variation in concentrations of LDL-C, apoB, and apoE, and distributions of apoE among lipoproteins in this population; these genotypes have a greater effect on apoB levels in women than in men.