Association of Apo E Polymorphism With Plasma Lipid Levels in a Multiethnic Elderly Population

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Abstract
Apolipoprotein E polymorphisms are important determinants of blood lipid levels and have been associated with longevity and atherosclerosis. However, information is limited on the effects of apo E variation on the lipids of nonwhite and elderly individuals. We tested the hypothesis that apo E polymorphisms are associated with plasma lipid levels in an elderly, multiethnic population. Cross-sectional data from 1068 noninstitutionalized individuals from northern Manhattan over the age of 64 who were not on a lipid-lowering diet or drug were analyzed. The ethnic distribution was 34% African-Americans, 47% Hispanics, and 19% non-Hispanic Caucasians. In the entire group, the most prevalent apo E allele was ε3 (76%), followed by ε4 (16%) and ε2 (8%); ε4 was more prevalent in African-Americans (21%) than in non-Hispanic Caucasians (12%) or Hispanics (14%). The apo ε2 allele was the most important correlate of plasma lipids, but this association varied across ethnoracial groups. After being adjusted for age, sex, obesity, diabetes mellitus, and alcohol intake, LDL cholesterol levels declined with each apo ε2 allele by 8.8 mg/dL in Hispanics and by 25.6 and 18.1 mg/dL in non-Hispanic Caucasians and African-Americans, respectively (P<.001). No significant independent effect was noted for any apo E genotype on HDL cholesterol. Overall, there was a reduction in the total/HDL cholesterol ratio, per apo ε2 allele, of 0.82 in non-Hispanic Caucasians and 0.43 and 0.48 in African-American and Hispanic individuals, respectively (P<.05). In a multivariate model, apo ε4 did not significantly affect plasma lipid levels. Plasma triglyceride levels were inversely correlated with the number of apo ε4 alleles (175, 159, and 143 mg/dL with 0, 1, and 2 alleles, respectively; P =.002), and this effect increased with age. Thus, in an elderly, multiethnic population, apolipoprotein E polymorphisms were important determinants of blood lipids, with differing effects depending on ethnicity. The presence of apo ε2 was associated with lower LDL cholesterol levels and total/HDL cholesterol ratio, although apo ε genotype did not influence HDL cholesterol levels. Prospective studies are needed to test whether apo ε2 protects against incident cardiovascular disease in the elderly.