POPULATION-DISTRIBUTIONS OF APOE, APOH, AND APOA4 POLYMORPHISMS AND THEIR RELATIONSHIPS WITH QUANTITATIVE PLASMA-LIPID LEVELS AMONG THE EVENKI HERDERS OF SIBERIA

We examined the distributions of seven polymorphic sites in three apol ipoprotein genes (APOE, APOA4, and APOH) and their relationships with quantitative lipid levels (total cholesterol, LDL cholesterol, HDL cho lesterol, and triglycerides) among the Evenki reindeer herders of cent ral Siberia. The polymorphism data reveal several distinctive features that differentiate the Evenki from white populations: the near absenc e of the APOE2 allele, the highest ever recorded frequency of the APO H3 allele, the complete absence of the APOA*2 allele at codon 360, an d significantly different frequencies at three other APOA4 polymorphic sites. Our analyses of the relationships of common apolipoprotein pol ymorphism and plasma lipid levels also revealed interesting results, T he well-established positive association between the APOE4 allele and LDL cholesterol level reported in white populations was not seen in t he Evenki despite a comparable frequency of the APOE4 allele. Because the Evenki have significantly lower cholesterol levels than Westerniz ed whites, this difference in allelic effect probably reflects gene-di et interaction, which modulates the effect of APOE polymorphism on LDL cholesterol. At the APOA4 locus the HincII polymorphism at codon 127 shows a significant impact on plasma triglyceride variation in the Eve nki sample: The HincII - allele was associated with higher triglycerid e levels than the HincII + allele. Our data indicate that both the gen etic and the environmental factors conventionally associated with card iovascular disease risk in Western societies are different in the Even ki.