HIGH-FREQUENCY OF THE APO EPSILON-4 ALLELE IN KHOI-SAN FROM SOUTH-AFRICA

Variation at the apolipoprotein E (apo E) gene locus affects cholester ol concentrations, the risk for atherosclerosis and Alzheimer disease (AD), and is associated with longevity in Caucasians. We have determin ed apo E gene frequencies and effects on cholesterol levels in Khoi Sa n (Bushmen) from South Africa. The frequency of the apo epsilon 4 alle le (0.37), which confers dose-dependent susceptibility to atherosclero sis and AD in Caucasians, was twice as high, and apo E4 homozygotes we re 3-5 fold more frequent in the Khoi San (approximate to 10%) compare d with Caucasians (2%-3%). No significant effect of apo E variation on cholesterol concentration was noted in this non-Westernized populatio n with low plasma cholesterol (mean cholesterol 149 mg/dl). This sugge sts that Bushmen carry a heavy genetic burden for these late-onset dis orders if exposed to a Western lifestyle.