Apolipoprotein B gene polymorphisms are associated with lipid levels in men of South Asian descent

Abstract

Three polymorphic sites of the apolipoprotein B gene — the insertion/deletion signal peptide, Xbal and EcoRI sites — were examined in a sample of 107 healthy men and in 46 men with evidence of coronary heart disease selected from a large population survey of South Asians aged 40–69 in London, U.K. There were no significant differences in allele frequencies between cases and controls. Frequencies of the ins (insertion) and X — (absence of XbaI cutting site) alleles were higher in South Asians than in Europeans studied previously (South Asians versus Europeans ins: 0.80 vs. 0.68, P < 0.025; X - : 0.71 vs. 0.47−0.56, P < 0.001). The del allele was associated with higher levels of total cholesterol ( P < 0.05) and the X + allele with lower levels of HDL cholesterol ( P < 0.05), and thus both polymorphisms were associated with differences in the ratio of HDL cholesterol to total cholesterol (ins/del, P < 0.01; Xbal, P < 0.001). Mean waist-hip girth ratio was lower in the 10 men homozygous for the X + allele than in the 42 men with X - /X + and 55 men with X - /X - genotypes; the means (±SEM) were 0.92 ± 0.02, 0.97 + 0.01 and 0.96 + 0.01 respectively ( P = 0.03). These data suggest that genetic variation in linkage disequilibrium with the XbaI and ins/del polymorphisms of the apo B gene contributes to the determination of total cholesterol and HDL cholesterol levels and possibly to obesity in South Asians.