Apolipoprotein AI and CIII gene polymorphisms and their association with lipid levels in Italian, Greek and Anglo-Irish populations of Australia

Abstract

The apolipoprotein (apo) AI-CIII-AIV gene cluster on chromosome 11 has been identified as a candidate region for hyperlipidaemia and in particular for hypertriglyceridaemia. Our aim was to detect associations between the apo AI and CIII polymorphisms and the plasma lipids, total cholesterol, triglycerides, high density lipoprotein (HDL) and low density lipoprotein (LDL) cholesterol in normal, healthy, adults from three ethnic groups of Australia--Italian, Greek and Anglo-Irish, separately by gender. The SstI restriction fragment length polymorphisms (RFLP) in the 3' untranslated region of the apo CIII gene and the MspI RFLP in the third intron of the apo AI gene were scored and the lipid concentrations were ascertained using standard methodologies. t-tests were used to compare lipid levels between sexes and between populations, and multivariate ANOVA was used to detect if the two RFLPs had an effect on any of the lipid concentrations. The two RFLPs exhibit strong linkage disequilibrium in all three populations (p < 0.001). There were some significant differences in allele frequencies among the populations: the minor S2 allele was more frequent in Italians (0.12) than Greeks (0.03) (p = 0.003), and the minor M2 allele was more common in Greeks (0.14) than Anglo-Irish (0.05) (p = 0.026). We found no significant association between either of the RFLPs and any of the lipid concentrations in either sex of all three populations. However, Kruskal-Wallis tests detected associations of borderline significance between apo AI MspI genotypes and triglycerides (p = 0.04) and between apo AI MspI genotypes and cholesterol levels (p = 0.03) in Anglo-Irish females. Because only two statistically significant associations were detected among a number of comparisons, our data suggest that the apo AI and CIII polymorphisms play only a very limited role in mediating variation in lipid concentrations in these three ethnic groups.