[Influence of genetic combinations on HDL-C levels in a Southern Brazilian population]

Abstract

Background: low HDL-C levels are important predictors of coronary disease, the first cause of death worldwide. Many factors affect HDL-C levels, such as polymorphisms of genes encoding for key proteins of the reverse cholesterol transport pathway.

Objective: to investigate the influence of seven polymorphisms of the CETP, APOA1, ABCA1 and SCARB1 genes on HDL-C levels in a southern Brazilian population.

Methods: the polymorphisms were investigated in a sample of 500 individuals of European descent, but HDL-C levels from only 360 individuals were adjusted for cofactors using multiple linear regressions in the association study. The sample was divided in tertiles according to adjusted HDL-C levels, and allele and haplotype frequencies were compared between the 1st and 3rd tertiles of adjusted HDL-C levels.

Results: When combinations of risk alleles were tested, the frequency of allele combinations in three genes (haplotype 1 of APOA1 gene, variant 2S of SCARB1 gene, and allele B1 of CETP gene) was significantly higher in the lower tertile of adjusted HDL-C (28.3%) than in the upper tertile (14.9%; p=0.008), which indicated that the presence of these variants increased 2.26 times the chances of having HDL-C levels below 39.8 mg/dl.

Conclusion: these markers, when studied separately, are expected to have a small influence on the characteristic under analysis, but greater influence was detected when the markers were studied in combination. In a population of southern Brazilians, our data showed a significant influence of variant combinations of APOA1, SCARB1 and CETP genes on HDL-c levels.