Apolipoprotein E gene polymorphisms and risk for coronary artery disease in Chinese Xinjiang Uygur and Han population

To examine the relationship between apolipoprotein E (Apo E) gene polymorphism and risk of coronary artery disease (CAD), analyzing association of polymorphism with classical risk factors.

A total of 124 patients (including 84 Han population and 40 Uygur population) with angiographically verified CAD or myocardial infarction were prospectively evaluated. Data referring to hypertension, diabetes, and tobacco consumption were recorded. The levels of total cholesterol (TC), high density lipoprotein (HDL) cholesterol, Apo A1 and B, and triglycerides (TG) were determined. DNA was obtained from 124 patients and 70 controls. In order to determine Apo E genotypes, DNA was PCR amplified and digested with HhaI. The genetic polymorphism of Apo E is due to three common alleles, epsilon (epsilon) 2, epsilon3, epsilon4, at a single autosomal gene locus. These alleles determine the six phenotypes E2/2, E3/3, E4/4, E4/2, E4/3, and E3/2.

In Uygur population, the frequency of the epsilon2, epsilon3, and epsilon4 was 0.155, 0.648, and 0.197 respectively. In Han population, the frequency of the epsilon2, epsilon3, and epsilon4 was 0.081, 0.772, and 0.146 respectively. In the patient group, the frequency of the epsilon2, epsilon3, and epsilon4 was 0.060, 0.758, and 0.182 respectively. In the control group, the frequency of the epsilon2, epsilon3, and epsilon4 was 0.193, 0.671, and 0.136 respectively. epsilon2 frequency of Uygur' patients and controls was 0.050 and 0.290 respectively. Serum low density lipoprotein (LDL) cholesterol, TC, and TG values tended to decrease from the Apo E-4 phenotypes to Apo E-2 phenotypes. When deletion polymorphism of epsilon2 was compared with the common risk factors for CAD, its risk ratio (RR) is 4.38.

These studies confirm and find that Apo E phenotype distribution in Uygur population differs significantly from that in Han population in Xinjiang. CAD patients have significantly lower epsilon2 allele and slightly higher epsilon3 or epsilon4 allele frequency than controls, especially in Uygur population. It shows protective effects of epsilon2 on CAD.