Interaction between APOB gene polymorphism and risk factors in coronary heart disease patients without lipid-lowering treatment

Abstract

Objective: To investigate the association between APOB gene R532W polymorphism and the risk of coronary heart disease (CHD) in patients without lipid-lowering treatment and to analyze the interactions between the variation of R532W and different risk factors of CHD. Methods: CHD and non-CHD were diagnosed according to coronary artery angiography (CAG) and/or coronary computed tomography angiogram (CTA) results, as well as clinical features. Blood samples from 771 CHD patients and 772 age- and sex-matched non-CHD controls, who never accepted any lipid-lowering treatments, were collected. R532W was genotyped by HumanExome BeadChip at BGI and strict quality control was made. Firstly, the association between R532W polymorphism and the risk of CHD in 3 genetic models (GA+ AA vs.GG, AA vs. GG+ GA, AA vs. GA vs. GG) after adjusting confounding factors was explored. Then, the interactions between the variation of this loci and risk factors related to CHD were investigated. Results: (1) Total cholesterol (TC) levels were significantly lower in AA genotype than in GA genotype in the total cohort and non-CHD controls, but was similar among the 3 genotypes in CHD patients. (2) R532W GG, GA and AA distribution was 80.7%, 18.2% and 1.2% in CHD patients, and 74.6%, 23.8% and 1.6% in non-CHD controls (P<0.05). (3) R532 polymorphism was related to the incidence of CHD in the dominant model, and A-allele carriers were related to about 35% reduced risk of CHD (OR=0.653, 95% CI 0.502-0.849, P=0.001) after adjusting for confounding factors. (4) R532W polymorphism had positive interactions with hypertension (1.452) and smoke (1.077), while negative interaction with diabetes (0.553) in the occurrence of CHD. Conclusions: APOB gene R532W polymorphism is related to TC levels in Chinese north Han population. A-allele carries of R532W loci is linked with reduced risk of CHD in the absence of lipid-lowering treatment. R532W polymorphism has a positive additive interaction with hypertension and smoke, while a negative additive interaction with diabetes mellitus in the occurrence of CHD.