Associations of polymorphism of P22phox C242T, plasma levels of vitamin E, and smoking with coronary heart disease in China

Background The C242T polymorphisms of P22phox and plasma vitamin E have been associated with the risk of coronary heart disease (CHD) in several studies, but the results have been inconsistent. In this study, we sought to examine potential interactions between P22phox genotypes, plasma vitamin E concentrations, and smoking in relation to CHD risk. Methods We determined C242T genotype frequency in the P22phox gene and plasma levels of vitamin E in 565 Chinese patients with CHD and 609 control subjects. Logistic regression was used to control for potential confounders in multivariate analyses. Results Compared with subjects with a CC genotype, subjects with a CT or TT genotype had a lower risk of CHD (multivariate-adjusted odds ratio [OR] 0.45, 95% CI 0.28-0.74, P = .001). Plasma concentrations of vitamin E were lower in case patients than in control subjects (multivariate-adjusted OR 0.65, 95% CI 0.50-0.86, P = .025). Compared with nonsmokers with a CC genotype, nonsmokers with a CT or TT genotype had a decreased risk of CHD (OR 0.25, 95% CI 0.12-0.53), but smokers with a CT or TT genotype had an increased risk (OR 2.04, 95% CI 0.74-5.61, P for interaction = .039). Smokers with a lower vitamin E concentration had a >3.0-fold greater risk of CHD than did nonsmokers with a higher vitamin E concentration (OR 3.52, 95% CI 2.36-5.24, P for interaction = .041). Conclusions These data provide evidence that P22phox genotypes are significantly associated with CHD risk in a Chinese population and suggest potential interactions among smoking, P22phox genotypes, and vitamin E in relation to CHD risk.