Association between IL-6 -174G/C and -572G/C polymorphisms and risk of coronary artery disease in a Chinese population

We have conducted a case-control study in a Chinese population, and investigate the role of two common promoter genomic variants in IL-6 (-174G/C and -572G/C) in the development of CAD in a Chinese population. A hospital-based case-control study was taken. A total of 275 patients with CAD and 286 control subjects were selected between January 2012 and December 2014. The genotyping of IL-6 -174G/C and -572G/C were performed by polymerase chain reaction (PCR) coupled with restriction fragment length polymorphism (RFLP). Using chi-square test, a significant difference was found in IL-6 -174G/C genotype distributions between patients with CAD and control subjects (χ2=16.80, P<0.001). Using unconditional logistic regression analysis, we found that the CC genotype of IL-6 -174G/C was associated with an increased risk of CAD when compared with the GG genotype (OR=3.43, 95% CI=1.79-6.86; P<0.001). Moreover, the IL-6 -174G/C polymorphism was correlated with development of CAD in dominant (OR=1.82, 95% CI=1.23-2.70; P=0.002) and recessive models (OR=3.26, 95% CI=1.71-6.48; P<0.001). However, we found that IL-6 -572G/C polymorphism was not associated with an elevated increased risk of CAD in codominant, dominant and recessive models. In conclusion, we suggest that IL-6 -174G/C is associated with the development of CAD in codominant, dominant, and recessive models. Further studies with large sample size are greatly needed to confirm the findings of our study.