Polymorphisms of -174G>C and -572G>C in the interleukin 6 (IL-6) gene and coronary heart disease risk: a meta-analysis of 27 research studies

Objective

Elevated serum IL-6 level is a risk factor for coronary heart disease (CHD). The ?174G>C and ?572G>C polymorphisms in the IL-6 gene have previously been shown to modulate IL-6 levels. But the association between the ?174G>C and ?572G>C polymorphisms and the risk of CHD is still unclear. A meta-analysis of all eligible studies was carried out to clarify the role of IL-6 gene polymorphisms in CHD.

Methods and Results

PubMed, EMBASE, Vip, CNKI and CBM-disc were searched for eligible articles in English and Chinese that were published before October 2010. 27 studies involving 11580 patients with CHD and 17103 controls were included. A meta-analysis was performed for the included articles using the RevMan 5.0 and Stata 10.0 softwares. Overall, the ?174C allele was not significantly associated with CHD risk (ORs?=?1.04, 95%CI?=?0.98 to 1.10) when compared with the ?174G allele in the additive model, and meta-analysis under other genetic models (dominant, recessive, CC versus GG, and GC versus GG) also did not reveal any significant association. On the contrary, the ?572C allele was associated with a decreased risk of CHD when compared with the ?572G allele (ORs?=?0.79, 95%CI?=?0.68 to 0.93). Furthermore, analyses under the recessive model (ORs?=?0.69, 95%?=?0.59 to 0.80) and the allele contrast model (genotype of CC versus GG, ORs?=?0.49, 95%?=?0.35 to 0.70) yielded similar results. However, statistical significance was not found when the meta-analysis was restricted to studies focusing on European populations, studies with large sample size, and cohort studies by using subgroup analysis.

Conclusions

The ?174G>C polymorphism in the IL-6 gene is not significantly associated with increased risks of CHD. However, The ?572G>C polymorphism may contribute to CHD development. Future investigations with better study design and large number of subjects are needed.