Association between interleukin-6 gene − 174 G/C polymorphism and the risk of coronary heart disease: A meta-analysis of 20 studies including 9619 cases and 10,919 controls

Interleukin-6 (IL-6) gene − 174 G/C polymorphism has been reported to be associated with coronary heart disease (CHD), but the results remain inconclusive. The present meta-analysis was therefore designed to clarify these controversies. This meta-analysis was performed by searching PubMed, Embase and Web of Science databases. A total of 20 studies including 9619 CHD cases and 10,919 controls were combined showing no evidence of association between IL-6 gene − 174 G/C polymorphism and CHD risk (for C/C + C/G vs. G/G: OR = 1.10, 95% CI = 0.99–1.22, p = 0.07; for C/C vs. C/G + G/G: OR = 1.08, 95% CI = 0.93–1.24, p = 0.33; for C/C vs. G/G: OR = 1.16, 95% CI = 0.97–1.39, p = 0.11; for C allele vs. G allele: OR = 1.10, 95% CI = 1.00–1.21, p = 0.06). Moreover, we also did not find significant association between IL-6 gene − 174 G/C polymorphism and myocardial infarction (MI) risk. However, in the subgroup analysis by ethnicity, significant association was found among Asians (for C/C + C/G vs. G/G: OR = 1.35, 95% CI = 1.05–1.63, p = 0.02). In summary, the present meta-analysis suggests that IL-6 gene − 174 G/C polymorphism is associated with increased CHD risk among Asians. However, due to the small subjects included in the subgroup analysis of Asians, the results should be interpreted with caution.