IL-6 174 G/C Polymorphism in Inflammatory Bowel Disease: A Systematic Review and Meta-Analysis

The results of previous studies on the association between IL-6-174G/C (rs1800795) polymorphism and inflammatory bowel disease (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC) are not consistent. The present meta-analysis has pooled all eligible studies to understand the relation between this gene polymorphism and IBD risk. A structured search of Medline, EMBASE, and Scopus databases were performed to identify all eligible studies published before June 2017. Odds ratio (OR) and 95% confidence intervals (CIs) were assessed applying fixed- or random-effect models to evaluate the strength of association in recessive model, dominant model, allelic model, heterozygote contrast, and homozygotes contrast. A sum of 9 articles with 1524 IBD cases and 1586 healthy subjects were included in this study. No significant association between the IL-6 -174 G/C polymorphism and overall IBD susceptibility in any tested genetic model was found. Moreover, in the subgroup analysis based on subtypes, the associations between the IL-6 174-G/C polymorphism and CD and UC missed statistical significance. The current meta-analysis suggests that the IL-6-174 G/C polymorphism is not associated with IBD susceptibility. Further and comprehensive studies are necessary to warrant this result.