Association between interleukin-18 gene promoter (− 607C/A and − 137G/C) polymorphisms and chronic hepatitis C virus infections: A meta-analysis

OBJECTIVE HCV infection has a chronicity rate of about 70%, several studies have shown that interleukin-18 (IL-18) was associated with etiology and progression of hepatitis C virus (HCV) infections. However, the association between single-nucleotide polymorphisms - 607C/A (rs1946518) and - 137G/C (rs187238) located in the IL-18 gene promoter and chronic hepatitis C virus infections was still controversial and ambiguous. To derive a more precise effect on the association between these polymorphisms and chronic hepatitis C virus infections, we performed this first meta-analysis based on the currently available evidence of the literature. METHODS A total of 4 studies with 1222 cases and 1115 controls for - 607C/A polymorphism and 3 studies with 959 cases and 987 controls for - 137G/C polymorphism were identified to perform a meta-analysis. Summary ORs and corresponding 95% CIs for IL-18 polymorphisms and chronic hepatitis C virus infections were estimated using fixed- and random-effects models when appropriate. Heterogeneity, sensitivity analysis, and publication bias were evaluated. RESULTS We found a significant association between - 137G/C polymorphism and chronic hepatitis C virus infections (CG + CC versus GG: OR = 2.157, 95% CI [1.822, 2.553]; CC versus CG + GG: OR = 2.007, 95% CI [1.441, 2.797]). However, no significant association was observed between - 607C/A polymorphism and chronic hepatitis C virus infections under different contrast models. CONCLUSIONS The present meta-analysis suggested that IL-18 - 137G/C polymorphism in promoter region was associated with chronic hepatitis C virus infections, but no evidence indicate association between - 607C/A polymorphism and chronic hepatitis C virus infections. High-quality studies with larger sample size and larger number are warranted.