Interleukin-4 (IL-4) polymorphisms have been reported to influence an individual's susceptibility to
liver disease as it is a central anti-inflammatory Th2
cytokine; however, these results remain controversial.A comprehensive meta-analysis of the relevant literature was thus performed to better estimate the relationship between
IL-4 polymorphisms and
liver disease.Systematic searches of various databases (PubMed, Embase, Cochrane Library, and China National Knowledge Infrastructure) for studies published before July 5, 2015 were performed. Odds ratios (
ORs) with 95% confidence intervals (CIs) calculated in fixed or random-effects models were used to estimate the strength of the association. Subgroup analyses, meta-regression, Galbraith plots, and sensitivity analyses were also performed.A total of 16 case-control studies, of which 15 involved the -590C/T polymorphism and 3 involved the -33T/C polymorphism, were included in the study. With respect to the -590C/T polymorphism, a significantly increased risk of
liver diseases was found in the overall population (TT + CT vs CC: OR = 1.25, 95% CI = 1.06-1.49, P = 0.009 and CT vs CC: OR = 1.22, 95% CI = 1.00-1.48, P = 0.048) and the Asian population (TT + CT vs CC: OR = 1.28, 95% CI = 1.04-1.57, P = 0.020). Further subgroup analyses also showed significant associations between the -590C > T polymorphism and the risk of
hepatitis C infection and
hepatocellular carcinoma. However, no association was found between the -33T/C polymorphism and risk of
liver diseases in all comparison models.This meta-analysis suggested that the
IL-4 -590C > T polymorphism is associated with an increased risk of
hepatitis C infection and
hepatocellular carcinoma, especially among the Asian population.