Interleukin-18 Polymorphisms Deficiency Association with Asthma Risk: An Update Meta-analysis.

Growing evidence indicated conflicting results that Interleukin-18 (IL-18) promoter polymorphisms rs1946518 (A-607C), rs187238 (G-137C) and rs549908 (A-105C) were associated with asthma risk. The aim of this study is to comprehensively evaluate the IL-18 polymorphisms and asthma by a systematic review and meta-analysis. A total of 12 studies testing the association between these polymorphisms and asthma were examined (8 studies for A-607C, 8 studies for G-137C, and 4 studies for A-105C) in the update meta-analysis, up to Dec 30, 2017. Summary odds ratios (ORs) and 95% confidence intervals (CI) were used to estimate the strength of association between each polymorphism and asthma using fixed- and random-effects models when appropriate. Heterogeneity and publication bias were evaluated. The meta-analysis results indicated that any allele frequencies of the IL-18 polymorphisms (A-607C, G-137C and A-105C) was not associated with asthma risk (p>0.05). And no statistically significant association was observed between genotype frequencies of these polymorphisms and asthma under different genetic models (p>0.05). Subgroup analysis results were similar to the main analysis by ethnicity, sample size, genotyping methods, matching criteria and quality score. There was no evidence of publication bias. The present meta-analysis suggests that IL-18 polymorphisms (A-607C, G-137C and A-105C) were unlikely to be associated with asthma risk.