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.