Interleukin-18 promoter polymorphism and asthma risk: a meta-analysis

Some studies have shown that IL-18 was associated with aetiology and progression of asthma. However, the association between single-nucleotide polymorphisms -607C/A (rs1946518) and -137G/C (rs187238) located in the IL-18 gene promoter and asthma risk was still controversial and ambiguous. To derive a more precise effect on the association between these polymorphisms and asthma risk, we performed a meta-analysis based on the currently available evidence of the literature. A total of 5 studies with 1411 cases and 1525 controls for -607C/A polymorphism and 5 studies with 1883 cases and 6645 controls for -137G/C polymorphism were identified to perform a meta-analysis, up to October 2010. Summary ORs and corresponding 95% CIs for IL-18 polymorphisms and asthma were estimated using fixed-and random-effects models when appropriate. Heterogeneity and publication bias were evaluated. We found that individuals carrying AC/CC genotype of -607C/A polymorphism were associated with an increased asthma risk in recessive model (OR = 1.278; 95% CI, 1.073-1.522). However, no significant association was observed between -137G/C polymorphism and asthma risk under different contrast models. There was no evidence of publication bias. The present meta-analysis suggested that IL-18 -607C/A polymorphism in promoter region was associated with asthma risk.