Association between the interleukin-4, interleukin-13 polymorphisms and asthma: a meta-analysis

A numbers studies had been reported that the polymorphisms in the Interleukin 4 (IL-4) and Interleukin 13 (IL-13) genes were associated with susceptibility to asthma. However, the results were inconsistent and inconclusive. We carried out a meta-analysis of case-control genetic association studies to assess whether the combined data showed this association by using a genetic model-free approach. Thirty studies (total 12,781 asthma and 11,500 controls) for the IL-4 C-33T and C-589T, IL-13 C-1112T and G+2044A with asthma were included in the meta-analysis. The results indicated that there were an association between the IL-4 C-33T (P = 0.006) and C-589T (P = 0.04), IL-13 C-1112T (P = 0.002) and G+2044A (P = 0.04) and susceptibility to asthma. And the definition of asthma subgroup meta-analysis demonstrates that the IL-4 C-33T is not associated with nonatopic or atopic, and IL-4 C-589T and IL-13 C-1112T polymorphisms are not associated with atopic. In the ethnicity subgroup meta-analysis, the IL-4 -589T (P = 0.003) and the IL-13 -1112T (P < 0.00001) alleles are associated with asthma among Caucasian, but not on the IL-13 +2044A allele. In conclusion, IL-4 C-33T and C-589T, IL-13 C-1112T and G+2044A could be proposed as asthma susceptible SNPs. Further investigation in larger studies and meta-analysis is required.