Association between C-589T polymorphisms of interleukin-4 gene promoter and asthma: A meta-analysis

Background: A number of studies of genetic epidemiology have assessed the association of C-589T (also referred to as C-590T, rs number, 2243250) polymorphisms in the promoter region of interleukin-4 (IL-4) gene with asthma in different populations. However, the results are inconsistent and inconclusive. Objectives: We performed a meta-analysis of the association between C-589T polymorphisms of IL-4 and asthma with the following objectives: to estimate the magnitude of the gene effect and the possible mode of inheritance. Methods: A genetic model-free approach was used to perform a meta-analysis. Asthma (atopy status nondefined), nonatopic and atopic asthma subgroups were separately analyzed. Heterogeneity and publication bias were also explored. Results: Our meta-analysis summarized the evidence regarding the association between C-589T polymorphisms in the promoter region of IL-4 gene and asthma. When all asthma groups were pooled, a significant association of increased asthma risk and T allele was found. In subgroup analysis, our results indicated a significant association and a recessive genetic mode of C-589T polymorphisms of IL-4 with atopic asthma. The CC genotype was about 21 percent less likely to have atopic asthma than the genotype CT and TT. However, C-589T polymorphisms were not significantly associated with nonatopic asthma. Conclusions: This meta-analysis suggests there may be an important effect of single nucleotide polymorphisms (SNPs) in the promoter region of IL-4 gene on the pathogenesis of atopic asthma. This warrants further investigation in larger studies and meta-analysis. (c) 2008 Elsevier Ltd. All rights reserved.