Published data on the association between interleukin-4 (IL-4) rs2243250 (C-589T) polymorphism and asthma susceptibility are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. A total of 17 studies with 3037 asthma patients and 3032 healthy controls were included. Overall, significantly elevated asthma risk was associated with IL-4 T allele when all studies were pooled into the meta-analysis (CT vs. CC: OR=1.187, 95% CI=1.016-1.387; dominant model: OR=1.213, 95% CI=1.046-1.405). In the subgroup analysis by ethnicity, significantly increased risk was only found for Caucasians (TT vs. CC: OR=1.591, 95% CI=1.032-2.452; dominant model: OR=1.292, 95% CI=1.028-1.624). When stratified by asthma type, statistically significantly elevated risk was only found in atopic asthma group (dominant model: OR=1.313, 95% CI=1.033-1.667). Despite some limitations, this meta-analysis suggests that T allele at position -589 of the IL-4 gene promoter region is a low-penetrant risk factor for asthma development especially for Caucasians and atopic type.
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