Association of IL4 and IL4R polymorphisms with multiple sclerosis susceptibility in Caucasian population: A meta-analysis

Background: Previous studies have suggested a role for interleukin-4 (1L4) and its receptor (IL4R) gene in susceptibility to multiple sclerosis (MS), but the results remain controversial and under-powered. Objectives: To investigate the contradictory results, we performed a meta-analysis to assess the possible association between polymorphisms of the IL4 rs2243250 (C/T), variable number of tandem repeat (VNTR) polymorphism in intron-3 (I3(709)VNTR), IL4R rs1801275 (T/C) and MS in Caucasian populations. Methods: A comprehensive search was conducted to identify all case-control or cohort design studies. The fixed or random effect pooled measure was selected based on the homogeneity test among studies that was evaluated with I-2. Publication bias was estimated using the Begg's and Egger's test. Results: A total of ten studies were included in the meta-analysis. The crude odds ratios (ORs) with 95% confidence intervals (95% CI) were calculated to evaluate the association. Overall, after excluding articles deviating from Hardy-Weinberg equilibrium in controls and sensitive analysis, the meta-analysis showed a significant association between polymorphism of IL4 rs2243250 and MS susceptibility in allele model (OR = 1.209, 95% CI = 1.022-1.429, P = 0.026) and dominant model (OR = 1.225, 95% CI = 1.013-1.480, P = 0.036). However, no significant association was found between polymorphisms of IL4 13(709)*VNTR, IL4R rs1801275 and MS susceptibility, respectively. Conclusions: The meta-analysis indicates that the T allele, CT and TT genotype of polymorphism of IL4 rs2243250 (C/T) may reduce the risk of MS in Caucasian populations, while polymorphisms of IL4 I3(709)*VNTR and IL4R rs1801275 may not associated with risk of MS in Caucasian populations. (C) 2016 Elsevier B.V. All rights reserved.