Association between the IL7R T244I polymorphism and multiple sclerosis: a meta-analysis.

Previously published analyses of the association between the interleukin 7 receptor (IL7R) T244I polymorphism (rs6897932) and multiple sclerosis (MS) have yielded conflicting results. We performed a meta-analysis to assess whether the combined data showed this association, and to investigate its effect size. We analyzed 10 studies identified from PubMed (12,185 MS patients and 15,855 controls) and calculated the odds ratios (ORs) and 95% confidence intervals (CIs) for the C-allele, the C/C genotype (recessive effect) and the C/C + C/T (dominant effect) genotype. Heterogeneity within and between studies was observed: allele C: Q = 30.86, P = 0.002; genotype C/C: Q = 30.28, P = 0.003. Using a random-effects model, the C-allele and the C/C genotype were associated with MS (OR = 1.11, 95% CI = 1.04-1.19, P = 0.001 for the C-allele; OR = 1.15, 95% CI = 1.06-1.24, P = 0.0009 for the C/C genotype). The C/C + C/T genotype was also associated with MS using a fixed-effects model (OR = 1.15, 95% CI = 1.05-1.26, P = 0.003). There was no significant publication bias among the selected studies according to the funnel plot. We also performed the analysis on a European subgroup. This revealed an association between IL7R T244I and MS (P < 0.00001 for the C-allele and the C/C genotype; P = 0.0004 for the C/C + C/T genotype), no heterogeneity was observed (allele C: P = 0.07; genotype C/C: P = 0.10). In conclusion, the meta-analysis demonstrated that the IL7R T244I polymorphism was associated with susceptibility to MS.