Objectives: Previous published data indicated that interleukin-21 (IL-21) gene polymorphisms were shown to associate with multiple autoimmune diseases (ADs), but the results remain inconclusive. The aim of this study was to perform a meta-analysis to assess the overall association between IL-21 gene polymorphisms (rs907715, rs2221903) and multiple ADs.
Methods: All eligible case-control studies were searched in the PubMed and Embase database. A meta-analysis was conducted on the association between the IL-21 gene variants and ADs using: (1) allelic contrast, (2) homozygote contrast, (3) the recessive model, and (4) the dominant model.
Results: A total of 12 relevant studies including 10,535 cases and 19,356 controls were enrolled in this meta-analysis. A significant association between IL-21 rs907715 gene polymorphism and AD was found under the allelic (OR: 1.102, 95% CI: 1.057-1.149, p = 0.000), homozygous (OR: 1.220, 95% CI: 1.089-1.368, p = 0.001), dominant (OR: 1.160, 95% CI: 1.027-1.309, p = 0.017), and recessive genetic model (OR: 1.119, 95% CI: 1.055-1.187, p = 0.000) among Caucasian populations. However, there was no significant association between IL-21 rs2221903 polymorphism and AD in different genetic models.
Conclusions: Data from the present study suggest that the IL-21 rs907715 polymorphism might be associated with multiple ADs susceptibility in Caucasians. Especially, the allele G of intronic rs907715 in IL-21 confers increased risk of ADs.
Keywords: Autoimmune diseases; IL-21; polymorphisms; susceptibility.