Interleukin-1 receptor antagonist (IL-1Ra) is a natural anti-inflammatory molecule that blocks the action of IL-1 signaling. A variable-number tandem repeat polymorphism (VNTR) in IL-1Ra gene (IL-1RN) intron 2 has been reported to be associated with rheumatoid arthritis (RA), with inconsistent results. Here, we perform a meta-analysis to assess the common effect size of this polymorphism on RA susceptibility.
Case-control studies on IL-1RN VNTR association with RA were searched up to January 2010. The effect summary odds ratio (OR) and 95% confidence intervals was obtained by meta- analysis.
A total of 15 studies involving in IL-1RN VNTR with RA susceptibility were included in this meta-analysis. No association between A2/A2 genotype and risk of RA to other genotypes (odds ratio [OR], 0.96; 95% CI =0.75-1.24, p=0.77), and between A2 allele and risk of RA (OR, 0.98; 95% CI=0.83-1.16, p=0.85), were demonstrated in the total meta-analysis. In both Asian and European subgroups, the overall effect of A2/A2 genotype and A2 allele also showed no significant difference.
This meta-analysis demonstrates that the IL-1RN VNTR polymorphism is not related to susceptibility to RA.