The association between interleukin-6 polymorphisms and rheumatoid arthritis: A meta-analysis

Objective: The aim of this study was to determine whether the functional interleukin-6 (IL-6) promoter -174 G/C and -572 G/C polymorphisms confer susceptibility to rheumatoid arthritis (RA) in ethnically different populations. Methods: Meta-analysis was conducted on the associations between these IL-6 polymorphisms and RA. Results: A total of nine studies involving 3,851 subjects (RA 2,053 and controls 1,798) were considered in this study and ethnicity-specific meta-analysis was performed on European subjects. In all study subjects, meta-analysis revealed a trend toward to an association between RA and the IL-6 -174 G allele (odds ratio [OR] = 0.699, 95 % confidence interval [CI] = 0.463-1.054, p = 0.088). Stratification by ethnicity indicated a significant association between RA and the IL-6 -174 G/C polymorphism in Europeans using the dominant (OR = 0.329, 95 % CI = 0.155-0.699, p = 0.004) and recessive (OR = 0.823, 95 % CI = 0.679-0.997, p = 0.047) models. Meta-analysis of the IL-6 -572 G/C polymorphism showed no association between RA and the IL-6 -572 G allele in all study subjects (OR = 1.641, 95 % CI = 0.613-4.397, p = 0.324). Conclusions: This meta-analysis shows that the IL-6 -174 G/C polymorphism may confer susceptibility to RA in Europeans.