The rs2055979/rs2221903 AT haplotype also poses a higher risk of RA, suggesting that these SNPs, mainly IL-21 rs2055979 polymorphism, are genetic markers of RA susceptibility, and of poor prognostic factors such as anti-CCP, but they are not related to the increased IL-21 levels observed in RA patients. This evidence concerns the gene IL21 and rheumatoid arthritis.