IL1RN and rheumatoid arthritis: We found that radiographic severity was associated only with a three SNP haplotype (rs419598, rs315952 and rs9005) of IL1RN, the product of which is IL-1Ra.13 The goal of this study was to validate these findings in over 1000 additional individuals with or at risk for knee OA and to determine whether the findings extended to patients with rheumatoid arthritis (RA).