HLA-DRB1 and rheumatoid arthritis: In RA patients, HLA-DRB1 *0404, *0405 allele frequencies were significantly higher among cases than controls (OR 10.05, 95% CI 4.04—25.02, P = 0.001) and (OR 5.05, 95% CI 2.26–11.27, P < 0.0001) respectively.