HLA-DRB1 and rheumatoid arthritis: Inversely, HLA-DRB1 alleles encoding the DERAA sequence were more frequent in controls than in ACPA-positive RA patients (26.8% versus 17.5%, OR 0.58, CI 0.34 to 0.96, P = 0.03), and a similar trend was found for HLA-DR3 (19.7% versus 12.6%, OR 0.32 to 1.04, P = 0.07).