In seropositive RA, Raychaudhuri et al showed multiple independent associations within the HLA-DRB1 gene at three amino acid positions (11, 71 and 74) and also independent associations at amino acid position 9 in HLA-B and amino acid position 9 in HLA-DPB1. This evidence concerns the gene HLA-DPB1 and rheumatoid arthritis.