Even though a few studies have attempted to evaluate the participation of HLA-ABC alleles as a risk factor for RA, most of them have performed fine mapping of the HLA region in RA patients versus controls, ratifying the established role of the HLA-DRB1 alleles and identifying additional HLA-A and HLA-B alleles associations, as well as particular amino acid residues involved as independent contributors. This evidence concerns the gene HLA-DRB1 and rheumatoid arthritis.