Regueiro C, et al. - Serum samples from 1126 rheumatoid arthritis (RA) candidates were analyzed to assess the association between anti–carbamylated protein antibodies (anti-CarP) antibodies and HLA–DRB1 alleles in RA. Researchers observed a significant improvement in the frequency of HLA–DRB1*03 carriers in the ACPA−/anti-CarP⁺ subgroup as compared to ACPA−/anti-CarP− RA cases and healthy controls. They found that association of HLA–DRB1*03 with ACPA−/anti-CarP⁺ RA was independent of the presence of the shared allele (SE). They found a significantly improved frequency of the SE in the ACPA+/anti-CarP− and ACPA+/anti-CarP+ RA case subgroups.