Scally SW, et al. – In this present study, the researchers explored the pathogenetic mechanisms by which HLA–DRB1 alleles were associated with anticitrullinated peptide antibody (ACPA)–positive rheumatoid arthritis (RA) in Indigenous North American (INA) population. They explained that HLA–DRB1*14:02 broadens the capacity for citrullinated and native self–peptide presentation and T cell expansion, and increased the risk of ACPA+ RA.