HLA-DRB1 and rheumatoid arthritis: Furthermore, previous studies have shown that polymorphisms near the shared epitope in these alleles are also associated with RA and can influence the binding affinity of citrullinated and native peptides, such as His13βSer in HLA-DRB114:02 and Lys-71β/Arg-71β and Gly-86β/Val-86β in HLA-DRB1*04:01, *04:05, and *04:04 molecules, impacting peptide presentation and T cell responses [13,14].