HLA-DRB1 and rheumatoid arthritis: Notably, newer findings propose that positions 11, 13, 71, and 74 within the DRB1 chain may be intricately linked to RA susceptibility.[4, 7] Intriguingly, a comparative analysis of these positions between the susceptible *04:01 allele and the protective *04:02 allele unveiled only one distinction: lysine (K) at position 71 for *04:01, as opposed to glutamic acid (E) for *04:02.[8] Thus, this amino acid allelic difference could be a starting point to experimentally investigate the intricate mechanisms causing a complex autoimmune disease.