Rheumatoid arthritis (RA) is an autoimmune disease in which susceptibility is associated with expression of several HLA-DR alleles, including DR1 (DRB1*01:01) and DR4 (DRB1*04:01, *04:04, *04:05, and *04:08) [5–7]. Here, HLA-DRB1 is linked to autoimmune disease.