In extensive studies involving populations with European ancestry, the SE alleles found to be most significantly associated with ACPA-positive RA risk follow an effect size hierarchy and are part of the allelic groups HLA-DRB1*04 (*04:01, *04:04, *04:08), HLA-DRB1*10 (*10:01), and HLA-DRB1*01 (*01:01) (8, 9). Here, HLA-DRB1 is linked to rheumatoid arthritis.