HLA-DRB1 and rheumatoid arthritis: Class‐I HLA‐B44 and HLA‐B15, HLA‐DRB1*04 (the major susceptibility allele for rheumatoid arthritis) and other class II alleles sharing the third hypervariable region were associated with ASD in various studies among Caucasians,55, 56 with DRB1*13 having some protective functions.55