Taken together with our previous observations (which demonstrated protective association of DRB1*13:02 with rheumatoid arthritis (RA) [16] and systemic lupus erythematosus (SLE) [17]), the haplotype carrying DRB1*13:02 was suggested to be a common protective factor against multiple autoimmune diseases. Here, HLA-DRB1 is linked to rheumatoid arthritis.