HLA-DRB1 and rheumatoid arthritis: For instance, HLA-DRB1*8, HLA-DRB1*11 and HLA-DRB1*13 are risk alleles of seronegative JIA, but do not exhibit association with seropositive polyarticular JIA and seronegative RA, and these HLA alleles render protective effect for seropositive RA.