HLA-DRB1 and rheumatoid arthritis: The results of the present analyses suggest that in subjects with RA or HS, carriage of the HLA-DRB1*01 and HLA-DQB1*05 alleles may protect against AAA formation whereas carriage of the HLA-DQB1*03, HLA-DRB1*04, and HLA-DRB1*03 alleles may increase the risk of AAA formation.