HLA-DRB1 and rheumatoid arthritis: Seven HLA-DRB1 alleles are associated with RA in our population, HLA-DRB1*04∶01, HLA-DRB1*04∶04, HLA-DRB1*04∶05, HLA-DRB1*04∶08, HLA-DRB1*01, HLA-DRB1*10, HLA-DRB1*09.