HLA-DRB1 and systemic lupus erythematosus: Because DRB1*15:01 and DRB1*13:02 are associated with risk and protection of SLE, respectively, we performed conditional logistic regression analysis to investigate the independent contribution of HLA-G from DRB1 alleles on 827 patients and 576 healthy controls in whom we already genotyped DRB1 alleles [8].