HLA-DRB1 and graft versus host disease: Another study of unrelated HSCT cases with one mismatch at HLA-A, -B, -C, -DRB1, or -DQB1, found associations between HLA-B leader mismatch and genotype with mismatches at either HLA-DQB1 or -DRB1 that were associated with increased non-relapse mortality and GVHD (12).