- Patients must have an HLA-A, B, DRB1 identical or 1 antigen mismatched related or unrelated BM donor or have an HLA-A, B, DRB1 identical, 1 antigen or 2 antigen mismatched related or unrelated umbilical cord blood (UCB) donor. Patients and donors will be typed for HLA-A and B using serological level typing and for DRB1 using high resolution molecular typing.