- Patients with mutations in GATA2 with a 10/10 matched related or 10/10 matched unrelated donor, will receive a reduced-intensity pre-transplant conditioning regimen consisting of fludarabine 30 mg/m(2)/day on days -4, -3, and -2, 200 centigray (cGy) total body irradiation (TBI) on day -1, and HSCT on day 0. Patients with mutations in GATA2 and a 9/10 matched unrelated donor will receive a reduced-intensity pre-transplant conditioning regimen consisting of fludarabine 30 mg/m(2)/day on days -4, -3, and -2, 300cGy total body irradiation (TBI) on day -1, and HSCT on day 0. Patients with mutations in GATA2 with umbilical cord blood units will receive a reduced-intensity conditioning regimen with cyclophosphamide 50 mg/kg on day -6, fludarabine 40 mg/m(2) on days -6 to -2, equine anti-thymocyte globulin (ATG) 30 mg/kg intravenous (IV) on days -6, -5 and -4, 200 cGy TBI on day -1, and HSCT on day 0. Patients with a haploidentical donor will receive a reduced intensity-conditioning regimen with cyclophosphamide 14.5 mg/kg on days -6 and -5, fludarabine 30 mg/m(2) on 4days -6 to -2, and 200 cGy TBI on day -1. Donor bone marrow cells will be infused on day 0.