Treo/Flu/TBI With Donor Stem Cell Transplant for Patients With Myelodysplastic Syndrome or Acute Myeloid Leukemia

Inclusion Criteria: * MDS, myelodysplastic syndrome/myeloproliferative neoplasia overlap disorders (including chronic myelomonocytic leukemia \[CMML\], and MDS/myeloproliferative neoplasm \[MPN\] unclassifiable syndromes) * AML, other than acute promyelocytic leukemia (APL), in first or second remission or with minimal residual disease * With Karnofsky index or Lansky Play-Performance scale \> 70% on pre-transplant evaluation * Able to give informed consent (if \> 18 years), or with a legal guardian capable of giving informed consent (if \< 18 years) * Patients with previous autologous or allogeneic HCT are allowed to enroll * DONOR: Human leukocyte antigen (HLA)-identical related donors or * DONOR: Unrelated donors matched for HLA-A, B, C, DRB1, and DQB1 as defined by high resolution deoxyribonucleic acid (DNA) typing; mismatch for one HLA allele is allowed * DONOR: Donors able to undergo peripheral blood stem cell collection or bone marrow harvest * DONOR: Donors in good general health, with a Karnofsky or Lansky play performance score \> 90% * DONOR: Donors able to give informed consent (if \> 18 years), or with a legal guardian capable of giving informed consent (if \< 18 years) Exclusion Criteria: * Receiving umbilical cord blood * With impaired cardiac function as evidenced by ejection fraction \< 35% (or, if unable to obtain ejection fraction, shortening fraction of \< 26%) or cardiac insufficiency requiring treatment or symptomatic coronary artery disease; patients…