Treosulfan-Based Conditioning Regimen Before a Blood or Bone Marrow Transplant for the Treatment of Bone Marrow Failure Diseases (BMT CTN 1904)

Inclusion Criteria: * Patient must be \>= 1.0 year of age and less than 50.0 years of age at the time of enrollment (i.e. patient must have celebrated their 1st birthday when enrolled and must NOT have celebrated their 50th birthday when enrolled; 49.99 years) * Underlying BMFD treatable by allogenic HCT * Shwachman-Diamond syndrome * Criteria for Diagnosis: * A pathogenic mutation(s) for Shwachman-Diamond syndrome * For those patients tested but lacking a genetic mutation they must meet both \*\*\* criteria below: * Exocrine pancreatic dysfunction as defined by at least one of the following: * Pancreatic isoamylase below normal (age \>= 3 years old), OR * Fecal elastase \< 200, AND * Bone marrow failure as evidence by at least one of the following: * Intermittent or persistent neutropenia (absolute neutrophil count \< 1,500/uL), OR * Hypo-productive anemia with a hemoglobin concentration below the age-related adjusted norms, OR * Unexplained macrocytosis, OR * Platelet count \< 150,000/uL without alternative etiology, OR * Hypocellular bone marrow * Indications for HCT: * Severe neutropenia (absolute neutrophil count \[ANC\] \< 500/uL), OR * Severe anemia (hemoglobin \< 8 g/dL) or transfusion-dependent anemia, OR * Severe thrombocytopenia (platelet count \< 20,000/uL) or transfusion-dependent thrombocytopenia, OR * Additional clinical or laboratory data may be considered fo…