Fludarabine Based RIC for Bone Marrow Failure Syndromes

Patients 0-22 years with acquired aplastic anemia or a diagnosed inherited bone marrow failure syndrome, and a fully Human leukocyte antigen (HLA)-matched (10/10) related donor. Inclusion Criteria: Patient: 1. Ages 0-22 years at time of enrollment 2. Diseases: * Patients with severe or very severe acquired AA, defined by: * Bone marrow biopsy demonstrating cellularity of \<25% (at least 2 weeks from last dose of G-CSF), in addition to 2 of the following: absolute neutrophil count (ANC) \<500/µL, platelets \< 20,000/µL and absolute reticulocytes \<40,000/µL * Negative evaluation for inherited bone marrow failure conditions and negative evaluation for dysplasia or cytogenetic abnormalities associated with myelodysplastic syndromes * Patients with concurrent paroxysmal nocturnal hemoglobinuria (PNH) clones are eligible, as long as they meet criteria for severe or very severe aplastic anemia as defined above * Patients with clinically diagnosed and/or genetically proven iBMF syndromes, resulting in chronic red blood cell or platelet-transfusion dependence and/or an absolute neutrophil count \<500/µL. These disorders include, but are not limited to: * Fanconi Anemia * Dyskeratosis Congenita * Severe Congenital Neutropenia * Diamond-Blackfan Anemia * Congenital Dyserythropoietic/Sideroblastic Anemias * Congenital Amegakaryocytic Thrombocytopenia * Shwachman-Diamond Syndrome 3. Lansky or Karnofsky performance \>60 4. HLA matched related donor available. 5. No active untreated infection 6. Females of childbearing potential must have negative pregnancy test. Organ Function: * Serum creatinine \<1.5xupper limit of normal for age Hepatic: Transaminases \<5x normal * Cardiac shortening fraction \>27% * Bilirubin \<2.5x normal (unless elevation due to Gilberts disease). Donor Selection Criteria: * Donor selection will comply with U.S. Food and Drug Administration's Code of Federal Regulations * Fully HLA-matched related donor. * Donor must be at least 6 months of age * Donor suitable for bone marrow collection and meets eligibility for donation, including fulfilling infectious disease criteria as per SOP, including HIV, Hepatitis B, Hepatitis C Polymerase chain reaction (PCR) negative. * If subject has confirmed iBMF syndrome, donor must be evaluated for this disorder and testing must be negative * Children's Hospital of Philadelphia (CHOP) bone marrow transplant (BMT) procedures apply for determining donor eligibility, including donor screening and testing for relevant communicable disease agents and diseases. * Donor evaluation and collection procedure as per CHOP Standard Operating Procedures (SOP) Exclusion Criteria: * Uncontrolled bacterial, viral or fungal infections * HLA matched related donor unable to donate bone marrow. * No eligible fully HLA-matched related donor * Pregnant females * Patients with a clinical diagnosis of Myelodysplastic syndrome (MDS) defined by combination of bone marrow dysplasia and classic cytogenetic lesion (Monosomy 7, Trisomy 8 eg.), with or without excess blasts. * Patients with PNH without underlying bone marrow aplasia