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