Stem Cell Transplant in Sickle Cell Disease and Thalassemia

Inclusion Criteria: Sickle Cell Disease: * Diagnosis of Homozygous Hemoglobin S Disease or Heterozygous Hemoglobin Sickle Cell (SC) or S 0/+ thalassemia, or Sickle/variant resulting in Chronic Hemolytic Anemia with hemoglobin (HgB) ≤10 mg/dL * Age ≤30 * Matched sibling donor and asymptomatic, or 8/8 human leukocyte antigen (HLA) matched unrelated adult donor Patient must have adequate organ function as below: * Adequate renal function defined as serum creatinine ≤1.5 x normal, or Creatinine clearance or radioisotope glomerular filtration rate (GFR) \>100 ml/min/1.73 m2 or \>70ml/min/1.73m2 for patients \>16 years old * Adequate liver function defined as serum glutamic oxaloacetic transaminase (SGOT) (aspartate aminotransferase (AST)) or serum glutamic-pyruvic transaminase (SGPT) (alanine aminotransferase (ALT)) \< 5.0 x normal * Adequate Cardiac Function defined as shortening fraction of ≥28% by echocardiogram, or ejection fraction of ≥48% by radionuclide angiogram or echocardiogram * Adequate pulmonary function defined as corrected Diffusing capacity of the lungs for carbon monoxide (DLCO) ≥40% by pulmonary function test, or for children who are unable to perform DLCO maneuver ≥85% O2 saturation, no evidence of dyspnea at rest Exclusion criteria: General * Karnofsky/Lansky Performance Score \<60% * Demonstrated lack of compliance with medical care * Pregnant or nursing * Evidence of uncontrolled bacterial, viral or fungal infections (currently taking medication and pr…