Cord Blood Transplantation for Sickle Cell Anemia and Thalassemia

Inclusion Criteria: * Suitable UCB collection from an HLA-identical sibling * Sickle cell anemia (Hb SS or S beta thalassemia) with significant disease manifestations as defined by at least one of the following criteria: 1. A history of painful events defined as three or more painful events in the 2 years prior to enrollment. Pain may occur in typical sites associated with vaso-occlusive painful events and cannot be explained by causes other than sickle cell disease. The pain must last at least 4 hours and require treatment with either parenteral narcotics, an equianalgesic dose of oral narcotics (if pain is treated in a local facility where parenteral narcotics are not routinely used to treat painful events), or parenteral nonsteroidal anti-inflammatory drugs. Painful events managed at home will be considered only if there is documentation of the event in a clinical record that may be reviewed by an investigator. 2. Acute chest syndrome (ACS) with two or more episodes of ACS with the development of a new infiltrate on chest radiograph and/or having a perfusion defect demonstrable on a lung radioisotope scan 3. Any combination of painful events and episodes of ACS that total three events in the 2 years before transplantation 4. Any clinically significant neurologic event (stroke or hemorrhage) or any neurologic defect lasting more than 24 hours 5. Abnormal cerebral MRI and abnormal cerebral MRA 6. An episode of dactylitis in the first year of life with significant anemia (Hbg less than 7 g/dL), or leukocytosis in the second year of life such that the risk of a severe adverse outcome before 18 years of age exceeds 54% (as defined by the cooperative study of sickle cell disease (CSSCD) infant cohort study) 7. History of positive trans-cranial Doppler studies (average greater than 200 cm/sec) * Beta thalassemia major with significant disease manifestations as defined by the following criteria: Beta thalassemia genotype consistent with clinical diagnosis of beta thalassemia major (could include patients with E-beta thalassemia genotype) and requiring eight or more red blood cell (RBC) transfusions a year and iron chelation therapy. Younger patients who are at risk of transfusional iron overload but who have not yet initiated iron chelation therapy will be eligible. * Adequate physical function as measured by the following criteria: 1. Cardiac: Asymptomatic or, if symptomatic, then left ventricular ejection fraction at rest must be greater than 40% and must improve with exercise, or shortening fraction greater than 26% 2. Hepatic: Less than 5 times the clinical baseline of AST and less than 2.5 times the clinical baseline mg/dL of total serum bilirubin (clinical baseline is determined from the mean of the four most recent test results) 3. Renal: Serum creatinine within normal range for age or if serum creatinine is outside normal range for age then renal function (creatinine clearance or GFR) greater than 50% of the lower limit of normal (LLN) for age 4. Pulmonary: Asymptomatic, or, if symptomatic, DLCO, FEV1, FEC (diffusion capacity) greater than 45% of predicted (corrected for hemoglobin); if unable to obtain PFT, oxygen saturation greater than 85% on room air