RH Genotype Matched RBC Transfusions

Inclusion Criteria: * Subjects age \>6 months * Diagnosis of SCD, all genotypes * Require a period of chronic red cell transfusion therapy * Subject/parental/guardian permission (informed consent) and if appropriate, child assent Exclusion Criteria: * Rare RH genotype that would preclude identification of sufficient RBC units * Antigen negative requirements due to alloimmunization that would preclude identification of sufficient RBC units * Alloimmunized to D antigen * Rh alloimmunized patients for whom providing RH genotype matched blood would expose the patient to an antigen that would not be consistent with standard of care and blood bank protocols * Parents/guardians or subjects who, in the opinion of the Investigator, may be non-compliant with study schedules or procedures