Transfusing children with sickle cell disease using blood group genotyping when the pool of Black donors is limited.

BACKGROUND: Red blood cell transfusion is an effective treatment for patients with sickle cell disease (SCD). Alloimmunization can occur after a single transfusion, limiting further usage of blood transfusion. It is recommended to match for the ABO, D, C, E, and K antigens to reduce risks of alloimmunization. However, availability of compatible blood units can be challenging for blood providers with a limited number of Black donors. STUDY DESIGN AND METHODS: A prospective cohort of 205 pediatric patients with SCD was genotyped for the RH and FY genes. Transfusion and alloimmunization history were collected. Our capacity to find RhCE-matched donors was evaluated using a database of genotyped donors. RESULTS: Nearly 9.8% of patients carried a partial D variant and 5.9% were D-. Only 45.9% of RHCE alleles were normal, with the majority of variants affecting the RH5 (e) antigen. We found an alloimmunization prevalence of 20.7% and a Rh alloimmunization prevalence of 7.1%. Since Black donors represented only 1.40% of all blood donors in our province, D- Caucasian donors were mostly used to provide phenotype matched products. Compatible blood for patients with rare Rh variants was found only in Black donors. A donor with compatible RhCE could be identified for all patients. CONCLUSION: Although Rh-compatible donors were identified, blood units might not be available when needed and/or the extended phenotype or ABO group might not match the patient. A greater effort has to be made for the recruitment of Black donors to accommodate patients with SCD.

Management of a patient with sickle cell disease and multiple red blood cell alloantibodies in preparation for a hematopoietic stem cell transplantation.

BACKGROUND: Hematopoietic stem cell transplant (HSCT) is currently the only widely available curative option for patients with sickle cell disease (SCD). Alloimmunization in this population is frequent and can complicate transfusion management during the HSCT period. The case of a pediatric patient with severe SCD clinical phenotype, multiple alloantibodies (9), and hyperhemolysis syndrome who underwent haploidentical HSCT is described. STUDY DESIGN AND METHODS: The patient was known for an anti-e, despite RHCE*01.01 allele, which predicts a C- c+ E- weak e+ phenotype. Donors matching the patient's extended phenotype were targeted for RHCE genotyping. RESULTS: Donors homozygotes or heterozygotes for RHCE*01.01 were selected for compatibility analyses and ranked based on strength of reactions. Discordance between zygosity and strength of reactions was observed, as the most compatible donors were heterozygotes for RHCE*01.01. In total, the patient received seven RBC units from two different donors during HSCT process without transfusion reaction or development of new alloantibodies. Six months post-HSCT, his hemoglobin level is stable at around 120 g/L and his chimerism is 100%. DISCUSSION: This case highlights the complexity of transfusion management during HSCT of alloimmunized patients with SCD. Collecting sufficient compatible units requires early involvement of transfusion medicine teams and close communication with the local blood provider. Genotyping of donors self-identifying as Black is useful for identifying compatible blood for those patients but has some limitations. HSCT for heavily alloimmunized patients is feasible and safe with early involvement of transfusion medicine specialists. Further research on the clinical impact of genotypic matching is needed.