Availability of related donors for bone marrow transplantation in sickle cell anemia

To determine who might qualify for allogeneic bone marrow transplantation (BMT), we reviewed the medical records of all 143 patients with sickle cell anemia under the age of 16 years who were registered at our center.

A total of 135 records were complete and were used to estimate donor availability and disease severity. The mean number of siblings per patient was two, but this number decreased to 0.73 if half-siblings and siblings who had sickle cell anemia were excluded. Probability calculations indicated that a human leukocyte antigen (HLA)-matched sibling donor would be available for only 18% of patients with sickle cell disease.

With regard to clinical severity, if only stroke and chronic debilitating pain are considered criteria for bone marrow transplantation, only 16% of sickle cell patients would qualify, but with use of the broader criteria of the National Collaborative Study, 38% of patients would qualify. However, not all parents will consent to have bone marrow transplantation for their child, and only a minority of patients (18%) will have an HLA-matched sibling donor. Thus, as few as 1-2% of the total population of children with sickle cell anemia will ultimately qualify for marrow transplantation. Increasing the number who can undergo transplantation will require increasing the size of the donor pool.

Search for other therapies not based on marrow transplantation should continue. For the majority of patients with sickle cell disease, these nontransplant treatments offer the best chance for enabling patients to achieve greater longevity and a better quality of life.