Stem Cell Donor Matching for Patients of Mixed Race

Abstract Much attention has been given to the plight of minorities and persons of mixed race in need of a bone marrow transplant. This has led to increased efforts to recruit minority and mixed-race donors. There is strong evidence that members of racial minorities are less likely to find a match than those of European descent. Because the relevant sample sizes are small, direct estimation of the distribution of immunity types for mixed-race populations have not been available. We show how to estimate the distribution of HLA types for persons of mixed race indirectly, using simple principles of probability and the combinatorics of diploid reproduction. We show that recruitment of mixed race donors is cost-effective, but not for the expected reasons. While recruitment of mixed-race donors increases the welfare of patients with the same racial background, the benefits to the targeted recipients do not exceed the costs. However, when account is taken of the likelihood that a mixed-race registrant will be the only available match for a patient classified as being of a single race, the recruitment of mixed race donors turns out to be highly cost-effective.