East Meets West-Impact of Ethnicity on Donor Match Rates in the Ezer Mizion Bone Marrow Donor Registry

- We report on the likelihood of HLA matching provided by donors from the Ezer Mizion Bone Marrow Donor Registry (BMDR) for patients seeking hamstopoietic stem cell transplantation (HSCT) in multiple Israeli populations.
- We project the effects of donor registry growth on the likelihood of successful donor searches within the registry.
- The need for registry expansion was assessed by looking at the match rates from extramural donors, taken from the Be the Match registry.
- Existence of the Ezer Mizion BMDR adds substantial benefit for Israelis who would require unrelated HSCT.
- This work is significant in the context of providing data-driven approaches for donor recruitment and planning registry growth.

HLA haplotype frequencies in a volunteer bone marrow donor registry should reflect the frequencies of potential transplant recipients served by that registry, a challenge in a country with diverse subethnicities of immigrants from Eastern and Western cultures, such as Israel. We evaluated the likelihood of finding suitable donors for hypothetical patients drawn from defined subethnicities in the Ezer Mizion Bone Marrow Donor Registry (EM BMDR) from donors both within and outside the registry now and during the coming decade. On average, bioinformatics modeling predicts that, given current donor recruitment trends, 6/6 high-resolution HLA match rates for Israelis, which currently stand at 40% to 55% for most subethnicities, will rise by up to 1% per year over the next decade. Subethnicities with historically lower rates of interethnic admixture are less likely to find matches outside of their designated group but will benefit from expansion of the registry, whereas ethnically directed drives will enhance matching rates for currently underrepresented subethnicities. Donor searches for the same cohort using a large extramural registry was of only slight benefit for most of the 19 EM BMDR subethnicities evaluated, confirming that local donor registries that reflect the ethnic diversity of the community being served are best equipped to serve the needs of their respective communities. Contemporary trends of an increasingly multiethnic admixture in Israel may impact the effect of ethnic profiling in assessing future match rates for EM BMDR.