93-P

Abstract

The HLA match rates for the populations served by the Canadian OneMatch registry have not yet been well ascertained. We aimed to use population haplotype frequencies to project HLA match rates for this registry of over 300,000 adult donors and estimate the impact of developing a new cord blood bank. We calculated high-resolution HLA A∼C∼B∼DRB1 haplotype frequencies from 141,405 OneMatch donors typed by DNA methods, resolving both allelic and phase ambiguity using the EM algorithm. Because of population substructure in Aboriginals, we divided the Aboriginal peoples of Western provinces from Eastern provinces. Using frequencies from 13 Canadian sub-populations, we estimated HLA match rates for five years of increasing adult donor registry size and for the establishment and growth of a nascent cord inventory. Matching models considered availability for adult donors and cell dose requirements for cord of 2.5 × 10 7 TNC/kg. Allele-level 8/8 HLA match rates for patients searching for adult donors ranged from 2% for Blacks to 46% for Caucasians. Estimated 7/8 match rates ranged from 12% for Blacks to 86% for Caucasians. We expect that 8/8 and 7/8 match rates will improve by 1-2% per population per year through 2019. Estimated 4/6 match rates for pediatric patients who also search the cord inventory after accrual of 20,000 units ranged from 88% for Blacks to 99% for Caucasians, a substantial marginal benefit. Continued recruitment of adult donors will improve HLA match rates at a steady pace, while development of a cord blood inventory has the potential to close current gaps in stem cell availability, especially for minorities. When analyzing indigenous populations, it is important to consider dividing populations into geographical regions to avoid error in matching models due to population substructure. Recruitment strategy must also be considered in the global context, and we encourage application of similar matching models to all stem cell registries worldwide.