Background: For patients who do not have a suitable human leukocyte antigen (HLA)-matched family donor, unrelated donor registries of adult volunteers and banked umbilical cord blood (UCB) units provide the potential for successful haemopoietic stem-cell transplantation. The size and genetic composition of such registries determines the proportion of patients who will be able to fi nd a suitable match. We aimed to assess the proportion of positive matches for Indian patients. Methods: Using HLA data from ten existing donor and UCB registries and clinical transplant centres in India, we built population-based genetic models for 14 Indian regions to model Indian registry growth to predict the likelihood of identifying a suitable donor-either an adult donor or UCB-for Indian patients. We computed ranking tables of the top ten haplotypes in each regional group and compared these with four US samples from the National Marrow Donor Program (NMDP) registry. Findings: The mean proportion of individuals who would have a 10/10 adult donor match within India ranged from 14·4% with a registry size of 25 000 to 60·6% with a registry size of 1 000 000. Only when donor registries increased to 250 000 did the match rate within India exceed that found by searching the US-NMDP registry combined with an Indian registry of 25 000 donors. The proportion of matches increased logarithmically with increased registry size (R2=0·993). For a UCB registry size of 25 000, 96·4% of individuals would fi nd a 4/6 match; however, only 18·3% would have a 6/6 match. Interpretation: Serial match modelling and follow-up comparisons can identify the relative and progressively greater value of an India-based donor registry and UCB banking network to serve the Indian population. Understanding regional HLA haplotype diversity could guide registry growth and maximise benefi t to patients. Similar modelling could guide planning for the needs of other ethnically distinct populations.
Bibliographical noteFunding Information:
This research was funded by a grant from the ICMR and the University of Minnesota. SJ and DD have received grants from the ICMR and the University of Minnesota. RWM has received grants from the ICMR. NC and SYY report HLA typing contracts with the NMDP. DW has received grants from the ICMR and the National Institutes of Health. We thank the ten clinical and registry centres in India for sharing their data. The bioinformatics methods used for this analysis were developed through a research grant funded by the US Office of Naval Research (N00014-11-1-0339). Proofreading and image preparation were done by Michael Wright and Catherine Calistro (NMDP, Minneapolis, MN, USA). We thank the four anonymous reviewers for their input and improvements.
DW has received grants from Amgen and other support from Alexion and Pharmacyclics. All other authors declare no competing interests.