Assessing the HLA diversity of cord blood units collected from a birth clinic caring for pregnant women in an ethnically diverse metropolitan area.

Background New strategies are emerging in cord bloodbanking where focusing on birth clinics caring for a high number of mothers belonging to ethnic minorities could offer new possibilities for allotransplantationboth for patients of European origin and for patients from ethnic minorities or mixed ancestries. Study Design and Methods Marseilles Cord BloodBank works with one university birth clinic caring for a culturally and sociologically diverse population. Stringent French legal restrictions apply to recording the geographic origin of parents. To circumvent this limitation and evaluate the contribution of newly banked cord bloodunits (CBUs) to increasing HLAdiversity, we applied an algorithm that allows for the determination of parents' putative haplotypesand thus grossly deduce information on their ancestry. Generic resolution HLA-A, HLA-B, and allelic resolution HLA-DRB1genotyping for 328 CBUs and 2691 unrelated donors (UDs) between January 2009 and May 2012 were performed. Enrichment from international CBU registry with nonreferenced generic HLA-A, HLA-B, and allelic HLA-DRB1phenotypes was compared between CBUs identified with one or two non-European haplotypesand CBUs identified with two European haplotypes. Results Marseilles CBUs display an increased proportion of HLAantigens frequently expressed in African populations compared to UDs. Whereas 93% of 199 CBUs identified with one or two non-European haplotypesenrich international CBU registry, this result is reduced to 42% for the 129 CBUs identified with two European haplotypes. Conclusion This study supports a new method to assess HLAdiversity. However, such an increased of HLAdiversity raises questions about frequencies of CBUs released and clinical relevance from their uses.