Closing gaps in transplant access Open Access

In this issue of Blood Global Hematology, Sauter et al¹ show that strategic recruitment of Black African donors in South Africa can close long-standing equity gaps, thereby enabling 10/10 HLA matches at levels comparable with European populations.

Allogeneic hematopoietic stem cell transplantation remains the only curative therapy for a wide range of hematologic disorders. The success of this treatment, however, is critically dependent on the availability of HLA-compatible donors within registries. Patients of African ancestry historically have faced significant challenges in this regard, largely because of the underrepresentation of suitable donors. Sauter et al address this issue by examining whether expanding donor recruitment in South Africa can substantially improve the chances of identifying compatible matches.

Sauter et al present one of the most comprehensive analyses to date of HLA haplotype frequencies (HLA-A, -B, -C, -DRB1, and -DQB1) in South Africa based on a large cohort of 56 961 registered donors (Black African, Coloured, Indian/Asian, and White). They observed that Black African and White communities displayed remarkably similar patterns of HLA haplotype diversity, an unexpected result that challenges long-standing assumptions. In contrast, the Coloured and Indian/Asian groups showed greater internal variability, which makes it more difficult to secure perfectly matched donors. When modeling registry expansion, the data revealed that building a donor pool of 1 million Black Africans could enable up to 80% of Black African patients to find a fully matched 10/10 donor with probabilities approaching those seen in White populations. However, matches across different groups, such as between Black Africans and African Americans, remained very limited, thereby reinforcing the importance of recruiting donors within the same population. Importantly, the study also showed that when complete matches are not feasible, accepting 1 or 2 mismatches still offers high chances of identifying suitable donors, highlighting the growing role of partially matched transplants under modern prophylactic approaches.¹ 

The novelty of this work lies in its demonstration that targeted recruitment within underrepresented populations can yield results comparable with those seen in European cohorts. This directly counters the long-held notion that high HLA diversity in populations of African-descent inevitably hampers donor searches.^2,3 At the same time, the authors acknowledged the relevant limitations, namely donor cohorts are not random samples of the general population; population group assignment relied on self-identification; and the exclusion of novel alleles slightly underestimated the diversity. Equally important is to investigate how, clinically, DPB1 permissive mismatches or epitope-based approaches might reshape practical match estimates. Still, the study highlights opportunities to optimize the use of mismatched unrelated donors, particularly in combination with approaches, such as posttransplant cyclophosphamide, which may mitigate the adverse effects of HLA disparities.^4-6 

The implications of this study extend well beyond South Africa. A major challenge in low- and middle-income countries is the limited availability of unrelated volunteer donors, often compounded by the lack of national registries and the high costs of establishing and sustaining them. In many cases, patients must depend on international searches that are logistically complex, financially burdensome, and frequently unsuccessful because of the underrepresentation of local haplotypes.^7,8 Expanding HLA frequency databases would not only improve donor representation in registries but also enhance the accuracy of immunogenetic panels used for the evaluation of donor-specific antibodies, thereby strengthening both donor selection and transplant risk assessment. These barriers highlight the urgent need for sustainable, locally anchored donor recruitment strategies tailored to the genetic makeup of each population.⁹ The study provides a compelling example of how targeted donor recruitment can reshape the landscape of hematopoietic stem cell transplantation in resource-constrained settings. Ultimately, addressing inequities in access will demand not only scientific innovation but also long-term investment in public health infrastructure and education to foster a culture of donation.

Sauter et al convincingly demonstrated that expanding donor diversity in Africa is both feasible and impactful. Building registries in underrepresented communities is not simply an ethical imperative but a strategy with tangible clinical benefits, capable of reshaping global equity in transplantation.

Conflict-of-interest disclosure: The authors declare no competing financial interests.