Chances of Finding Matched Unrelated Donors for Saudi Patients in Need of Hematopoietic Stem Cell Transplantation.

Finding HLA-matched donors for patients in need of hematopoietic stem cell transplantation (HSCT) stands a better chance in their own ethnic group. This information led many nations to establish unrelated stem cell donor registries. We started our Saudi Stem Cell Donor registry (SSCDR) in 2011. The calculated donor pool size was nearly 1 million donors to find a matched donor for every patient. So far we have recruited 75,145 donors. In this exercise we attempted to investigate the chances of finding a matched donor for Saudi patients in need of HSCT. A total of 445 patients were recruited for this study. Donor searches were carried out locally and internationally using Prometheus software and World Marrow Donor Association Search and Match Service, respectively. Only 24% of the patients found a matched donor in our registry, 12% found a donor in other registries, making it a total of 36% of our patients who have the chance to find a full 10/10 HLA-matched donor. However, when we included 9/10 and 8/10 with the full matched donors, the chances go up to 83%. The top scoring registries for number of patients finding 10/10 matched donors were SSCDR (108), Deutsche Stammzellspenderdatei Nabelschnurblut (n = 52), King Faisal Specialist Hospital & Research Centre Stem Cell Donor Registry (n = 52), NMDP-National Marrow Donor Program/Be The Match (n = 43), TURKOK-Turkish Stem Cell Coordination Centre (n = 39), DKMS United Kingdom (n = 24), and Ezer Mizion Bone Marrow Donor Registry (n = 20). The patient who found the highest number of donors in international registries carried the European haplotype A1-B8-DR3; a total of 272 donors were found, and none of them were from our registry. Patients with the highest matched donor numbers in SSCDR carried haplotypes that were not common in international registries. Having a local registry increases the chances of finding a matched donor for our patients; however, international registries can still add to the chances of finding matched donors. Increasing our donor pool will increase chances of our patients finding a matched donor.

Novel HLA-B*50:66 allele, identified by next-generation sequencing in a Saudi individual.

HLA-B*50:66 differs from HLA-B*50:01:01:01 by a single nucleotide substitution (C>A) in codon 153.

The novel HLA-DRB3*03:39 allele, identified by next-generation sequencing in a Saudi individual.

HLA-DRB3*03:39 differs from HLA-DRB3*03:01:01 by a single nucleotide substitution in codon 22 (Glutamic acid to Lysine).