Between January 2018 and June 2021, the Ezer Mizion recruited 223,960 donors. All donors were typed for their HLA class I and II alleles at high resolution by Next Generation Sequencing techniques. Comparison between the sequences obtained from these donors and those in the IPD‐IMGT/HLA Database, revealed 122 Novel HLA alleles that were found in 133 donors. Most of the alleles, 94 (77%) were identified in the HLA class I genes (30, 35, and 29 in HLA‐A, ‐B, and –C, respectively), and 28 (23%) were detected in the HLA class II genes (9 in HLA‐DRB1 and ‐DQB1 and 10 in ‐DPB1). Most of these novel alleles, 106 (86.9%) comprised single nucleotide variation (SNV), 9 (7.4%) present multiple amino acids variation, 4 and 3 were generated because of deletions and insertions, respectively. Ten of these novel alleles were seen to be null alleles.

Five locus allele-level HLA-A, -B, -C, -DRB1, -DQB1 allele and haplotype frequencies have been calculated for almost 29,000 people from three Arab populations that live in Israel and were recruited as donors to the Hadassah bone marrow donor registry. These groups are of Muslim, Christian and Bedouin Arab descent which represent more than 90% of the Arabs that live in Israel. The goal of the study was to describe the HLA genetic profiles of the Hadassah Arab registry donors and investigate the utility of these donors for the local and international hematopoietic stem-cell transplant community. The results demonstrate that the analyzed Arab populations share at least seven of the top ten most frequent alleles. Comparison with other populations confirmed the proximity of the three Arab populations to each other and to the Be The Match® Middle Eastern population. Despite these similarities, some alleles are private to each of the three groups, possibly because of historical, environmental or societal events. Clinical data showed that Arab donors were HLA matched with Arab and international patients. This analysis indicates the value added by the Hadassah Arab donors to the local and global transplant community.

Between 2008 and April 2018, we recruited more than 37 000 potential Arab donors to the Hadassah Bone Marrow Donor Registry, all of whom were typed for high resolution HLA‐A, ‐B, and ‐DRB1. In addition, more than 22% of them were also typed for their HLA‐C and ‐DQB1 alleles. A comparison of the sequences obtained from these donors with the IPD‐IMGT/HLA Database showed 33 novel alleles from five loci (HLA‐A, ‐B, ‐C, ‐DR, ‐DQ). All of these novel HLA alleles were detected in the local Arab communities; 79% of these alleles have not been described in other groups yet and remain unique to the local Arab communities.