Identification and characterization of 122 novel HLA alleles in bone marrow donors recruited to the Ezer Mizion Bone Marrow Donor Registry.

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.