Recognition of the deduced probable HLA haplotypes associated with HLA low incidence alleles B*13: 50 (A*11:02-B*13:50-DRB1*07:01) and B*51:39 (A*02-B*51:39-DRB1*15; and A*11-B*51:39-DRB1*15) in Taiwanese unrelated hematopoietic stem cell donors

Objectives: HLA-B*13:50 and -B*51:39 are two low incidence alleles in the HLA-B locus. The objective of this study is to report the deduced probable human leukocyte antigen (HLA) haplotypes in association with HLA-B*13:50 and -B*51:39 in Taiwanese unrelated bone marrow hematopoietic stem cell donors. Materials and Methods: A sequence-based typing method was used to confirm the two low incidence alleles observed. Polymerase chain reaction was performed to amplify exons 2 and 3 in the HLA-A and HLA-B loci and exon 2 in the HLA-DRB1 locus with group-specific primer sets. Amplicons were sequenced using the BigDye Terminator Cycle Sequencing Ready Reaction Kit in both directions according to the manufacturer's protocols. Results: The DNA sequence of B*13:50 is identical to B*13:01:01 in exons 2 and 3, except for a one nucleotide substitution at residue 482 (A→T), which results in a one amino acid replacement at position 137 (aspartic acid→valine). We deduced the probable HLA haplotype in association with B*13:50 in Taiwanese as A*11:02-B*13:50-DRB1*07:01. The DNA sequence of B*51:39 is identical to B*51:01:03 in exons 2 and 3 except for two nucleotide exchanges at residue 226 (A→G) and residue 228 (A→G), which result in a one amino acid substitution at position 52 (isoleucine→valine).The probable HLA haplotypes associated with B*51:39 in Taiwanese may be deduced as A*02-B*51:39-DRB1*15 and A*11-B*51:39-DRB1*15. Conclusion: Information on the deduced HLA haplotypes in association with the low incidence B*13:50 and B*51:39 alleles that we report here is valuable for HLA testing laboratories for reference purposes and for stem cell transplantation donor search coordinators, to determine the likelihood of finding compatible donors in unrelated bone marrow donor registries for patients carrying these two uncommon HLA alleles.