HLA-A*33-B*58:45-DRB1*03, a deduced probable human leukocyte antigen haplotype associated with a human leukocyte antigen low-incidence allele B*58:45 in Taiwanese unrelated hematopoietic bone marrow stem cell donors

Abstract

ObjectiveHLA-B*58:45 is a low-incidence allele in the human leukocyte antigen-B (HLA) locus. The aim of this study is to confirm the ethnicity of B*58:45 and its deduced probable HLA-associated haplotype in Taiwanese unrelated bone marrow hematopoietic stem cell donors. Materials and methodsA total of 40,000 healthy unrelated volunteer bone marrow stem cell donors (aged, 20–45 years) were tested using a sequence-based typing method. We confirmed the low-incidence allele B*58:45 in Taiwanese donors. Polymerase chain reaction was performed to amplify exon 2 and exon 3 of the HLA-A and HLA-B loci and exon 2 of the HLA-DRB1 locus using group-specific primer sets. The amplicons were sequenced in both directions with the BigDye Terminator Cycle Sequencing Ready Reaction Kit according to the manufacturer's protocols. ResultsThe DNA sequence of B*58:45 is identical to B*58:01:01 in exon 2 and exon 3 except for residue 595, where G is changed to A (codon 175, GGG→AGG). The nucleotide replacement causes an amino acid change at codon 175 where G (glycine) of B*58:01:01 is replaced by R (arginine). We deduced the probable HLA haplotype associated with B*58:45 in Taiwanese donors to be A*33-B*58:45-DRB1*03. ConclusionInformation on this deduced probable HLA haplotype in association with the low-incidence B*58:45 allele is of value for HLA testing laboratories for reference purposes and can help bone marrow donor registries find compatible donors for patients with this uncommon HLA allele.