Recognition of the three deduced probable human leukocyte antigen haplotypes in association with HLA-A∗31:30 (A∗31:30-B∗15-DRB1∗14) and HLA-B∗40:55 (A∗02:07-B∗40:55-DRB1∗04:05 and A∗26:01-B∗40:55-DRB1∗09:01) in a Taiwanese population

Kuo-Liang Yang^{a, b}, Py-Yu Lin^a

^a Laboratory of Immunogenetics, Tzu Chi Cord Blood Bank and Buddhist Tzu Chi Marrow Donor Registry, Buddhist Tzu Chi Stem Cells Center, Buddhist Tzu Chi General Hospital, Hualien, Taiwan
^b Department of Laboratory Medicine, Tzu Chi University, Hualien, Taiwan

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Abstract
Objectives

HLA-A∗31:30 and HLA-B∗40:55 are two rarely observed alleles in the HLA-A locus and HLA-B locus, respectively. The objective of this study is to report three deduced probable human leukocyte antigen (HLA) haplotypes in association with HLA-A∗31:30 and HLA-B∗40:55 in 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. A polymerase chain reaction was performed to amplify exons 2, 3, and 4 of the HLA-A, -B, and -C loci and exon 2 of 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 A∗31:30 is identical to A∗31:01:02 in exons 2, 3, and 4, except for a nucleotide substitution at residue 539 (T→G) resulting in an amino acid replacement at position 156 (Leu→Trp). We deduced the probable HLA haplotype in association with A∗31:30 as A∗31:30-B∗15-DRB1∗14. The DNA sequence of B∗40:55 is identical to B∗40:01:01 in exons 2, 3, and 4 except for a nucleotide exchange at residue 814 (G→A) resulting in an amino acid substitution at position 248 (Val→Met). Two probable HLA haplotypes associated with B∗40:55 may be deduced as A∗02:07-B∗40:55-DRB1∗04:05 and A∗26:01-B∗40:55-DRB1∗09:01.

Conclusion

Information about the deduced HLA haplotypes associated with the rare A∗31:30 and B∗40:55 alleles that we reported here is valuable for HLA tissue typing 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 bearing these two uncommon HLA alleles. Because A∗31:30 and B∗40:55 have been found in Taiwanese population so far, we think the haplotypes that we reported here are most likely conserved in their population.

Keywords
Haplotypes; HLA; Sequence-based typing; Stem cell; Transplantation