Deduced probable human leukocyte antigen haplotypes associated with HLA-A*11:256Q and HLA-A*02:621 identified by case analyses of Taiwanese individuals

OBJECTIVE: HLA-A*11:256Q and HLA-A*02:621 are two low-frequency HLA-A alleles. The aim here is to report the ethnicity of A*11:256Q and A*02:621 and associated human leukocyte antigen (HLA) haplotypes among Taiwanese individuals. MATERIALS AND METHODS: HLA data from randomized Taiwanese registered in the Tzu Chi Stem Cells Centre and China Shanghai Tissuebank Diagnostics were analyzed. HLA typing of the donors was carried out using a sequence-based typing method to confirm the two low-incidence alleles. Polymerase chain reaction was performed to amplify exons 2 and 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 using BigDye Terminator Cycle Sequencing Ready Reaction kits and the manufacturer's protocols. Exon 1 and exons 4-8 of the A*11:256Q allele were also sequenced and analyzed. RESULTS: The Taiwanese ethnicity for both A*11:256Q and A*02:621 alleles was confirmed in this study. Further, the DNA sequence of A* 11:256Q was confirmed to be identical to A*11:02:01from exon 1 to exon 8 except for the residues from 409 to 417 where a segment of nine nucleotides (TACCGGCAG) is deleted in A*11:256Q. The HLA haplotype associated with A*11:256Q was deduced as A*11:256Q-B*27-DRB1*12. In exons 2 and 3, the DNA sequence of A*02:621 is identical to A*02:01:01:01 except at residue 169 where T of A*02:01:01:01 is replaced by C in A*02:621 (at codon 33; TTC->CTC). The HLA haplotype in association with A*02:621 was deduced as A*02:621-B*15:18-DRB1*12:02. CONCLUSION: The information on the ethnicity of the A*11:256Q and A*02:621 alleles and the deduced probable HLA haplotypes associated with the two low-incidence alleles reported here are valuable to HLA testing laboratories for reference purposes. In addition, they can be used by stem cell transplantation donor search coordinators to aid in finding compatible donors in unrelated bone marrow donor registries when a patient carries these uncommon HLA alleles.