Kuo-Liang Yanga, b
a Laboratory of Immunogenetics, Tzu Chi Cord Blood Bank and Buddhist Tzu Chi Marrow Donor Registry, Buddhist Tzu Chi Stem Cells Centre, Hualien Tzu Chi Hospital, Hualien, Taiwan
b Department of Laboratory Medicine, Buddhist Tzu Chi University, Hualien, Taiwan
Open Access funded by Buddhist Compassion Relief Tzu Chi Foundation
Abstract
Objective
HLA-DRB1*16:35 is a low incidence allele in the HLA-DRB1 locus. The objective of this study is to report the ethnicity of DRB1*16:35 and its deduced probable HLA associated haplotype in two Taiwanese unrelated bone marrow hematopoietic stem cell donors and to determine its variation from DRB1*16:02:01 and DRB1*16:01:01.
Materials and Methods
A sequence-based typing method was employed to confirm the low incidence allele DRB1*16:35. 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 employing BigDye Terminator Cycle Sequencing Ready Reaction kits in both directions according to the manufacturer's protocols.
Results
The DNA sequence of DRB1*16:35 is identical to DRB1*16:02:01 in exons 2, except for residue 364 where the C of DRB1*16:02:01 is replaced by the T of DRB1*16:35 (codon 93, CGG->TGG). The nucleotide exchange leads to an amino acid alteration to the protein sequence of DRB1*16:02:01 at residue 93 where the arginine (R) of DRB1*16:02:01 is changed to the tryptophan (W) of DRB1*16:35. We deduced the probable HLA haplotype in association with DRB1*16:35 in Taiwanese to be A*11-B*13-DRB1*16:35.
Conclusion
Information on the deduced probable HLA haplotype in association with the low incidence DRB1*16:35 allele that we report here is of value for HLA testing laboratories for reference purposes. In addition, it can be used by stem cell transplantation donor search coordinators to determine a strategy for finding compatible donors in unrelated bone marrow donor registries when a patient has this uncommon HLA allele.
Keywords
Haplotype; Hematopoietic stem cell; HLA; Sequence-based typing; Transplantation