Deduced probable human leukocyte antigen haplotypes associated with human leukocyte antigen DRB1*04:36 identified by case analysis of Taiwanese individuals

OBJECTIVE Human leukocyte antigen (HLA) DRB1*04:36 is a low-frequency HLA-DRB1 allele. The aim here is to report the ethnicity of DRB1*04:36 and its associated HLA haplotypes among Taiwanese individuals. MATERIALS AND METHODS A sequence-based typing method was employed to confirm this low incidence allele. 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. One group of unrelated blood donors used in this study consists of randomized individuals with Taiwanese ethnicity who participate in the Tzu Chi Bone Marrow Donor Registry and the other group are randomized unrelated individuals from mainland China. The family members in the family part of the study are volunteer blood donors. RESULTS In exon 2, the DNA sequence of DRB1*04:36 is identical to DRB1*04:03:01 except for a nucleotide segment from residue 286 to residue 308. The nucleotide segment from residue 286 to residue 308, incidentally, is identical to that of DRB1*11:01:01:01. These observations suggest that DRB1*04:36 may have been derived through a gene recombination event involving DRB1*04:03:01 and DRB1*11:01:01:01. Our family study indicated that the HLA haplotype in association with DRB1*04:36 can be deduced to be A*24:02-B*39:01-DRB1*04:36. A randomized population study using Taiwanese suggests that additional DRB1*04:36 associated HLA haplotypes seem to exist. CONCLUSION The information on the ethnicity of the DRB1**04:36 allele, and the deduced probable HLA haplotypes associated with the low incidence DRB1*04:36 allele that we report here, is of value to HLA testing laboratories for reference purposes. In addition, they can be used by stem cell transplantation donor search coordinators to aid the creation of strategy for finding compatible donors who are part of unrelated bone marrow donor registries when a patient carries this uncommon HLA allele.