Allele and Haplotype Frequencies of HLA-A, -B, -C, and -DRB1 Genes in 3,750 Cord Blood Units From a Kinh Vietnamese Population.

The frequencies and diversities of human leukocyte antigen (HLA) alleles and haplotypes are representative of ethnicities. Matching HLA alleles is essential for many clinical applications, including blood transfusion, stem cell transplantation, and tissue/organ transplantation. To date, the information about the frequencies and distributions of HLA alleles and haplotypes among the Kinh Vietnamese population is limited because of the small sample size. In this study, more than 3,750 cord blood units from individuals belonging to the Kinh Vietnamese population were genotyped using PCR sequence-specific oligonucleotide (PCR-SSO) for HLA testing. The results of the study demonstrated that the most frequently occurring HLA-A, -B, -C, and -DRB1 alleles were A11:01 (25%), A24:02 (12.3%), A02:01 (11.2); A03:03 (8.95%), A02:03 (7.81%), A29:01 (7.03%); B15:02 (15.1%), B46:01 (10.7%), B58:01 (7.65%), B38:02 (7.29%); C08:01 (17.2), C07:02 (16.2%), C01:02 (15.2), C03:02 (8.3%), C15:05 (6.13); DRB112:02 (31.0%), DRB109:01 (10.47%), DRB115:02 (7.54%); DRB107:01 (6.68%), DRB110:01 (6.63%), respectively, with the highest allele diversity level observed in locus B (93 alleles). The most frequent haplotypes of two-locus combinations of HLA-A-B, HLA-A-C, HLA-A-DRB1, HLA-B-C, HLA-B-DRB1, and HLA-C-DRB1 haplotypes were A11:01-B15:02 (7.63%), A11:01-C08:01 (7.98%), A11:01-DRB112:02 (10.56%), B15:02-C08:01 (14.0%), B15:02-DRB112:02 (10.47%), and C08:01-DRB112:02 (11.38%), respectively. In addition, the most frequent haplotypes of three- and four-locus sets of HLA-A-B-C, HLA-A-B-DRB1, HLA-A-C-DRB1, HLA-B-C-DRB1, and HLA-A-B-C-DRB1 were A11:01-B15:02-C08:01 (7.57%), A11:01-B15:02-DRB112:02 (5.39%), A11:01-C08:01-DRB112:02 (5.54%), B15:02-C08:01-DRB112:02 (10.21%), and A11:01-B15:02-C08:01-DRB112:02 (5.45%), respectively. This study provides critical information on the frequencies and distributions of HLA alleles and haplotypes in the Kinh Vietnamese population, accounting for more than 85% of Vietnamese citizens. It paves the way to establish an umbilical cord blood bank for cord blood transplantation programs in Vietnam.