HLA-A, -B and -DRB1 polymorphism in Koreans defined by sequence-based typing of 4128 cord blood units

Human leucocyte antigen (HLA) alleles and haplotypes differ significantly among different ethnic groups, and high-resolution typing methods allow for the detection of a wider spectrum of HLA variations. In this study, HLA-A, -B and -DRB1 genotypes were analysed in 4128 cord blood units obtained from Korean women using the sequence-based typing method. A total of 44 HLA-A, 67 HLA-B and 48 HLA-DRB1 most probable alleles were identified. Of these, high-frequency alleles found at a frequency of ≥5% were 6 HLA-A (A*02:01, A*02:06, A*11:01, A*24:02, A*31:01, A*33:03), 5 HLA-B (B*15:01, B*44:03, B*51:01, B*54:01, B*58:01) and 7 HLA-DRB1 (DRB1*01:01, DRB1*04:05, DRB1*07:01, DRB1*08:03, DRB1*09:01, DRB1*13:02, DRB1*15:01) alleles. At each locus, A*02, B*15 and DRB1*04 generic groups were most diverse at allelic level, consisting of 8, 11 and 10 different alleles, respectively. Two- and three-locus haplotypes estimated by the maximum likelihood method revealed 73 A-B, 74 B-DRB1 and 42 A-B-DRB1 haplotypes with frequencies of ≥0.3%. A total of 193 A-B-DRB1 haplotypes found at a frequency of ≥0.1% were presented, and the six most common haplotypes were A*33:03-B*44:03-DRB1*13:02 (4.6%), A*33:03-B*58:01-DRB1*13:02 (3.0%), A*24:02-B*07:02-DRB1*01:01 (2.7%), A*33:03-B*44:03-DRB1*07:01 (2.5%), A*30:01-B*13:02-DRB1*07:01 (2.2%) and A*24:02-B*52:01-DRB1*15:02 (2.1%). Compared with previous smaller scale studies, this study further delineated the allelic and haplotypic diversity in Koreans including low-frequency alleles and haplotypes. Information obtained in this study will be useful for the search for unrelated bone marrow donors and for anthropologic and disease association studies.