Distribution of HLA-DQA1^*01, ^*03, ^*05 and DQB1^*02 Subtypes and the Associated Haplotypes in the Korean Population

Background: As all HLA class II genes, the DQ genes show their polymorphic variation mainly in the second exon, which encodes the first extracellular domain of the molecule. PCR-SSOP (Polymerase chain reaction-Sequence specific oligonucleotide probe) techniques were frequently used for HLA-DQA1 and DQB1 typing but certain alleles, $DQA1^*0101/0104/0105$, $^*302/0303$, $*0501/0505$ and $DQB1^*0201/^*0202$ which differ from each other in segment other than exon 2, could not be unequivocally assigned. Methods: To overcome this problem, we applied additional PCR-SSP (PCR-Sequence specific primer) method to analyze DQA1 exons 1, 3 and 4 and DQB1 exon 3. And we investigated the distributions and haplotypes of HLA-DRB1, DQA1 and DQB1 alleles in 406 unrelated Korean healthy individuals. Results: Using this method the indistinguishable alleles of DQA1 and DQB1 in PCR-SSOP were typed definitively. We also found several important associations between DQA1 and DQB1 alleles in the Korean population; $DQA1^*0101-DQB1^*0501$, $DQA1^*0104-DQB1^*0502$ or $-^*0503$, $DQA1^*0105-DQB1^*0501$, $DQA1^*0302-DQB1^*0303$, $DQA1^*0303-DQB1^*0401$ or $-^*0402$, $DQA1^*0501-DQB1^*0201$, $DQA1^*0505-DQB1^*0301$, and $DQA1^*0201-DQB1^*0202$. The haplotypes of DRB1-DQA1-DQB1 associated with $DQA1^*01$, $^*03$, $^*05$, and $DQB1^*02$ subtypes were investigated. Several haplotypes associated with these alleles were observed in the Korean population. Conclusion: Our results can be helpful to find potential unrelated donors for bone marrow registries and study the HLA-associated disease and anthropology at high-resolution allelic level.