Molecular analysis of HLA polymorphism in Khoton-Mongolians

We have investigated polymorphism of the HLA class I and class II genes in Mongolians for the first time using PCR-based techniques. A minor population of Khoton-Mongolians was studied and compared to the major Khalkh-Mongolian population. Eighty-five Khoton- and 41 Khalkh-Mongolian samples were analyzed for polymorphism in HLA-A, -B, -DRB1, -DRB3, -DRB5, -DQA1, -DQB1, -DPA1, and -DPB1 loci using PCR-SSOP and PCR-RFLP methods. Allele and haplotype frequencies were calculated. The results were then compared to those obtained from other human populations. In Khoton-Mongolians, the frequency of HLA-B38, DRB1*0301, DQA1*0502, DQB1*0201 and DPB1*0401 were significantly higher than those in other Mongoloid populations including Khalkh-Mongolians, Buryat, Chinese, Northern Han, Southern Han, Koreans and Japanese. In contrast, the frequency of HLA-A2, DQA1*0102, DPB1*0201 and DPB1*0501 were significantly lower in Khoton-Mongolians. Haplotype frequency analysis revealed that Khoton-Mongolians shared the same haplotypes specific to Mongoloids as well as to Caucasoids. On the other hand, several haplotypes were found to be specific for the Khoton. The phylogenetic tree analysis constructed by the NJ method based on allele frequencies of HLA-A, -B, -DRB1, -DQA1, and -DQB1 genes revealed that the Khoton belong to the Northeast Asian cluster and are most closely related to the Khalkh, Inner Mongolian, Uygur and Buryat populations. These data suggest a unique genetic background for Khoton-Mongolians. Furthermore, they are closely related genetically to both Mongoloids and Caucasoids.