Distributions of HLA-DRB1/DQB1 alleles and haplotypes in the Northeastern Thai population: indicative of a distinct Thai population with Chinese admixtures in the Central Thais

The phenotype and gene frequencies of HLA class II alleles were studied in the North-eastern Thai population. Blood samples were collected from 100 un related healthy North-eastern Thais. The HLA-DRB1 and DQB1 genes were typed using the polymerase chain reaction - sequence specific primer (PCR-SSP) a nd polymerase chain reaction - sequence specific oligonucleotide probe (PCR -SSO) techniques. Twenty-six HLA-DRB1 and 11 DQB1 alleles were found in thi s population. DRB1*1202, 1502, 0405 and DQB1*0502/0504, 0301/0304 alleles w ere commonly found. Linkage disequilibrium analysis suggested the existence of 13 DR-De haplotypes. The DRB1*1502-DQB1*0501 haplotype was the most com mon. The DRB1*1106-DQB1*0301/0304 haplotype was found only in North-eastern Thais and not in other Thai populations. Comparative analysis of the HLA-D R/DQ alleles revealed differences in the distributions of these alleles amo ngst different ethnic groups. Interestingly, the distributions of HLA class II alleles in Central Thai, North-eastern Thai and Southern Chinese popula tions are similar. However, it appears that the distribution in the Central Thais is a mixture of those in Southern Chinese and North-eastern Thais, s uggesting the existence of Thai-Chinese admixtures in the Central Thai popu lation. This study provides basic information for further studies of the MH C in anthropology, organ transplantation and disease susceptibility in the North-eastern Thai population.