The Three Northern Minority Of Hla-drb1 Gene Polymorphism Study

HLA (Human Leukocyte Antigen) participate in and regulate immune function. HLA gene is a very important human genetic mark for its high polymorphism with significant difference among races and regions. HLA-DRB1 allele gene is the most polymorphic gene in HLA class II. The subtypes of HLA-DRB1 are widely used in the molecular anthropology, genetic polymorphism research and analysis of the race origin. Yugu in Gansu, Hezhen in Heilongjiang and Daur in Mongolia are three nationalities with small populations and distribution scales, therefore the analysis on HLA-DRB1 DNA polymorphism of these nationalities can provide population genetic data for understanding the origin of minor nationalities in China. For these reasons, HLA-DRB1 gene typing and polymorphism analysis were carried out in unrelated health individuals of Yugu, Hezhen and Daur nationalities using the method of PCR-SSP in our study, and racial relationship, genetic structure, human origin and movement of three nationalities were discussed. The main results are as follows:Eighteen alleles on HLA-DRB1 locus were found in three nationalities. All alleles were found in Yugu and Daur, and DR1, DR11 and DR16 were not found in Hezhen. In Yugu, the alleles with highest frequency are DR5 (0.2115), DR4 (0.1346), DR7 (0.1250), the lowest frequency alleles are DR16 (0.0096), DR14 (0.0096), DR13 (0.0192). In Hezhen, the highest frequency alleles are DR3 (0.2603), DR5 (0.1781), DR17 (0.1370), the lowest are DR4 (0.0411) and DR13 (0.0548). In Daur the highest frequency alleles are DR6 (0.2277), DR5 (0.1881), DR14 (0.1584), the lowest are DR9 (0.0099) and DR7 (0.0198). The results of Hardy-Weinberg equilibrium test indicate that the genotype distributions are not significantly deviated from HWE in three nationalities.DR5 is the most prevalent gene in three nationalities. There is no obvious frequency difference in DR15 (0.0594-0.0959), DR8 (0.0594-0.0865) and DR10 (0.0385-0.0990) among three nationalities. The results indicate a closer relationship among three nationalities. However, the frequency of other alleles were different significantly among three nationalities, which could be explained by geographic isolation of three nationalies. These alleles can be taken as the genetic charactors of different nationalities. The results of the cluster analysis among three nationalities and other 12 Chinese nationalities indicate that Yugu and Mongolia are closer ( genetic distance = 0.0982), which suggest the two nationalities had a common ancestor. Hezhen and Han are closer (genetic distance=0.1770). The reason of this result might be the mating beween Hezhen and Han. The genetic distance between Daur and Tibetan is nearest, which provids a genetic evidence for the origin of Daur.