Tibetans live in Qinghai-Tibet Plateau rising about 4000 m a.s.l. in south-west China. Archaeological evidences suggested that there have been humans living in Tibet at least 5000 years ago. However, Tibetan earlier history remains elusive. In the present study, allelic distribution of human leucocyte antigen (HLA)-A, -B and -Cw in 158 unrelated Tibetan Chinese was investigated using sequencing-based typing methods, and a total of 25 HLA-A, 45 HLA-B and 20 HLA-Cw alleles were identified. A*24G1 (27.2%), B*51G1 (16.8%), Cw*04G1 (13.3%) and Cw*070201G1 (13.3%) are the most common HLA-A, -B and -Cw alleles. The most frequently detected haplotypes were A*24G1-B*51G1-Cw*140201 (3.6%), A*24G1-B*51G1 (6.8%), A*02G1-Cw*070201G1 (6.5%) and B*51G1-Cw*140201 (5.0%). Chi-squared test suggested that all three loci fitted the Hardy-Weinberg expectations. No evidence for a departure from selective neutrality at the HLA-A and -B loci was observed. However, significant departure of the observed homozygosity from the expected values was found for HLA-Cw. Though the contemporary Tibetans inhabit the south-west China, Nei's genetic distance measure based on frequencies of HLA-A, -B and -Cw indicated that Tibetans were closer to northern Han Chinese, Mongolian Chinese, Koreans and Japanese rather than to southern Han Chinese. The corresponding dendrogram constructed according to the neighbour-joining method supported that Tibetans separated from southern Han and located in North-East Asian cluster which included northern Han Chinese and Mongolian Chinese. These data were in good agreement with language classification and with a recent hypothesis that Tibetan might originate from northern China along Yellow river.
In the present study, the polymorphism of human leucocyte antigen class II genes was investigated by the sequence-based typing method in two Chinese populations: the Miaos (n = 85) from Guizhou province and the Yaos (n = 66) from Yunnan province. These two populations exhibited certain similarity in their allelic distributions. Among 24 DRB1 alleles detected, DRB1*150101, DRB1*140101, DRB1*160201 and DRB1*090102 in Miao and DRB1*120201, DRB1*140101, DRB1*150101 and DRB1*090102 in Yao were highly predominant. Sixteen DQB1 alleles in total were found in these two populations among which DQB1*050201, DQB1*060101/060103 and DQB1*030101/0309 in both Miao and Yao and DQB1*050301 in Yao were commonly observed. In the 13 DPB1 alleles detected, the most frequent allele was DPB1*0501 in Miao and Yao followed by DPB1*02 and DPB1*1301. Frequent comparisons with other Chinese populations suggested the southern Chinese feature for both the Miao and Yao nationalities.
Human leukocyte antigen (HLA) is an invaluable marker for anthropological studies because of its extreme polymorphism. Most of the studies carried out in Chinese populations are about HLA class II genes, but few about class I genes. In the present study, we investigated HLA class I polymorphism using polymerase chain reaction-sequencing-based typing (PCR-SBT) method in 104 unrelated Han individuals in Meizhou of Guangdong, southern China. Twenty-three HLA-A, 43 HLA-B and 27 HLA-C alleles were identified and allele frequencies and two-locus (C/B) and three-locus (A/C/B) haplotypes were statistically analysed. The most frequent HLA-A allele is A*110101 with a frequency of 30.3%, followed by A*24020101 (22.2%) and A*2420 (11.6%). Among the 43 detected HLA-B alleles, B*5801 (17.0%), B*400101 (15.5%) and B*4601 (10.0%) were frequently observed. Among the 27 detected C alleles, the most predominant one is Cw*07020101 (25.8%), followed by Cw*0717 (14.7%). The most frequent HLA-C/B two-locus haplotype is Cw*07020101/B*400101 (10.1%). The most common HLA-A/C/B three-locus haplotype in Meizhou Han is A*110101/Cw*07020101/B*400101 (3.4%). Phylogenetic tree based on HLA class I allele frequencies genetically suggested that Meizhou Han has an affinity to southern Asian populations. The result may also reflect an admixture of Han and ethnic minorities of southern China.
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