Genetic and structural characterization of 20 autosomal short tandem repeats in the Chinese Qinghai Han population and its genetic relationships and interpopulation differentiations with other reference populations

China is a multinational country composed of 56 ethnic groups of which the Han Chinese accounts for 91.60%. Qinghai Province is located in the northeastern part of the Qinghai–Tibet Plateau, has an area of 72.12 km2, and is the fourth largest province in China. In the present study, we investigated the genetic polymorphisms of 20 short tandem repeat (STR) loci in a Qinghai Han population, as well as its genetic relationships with other populations. A total of 273 alleles were identified in 2 000 individuals at 20 loci, and the allelic frequency ranged from 0.000 2 to 0.532 7. The 20 STR loci showed a relatively high polymorphic rate in the studied group. Observed and expected heterozygosities ranged 0.613 0–0.907 5 and 0.614 8–0.920 0, respectively. The combined power of discrimination, and the probability of exclusion in duo and trio cases were 0.999 999 999 999 999 999 999 999 34, 0.999 996 0 and 0.999 999 996 5, respectively. Analyses of interpopulation differentiation revealed that the most significant differences were found between the Qinghai Han and Malaysian, while no significant differences were found between the Qinghai Han and Han people from Shaanxi and Jiangsu. The results of principal component analysis, multidimensional scaling analysis and phylogenetic reconstructions also suggested the close relationships between the Qinghai Han and other two Han populations. The present results, therefore, indicated that these 20 STR loci could be used for paternity testing and individual identification in forensic applications, and may also provide information for the studies of genetic relationships between Qinghai Han and other groups.

中国是一个由56个民族构成的多民族国家，其中汉族人口占比达91.60%。青海省地处青藏高原东北部，面积72.12平方千米，为中国第四大省份。本研究对青海汉族群体的20个短串联重复序列（short tandem repeat, STR）基因座的遗传多态性进行了分析，并探讨其与其他群体的遗传亲缘关系。在2000名个体的20个基因座中共检出273个等位基因，等位基因频率范围为0.0002至0.5327。该研究群体的20个STR基因座均表现出较高的多态性。观察杂合度与期望杂合度分别介于0.6130~0.9075和0.6148~0.9200之间。联合个体识别能力、二联体亲权鉴定排除概率及三联体亲权鉴定排除概率分别为0.99999999999999999999999934、0.9999960和0.9999999965。群体间分化分析结果显示，青海汉族与马来西亚群体间的遗传差异最为显著，而与陕西、江苏汉族群体无显著遗传差异。主成分分析、多维标度分析及系统发育重建的结果同样表明，青海汉族与上述两个汉族群体亲缘关系较近。综上，本研究结果提示，这20个STR基因座可应用于法医学领域的亲权鉴定与个人识别，同时也可为青海汉族与其他群体的遗传亲缘关系研究提供基础数据。