通过常染色体STR基因座进行两两族源推断初探

Inferring Ethnic origin between the two groups by autosomal STR locus

目的 通过常染色体STR基因座在汉、藏、蒙、维4个民族人群中的等位基因分布特征,对4个民族进行两两族源推断。方法 收集呼伦贝尔蒙古族(500例)、辽宁汉族(300例)、新疆维吾尔族(450例)和西藏藏族(2528例)无关个体生物样本,检验各自17个常染色体STR基因座等位基因并得到基因型,计算每个民族各样本基因型频率。以目前所报道的上述民族样本数最多的各民族等位基因频率为基础,用两种方法进行族源推断:(1)基因型频率商值法:4个民族进行两两比较,将单个样本出现的基因型所对应两民族的基因型频率分别作为分母和分子,分别计算17个基因座基因型频率的商并加和,得到两个商值之和并比较大小,由此判定该样本为两次商值加和中结果较大值所用除法中分子所对应民族;(2)Fisher判别分析法:运用SPSS软件中Fisher判别分析法对各民族17个常染色体基因型频率与民族关系进行分析,探讨该方法对现场生物检材族源推断的可行性。结果 使用基因型频率商值法对4个民族进行两两族源推断计算,藏族与维族判别率最高,达92.00%;藏族与蒙古族次之,为89.67%;再次为蒙古族与维族,为87.00%;汉族与维族判别率达80.00%,汉藏、汉蒙的判别率最低,分别为76.67%和70.67%。判别分析法得到4个民族综合判别率只有47.5%,两两民族判别率也远低于商值法所得结果准确率,与判别分析相比基因型频率商值法更优。结论 根据常染色体STR的等位基因频率,利用基因型频率商值法,在两两民族间进行民族来源的推断或筛查切实可行。

Objective The ethnic groups were identified by the allele distribution characteristics of autosomal STR loci in Han, Tibetan, Mongolian and Uygur ethnic groups. Methods Oral swabs from unrelated individuals of Hulunbuir Mongolian(500 cases), Liaoning Han(300 cases), Xinjiang Uygur(450 cases) and Tibetan(2528 cases) were collected,17 autosomal STR loci were examined for each sample. Genotypes were obtained, and the genotype frequencies of each ethnic group were calculated. Based on the allele frequencies of the ethnic groups with the largest sample number of reported ethnic samples, the ethnic origin was inferred by two methods:(i) Genotype frequency quotient method. Four ethnic groups were compared pairwise. The genotypic frequencies of the two ethnic groups corresponding to the genotypes present in a single sample were used as denominator and numerator respectively, and the quotients and additions of the genotypic frequencies of 17 loci are calculated respectively. The relative size of the sum of the two quotient values was obtained, and it was determined that the sample belonged to the ethnic group corresponding to the molecule in the division of the larger value of the result in the sum of the two quotient values.(ii) Discriminant Fisher analysis. The Fisher discriminant analysis in SPSS was used to analyze the frequency of 17 autosomal genotypes of each ethnic group and the ethnic relationship and to explore the feasibility of this method to judge the ethnic origin of biological samples on the spot. Results By using the method of genotype frequency quotient to judge the origin of individual ethnic groups, the discriminant rate of Tibetan and Uygur was the highest(92.00 %), followed by Tibetan and Mongolian(89.67 %), Mongolian and Uygur(87.00 %), Han and Uygur(80.00 %). The lowest discrimination rates were obtained for Han-Tibeta and Han-Mongolia, 76.67 % and 70.67 %, respectively. The total discrimination rate of the four ethnic groups obtained by the discriminant analysis method was only 47.5%, and the discrimination rate of the two ethnic groups was much lower than that of the quotient method as well. Therefore, the genotype frequency quotient method is better than the discriminant analysis. Conclusion According to the allele frequency of autosomal STR, it is feasible to infer or screen the ethnic origin between the two ethnic groups by using the method of genotype frequency quotient.