Genetic Polymorphism Of The STR Loci And Its Application For Forensic Science Base On Chang-Zhu-Tan Of Han Nationality Population

Short tandem repeats (STRs), also known as microsatellites, are strings of short nucleotides that are heritable, highly polymorphic, and distributed throughout the human genome. They can be classified into autosomal STR loci and STR loci on sex chromosomes, according to their distributions on different chromosomes. Autosomal STR loci are notable for their characteristics of high diversity, widely distribution, high polymorphism, high mutation rates, and easy to detect. They are the most widely used genetic markers in DNA paternity identification nowadays, and have significances and prospects in the application of paternity identification. In this study, Powerplex(?)21 System and GlobalFilerTM Amplification were used to test STR loci for 200 unrelated individuals of the Han populationin Hunan Changsha, Zhuzhou, and Xiangtan. so as to build new database of population living in Changsha, Zhuzhou, and Xiangtan regions on gene frequencies, mutation rates, rare alleles of STR loci, providing fundamental data to the improvement of local gene database, and ensuring accurate and scientific results of paternity testing. This study has achieved the following results:1.297 alleles of 200 unrelated individuals of the Han populationin Hunan Changsha, Zhuzhou, and Xiangtan were detected using 24 autosomal STR loci in Powerplex(?)21 System and GlobalFilerTM Amplification, gene frequency is between 0.0025 and 0.5250, the average heterozygosity of alleles was 0.8056. Powerplex(?)21 System and GlobalFilerTM Amplification identified 24 autosomal STR loci in population of the Han population Hunan Changsha, Zhuzhou, and Xiangtan that are highly polymorphic, with high Pe and PD, and is able to meet requirements of individual identification and relationship identification in that region.2.7 off ladder (OL) alleles were discovered in the population of the Han populationin Hunan Changsha, Zhuzhou, and Xiangtan using Powerplex(?)21 System and GlobalFilerTM Amplification. They appeared 2 to 3 times with frequency of 0.0025～0.005, among them. OL alleles 31.1,17.1, and 20.1 of SE33, and OL alleles 8.1 and 10.1 of D2S441 have never been reported in gene frequency of population in other regions, therefore, they were presumed to be unique in this area.3. In relationship identification, when it is unable to identify the true father by the Powerplex(?)21 System in standard triplet identification using 20 STR loci on autosome both X-STR loci and autosomal STR loci should be included in DNA testing, so as to raise the testing accuracy and reduce testing risks of judicial forensic institutions.4. When using fluorescence labeled multiplex amplification kit GlobalFilerTM Amplification, extra attention must be paid to the peak value of homozygote TH01 loci, and then compare it with the peak value of an adjacent locus. If the value is similar to the peak value of adjacent heterozygote loci, it is suggested to conduct proof testing using PowerPlex21 kit to ensure accurate results.