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This paper describes the development and validation of a novel 31-locus, 6-dye STR multiplex system which is designed to meet the needs of the rapidly growing Chinese forensic database. This new assay combines 20 extended-CODIS core loci (D3S1358, D5S818, TPOX, CSF1PO, TH01, vWA, D7S820, D21S11, D8S1179, D18S51, D16S539, D13S317, FGA, D1S1656, D2S441, D2S1338, D10S1248, D12S391, D19S433 and D22S1045), 9 highly polymorphic loci in Chinese Han population (D3S3045, D6S1043, D6S477, D8S1132, D10S1435, D15S659, D19S253, Penta D and Penta E) and two gender determining markers, amelogenin and Y-Indel, which could amplify DNA from extracts, as well as direct amplification from substrates. To demonstrate the suitability for forensic applications, this system was validated by precision and accuracy evaluation, concordance tests, case sample tests, sensitivity, species specificity, stability, stutter calculation and DNA mixtures, according to the guidelines described by the Scientific Working Group on DNA Analysis Methods (SWGDAM) and regulations published by the China Ministry of Public Security. The validation results indicate the robustness and reliability of this new system, and it could be a potentially helpful tool for human identification and paternity testing in the Chinese population, as well as facilitating global forensic DNA data sharing. Additional supporting information may be found in the online version of this article at the publisher's web-site. Color online: See article online to view Figs. 1-5 and 7 in color. This article is protected by copyright. All rights reserved.

Human identification and paternity testing are usually based on the study of STRs depending on their particular characteristics in the forensic investigation. In this paper, we developed a sensitive genotyping system, SiFaSTR™ 23-plex, which is able to characterize 18 expanded Combined DNA Index System STRs (D3S1358, D5S818, D2S1338, TPOX, CSF1PO, TH01, vWA, D7S820, D21S11, D10S1248, D8S1179, D1S1656, D18S51, D12S391, D19S433, D16S539, D13S317, and FGA), three highly polymorphic STRs among Chinese people (Penta D, Penta E, and D6S1043), one Y-chromosome Indel and amelogenin using a multiplex PCR; the PCR amplified products were analyzed using the Applied Biosystems 3500 Genetic Analyzer. Full genotyping profiles were obtained using only 31.25 pg of control DNA; various case-type specimens, as well as ten-year-old samples were also successfully genotyped. Additionally, in the validation studies, this multiplex was demonstrated to be human-specific and compatible with the interference of multiple PCR inhibitors. The system also enabled the detection of mixtures, and complete profiles could be obtained at the mixed ratios of 1:1, 1:3, and 3:1. The development and validation study here illustrated that the SiFaSTR™ 23-plex system is accurate, powerful, and more sensitive than many other systems. What's more, the population data in our study not only illustrated that this 23-plex typing system was straightforward and efficient but also expanded the Chinese STR database, which could facilitate the appropriate application of the 23 genetic markers in forensic genetics, especially in the Chinese population.

In this study, a total of 484 unrelated healthy individuals and 359 two-generation families in the Han population in Shanghai, China were successfully analyzed with the Investigator HDplex Kit (Qiagen, Hilden, Germany). Hardy-Weinberg equilibrium tests demonstrated no significant deviation from expected values (p > 0.05) for the 12 autosomal STRs included in this kit. A total of 173 alleles were detected in 12 autosomal STR loci; the largest number of alleles (32) was detected for the SE33 locus. The combined power of discrimination was 0.99999999992. The combined mean exclusion chance in duo cases was 0.99982, whereas the combined mean exclusion chance in trio cases was 0.9999986. The average mutation rate across all loci was 0.0023 (95% confidence intervals: 0.0013-0.0039). These results suggest that the 12 autosomal STR loci can provide highly informative polymorphic data for paternity testing and forensic identification in the Han population in Shanghai, China.

This study developed a new multiplex PCR system that simultaneously amplifies 16 X-STR loci in the same PCR reaction, and the polymorphism and mutation rates of these 16 X-STR loci were explored in a Shanghai Han population from China. These loci included DXS10134, DXS10159, DXS6789, DXS6795, DXS6800, DXS6803, DXS6807, DXS6810, DXS7132, DXS7424, DXS8378, DXS9902, GATA165B12, GATA172D05, GATA31E08, and HPRTB. Samples from 591 unrelated individuals (293 males and 298 females) and 400 two-generation families were successfully analyzed using this multiplex system. Allele frequencies and mutation rates of the 16 loci were investigated, with the comparison of allele frequency distributions among different populations performed. Polymorphism information contents of these loci were all >0.6440 except the locus DXS6800 (0.4706). Nine cases of mutations were detected in the 16 loci from the investigation of 9232 meioses. Pairwise comparisons of allele frequency distributions showed significant differences for most loci among populations from different countries and ethnic groups but not among the Han population living in other areas of China. These results suggest that the 16 X-STR loci system provides highly informative polymorphic data for paternity testing and forensic identification in the Han population in Shanghai, China, as a complementary tool.

This study developed a new multiplex PCR system that simultaneously amplifies 16 X-STR loci in the same PCR reaction, and the polymorphism and mutation rates of these 16 X-STR loci were explored in a Shanghai Han population from China. These loci included DXS10134, DXS10159, DXS6789, DXS6795, DXS6800, DXS6803, DXS6807, DXS6810, DXS7132, DXS7424, DXS8378, DXS9902, GATA165B12, GATA172D05, GATA31E08, and HPRTB. Samples from 591 unrelated individuals (293 males and 298 females) and 400 two-generation families were successfully analyzed using this multiplex system. Allele frequencies and mutation rates of the 16 loci were investigated, with the comparison of allele frequency distributions among different populations performed. Polymorphism information contents of these loci were all0.6440 except the locus DXS6800 (0.4706). Nine cases of mutations were detected in the 16 loci from the investigation of 9232 meioses. Pairwise comparisons of allele frequency distributions showed significant differences for most loci among populations from different countries and ethnic groups but not among the Han population living in other areas of China. These results suggest that the 16 X-STR loci system provides highly informative polymorphic data for paternity testing and forensic identification in the Han population in Shanghai, China, as a complementary tool.

In this study, a total of 484 unrelated healthy individuals and 359 two-generation families in the Han population in Shanghai, China were successfully analyzed with the Investigator HDplex Kit (Qiagen, Hilden, Germany). Hardy-Weinberg equilibrium tests demonstrated no significant deviation from expected values (p0.05) for the 12 autosomal STRs included in this kit. A total of 173 alleles were detected in 12 autosomal STR loci; the largest number of alleles (32) was detected for the SE33 locus. The combined power of discrimination was 0.99999999992. The combined mean exclusion chance in duo cases was 0.99982, whereas the combined mean exclusion chance in trio cases was 0.9999986. The average mutation rate across all loci was 0.0023 (95% confidence intervals: 0.0013-0.0039). These results suggest that the 12 autosomal STR loci can provide highly informative polymorphic data for paternity testing and forensic identification in the Han population in Shanghai, China.