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Insertion/deletion (INDELs) marker sets can serve as a useful supplementary tool for human identification. A commercial kit, the Qiagen DIPplex® Investigator kit, multiplexes 30 biallelic autosomal INDELs and Amelogenin for forensic use. We performed a validation study based on the DIPplex® kit in four Chinese populations: Han, Tibetan, Uyghur, and Kazakh. There were no significant departures from Hardy–Weinberg equilibrium or significant linkage disequilibrium (pair-wised r 2 <0.2) between the 30 INDELs. The random match probabilities were in the range of 3.84×10−11 to 1.20×10−12, and the power of exclusion was >0.99. The multiplex PCR was optimized for a 5-μL volume, full profiles were obtained with 0.062ng/μL of template DNA, and excellent performance was obtained with degraded casework samples. This study demonstrates that the multiplex INDEL assay can be used as a supplementary method for degraded DNA detection in the studied Chinese populations. [ABSTRACT FROM AUTHOR]

Han Chinese, Korean and Japanese are the main populations of East Asia, and Han Chinese presents a gradient admixture from north to south. There are differences among the East Asian populations in genetic structure. To achieve fine-scale genetic classification of southern (S-) and northern (N-) Han Chinese, Korean and Japanese individuals in this study, we collected and analyzed 1185 ancestry informative SNPs (AISNPs) from previous literature reports and our laboratory findings. First, two machine learning algorithms, softmax and randomForest, were used to build genetic classification models. Then, phylogenetic tree, STRUCTURE and principal component analysis were used to evaluate the performance of classification for different AISNP panels. The 234-AISNP panel achieved a fine-scale differentiation among the target populations in four classification schemes. The accuracy of the softmax model was 92%, which realized the accurate classification of the S-Han, N-Han, Korean and Japanese individuals. The two machine learning models tested in this study provided important references for the high-resolution discrimination of close-range populations and will be useful tools to optimize marker panels for developing forensic DNA ancestry inference systems.

Population stratification analyses targeting genetically closely related East Asians have revealed that distinguishable differentiation exists between Han Chinese, Korean, and Japanese individuals, as well as between southern (S-) and northern (N-) Han Chinese. Previous studies offer a number of choices for ancestry informative single nucleotide polymorphisms (AISNPs) to discriminate East-Asian populations. In this study, we collected and examined the efficiency of 1185 AISNPs using frequency and genotype data from various publicly available databases. With the aim to perform fine-scale classification of S-Han, N-Han, Korean, and Japanese subjects, machine-learning methods (Softmax and Random Forest) were used to screen a panel of highly informative AISNPs and to develop a superior classification model. Stepwise classification was implemented to increase and balance the discrimination in the process of AISNP selection, first discriminating Han, Korean, and Japanese individuals, and then characterizing stratification between S-Han and N-Han. The final 272-AISNP panel is an alternative optimization of various previous works, which promises reliable and >90% accuracy in classification of the four East-Asian groups. This AISNP panel and the machine-learning model could be a useful and superior choice in medical genome-wide association studies and in forensic investigations for unknown suspect identity., (© 2022 Wiley-VCH GmbH.)

In recent years, forensic scientists have focused on the discrimination of body fluids using microbial signatures. In this study, we performed PCR-based detection of microbial signatures of vaginal fluid, saliva, and feces in a Han Chinese population. We investigated the 16S rRNA genes of Lactobacillus crispatus, Lactobacillus gasseri, Lactobacillus jensenii, Lactobacillus iners, and Atopobium vaginae in vaginal fluid, the 16S rRNA and the glucosyltransferase enzyme genes of Streptococcus salivarius and Streptococcus mutans in saliva, and the 16S rRNA genes of Enterococcus species, the RNA polymerase β-subunit gene of Bacteroides uniformis and Bacteroides vulgatus, and the α-1-6 mannanase gene of Bacteroides thetaiotaomicron in feces. As a result, the detection proportions of L. crispatus, L. gasseri, L. jensenii, L. iners, and A. vaginae were 15/16, 5/16, 8/16, 14/16, and 3/16 in 16 vaginal fluid donors, respectively. L. crispatus and L. jensenii were specifically detected in vaginal fluid; L. gasseri, L. iners, and A. vaginae were also detected in non-vaginal fluid. S. salivarius and S. mutans were not specifically detected in saliva. The detection proportions of Enterococcus species, B. uniformis, B. vulgatus, and B. thetaiotaomicron in 16 feces samples were 16/16, 12/16, 15/16, and 11/16, respectively. B. uniformis and B. thetaiotaomicron were specifically detected in feces. In addition, DNA samples prepared for the identification of body fluid can also be used for individual identification by short tandem repeat typing. The mean detection sensitivities of L. crispatus and L. jensenii were 0.362 and 0.249 pg/uL, respectively. In conclusion, L. crispatus, L. jensenii, B. uniformis, and B. thetaiotaomicron can be used as effective markers for forensic identification of vaginal fluid and feces., (Copyright © 2016 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.)

Previously, we developed and validated a multiplex assay of 27 ancestry-informative markers (AIMs) for analyzing African (AFR), European (EUR), and East Asian (EAS) ancestry components. In this study, we typed and collectively analyzed a large Uyghur sample of 979 individuals to estimate the genetic coefficients of the 27 AIMs and investigate differentiation parameters between Uyghur and Han. The Uyghur allele frequencies ranged from 0.243 to 0.952, and heterozygosities ranged from 0.091 to 0.500. Values of F st 3 and I n 3 for EUR, Uyghur, and EAS ranged from 0.028 to 0.550 and 0.0002 to 0.345, respectively. The Uyghur population displays a substantial ancestry contribution of 50.3:49.7 (EUR:EAS) and was efficiently discriminated from Han Chinese with an accuracy of 99.285 %. All populations were clustered into AFR, EUR, EAS, and admixture groups of these three ancestries. Central Asian was obviously stratified from the other admixture populations of South Asians, North Asians, and the Americans. The 27 SNPs yield a circle with an average distance of 0.936 from the center (0, 0) in PCA analysis. Using this set, Chinese Uyghur and Han populations achieved accurate differentiation, and our updated genotype database (by citing 1000 Genomes data) of 43 worldwide populations is a useful resource for forensic applications and disease association studies.

Objective: To validate the efficiency of 27-plex single nucleotide polymorphism (SNP) multiplex system for ancestry inference., Methods: The 27-plex SNP system was validated for its sensitivity and species specificity. A total of 533 samples were collected from African, Southern Chinese Han, China's ethic minorities (Yi, Hui, Miao, Tibet, and Uygur), European, Central Asian, Western Asian, Southern Asian, Southeast Asian and South American populations for clustering analysis of the genotypes by citing 3 representative continental ancestral groups [East Asia (CHB), Europe (CEU), and Africa (YRI)] from HapMap database., Results: The system sensitivity is 0.125 ng. Twenty and six genotypes were detected in chimpanzee and monkeys, respectively. Except in rs10496971, no more products were found in other animals. The system was capable of differentiating intercontinental populations but not of distinguishing between East Asian and Southeast Asian population or between Southern Chinese Han population and Chinese Ethnic populations (Hui, Miao, Yi and Tibet). This system achieved a 100% accuracy for intercontinental population source inference for 46 blind test samples., Conclusion: 27-plex SNPs multiplex system has a high sensitivity and species specificity and can correctly differentiate the ancestry origins of individuals from African, European and East Asian for criminal case investigation. But this system is not capable of distinguishing subpopulation groups and more specific ancestry-informative markers are needed to improve its recognition of Southeast Asian and Chinese ethnic populations.

Aim: To genotype and evaluate a panel of single-nucleotide polymorphisms for individual identification (IISNPs) in three Chinese populations: Chinese Han, Uyghur, and Tibetan., Methods: Two previously identified panels of IISNPs, 86 unlinked IISNPs and SNPforID 52-plex markers, were pooled and analyzed. Four SNPs were included in both panels. In total, 132 SNPs were typed on Sequenom MassARRAY® platform in 330 individuals from Han Chinese, Uyghur, and Tibetan populations. Population genetic indices and forensic parameters were determined for all studied markers., Results: No significant deviation from Hardy-Weinberg equilibrium was observed for any of the SNPs in 3 populations. Expected heterozygosity (He) ranged from 0.144 to 0.500 in Han Chinese, from 0.197 to 0.500 in Uyghur, and from 0.018 to 0.500 in Tibetan population. Wright's Fst values ranged from 0.0001 to 0.1613. Pairwise linkage disequilibrium (LD) calculations for all 132 SNPs showed no significant LD across the populations (r(2)<0.147). A subset of 58 unlinked IISNPs (r(2)<0.094) with He>0.450 and Fst values from 0.0002 to 0.0536 gave match probabilities of 10-25 and a cumulative probability of exclusion of 0.999992., Conclusion: The 58 unlinked IISNPs with high heterozygosity have low allele frequency variation among 3 Chinese populations, which makes them excellent candidates for the development of multiplex assays for individual identification and paternity testing.

As a powerful alternative to short tandem repeat (STR) profiling, we have developed a novel panel of 47 single nucleotide polymorphisms (SNPs) for DNA profiling and ABO genotyping. We selected 42 of the 47 SNPs from a panel of 86 markers that were previously validated as universal individual identification markers and identified five additional SNPs including one gender marker and four ABO loci. Match probability of the 42 validated SNPs was found to be 9.5 × 10(-18) in Han Chinese. SNP analysis correctly assessed a panel of historical cases, including both paternity identifications in trios and individual identifications. In addition, while STR profiling of degraded DNA provided information for 11 loci of 16 potential markers with low peak intensities, SNPstream(®) genotyping was sufficient to identify all 47 SNPs. In summary, SNP analysis is equally effective as STR profiling, but appears more suited for individual identification than STR profiling in cases where DNA may be degraded., (© 2012 American Academy of Forensic Sciences.)