Optimization and Developmental Validation of 38-plex InDel Panel for Ancestry Inference / 法医学杂志

OBJECTIVES@#The previously established 38-plex InDel system was optimized and its performance was validated according to the Scientific Working Group on DNA Analysis Method (SWGDAM) application guidelines. The ancestry inference accuracy of individuals from East Asian, European, African and mixed populations was verified.@*METHODS@#DNA standard sample 9947A was used as the template to establish the optimal amplification conditions by adjusting primer balance, Mg2+ final concentration and optimizing PCR thermal cycle parameters and amplification volume. The allelic dropout, nonspecific amplification and whether the origin of the inferred samples matched the known information were compared to evaluate the performance of this system.@*RESULTS@#The optimal dosage of this system was 0.125-2 ng DNA template. The results of InDel typing were accurate, the amplification equilibrium was good, and the species specificity was good. This system showed certain tolerance to DNA samples including the inhibitor such as hemoglobin (≤80 μmol/L), indigo (≤40 mmol/L), calcium ion (≤1.0 mmol/L), and humic acid (≤90 ng/μL). The system enabled the direct amplification of DNA from saliva and blood on filter paper, and the results of ethnic inference were accurate. The system successfully detected the mixed DNA sample from two individuals. The test results of the system for common biological materials in practical cases were accurate.@*CONCLUSIONS@#The results of the 38-plex InDel system are accurate and reliable, and the performance of the system meets the requirement of the SWGDAM guidelines. This system can accurately differentiate the ancestry origins of individuals from African, European, East Asian, and Eurasian populations and can be implemented in forensic practice.

SNP Panel Analysis of Ancestry Inference in East Asian Populations / 法医学杂志

Objective To develop an SNP Panel for East Asian population, which has a high individual identification rate and the capability of ancestry analysis. Methods The 55 SNP Panel by Professor KIDD of Yale University and the 128 SNP Panel by Professor SELDIN of Davis School of California University, 170 SNP Panel in total was used as the basis and its test data in the East Asian population was collected. The genetic parameters of SNP loci were calculated and combined with the results of heatmap analysis to screen SNP loci suitable for East Asian population. Some Tibetan and Han samples were tested. The possibility of using the SNP loci in ancestry inference was analyzed by means of STRUCTURE analysis, principal component analysis and heatmap analysis. Results A Panel with 45 SNPs （45 SNP Panel） was screened out, and the average genetic parameters of each SNP were better than 170 SNP Panel, with the same ancestry analysis and inference ability. Conclusion In terms of ancestry inference information, the 45 SNP Panel can completely replace the 170 SNP Panel and achieve the same ancestry analysis and inference ability. In genetic parameters, 45 SNP Panel is better than 170 SNP Panel in the East Asian population, which shows its important potential forensic application value.

Ancestry Inference Using the ForenSeqTM DNA Signature Prep Kit / 法医学杂志

Objective To evaluate the effect of 56 ancestry informative single nucleotide polymorphism （aiSNP） genetic markers in the ForenSeqTM DNA Signature Prep Kit on ancestry inference. Methods A total of 85 samples from five populations including Hebei Han population, Inner Mongolia autonomous region Mongolian population, Tibet autonomous region Tibetan population, Xinjiang Uygur autonomous region Uygur population and Nigerian population were collected. The library was constructed with the ForenSeqTM DNA Signature Prep Kit and sequencing was performed based on the MiSeq FGx Forensic Genomics System. Using universal analysis software （UAS） of ForenSeqTM, principal component analysis （PCA）, Structure and likelihood ratio method was used on the genotyping data of 56 aiSNP markers, respectively, and the genetic relationships between populations and inference of the origin of ancestors were analyzed. Results Among the five populations tested, the four ethnic populations in China （Hebei Han population, Inner Mongolia autonomous region Mongolian population, Tibet autonomous region Tibetan population and Xinjiang Uygur autonomous region Uygur population） could be significantly distinguished from Nigerian population. Xinjiang Uygur autonomous region Uygur individuals were shown as having mixed origins of ancestors and could be distinguished from the other three Chinese populations. However, the other three populations in China （Hebei Han population, Inner Mongolia autonomous region Mongolian population and Tibet autonomous region Tibetan population） could not be effectively distinguished by the system. Conclusion The 56 aiSNP markers in the ForenSeqTM DNA Signature Prep Kit can make accurate ancestry inference from the intercontinental level, but it is not yet able to distinguish between Chinese subpopulations.

From the "Out of Africa Theory" Study to the Application of "DNA Biogeographic Ancestry Inference" in Criminal Investigation / 法医学杂志

Genetic markers, such as single nucleotide polymorphism （SNP）, insertion/deletion （InDel）, were discovered and widely used with the development of whole genome sequencing and bioinformatics technology. The origin and genetic structure of the modern population had been gradually revealed from the perspective of genetics. The study on biogeographic ancestry inference in the field of forensic genetics emerged and developed rapidly, providing clues and scientific basis for the determination of investigation direction and for the narrow of the scope of investigation in the process of case investigation. This paper briefly reviews the research progress, inference methods and development trends of DNA ancestry inference technology.

Progress on Molecular Biology for Forensic Ancestry Inference / 法医学杂志

Forensic ancestry inference refers to the application of ancestry inference of population genetics in forensic practice, which aims to assist police investigation and judicial trial. With the rapid development and extensive use of genomics, DNA as a direct carrier of genetic information, has soon replaced various phenotypic markers and become the main research topics of forensic ancestry inference. This paper reviews different kinds of genetic markers used for forensic ancestry inference, the statistical analysis methods applied, and the prospects of the development in this field.