Monozygotic (MZ) twins are theoretically genetically identical. Although they are revealed to accumulate mutations after the zygote splits, discriminating between twin genomes remains a formidable challenge in the field of forensic genetics. Single-nucleotide variants (SNVs) are responsible for a substantial portion of genetic variation, thus potentially serving as promising biomarkers for the identification of MZ twins. In this study, we sequenced the whole genome of a pair of female MZ twins when they were 27 and 33 years old to approximately 30 × coverage using peripheral blood on an Illumina NovaSeq 6000 Sequencing System. Potentially discordant SNVs supported by whole-genome sequencing were validated extensively by amplicon-based targeted deep sequencing and Sanger sequencing. In total, we found nine bona fide post-twinning SNVs, all of which were identified in the younger genomes and found in the older genomes. None of the SNVs occurred within coding exons, three of which were observed in introns, supported by whole-exome sequencing results. A double-blind test was employed, and the reliability of MZ twin discrimination by discordant SNVs was endorsed. All SNVs were successfully detected when input DNA amounts decreased to 0.25 ng, and reliable detection was limited to seven SNVs below 0.075 ng input. This comprehensive analysis confirms that SNVs could serve as cost-effective biomarkers for MZ twin discrimination.

With the improvement of DNA methylation detection techniques, studies on age-related methylation sites have found more age-specific ones across tissues, which improves the sensitivity and accuracy of age estimation. In addition, the establishment of various statistical models also provides a new direction for the age estimation of tissues from different sources. This review summarizes the related studies of age estimation based on DNA methylation from the aspects of detection technology, age-related cytosine phosphate guanine site and model selection in recent years.

OBJECTIVES:To evaluate the forensic application value of an age estimation model based on DNA methylation in eastern Chinese Han population, and to provide a theoretical basis for exploring age estimation models suitable for different detection platforms.METHODS:According to the 6 age-related methylation sites in the published blood DNA methylation age estimation models of Chinese Han population, the DNA methylation level of 48 samples was detected by pyrosequencing and next-generation sequencing (NGS). After submitting DNA methylation levels to the age estimation model, the DNA methylation ages were predicted and compared with their real ages.RESULTS:The 6 DNA methylation sites in both detection techniques were age-related, with an R2 of 0.85 and a median absolute deviation (MAD) of 4.81 years when using pyrosequencing；with an R2 of 0.84 and MAD of 4.41 years when using NGS.CONCLUSIONS:The blood DNA methylation age estimation model can be used under pyrosequencing and multi-purpose regional methylation enrichment sequencing technology based on NGS and it can accurately estimate the age.

Complex kinship analysis is a critical issue in forensic genetics. To address this issue, 55 STRs and 94 SNPs collected from four commercial forensic typing kits [three kits were based on a capillary electrophoresis (CE) platform and one was based on a next-generation sequencing (NGS) platform] were employed to test the system power for 2nd-degree and 3rd-degree kinship analysis. To measure the kinship index in related individuals, likelihood ratios (LRs) were calculated based on length and sequence polymorphism information (LRlength and LRsequence, respectively) from simulation as well as true pedigree samples. LRs calculated based on sequence information are generally higher than those based on length information. The sensitivity, specificity, and effectiveness to distinguish the 2nd-and 3rd-degree kinship were estimated from four marker sets with different numbers of markers. As expected, system power for kinship analysis improved by increasing the number of markers and using LRsequence, instead of LRlength. Furthermore, the system power based on 55 STRs from the CE platform is equal to the 40 STRs and 94 SNPs from one CE kit and the kit based on NGS platform for both 2nd -degree and 3rd-degree kinship analysis. For discrimination of 2nd-degree kinship, the system effectiveness is 86.63% with an error ratio < 0.01 using the 55 STRs from the CE platform. Using sequence information from the 55 STRs and 94 SNPs, the system effectiveness is 94.43%, with an error ratio < 0.001 for 2nd-degree kinship analysis and 64.34% with an error ratio < 0.05 for 3rd-degree kinship analysis, indicating that these markers are powerful for 2nd-degree kinship analysis and can be used for 3rd-degree kinship analysis.

To draw robust conclusions when trace DNA samples are detected in complex cases, it is essential to successfully recover and genotype short tandem repeats (STRs) from trace DNA. However, obtaining complete STR profiles by the conventional polymerase chain reaction-capillary electrophoresis (PCR-CE) method is generally difficult as trace DNA is often less than 100 pg. Previous studies have proven that through whole-genome amplification (WGA), the yield of DNA from trace DNA samples could be improved. In this study, we used two WGA kits, namely, REPLI-g® Single Cell kit and MALBAC® Single Cell DNA Quick-Amp Kit (hereafter referred to as REPLI and MALBAC), to amplify DNA samples with a series of dilutions (from 5.00 ng/μL to 0.391 pg/μL). Typing of STR markers in samples with and without WGA were then performed on a CE platform by the application of Goldeneye® DNA ID System 20 A kit, as well as directly calling sequences from massive parallel sequencing (MPS) for WGA samples with 1.00 ng, 125 pg and 25.0 pg as DNA inputs. Quantification results demonstrated that the yield of samples with WGA could reach the microgram level. The amplification fold was at least > 2000 and > 200 for REPLI and MALBAC, respectively. CE results showed that the number of correctly called loci was improved for trace DNA after WGA when the DNA inputs were lower than 25.0 pg for REPLI and 6.25 pg for MALBAC, respectively. WGA remarkably improved the percentage of called loci with DNA inputs lower than 50.0 pg, although poor performance in repeatability was observed. MPS results suggested that the correctly called loci calculated by MPS reads were mostly more than those calculated by CE, particularly for those of short length, implying MPS of samples after WGA is worth testing in the future. In conclusion, WGA has the potential usability for forensic trace DNA analysis at the single-cell level with good fidelity, although its repeatability requires further improvement.

In recent years, trafficking and abuse of hallucinogenic mushrooms have become a serious social problem. It is therefore imperative to identify hallucinogenic mushrooms of the genus Psilocybe for national drug control legislation. An internal transcribed spacer (ITS) is a DNA barcoding tool utilized for species identification. Many methods have been used to discriminate the ITS region, but they are often limited by having a low resolution. In this study, we sought to analyze the ITS and its fragments, ITS1 and ITS2, by using high-resolution melting (HRM) analysis, which is a rapid and sensitive method for evaluating sequence variation within PCR amplicons. The ITS HRM assay was tested for specificity, reproducibility, sensitivity, and the capacity to analyze mixture samples. It was shown that the melting temperatures of the ITS, ITS1, and ITS2 of Psilocybe cubensis were 83.72 ± 0.01, 80.98 ± 0.06, and 83.46 ± 0.08 °C, and for other species, we also obtained species-specific results. Finally, we performed ITS sequencing to validate the presumptive taxonomic identity of our samples, and the sequencing output significantly supported our HRM data. Taken together, these results indicate that the HRM method can quickly distinguish the DNA barcoding of Psilocybe cubensis and other fungi, which can be utilized for drug trafficking cases and forensic science.

Hallucinogenic mushroom is a kind of toxic strain containing psychoactive tryptamine substances such as psilocybin, psilocin and ibotenic acid, etc. The mushrooms containing hallucinogenic components are various, widely distributed and lack of standard to define, which made a great challenge to identification. Traditional identification methods, such as morphology and toxicology analysis, showed shortcomings in old or processed samples, while the DNA-based identification of hallucinogenic mushrooms would allow to identify these samples due to the stability of DNA. In this paper, four primer sets are designed to target Psilocybe cubensis DNA for increasing resolution of present identification method, and the target markers include largest subunit of RNA polymerase II (marked as PC-R1), psilocybin-related phosphotransferase gene (marked as PC-PT), glyceraldehyde 3-phosphate dehydrogenase (marked as PC-3) and translation EF1α (marked as PC-EF). Real-time PCR with high-resolution melting (HRM) assay were used for the differentiation of the fragments amplified by these primer sets, which were tested for specificity, reproducibility, sensitivity, mixture analysis and multiplex PCR. It was shown that the melting temperatures of PC-R1, PC-PT, PC-3 and PC-EF of P. cubensis were (87.93 ± 0.12) °C, (82.21 ± 0.14) °C, (79.72 ± 0.12) °C and (80.11 ± 0.19) °C in our kinds of independent experiments. Significant HRM characteristic can be shown with a low concentration of 62.5 pg/µL DNA sample, and P. cubensis could be detected in mixtures with Homo sapiens or Cannabis sativa. In summary, the method of HRM analysis can quickly and specifically distinguish P. cubensis from other species, which could be utilized for forensic science, medical diagnosis and drug trafficking cases. Supplemental data for this article are available online at https://doi.org/10.1080/20961790.2021.1875580.

Insertion/deletion polymorphisms (InDels) have been treated as a prospective and helpful genetic marker in the fields of forensic human identification, anthropology and population genetics for the past few years. In this study, we developed a six-dye multiplex typing system consisting of 34 autosomal InDels and Amelogenin for forensic application. The contained InDels were specifically selected for Chinese population with the MAF ≥ 0.25 in East Asia, which do not overlap with the markers of Investigator® DIPplex kit. The typing system was named as GoldeneyeTM DNA ID System 35InDel Kit, and a series of developmental validation studies including repeatability/reproducibility, concordance, accuracy, sensitivity, stability, species specificity and population genetics were conducted on this kit. We confirmed that the 35InDel kit is precise, sensitive, species specific and robust for forensic practice. Moreover, the 35InDel kit is capable of typing DNA extracted from forensic routine case-type samples as well as degraded samples and mixture samples. All markers are proved to be highly polymorphic with an average observed heterozygosity (He) of 0.4582. The combined power of discrimination (CPD) is 0.999 999 999 999 978 and the combined power of exclusion in duos (CPED) and trios (CPET) are 0.978 837 and 0.999573, respectively, which are higher than those of the Investigator® DIPplex kit. Thus, the GoldeneyeTM DNA ID System 35InDel kit is suitable for forensic human identification and could serve as a supplementary typing system for paternity testing. Supplemental data for this article is available online at https://doi.org/10.1080/20961790.2021.1945723 .

This paper describes the development and validation of a novel 31‐locus, six‐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), nine 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.

OBJECTIVES:To evaluate the ability of the ForenSeqTM DNA Signature Prep kit (ForenSeq kit) in analyzing the sequence information of STRs in Zhejiang She ethnic group and its forensic application efficacy.METHODS:A total of 50 Zhejiang She ethnic group samples were sequenced with the ForenSeq kit on the MiSeq FGx platform. The data was analyzed using ForenSeqTM universal analysis software to obtain the motif structure and flank regions of the 58 STRs, then compared with PCR-CE typing results to test the consistency. At last, the allele frequency and population genetic parameters were calculated.RESULTS:A total of 448 sequence polymorphic alleles were detected in 50 samples of Zhejiang She ethnic group. Compared with fragment length polymorphism detected by PCR-CE, 82 alleles were increased by MPS detection based on ForenSeq kit, and 7 SNPs variation were detected in the flanking regions of 6 loci. The 22 male individuals were genotyped, and total 19 haplotypes were detected in 24 Y chromosome STRs of these 22 males. The cumulative discrimination power of the 27 autosomal STRs was 1-8.87×10-30, the cumulative probability of exclusion of duo-testing was 0.999 999 962 640 657, the cumulative probability of exclusion of trios-testing was 0.999 999 999 999 633.CONCLUSIONS:Based on MPS typing technology, using the ForenSeq kit greatly improves the detection efficiency. In addition, the 58 STRs have good genetic polymorphisms in Zhejiang She ethnic group, which are suitable for individual identification and paternity identification in forensic application.

Nowadays, vehicle inspection has an urgent demand for automatic target information recognition technology. Target text location is the prerequisite for target text recognition and has a great influence on recognition. Experimental results show that deep learning algorithms, such as faster RCNN, are not effective on such problems to some extent. Therefore, this paper adopted the method of template matching, took the vehicle license application form as the research subject, realized the target text location according to the relative location between the target texts in the image, and achieved satisfactory results. The application of this method on the driving license proves that it is a target text location technology that can be applied to document images with relatively fixed layout.