Developments in forensic DNA analysis

On forensic likelihood ratios from low-coverage sequencing

With advances in sequencing technology, forensic workers can access genetic information from increasingly challenging samples. A recently published computational approach, IBDGem , analyzes sequencing reads, including from low-coverage samples, in order to arrive at likelihood ratios for tests of identity. Here, we show that likelihood ratios produced by IBDGem test a null hypothesis different from the traditional one used in a forensic genetics context. In particular, rather than testing the hypothesis that the sample comes from a person unrelated to the person of interest, IBDGem tests the hypothesis that the sample comes from an individual who is included in the reference sample used to run the method. This null hypothesis is not generally of forensic interest, because the defense hypothesis is not that the evidence comes from an individual included in a reference panel. Further, it does not take into account genetic variation outside the reference panel, and as a result, the computed likelihood ratios can be much larger than likelihood ratios computed for the standard forensic null hypothesis, often by many orders of magnitude, thus potentially creating an impression of stronger evidence for identity than is warranted. We lay out this result and illustrate it with examples, giving suggestions for directions that might lead to likelihood ratios that have the traditional interpretation.

Assessing the consistency of shedder status under various experimental conditions

Shedder status is defined as the propensity of an individual to leave DNA behind on touched items or surfaces and has been suggested as one of the major factors influencing DNA transfer. However, little is known about whether shedder status is a constant property of an individual across multiple measurements or when the environmental conditions are changed. We have assessed DNA depositions of six males on 20 occasions to acquire a reference data set and to classify the participants into high, intermediate, or low shedders. This data set was also used to investigate how the probability of a correct shedder status classification changed when the number of DNA deposition measurements increased. Individual sweat rates were measured with a VapoMeter and data regarding hygiene routines were collected through a questionnaire on each sampling occasion. Next, we investigated how changes in the experimental conditions such as seasonal variation, hygiene routines, the temperature of the touched object, and repeated handling of an object influenced the DNA shedding. Additionally, we assessed DNA collected from the face and from T-shirts worn by the six participants to explore whether shedder status may be associated with the relative amount of DNA obtained from other body parts. Our results indicate that shedder status is a stable property across different seasons and different temperatures of handled objects. The relative DNA amounts obtained from repeatedly handled tubes, worn T-shirts, and from faces reflected the shedder status of the participants. We suggest that an individual's shedder status is highly influenced by the DNA levels on other body parts than hands, accumulating on the palms by frequently touching e.g., the face or previously handled items harboring self-DNA. Assessing physiological differences between the participants revealed that there were no associations between DNA shedding and individual sweat rates.

Estimation of Human Chronological Age from Buccal Swab Samples through a DNA Methylation Analysis Approach of a Five-Locus Multiple Regression Model

Recent advancements in forensic genetics have facilitated the extraction of additional characteristics from unidentified samples. This study delves into the predictive potential of a five-gene (ELOVL2, FHL2, KLF14, C1orf132, and TRIM59) methylation rate analysis for human age estimation using buccal swabs collected from 60 Italian volunteers. The methylation levels of specific CpG sites in the five genes were analyzed through bisulfite conversion, single-base extension, and capillary electrophoresis. A multivariate linear regression model was crafted on the training set, then the test set was employed to validate the predictive model. The multivariate predictive model revealed a mean absolute deviation of 3.49 years in the test set of our sample. While limitations include a modest sample size, the study provides valuable insights into the potential of buccal swab-based age prediction, aiding in criminal investigations where accurate age determination is crucial. Our results also highlight that it is necessary to investigate the effectiveness of predictive models specific to biological tissues and individual populations, since models already proven effective for other populations or different tissues did not show the same effectiveness in our study.

Construction and evaluation of a novel set of 90 microhaplotypes for forensic applications using NGS technology

Microhaplotypes (MHs), small sets of linked single nucleotide polymorphisms (SNPs), are becoming a valuable tool for paternity testing, personal identification and other different forensic purposes due to their advantages of both short tandem repeats (STRs) and SNPs. However, only a small part of MHs with small segments have been developed and reported so far. And the current population genetic data of MHs are still insufficient. MHs with small segments possess unique advantages in mixture deconvolution, degradation material identification, noninvasive prenatal paternity testing and even medical tumor diagnostic applications. In the present study, a set of 90 autosomal MHs whose PCR amplicon lengths are from 90-150 bp, of which 58 MHs are less than or equal to 100 bp are selected, and assembled into an amplification multiplex system optimized for Ion S5™ System for forensic application. Genetic diversity study of 90 MHs in the populations from different intercontinental regions shows that the polymorphism information content (PIC) values of 83 MHs are greater than 0.4 in populations from East Asia (EAS), and the average PIC value of 90 MHs is greater than 0.5. A total of EAS populations shows the highest cumulative match probability (CMP) and cumulative probability of exclusion (CPE) values in five intercontinental populations. The CMP and CPE values of 90 MHs in EAS are 1.1688 × 10-54 and 0.999999999998954. The informativeness for assignment (In) values of the 90 MHs are calculated based on data from five intercontinental populations, and the In values of 20 MHs have greater than 0.1, indicating that the 20 MHs are high effectiveness in distinguishing different intercontinental populations, which can be used as candidate ancestry informative markers. Further, we have studied the polymorphisms of the 90 MHs based on 224 unrelated individuals of Henan Han population, China, and obtained the frequency data of the 90 MHs. In the Henan Han population, the effective number of alleles (Ae) of the 90 MHs ranges from 1.7649 (MH45) to 3.9792 (MH50), and the Ae values of 10 MHs reach to 3.0; the Ae values of 80 MHs are greater than 2, and the average Ae value for these MHs is 2.422. The average expected heterozygosity, observed heterozygosity, PIC, matching probability, discrimination power and probability of exclusion values of 90 MHs in the Henan Han population are 0.5788, 0.5851, 0.5039, 0.2608, 0.7392 and 0.2806, respectively. The CMP value of 90 MHs in the study population is less than 10-54, and their CPE value reaches 0.999999999999999923. Moreover, the results of the depth of coverage, allele coverage ratio and noise level indicate that the 90 MH amplification system has well sequencing performance, and the sequencing results are reliable. The results indicate the 90 MHs show higher polymorphisms in the study population. The present panel can be well used in paternity testing and individual identification in the study population and even the populations from EAS.

Indirect DNA Transfer and Forensic Implications: A Literature Review

Progress in DNA profiling techniques has made it possible to detect even the minimum amount of DNA at a crime scene (i.e., a complete DNA profile can be produced using as little as 100 pg of DNA, equivalent to only 15-20 human cells), leading to new defense strategies. While the evidence of a DNA trace is seldom challenged in court by a defendant's legal team, concerns are often raised about how the DNA was transferred to the location of the crime. This review aims to provide an up-to-date overview of the experimental work carried out focusing on indirect DNA transfer, analyzing each selected paper, the experimental method, the sampling technique, the extraction protocol, and the main results. Scopus and Web of Science databases were used as the search engines, including 49 papers. Based on the results of this review, one of the factors that influence secondary transfer is the amount of DNA shed by different individuals. Another factor is the type and duration of contact between individuals or objects (generally, more intimate or prolonged contact results in more DNA transfer). A third factor is the nature and quality of the DNA source. However, there are exceptions and variations depending on individual characteristics and environmental conditions. Considering that secondary transfer depends on multiple factors that interact with each other in unpredictable ways, it should be considered a complex and dynamic phenomenon that can affect forensic investigation in various ways, for example, placing a subject at a crime scene who has never been there. Correct methods and protocols are required to detect and prevent secondary transfer from compromising forensic evidence, as well as the correct interpretation through Bayesian networks. In this context, the definition of well-designed experimental studies combined with the use of new forensic techniques could improve our knowledge in this challenging field, reinforcing the value of DNA evidence in criminal trials.

Development and validation of a custom panel including 114 InDels using massively parallel sequencing for forensic application

Insertion/deletion polymorphisms (InDels) have particular characteristics, such as a relatively low mutation rate, small amplicon size, and no stutter artifacts when genotyped via the capillary electrophoresis platform. It would be an important complementary tool for individual identification and certain kinship analyses. At present, massively parallel sequencing (MPS) has shown excellent application value in forensic studies. Therefore, in this study, we developed a custom MPS InDel panel that contains 114 InDels [77 autosomal InDels (A-InDels), 32 X-chromosomal InDels (X-InDels), and 5 Y-chromosomal InDels) based on previous studies. To assess this panel's performance, several validation experiments were performed, including sensitivity, inhibitor, degraded DNA testing, species specificity, concordance, repeatability, case-type samples, and population studies. The results showed that the lowest DNA input was 0.25 ng. All genotypes were obtained in the presence of 80 ng/µL humic acid, 2000 µmol/L calcium, 3000 µmol/L EDTA and indigo. In degraded DNA testing, 90% of loci could be detected for 16-day-old formalin-fixed hearts. In addition, this panel has good species specificity. The values of combined power of discrimination and the combined power of exclusion for 77 A-InDels were 1-3.9951 × 10-32 and 1-4.2956 × 10-7 , respectively. The combined mean exclusion chance for 32 X-InDels was 0.99999 in trios and 0.99904 in duos. The validation results indicate that this newly developed MPS multiplex system is a robust tool for forensic applications.

Investigation of the impact of biogeographic ancestry on DNA methylation based age predictions comparing a Middle East and a Central European population

DNA methylation based age prediction is a new method in the toolbox of forensic genetics. Typically, the method is applied in the course of police investigation e.g. to predict the age of an unknown person that has left a biological trace at a crime scene. The method can also be used to answer other forensic questions, for example to estimate the age of unknown human bodies in the course of the identification process. In the present study, we tested for a potential impact of biogeographic ancestry (BGA) on age predictions using five age dependent methylated CpG sites within the genetic regions of ELOVL2, MIR29B2CHG, FHL2, KLF14 and TRIM59. We collected 102 blood samples each from donors living in Iraq, Middle East (ME) and Germany, Central Europe (EU). Both sample sets were matched in sex and age ranging from 18 to 68 years with exactly one male and female sample per year of age. All samples were analyzed by bisulfite pyrosequencing applying a multiplex pre-amplification strategy based on a single input of 35 ng converted DNA in the PCR. For the CpGs in MIR29B2CHG, FHL2 and KLF14, we observed significantly different methylation levels between the two populations. While we were able to train two highly accurate prediction models for the respective population with mean absolute deviations between predicted and actual ages (MAD) of 3.34 years for the ME model, and 2.72 years for the EU model, we found an absolute prediction difference between the two population specific models of more than 4 years. A combined model for both populations compensated the methylation difference between the two populations, providing MADs of prediction of only 3.81 years for ME and 3.31 years for EU samples. In total, the results of the present study strongly support the benefit of BGA information for more reliable methylation based age predictions.

Record-matching of STR profiles with fragmentary genomic SNP data

In many forensic settings, identity of a DNA sample is sought from poor-quality DNA, for which the typical STR loci tabulated in forensic databases are not possible to reliably genotype. Genome-wide SNPs, however, can potentially be genotyped from such samples via next-generation sequencing, so that queries can in principle compare SNP genotypes from DNA samples of interest to STR genotype profiles that represent proposed matches. We use genetic record-matching to evaluate the possibility of testing SNP profiles obtained from poor-quality DNA samples to identify exact and relatedness matches to STR profiles. Using simulations based on whole-genome sequences, we show that in some settings, similar match accuracies to those seen with full coverage of the genome are obtained by genetic record-matching for SNP data that represent 5-10% genomic coverage. Thus, if even a fraction of random genomic SNPs can be genotyped by next-generation sequencing, then the potential may exist to test the resulting genotype profiles for matches to profiles consisting exclusively of nonoverlapping STR loci. The result has implications in relation to criminal justice, mass disasters, missing-person cases, studies of ancient DNA, and genomic privacy.

Application of SNPs with low minor allele frequencies in missing person identification (MPI) through kinship analysis of DNA mixtures

The need to identify a missing person (MP) through kinship analysis of DNA samples found at a crime scene has become increasingly prevalent. DNA samples from MPs can be severely degraded, contain little DNA and mixed with other contributors, which often makes it difficult to apply conventional methods in practice. This study developed a massively parallel sequencing-based panel that contains 1661 single-nucleotide polymorphisms (SNPs) with low minor allele frequencies (MAFs) (averaged at 0.0613) in the Chinese Han population, and the strategy for relationship inference from DNA mixtures comprising different numbers of contributors (NOCs) and of varying allele dropout probabilities. Based on the simulated dataset and genotyping results of 42 artificial DNA mixtures (NOC = 2-4), it was observed that the present SNP panel was sufficient for balanced mixtures when referenced to the closest relatives (parents/offspring and full siblings). When the mixture profiles suffered from dropout, incorrect assignments were markedly associated with relatedness, NOC and the dropout level. We, therefore, indicate that SNPs with low MAFs could be reliably interpreted for MP identification through the kinship analysis of complex DNA mixtures. Further studies should be extended to more possible scenarios to test the feasibility of this present approach.

Forensic biogeographical ancestry inference: recent insights and current trends

BACKGROUND

As a powerful complement to the paradigmatic DNA profiling strategy, biogeographical ancestry inference (BGAI) plays a significant part in human forensic investigation especially when a database hit or eyewitness testimony are not available. It indicates one's biogeographical profile based on known population-specific genetic variations, and thus is crucial for guiding authority investigations to find unknown individuals. Forensic biogeographical ancestry testing exploits much of the recent advances in the understanding of human genomic variation and improving of molecular biology.

OBJECTIVE

In this review, recent development of prospective ancestry informative markers (AIMs) and the statistical approaches of inferring biogeographic ancestry from AIMs are elucidated and discussed.

METHODS

We highlight the research progress of three potential AIMs (i.e., single nucleotide polymorphisms, microhaplotypes, and Y or mtDNA uniparental markers) and discuss the prospects and challenges of two methods that are commonly used in BGAI.

CONCLUSION

While BGAI for forensic purposes has been thriving in recent years, important challenges, such as ethics and responsibilities, data completeness, and ununified standards for evaluation, remain for the use of biogeographical ancestry information in human forensic investigations. To address these issues and fully realize the value of BGAI in forensic investigation, efforts should be made not only by labs/institutions around the world independently, but also by inter-lab/institution collaborations.

Decreased accuracy of forensic DNA mixture analysis for groups with lower genetic diversity

Forensic investigation of DNA samples from multiple contributors has become commonplace. These complex analyses use statistical frameworks accounting for multiple levels of uncertainty in allelic contributions from different individuals, particularly for samples containing few molecules of DNA. These methods have been thoroughly tested along some axes of variation, but less attention has been paid to accuracy across human genetic variation. Here, we quantify the accuracy of DNA mixture analysis over 244 human groups. We find higher false inclusion rates for mixtures with more contributors, and for groups with lower genetic diversity. Even for two-contributor mixtures where one contributor is known and the reference group is correctly specified, false inclusion rates are 1e-5 or higher for 56 out of 244 groups. This means that, depending on multiple testing, some false inclusions may be expected. These false positives could be lessened with more selective and conservative use of DNA mixture analysis.

Construction and evaluation of in-house methylation-sensitive SNaPshot system and three classification prediction models for identifying the tissue origin of body fluid

The identification of tissue origin of body fluid can provide clues and evidence for criminal case investigations. To establish an efficient method for identifying body fluid in forensic cases, eight novel body fluid-specific DNA methylation markers were selected in this study, and a multiplex singlebase extension reaction (SNaPshot) system for these markers was constructed for the identification of five common body fluids (venous blood, saliva, menstrual blood, vaginal fluid, and semen). The results indicated that the in-house system showed good species specificity, sensitivity, and ability to identify mixed biological samples. At the same time, an artificial body fluid prediction model and two machine learning prediction models based on the support vector machine (SVM) and random forest (RF) algorithms were constructed using previous research data, and these models were validated using the detection data obtained in this study (n=95). The accuracy of the prediction model based on experience was 95.79%; the prediction accuracy of the SVM prediction model was 100.00% for four kinds of body fluids except saliva (96.84%); and the prediction accuracy of the RF prediction model was 100.00% for all five kinds of body fluids. In conclusion, the in-house SNaPshot system and RF prediction model could achieve accurate tissue origin identification of body fluids.

Sequence-based allelic variations and frequencies for 22 autosomal STR loci in the Lebanese population

This is the first study that characterizes the sequence-based allelic variations of 22 autosomal Short Tandem Repeat (aSTR) loci in a population dataset collected from Lebanon. Genomic DNA extracts from 195 unrelated Lebanese individuals were amplified with PowerSeq 46GY System Prototype. Targeted amplicons were subjected to DNA library preparation and sequenced on the Verogen MiSeq FGx Sequencing System. Raw FASTQ data files were processed by STRait Razor v3. Sequence strings were annotated according to the considerations of the DNA Commission of the International Society for Forensic Genetics (ISFG) and tabulated herein with their respective allelic frequencies and GeneBank accession and version numbers. The sequenced Lebanese dataset resulted in 429 distinct allelic sequences as compared to the 236 alleles identified by length only. The increase in the number of alleles was observed at 18 out of 22 aSTR loci and was attributed to the sequence variations residing in both the STR repeat motifs and flanking regions. The study uncovered 25 novel aSTR allelic sequences across 12 loci for which GenBank records did not previously exist in the STRSeq BioProject, PRJNA380127. For a concordance check, the length-based allelic calls derived from the full sequences were compared to those genotyped using capillary electrophoresis (CE) methods. Population genetic parameters relevant to the evaluation of forensic DNA evidence were assessed for the sequence-based data and compared to the parameters generated from the length-based information. Using the sequence-based data, Analysis of MOlecular VAriance (AMOVA), genetic distances, and population genetic structure were evaluated for 1231 individuals sampled from the Lebanese and four U.S. populations (African American, Asian, Caucasian, and Hispanic). The results were tabulated and visualized in a population tree, multidimensional scaling scatter plots, and bar plots. This newly established sequence-based database for the Lebanese population can be beneficial for extending NGS applicability to casework or paternity testing and assessing the strength of evidence for NGS-STR profiles. The described novel sequence variants at certain loci can further help in the effort to characterize the sequence diversity of STR markers from different populations around the world.

Forensic Age Estimation through a DNA Methylation-Based Age Prediction Model in the Italian Population: A Pilot Study

DNA methylation is one of the epigenetic marks which has been studied intensively in recent years for age predicting purposes in the forensic area. In order to integrate age prediction into routine forensic workflow, the purpose of this study was to standardize and optimize a DNA methylation-based protocol tailored to the Italian context. A previously published protocol and age-predictive method was implemented for the analysis of 84 blood samples originating from Central Italy. The study here presented is based on the Single Base Extension method, considering five genes: ELOVL2, FHL2, KLF14, C1orf132, now identified as MIR29B2C, and TRIM59. The precise and specific steps consist of DNA extraction and quantification, bisulfite conversion, amplification of converted DNA, first purification, single base extension, second purification, capillary electrophoresis, and analysis of the results to train and test the tool. The prediction error obtained, expressed as mean absolute deviation, showed a value of 3.12 years in the training set and 3.01 years in the test set. Given that population-based differences in DNA methylation patterns have been previously reported in the literature, it would be useful to further improve the study implementing additional samples representative of the entire Italian population.

Forty years of research and development on forensic genetics: A bibliometric analysis

The current study aims to investigate the research publication trends in the field of forensic genetics using Bibliometric analysis. An extensive search of the Scopus database was conducted to identify scholarly articles on forensic genetics published between 1977 and 2022, and a data set comprising 2945 articles was obtained. The analysis was carried out using VOSviewer, RStudio, MS Excel and MS Access to investigate the annual publication trend, most productive journals, organizations/authors/countries, authorship and citation patterns, most cited documents/articles and co-occurrence of keywords. The results revealed the first article in the field of forensic genetics was published in 1977. By the end of 1999, only 15 articles were published. Since then, there has been a considerable increase in the yearly number of publications and post-2006, there were more than 100 yearly published articles. USA, China, Spain, Germany and United Kingdom were found to be the most productive countries. Among various organizations, the Institute of Legal Medicine, Innsbruck Medical University, Austria was found to be the most productive organization. In terms of the number of publications and citations, Morling N. was found to be the most prolific author. The highest number of articles were published in Forensic Science International: Genetics, contributing about 34% of the total articles published in different sources/journals. The document with the highest number of citations was "HOMER N, 2008, PLOS GENET", with a total of 750 citations. The most frequent keywords were forensic genetics and forensic science, followed by STR, population genetics, DNA, mt-DNA and DNA-typing. The results also revealed that there had been collaborative research among countries, organizations and authors, which helps in the exchange of ideas across disciplines, developing new skills, getting access to financial resources and generating quality results.

A global snapshot of current opinions of next-generation sequencing technologies usage in forensics

The future of forensic DNA testing is being shaped by the research and usage of next-generation systems, which have increased the multiplexing capabilities of the field and the type and amount of genetic data that can be utilized for investigations. The NGS adoption for casework has been slow, albeit the plethora of data that has been published. This study evaluated the current opinions on sequencing in forensics. A 20-question online-survey focusing on NGS knowledge, training, and usage was distributed to 6001 forensic DNA researchers and practitioners worldwide. A total of 367 responses were obtained from all continents (North/South America (69.8%), Europe (21.2%), Asia (5.5%), Oceania (2.5%), and Africa (1%)). The respondents consisted of 50% practitioners, 31% researchers, and 19% both. Of these, 38% already own a next-gen sequencing instrument, and 13% are planning to purchase one. Overall, there exists an extensive knowledge on next-gen sequencing within the forensic community, including among laboratories that have not yet implemented this high-throughput technology in their workflows. Current usage focuses primarily on SNP analysis for investigative leads and mitochondrial DNA analysis while future applications included both STR and SNP testing applied to general casework. The major overall concerns respondents have for implementing a sequencing instrument include limited funding, staffing, lack of time, and the cost-effectiveness of providing this service. Specific technical concerns that the respondents had are the lack of training, statistical applications, bioinformatics support, and of rigorous guidelines and recommendations. Most of the respondents do believe there will be a technology shift from using CE only to the use of NGS on casework in 5-10 years. In addition, around 66% of respondents believe that it is moderately to very likely that the court will accept sequencing analysis. Sixteen percent fell in the middle, and the remaining 15% believe it is more unlikely, with 3% of respondents believing it is very unlikely. In conclusion, this work outlines current analytical challenges experienced by the global forensic DNA community and addresses different strategies for the implementation of next-gen sequencing technologies in casework.

Reporting on forensic biology findings given activity level issues in the Netherlands

There appears to be some hesitation within the forensic biology community to formally evaluate and report on findings given activity level propositions. This hesitance in part stems from concerns about the lack of relevant data on the dynamics of biological traces and doubt about the relevance of such expert opinions to the trier of fact. At the Netherlands Forensic Institute formal evaluative opinions on the probability of case findings given propositions at the activity level are provided since 2013, if requested by a mandating authority. In this study we share the results from a retrospective analysis of 74 of such requests. We explore which party initiates requests, the types of cases that are submitted, the sources of data being used to assign probabilities to DNA transfer, persistence, prevalence and recovery (TPPR) events, the conclusions that were drawn by the scientists, and how the conclusions were used by the courts. This retrospective analysis of cases demonstrates that published sources of data are generally available and can be used to address DNA TPPR events in most cases, although significant gaps still remain. The study furthermore shows that reporting on forensic biology findings given activity level propositions has been generally accepted by the district and appeal courts, as well as the other parties in the criminal justice system in the Netherlands.

Predicting Eye and Hair Color in a Turkish Population Using the HIrisPlex System

Forensic DNA Phenotyping (FDP) can reveal the appearance of an unknown individual by predicting the ancestry, phenotype (i.e., hair, eye, skin color), and age from DNA obtained at the crime scene. The HIrisPlex system has been developed to simultaneously predict eye and hair color. However, the prediction accuracy of the system needs to be assessed for the tested population before implementing FDP in casework. In this study, we evaluated the performance of the HIrisPlex system on 149 individuals from the Turkish population. We applied the single-based extension (SNaPshot chemistry) method and used the HIrisPlex online tool to test the prediction of the eye and hair colors. The accuracy of the HIrisPlex system was assessed through the calculation of the area under the receiver characteristic operating curves (AUC), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). The results showed that the proposed method successfully predicted the eye and hair color, especially for blue (100%) and brown (95.60%) eye and black (95.23) and brown (98.94) hair colors. As observed in previous studies, the system failed to predict intermediate eye color, representing 25% in our cohort. The majority of incorrect predictions were observed for blond hair color (40.7%). Previous HIrisPlex studies have also noted difficulties with these phenotypes. Our study shows that the HIrisPlex system can be applied to forensic casework in Turkey with careful interpretation of the data, particularly intermediate eye color and blond hair color.

A sequence-based 163plex microhaplotype assay for forensic DNA analysis

Novel genetic marker microhaplotype has led to an upsurge in forensic genetic research. This study established a 163 microhaplotype (MH) multiplex assay based on next-generation sequencing (NGS) and evaluated the assay’s performance and applicability. Our results showed that the 163 MH assay was accurate, repeatable and reliable, and could distinguish between African, European-American, Southern Asia and Eastern Asia populations. Among the 163 MH makers, 48 MHs with Ae > 3.0 in China Eastern Han were selected and confirmed to be highly polymorphic, with a combined power of discrimination of 1–8.26 × 10–44 and the combined power of exclusion in duos and trios of 1–1.26 × 10–8 and 1–8.27 × 10–16, respectively. Moreover, the mixture study demonstrated the realizability of the MHs in deconvoluting mixtures with different proportions of two to five-person. In conclusion, our findings support the use of this MH assay for ancestry inference, human identification, paternity testing and mixture deconvolution in forensic research.

Molecular biology applications of the red king crab duplex-specific nuclease

Duplex-specific nuclease (DSN) from hepatopancreas of the craboid Paralithodes camtschaticus (red king crab) has a unique combination of properties. Along with thermal stability and a high optimal temperature of catalysis, this enzyme exhibits high substrate selectivity, cleaving only DNA in duplexes (DNA-DNA or DNA-RNA). Accordingly, it digests neither single strands (nor single-stranded regions) of DNA, nor RNA strands with any secondary structure. Such properties make it possible to create unique protocols based on DSN, which is also an important object of fundamental research in the field of nuclease evolution. The review considers diverse applications of the red king crab DSN in modern methods of molecular biology.

Ethics as Lived Practice. Anticipatory Capacity and Ethical Decision-Making in Forensic Genetics

Greater scrutiny and demands for innovation and increased productivity place pressures on scientists. Forensic genetics is advancing at a rapid pace but can only do so responsibly, usefully, and acceptably within ethical and legal boundaries. We argue that such boundaries require that forensic scientists embrace 'ethics as lived practice'. As a starting point, we critically discuss 'thin' ethics in forensic genetics, which lead to a myopic focus on procedures, and to seeing 'privacy' as the sole ethical concern and technology as a mere tool. To overcome 'thin' ethics in forensic genetics, we instead propose understanding ethics as an intrinsic part of the lived practice of a scientist. Therefore, we explore, within the context of three case studies of emerging forensic genetics technologies, ethical aspects of decision-making in forensic genetics research and in technology use. We discuss the creation, curation, and use of databases, and the need to engage with societal and policing contexts of forensic practice. We argue that open communication is a vital ethical aspect. Adoption of 'ethics as lived practice' supports the development of anticipatory capacity-empowering scientists to understand, and act within ethical and legal boundaries, incorporating the operational and societal impacts of their daily decisions, and making visible ethical decision making in scientific practice.