International Society For Forensic Genetics Research Articles

Ethical considerations for Forensic Genetic Frequency databases: First Report conception and development

The Forensic Databases Advisory Board (FDAB), an independent board that assists the International Society for Forensic Genetics (ISFG), has presented a First Report on ethical aspects of the following Forensic Genetic Frequency Databases (FGFD): EMPOP, STRidER and YHRD. The FDAB designed an ethical framework to evaluate the content of these FGFD, and the factors to be considered for retention and acceptance of submissions. The FDAB framework proposes to categorize submissions according to the risk of having contravened the universal ethical principles outlined by international organizations, and the guidelines adopted by the ISFG. The report has been open to discussion by the scientific community since 2023. Herein we present the conception and development of the First Report along with a summary of its content, with consideration of the feedback received.

Phylogenetic analysis of mysterious burials revealed in the former penal labor camp Treblinka I.

The purpose of this paper is to formulate recommendations for the disclosure of biological traces in the laboratory and the handling of forensic evidence submitted for identification tests, recommended by the Polish Speaking Working Group of the International Society for Forensic Genetics. The paper organizes the knowledge of the most relevant stages of preliminary analysis of biological traces based on both literature sources and those resulting from years of research practice. Recommendations formulated in the course of multi-stage expert consultations contained in this study should be used in the development of laboratory procedures applied during the execution. * The research is part of doctoral dissertation of Dagmara Lisman entitled "Genetic analysis of a skeleton site revealed during the works on the premises of the former German Forced Labor Camp Treblinka I."

Recommendations of the Polish-speaking Working Group of the International Society for Forensic Genetics (ISFG-PL) regarding the disclosure of biological traces and the handling of evidence for identification tests.

The purpose of this paper is to formulate recommendations for the disclosure of biological traces in the laboratory and the handling of forensic evidence submitted for identification tests, recommended by the Polish Speaking Working Group of the International Society for Forensic Genetics. The paper organizes the knowledge of the most relevant stages of preliminary analysis of biological traces based on both literature sources and those resulting from years of research practice. Recommendations formulated in the course of multi-stage expert consultations contained in this study should be used in the development of laboratory procedures applied during the execution.

Microsatellites’ mutation modeling through the analysis of the Y-chromosomal transmission: Results of a GHEP-ISFG collaborative study

The Spanish and Portuguese Speaking Working Group of the International Society for Forensic Genetics (GHEP-ISFG) organized a collaborative study on mutations of Y-chromosomal short tandem repeats (Y-STRs). New data from 2225 father-son duos and data from 44 previously published reports, corresponding to 25,729 duos, were collected and analyzed. Marker-specific mutation rates were estimated for 33 Y-STRs. Although highly dependent on the analyzed marker, mutations compatible with the gain or loss of a single repeat were 23.2 times more likely than those involving a greater number of repeats. Longer alleles (relatively to the modal one) showed to be nearly twice more mutable than the shorter ones. Within the subset of longer alleles, the loss of repeats showed to be nearly twice more likely than the gain. Conversely, shorter alleles showed a symmetrical trend, with repeat gains being twofold more frequent than reductions. A positive correlation between the paternal age and the mutation rate was observed, strengthening previous findings. The results of a machine learning approach, via logistic regression analyses, allowed the establishment of algebraic formulas for estimating the probability of mutation depending on paternal age and allele length for DYS389I, DYS393 and DYS627. Algebraic formulas could also be established considering only the allele length as predictor for DYS19, DYS389I, DYS389II-I, DYS390, DYS391, DYS393, DYS437, DYS439, DYS449, DYS456, DYS458, DYS460, DYS481, DYS518, DYS533, DYS576, DYS626 and DYS627 loci. For the remaining Y-STRs, a lack of statistical significance was observed, probably as a consequence of the small effective size of the subsets available, a common difficulty in the modeling of rare events as is the case of mutations. The amount of data used in the different analyses varied widely, depending on how the data were reported in the publications analyzed. This shows a regrettable waste of produced data, due to inadequate communication of the results, supporting an urgent need of publication guidelines for mutation studies.

Recommendations of the DNA Commission of the International Society for Forensic Genetics (ISFG) on short tandem repeat sequence nomenclature

The DNA Commission of the International Society for Forensic Genetics (ISFG) has developed a set of nomenclature recommendations for short tandem repeat (STR) sequences. These recommendations follow the 2016 considerations of the DNA Commission of the ISFG, incorporating the knowledge gained through research and population studies in the intervening years. While maintaining a focus on backward compatibility with the CE data that currently populate national DNA databases, this report also looks to the future with the establishment of recommended minimum sequence reporting ranges to facilitate interlaboratory comparisons, automated solutions for sequence-based allele designations, a suite of resources to support bioinformatic development, guidance for characterizing new STR loci, and considerations for incorporating STR sequences and other new markers into investigative databases.

Introducing the New Editorial Team

Introducing the New Editorial Team

Weight of evidence of Y-STR matches computed with the discrete Laplace method: Impact of adding a suspect's profile to a reference database.

The discrete Laplace method is recommended by multiple parties (including the International Society for Forensic Genetics, ISFG) to estimate the weight of evidence in criminal cases when a suspect's Y-STR profile matches the crime scene Y-STR profile. Unfortunately, modelling the distribution of Y-STR profiles in the population reference database is time-consuming and requires expert knowledge. When the suspect's Y-STR profile is added to the database, as would be the protocol in many cases, the parameters of the discrete Laplace model must be re-estimated. We found that the likelihood ratios with and without adding the suspect's Y-STR profile were almost identical with 1,000 or more Y-STR profiles in the database for Y-STR profiles with 8, 12, and 17 loci. Thus, likelihood ratio calculations can be performed in seconds if an established discrete Laplace model based on at least 1,000 Y-STR profiles is used. A match in a population reference database with 17 Y-STR loci from at least 1,000 male individuals results in a likelihood ratio above 10,000 in approximately 94% of the cases, and above 100,000 in approximately 82% of the cases. We offer free software accessible without restrictions to estimate a discrete Laplace model using a Y-STR reference database and subsequently to calculate likelihood ratios.

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.

Developmental validation of STRmix™ NGS, a probabilistic genotyping tool for the interpretation of autosomal STRs from forensic profiles generated using NGS

We describe the developmental validation of the probabilistic genotyping software – STRmix™ NGS – developed for the interpretation of forensic DNA profiles containing autosomal STRs generated using next generation sequencing (NGS) also known as massively parallel sequencing (MPS) technologies. Developmental validation was carried out in accordance with the Scientific Working Group on DNA Analysis Methods (SWGDAM) Guidelines for the Validation of Probabilistic Genotyping Systems and the International Society for Forensic Genetics (ISFG) recommendations and included sensitivity and specificity testing, accuracy, precision, and the interpretation of case-types samples. The results of developmental validation demonstrate the appropriateness of the software for the interpretation of profiles developed using NGS technology.

American forensic DNA practitioners' opinion on activity level evaluative reporting.

The technical advancements made in DNA profiling now allow for very low DNA amounts to be analyzed. Accordingly, the argument often made in criminal courts is not who the DNA belongs to but rather how it was deposited. Despite the complexity of the relevant DNA transfer, persistence, prevalence, and recovery issues, forensic laboratories in some European countries have used evaluative reports with activity level propositions, while this is not current practice in the United States. The purpose of this study was to gain an overview of the opinions about activity level reporting (ALR) held by forensic biologists in the United States. A seventeen-question survey was distributed to members of the American Society of Crime Laboratory Directors and U.S. members of the International Society for Forensic Genetics. The survey included multiple-choice and open-response questions and received 54 responses. The majority of responses expressed moderate support of ALR. Participants mentioned six major concerns to be addressed prior to implementing ALR in the United States: (1) effect of number of variables involved; (2) need of education for practitioners/legal system; (3) inadequate number of activity studies with realistic scenarios; (4) difficulty of achieving admissibility in court; (5) need for standardized approaches/guidelines; and (6) requisite shift in perspective as to the validity of ALR. Overall, this small segment of U.S. forensic DNA practitioners appear to be willing to implement ALR once these concerns are fully addressed and resolved. As a follow-up, it would be worthwhile exploring these and other questions with a larger group and also other disciplines.

Second GHEP-ISFG exercise for DVI: “DNA-led” victims’ identification in a simulated air crash

The Spanish and Portuguese-Speaking Working Group of the International Society for Forensic Genetics (GHEP-ISFG) has organized a second collaborative exercise on a simulated case of Disaster Victim Identification (DVI), with the participation of eighteen laboratories. The exercise focused on the analysis of a simulated plane crash case of medium-size resulting in 66 victims with varying degrees of fragmentation of the bodies (with commingled remains). As an additional difficulty, this second exercise included 21 related victims belonging to 6 families among the 66 missings to be identified. A total number of 228 post-mortem samples were represented with aSTR and mtDNA profiles, with a proportion of partial aSTR profiles simulating charred remains. To perform the exercise, participants were provided with aSTR and mtDNA data of 51 reference pedigrees —some of which deficient—including 128 donors for identification purposes. The exercise consisted firstly in the comparison of the post-mortem genetic profiles in order to re-associate fragmented remains to the same individual and secondly in the identification of the re-associated remains by comparing aSTR and mtDNA profiles with reference pedigrees using pre-established thresholds to report a positive identification. Regarding the results of the post-mortem samples re-associations, only a small number of discrepancies among participants were detected, all of which were from just a few labs. However, in the identification process by kinship analysis with family references, there were more discrepancies in comparison to the correct results. The identification results of single victims yielded fewer problems than the identification of multiple related victims within the same family groups. Several reasons for the discrepant results were detected: a) the identity/non-identity hypotheses were sometimes wrongly expressed in the likelihood ratio calculations, b) some laboratories failed to use all family references to report the DNA match, c) In families with several related victims, some laboratories firstly identified some victims and then unnecessarily used their genetic information to identify the remaining victims within the family, d) some laboratories did not correctly use “prior odds” values for the Bayesian treatment of the episode for both post-mortem/post-mortem re-associations as well as the ante-mortem/post-mortem comparisons to evaluate the probability of identity. For some of the above reasons, certain laboratories failed to identify some victims. This simulated “DNA-led” identification exercise may help forensic genetic laboratories to gain experience and expertize for DVI or MPI in using genetic data and comparing their own results with the ones in this collaborative exercise.

Optimisation and application of a forensic microsatellite panel to combat Greater-one horned rhinoceros (Rhinoceros unicornis) poaching in India

The Greater one-horned (GoH) rhinoceros is one of the most charismatic endemic megaherbivores of the Indian subcontinent. Threatened by poaching, habitat loss and disease, the species is found only in small areas of its historical distribution. Increasing demands for rhino horns in chinese traditional medicine has put the existing population under continuing threat, and large profits and low conviction rates make poaching difficult to contain. DNA forensics such as the RhoDIS-Africa program has helped in combating illegal rhino horn trade, but the approach is yet to be optimised for Indian GoH rhinoceros. Here we followed the International Society for Forensic Genetics (ISFG) guidelines to establish a 14 dinucleotide microsatellite panel for Indian GoH rhinoceros DNA profiling. Selected from a large initial pool (n = 34), the microsatellite markers showed high polymorphism, stable peak characteristics, consistent allele calls and produced precise, reproducible genotypes from different types of rhino samples. The panel also showed low genotyping error and produced high statistical power during individual identification (PIDsibs value of 1.2*10−4). As part of the official RhoDIS-India program, we used this panel to match poached rhino carcass with seized contraband as scientific evidence in court procedure. This program now moves to generate detailed allele-frequency maps of all GoH rhinoceros populations in India and Nepal for development of a genetic database and identification of poaching hotspots and trade routes across the subcontinent and beyond.

The first GHEP-ISFG collaborative exercise on forensic applications of massively parallel sequencing

One of the main goals of the Spanish and Portuguese-Speaking Working Group of the International Society for Forensic Genetics (GHEP-ISFG) is to promote and contribute to the development and dissemination of scientific knowledge in the field of forensic genetics. The GHEP-ISFG supports several Working Commissions which develop different scientific activities. One of them, the Working Commission on “Massively Parallel Sequencing (MPS): Forensic Applications”, organized its first collaborative exercise on forensic applications of MPS technology in 2019. The aim of this exercise was to assess the concordance between the MPS results and those obtained with conventional technologies (capillary electrophoresis and Sanger sequencing), as well as to compare the results obtained within the different MPS platforms and/or the different kits/panels and analysis software packages (commercial and open-access) available on the market. The seven participating laboratories analyzed some samples of the annual GHEP-ISFG proficiency test (EIADN No. 27 (2019)), using Ion Torrent™ or MiSeq FGx® platforms. Six of them sent autosomal STR sequence data, five laboratories performed MPS analysis of individual identification SNPs, four laboratories reported MPS data of Y-chromosomal STRs, and X-chromosomal STRs, three laboratories performed MPS analysis of ancestry informative SNPs and phenotype informative SNPs, two labs performed MPS analysis of the mitochondrial DNA control region, and only one lab produced MPS data of lineage informative SNPs. Autosomal STR sequencing results were highly concordant to the consensus obtained by capillary electrophoresis in the EIADN No. 27 (2019) exercise. Furthermore, in general, a high level of concordance was observed between the results of the participating laboratories, regardless of the platform used. The main discordances were due to errors during the analysis process or from sequence data obtained with low depth of coverage. In this paper we highlight some issues that still arise, such as standardization of the nomenclature for STRs analyzed by sequencing with MPS, the universal uptake of a nomenclature framework by the analysis software, and well established validation and accreditation of the new MPS platforms for use in routine forensic case-work.

DNA commission of the International society for forensic genetics: Assessing the value of forensic biological evidence - Guidelines highlighting the importance of propositions. Part II: Evaluation of biological traces considering activity level propositions

The value of the evidence depends critically on propositions. In the second of two papers intended to provide advice to the community on difficult aspects of evaluation and the formulation of propositions, we focus primarily on activity level propositions. This helps the court address the question of “How did an individual’s cell material get there?”. In order to do this, we expand the framework outlined in the first companion paper. First, it is important not to conflate results and propositions. Statements given activity level propositions aim to help address issues of indirect vs direct transfer, and the time of the activity, but it is important to avoid use of the word ‘transfer’ in propositions. This is because propositions are assessed by the Court, but DNA transfer is a factor that scientists need to take into account for the interpretation of their results. Suitable activity level propositions are ideally set before knowledge of the results and address issues like: X stabbed Y vs. an unknown person stabbed Y but X met Y the day before. The scientist assigns the probability of the evidence, if each of the alternate propositions is true, to derive a likelihood ratio. To do this, the scientist asks: a) “what are the expectations if each of the propositions is true?” b) “What data are available to assist in the evaluation of the results given the propositions?” When presenting evidence, scientists work within the hierarchy of propositions framework. The value of evidence calculated for a DNA profile cannot be carried over to higher levels in the hierarchy – the calculations given sub-source, source and activity level propositions are all separate. A number of examples are provided to illustrate the principles espoused, and the criteria that such assessments should meet. Ideally in order to assign probabilities, the analyst should have/collect data that are relevant to the case in question. These data must be relevant to the case at hand and we encourage further research and collection of data to form knowledge bases. Bayesian Networks are extremely useful to help us think about a problem, because they force us to consider all relevant possibilities in a logical way. An example is provided.

Massively parallel sequence data of 31 autosomal STR loci from 496 Spanish individuals revealed concordance with CE-STR technology and enhanced discrimination power

This study reports Short Tandem Repeat (STR) sequence-based allele data from 496 Spanish individuals across 31 autosomal STR (auSTR) loci included in the Precision ID GlobalFiler™ NGS STR Panel v2: D12S391, D13S317, D8S1179, D21S11, D3S1358, D5S818, D1S1656, D2S1338, vWA, D2S441, D5S2800, D7S820, D16S539, D6S474, D12ATA63, D4S2408, D6S1043, D19S433, D14S1434, CSF1PO, D10S1248, D18S51, D1S1677, D22S1045, D2S1776, D3S4529, FGA, Penta D, Penta E, TH01 and TPOX. The sequence of each allele was aligned to the reference sequence GRCh37 (hg19) and formatted according to the guidance of the International Society for Forensic Genetics. A subset of 221 samples was evaluated for testing concordance with allele calls derived from CE-based analysis using PowerPlex Fusion 6C, and there was 99.95% allele concordance. Twenty-five out of 31 auSTR loci showed an increased number of alleles due to repeat region sequence variation and/or single nucleotide polymorphisms (SNP) residing in the flanking regions. A total of 18 loci showed increased observed heterozygosity due to sequence variation; the loci exhibiting the greatest increase were: D13S317 (12% points), D5S818 (10% points), D8S1179 (7% points), D3S1358 (7% points), and D21S11 (6% points). The combined match probability decreased from 2.022E-24 (length-based data) to 1.042E-27 (sequence-based data) for the 20 CODIS core STR loci. The combined match probability (sequence-based data) for the 31 STR loci studied was 4.777E-40. The combined typical paternity index increased from 1.118E + 12 to 8.179E + 13 using length and sequence-based data, respectively. This Spanish population study performed in the framework of the EU-funded DNASEQEX project is expected to provide STR sequence-based allele frequencies for forensic casework and support implementation of massively parallel sequencing (MPS) technology in forensic laboratories.

Genetic polymorphisms and mutation rates of 16 X-STRs in a Han Chinese population of Beijing and application examples in second-degree kinship cases.

As a supplementary tool in forensic cases, X chromosomal short tandem repeats (X-STRs) might bridge large pedigree gaps and bring inspiration to forensic practices for the special mode of inheritance. To standardize the application of X-STRs, the DNA Commission of the International Society for Forensic Genetics (ISFG) presented recommendations concentrating on biostatistical evaluations. Following this guideline, in this study, 1247 (655 females and 592 males) unrelated individuals and 770 families originating from a Han Chinese population of Beijing were investigated with 16 X-STRs. The combined PDF and PDM were 0.999999999999994 and 0.999999997, respectively. The combined MECKrüger, MECKishida, MECDesmarais, and MECDesmarais duo were 0.999972736708864, 0.999999975670766, 0.999999975720931, and 0.999993489709197, respectively. In addition, a population comparison demonstrated that genetic heterogeneity widely exists between the Han population of Beijing and other populations, especially southern Han Chinese, European, and West African populations. Additionally, the overall mutation rates of the paternal and maternal germlines of the 16 X-STRs were 0.0021 and 0.0003, respectively. Among them, HPRTB showed the highest paternal mutation rate of 0.0094. Finally, based on these forensic parameters, the likelihood ratios of four second-degree kinship cases were evaluated. Comparing with autosomal STR, X-STR showed significant advantages for hypothesis exclusion. Our study indicated that the 16 X-STR loci are highly polymorphic in the Han population of Beijing and could be a satisfactory complimentary tool for forensic applications.

Sequence-based U.S. population data for 27 autosomal STR loci

This manuscript reports Short Tandem Repeat (STR) sequence-based allele frequencies for 1036 samples across 27 autosomal STR loci: D1S1656, TPOX, D2S441, D2S1338, D3S1358, D4S2408, FGA, D5S818, CSF1PO, D6S1043, D7S820, D8S1179, D9S1122, D10S1248, TH01, vWA, D12S391, D13S317, Penta E, D16S539, D17S1301, D18S51, D19S433, D20S482, D21S11, Penta D, and D22S1045. Sequence data were analyzed by two bioinformatic pipelines and all samples have been evaluated for concordance with alleles derived from CE-based analysis at all loci. Each reported sequence includes high-quality flanking sequence and is properly formatted according to the most recent guidance of the International Society for Forensic Genetics. In addition, GenBank accession numbers are reported for each sequence, and associated records are available in the STRSeq BioProject (https://www.ncbi.nlm.nih.gov/bioproject/380127). The D3S1358 locus demonstrates the greatest average increase in heterozygosity across populations (approximately 10 percentage points). Loci demonstrating average increase in heterozygosity from 10 to 5 percentage points include (in descending order) D9S1122, D13S317, D8S1179, D21S11, D5S818, D12S391, and D2S441. The remaining 19 loci each demonstrate less than 5 percentage point increase in average heterozygosity. Discussion includes the utility of this data in understanding traditional CE results, such as informing stutter models and understanding migration challenges, and considerations for population sampling strategies in light of the marked increase in rare alleles for several of the sequence-based STR loci. This NIST 1036 data set is expected to support the implementation of STR sequencing forensic casework by providing high-confidence sequence-based allele frequencies for the same sample set which are already the basis for population statistics in many U.S. forensic laboratories.

DNA commission of the International society for forensic genetics: Assessing the value of forensic biological evidence - Guidelines highlighting the importance of propositions: Part I: evaluation of DNA profiling comparisons given (sub-) source propositions

The interpretation of evidence continues to be one of the biggest challenges facing the forensic community. This is the first of two papers intended to provide advice on difficult aspects of evaluation and in particular on the formulation of propositions. The scientist has a dual role: investigator (crime-focused), where often there is no suspect available and a database search may be required; evaluator (suspect-focused), where the strength of evidence is assessed in the context of the case. In investigative mode, generally the aim is to produce leads regarding the source of the DNA. Sub-source level propositions will be adequate to help identify potential suspects who can be further investigated by the authorities. Once in evaluative mode, given the defence version of events of the person of interest, it may become necessary to consider alternatives that go beyond the source of the DNA (i.e., to consider activity level propositions). In the evaluation phase, it is crucial that formulation of propositions allows the assessment of all the results that will help with the issue at hand. Propositions should therefore be precise (indication of the number of contributors, information on the relevant population etc.), be about causes, not effects (e.g. a ‘matching’ DNA profile) and to avoid bias, must not be findings-led. This means that ideally, propositions should be decided based on the case information and before the results of the comparisons are known. This paper primarily reflects upon what has been coined as “sub-source level propositions“. These are restricted to the evaluation of the DNA profiles themselves, and help answer the issue regarding the source of the DNA. It is to be emphasised that likelihood ratios given sub-source level propositions cannot be carried over to a different level – for example, activity level propositions, where the DNA evidence is put into the context of the alleged activities. This would be highly misleading and could give rise to miscarriages of justice; this will be discussed in a second paper.The value of forensic results depends not only on propositions, but also on the type of results (e.g. allelic designations, peak heights, replicates) and upon the model used: it is therefore important to discuss these aspects. Finally, since communication is key to help understanding by courts, we will explore how to convey the value of the results and explain the importance of avoiding the practice of transposing the conditional.

ToaSTR: A web application for forensic STR genotyping by massively parallel sequencing

Massively parallel sequencing (MPS) is emerging within the forensic community as a promising technique for high-resolution short tandem repeat (STR) genotyping, discovering both length and sequence polymorphisms. Conversely, the application of MPS to routine casework poses new challenges to the DNA analyst in view of the complex sequence data that is generated with this technology.We developed the web application toaSTR to help forensic experts work with MPS data simply and efficiently. An intuitive graphical user interface guides through the STR genotyping workflow. This versatile software handles data from various popular MPS platforms and supports both commercial and in-house multiplex PCR kits. Users can define locus-specific stutter thresholds and create custom sets of STR markers to be analyzed. toaSTR’s innovative sequence-based stutter model predicts and identifies common stutter variants. The algorithm automatically differentiates biological (iso-)alleles from stutter and other artefacts to assist the interpretation of mixed samples. toaSTR features a comprehensive data visualization with interactive diagrams and a dynamic tabular overview of sequence observations. The software provides an interface to biostatistics tools and enables PDF result export in compliance with the sequence notation recommended by the International Society for Forensic Genetics (ISFG).An initial compatibility and concordance study confirmed the software’s independent functionality and precise allele calling with data of different MPS platforms, STR amplification kits, and library preparation chemistries. Discussion of genotyping results for single source and mixed samples demonstrates toaSTR’s advantages and includes suggestions for future MPS software development.The beta version of toaSTR is freely accessible at www.toastr.online.

Systematic evaluation of the early access applied biosystems precision ID Globalfiler mixture ID and Globalfiler NGS STR panels for the ion S5 system

Systematic evaluation of the early access applied biosystems precision ID Globalfiler mixture ID and Globalfiler NGS STR panels for the ion S5 system