In mass disaster events, forensic DNA laboratories may be called upon to quickly pivot their operations toward identifying bodies and reuniting remains with family members. Ideally, laboratories have considered this possibility in advance and have a plan in place. Compared with traditional short tandem repeat (STR) typing, single nucleotide polymorphisms (SNPs) may be better suited to these disaster victim identification (DVI) scenarios due to their small genomic target size, resulting in an improved success rate in degraded DNA samples. As the landscape of technology has shifted toward DNA sequencing, many forensic laboratories now have benchtop instruments available for massively parallel sequencing (MPS), facilitating this operational pivot from routine forensic STR casework to DVI SNP typing. Herein, we present the commercially available SNP sequencing assays amenable to DVI, we use data simulations to explore the potential for kinship prediction from SNP panels of varying sizes, and we give an example DVI scenario as context for presenting the matrix of considerations: kinship predictive potential, cost, and throughput of current SNP assay options. This information is intended to assist laboratories in choosing a SNP system for disaster preparedness.

This study describes an optimized DNA extraction protocol targeting ultrashort DNA molecules from single rootless hairs. It was applied to the oldest samples available to us: locks of hairs that were found in relics associated with the Romanov family. Published mitochondrial DNA genome sequences of Tsar Nicholas II and his wife, Tsarina Alexandra, made these samples ideal to assess this DNA extraction protocol and evaluate the types of genetic information that can be recovered by sequencing ultrashort fragments. Using this method, the mtGenome of the Tsarina's lineage was identified in hairs that were concealed in a pendant made by Karl Fabergé for Alexandra Feodorovna Romanov. In addition, to determine if the lock originated from more than one individual, two hairs from the locket were extracted independently and converted into Illumina libraries for shotgun sequencing on a NextSeq 500 platform. From these data, autosomal SNPs were analyzed to assess relatedness. The results indicated that the two hairs came from a single individual. Genetic testing of hairs that were found in the second artifact, a framed photograph of Louise of Hesse-Kassel, Queen of Denmark and maternal grandmother of Tsar Nicholas II, revealed that the hair belonged to a woman who shared Tsar Nicholas' maternal lineage, including the well-known point heteroplasmy at position 16169.

Methods for SNP-based phenotype prediction have recently been developed, but prediction accuracy data for several populations and regions are missing. We analysed the accuracy of hair and eye colour predictions for 111 individuals residing in Sweden, using the ForenSeq system and the MiSeq FGx instrument (Verogen). Observed colours were compared to predicted colours, using the colour with the highest probability value for each prediction. Overall, 80% of eye colour predictions were correct, but the system failed to predict intermediate/green eye colour in our cohort. For hair colour, 58% of predictions were correct, and the majority of incorrect predictions were related to brown hair. To assess if prediction accuracy could be improved by the exclusion of predictions with low probabilities, we applied a threshold of amp;gt;= 0.7. The threshold improved eye colour prediction, from 80% to 85% correct predictions, whereas hair colour prediction accuracy was virtually unaffected (58% versus 57% correct predictions). In summary, the phenotype prediction accuracy was acceptable in our cohort and the use of a threshold was only useful for eye colour predictions.

Massive parallel sequencing (MPS) is increasingly used for human identification purposes in forensic DNA laboratories. Forensic DNA samples are by nature heterogeneous and of varying quality, both concerning DNA integrity and matrices, creating a need for assays that can handle low amounts of DNA as well as impurities. Commercial short tandem repeat (STR) analysis kits for capillary electrophoresis-based separation have evolved drastically over the past years to handle low-template samples and high amounts of various PCR inhibitors. If MPS is to be used extensively in forensic laboratories there is a need to ascertain a similar performance. We have evaluated the GeneRead Individual Identity SNP panel (Qiagen) that includes 140 SNP markers, following the GeneRead DNAseq Targeted Panels V2 handbook for library preparation, applying low levels of DNA and relevant impurities. Analysis of down to 0.1 ng DNA generated SNP profiles with at least 85% called SNPs, after increasing the number of PCR cycles in the initial PCR from 20 to 24. The SNP assay handled extracts from four different DNA extraction methods, including Chelex with blood and saliva, without detrimental effects. Further, the assay was shown to tolerate relevant amounts of inhibitor solutions from soil, cigarettes, snuff and chewing gum. In conclusion, the performance of the SNP panel was satisfactory for casework-like samples. © 2017 Elsevier B.V.

Male individuals, from a Swedish reference population, with identical 17 loci Y-chromosomal STR haplotypes were analyzed with more than 900,000 autosomal SNPs in order to estimate their degree of genetic relatedness. This study shows that even though identical Y-STR profiles are shared, there is no evidence that these individuals are related to a higher degree compared with randomly unrelated male individuals in the Swedish population. Based on the results in this study, we conclude that the data do not show any signs of a biased sampling when it comes to the studied male individuals representing the Swedish reference population. © 2017 Elsevier B.V.

Within forensic genetics, there is still a need for supplementary DNA marker typing in order to increase the power to solve cases for both identity testing and complex kinship issues. One major disadvantage with current capillary electrophoresis (CE) methods is the limitation in DNA marker multiplex capability. By utilizing massive parallel sequencing (MPS) technology, this capability can, however, be increased. We have designed a customized GeneRead DNASeq SNP panel (Qiagen) of 140 previously published autosomal forensically relevant identity SNPs for analysis using MPS. One single amplification step was followed by library preparation using the GeneRead Library Prep workflow (Qiagen). The sequencing was performed on a MiSeq System (Illumina), and the bioinformatic analyses were done using the software Biomedical Genomics Workbench (CLC Bio, Qiagen). Forty-nine individuals from a Swedish population were genotyped in order to establish genotype frequencies and to evaluate the performance of the assay. The analyses showed to have a balanced coverage among the included loci, and the heterozygous balance showed to have less than 0.5 % outliers. Analyses of dilution series of the 2800M Control DNA gave reproducible results down to 0.2 ng DNA input. In addition, typing of FTA samples and bone samples was performed with promising results. Further studies and optimizations are, however, required for a more detailed evaluation of the performance of degraded and PCR-inhibited forensic samples. In summary, the assay offers a straightforward sample-to-genotype workflow and could be useful to gain information in forensic casework, for both identity testing and in order to solve complex kinship issues.

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Mixture DNA profiles commonly appear in forensic genetics, and a large number of statistical methods and software are available for such cases. However, most of the literature concerns mixtures where the contributors are assumed unrelated and the genetic markers are unlinked. In this paper, we consider mixtures of linked markers and related contributors. If no relationships are involved, linkage can be ignored. While unlinked markers can be treated independently, linkage introduces dependencies. The use of linked markers presents statistical and computational challenges, but may also lead to a considerable increase in power since the number of markers available is much larger if we do not require the markers to be unlinked. In addition, some cases that cannot be solved with an unlimited number of unlinked autosomal markers can be solved with linked markers. We focus on two special cases of linked markers: pairs of linked autosomal markers and X-chromosomal markers. A framework is presented for calculation of likelihood ratios for mixtures with general relationships and with linkage between any number of markers. Finally, we explore the effect of linkage disequilibrium, also called allelic association, on the likelihood ratio.

Several applications necessitate an unbiased determination of relatedness, be it in linkage or association studies or in a forensic setting. An appropriate model to compute the joint probability of some genetic data for a set of persons given some hypothesis about the pedigree structure is then required. The increasing number of markers available through high-density SNP microarray typing and NGS technologies intensifies the demand, where using a large number of markers may lead to biased results due to strong dependencies between closely located loci, both within pedigrees (linkage) and in the population (allelic association or linkage disequilibrium (LD)). We present a new general model, based on a Markov chain for inheritance patterns and another Markov chain for founder allele patterns, the latter allowing us to account for LD. We also demonstrate a specific implementation for X chromosomal markers that allows for computation of likelihoods based on hypotheses of alleged relationships and genetic marker data. The algorithm can simultaneously account for linkage, LD, and mutations. We demonstrate its feasibility using simulated examples. The algorithm is implemented in the software FamLinkX, providing a user-friendly GUI for Windows systems (FamLinkX, as well as further usage instructions, is freely available at www.famlink.se). Our software provides the necessary means to solve cases where no previous implementation exists. In addition, the software has the possibility to perform simulations in order to further study the impact of linkage and LD on computed likelihoods for an arbitrary set of markers.

The use of genetic markers located on the X chromosome has seen a significant increase in the last years and their utility has been well studied. This paper describes the software FamLinkX, freely available at http://www.famlink.se, implementing a new algorithm for likelihood computations accounting for linkage, linkage disequilibrium and mutations. It is obvious that such software is sought for among forensic users as more and more X-chromosomal markers become available. We provide some simulated examples demonstrating the utility of the implementation as well as its application in forensic casework. Though algebraic derivations are generally unfeasible, the paper outlines some theoretical considerations and provides a discussion on the validation of the software. The focus of this paper is to compare the software to existing methods in a forensic setting, perform a validation study as well as to provide an idea of the discriminatory power for X-chromosomal markers. (C) 2015 Elsevier Ireland Ltd. All rights reserved.