| 1. |
- Bergseth, Erik F., et al.
(författare)
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Extended population genetic analysis of 12 X-STRs - Exemplified using a Norwegian population sample
- 2022
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Ingår i: Forensic Science International. - : Elsevier Ireland Ltd. - 1872-4973 .- 1878-0326. ; 60
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Tidskriftsartikel (refereegranskat)abstract
- The use of X-chromosomal markers to resolve questions of relatedness has experienced a significant increase during the last years in forensic genetics. Perhaps primarily due to the emergence of commercial kits, but equally important due to an increased awareness of the utility of those markers. The X-chromosomal inheritance pattern entails that some cases, for instance paternal half-sisters, can potentially be resolved using a few X-chromosomal markers alone. For the statistical assessment in kinship cases it is of importance to have relevant population frequency data. In the present study 631 unrelated males from a Norwegian population sample are analyzed. The resulting haplotypes are compared to previously studied population samples and a deeper analysis of the linkage disequilibrium (LD) structure is conducted. We demonstrate that the power to detect LD will be low when few males, say below 300, are analyzed. We use entropy to describe the degree of LD between multiallelic loci and describe how this measure varies between different studied populations. Large population frequency databases have been recommended when using X-chromosomal markers, and we show that by combining reference da-tabases from genetically similar populations, more precise haplotype frequency estimates can be obtained for rare haplotypes which improves the statistical assessment of the weight of evidence. In addition, we promote the use of simulations to assess the utility of STR markers in contrast to standard forensic parameters. Specifically we perform extensive simulations on cases where X-chromosomal markers are important and illustrate how the results can be used to infer the information gained from these markers.
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| 2. |
- Cavagnino, Courtney, et al.
(författare)
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Unearthing who and Y at Harewood Cemetery and inference of George Washington's Y-chromosomal haplotype
- 2024
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Ingår i: iScience. - : CELL PRESS. - 2589-0042. ; 27:4
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Tidskriftsartikel (refereegranskat)abstract
- An excavation conducted at Harewood Cemetery to identify the unmarked grave of Samuel Washington resulted in the discovery of burials presumably belonging to George Washington's paternal grandnephews and their mother, Lucy Payne. To confirm their identities this study examined Y -chromosomal, mitochondrial, and autosomal DNA from the burials and a living Washington descendant. The burial's Y-STR profile was compared to FamilyTreeDNA's database, which resulted in a one-step difference from the living descendant and an exact match to another Washington. A more complete Y-STR and Y -SNP profile from the descendant was inferred to be the Washington Y profile. Kinship comparisons performed in relation to the descendant, who is a 4 th and 5 th degree relative of the putative individuals, resulted in >37,000 overlapping autosomal SNPs and strong statistical support with likelihood ratios exceeding one billion. This study highlights the benefits of a multi -marker approach for kinship prediction and DNA -assisted identification of historical remains.
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| 3. |
- Kling, Daniel, et al.
(författare)
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Investigative genetic genealogy : Current methods, knowledge and practice
- 2021
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Ingår i: Forensic Science International. - : Elsevier Ireland Ltd. - 1872-4973 .- 1878-0326. ; 52
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Forskningsöversikt (refereegranskat)abstract
- Investigative genetic genealogy (IGG) has emerged as a new, rapidly growing field of forensic science. We describe the process whereby dense SNP data, commonly comprising more than half a million markers, are employed to infer distant relationships. By distant we refer to degrees of relatedness exceeding that of first cousins. We review how methods of relationship matching and SNP analysis on an enlarged scale are used in a forensic setting to identify a suspect in a criminal investigation or a missing person. There is currently a strong need in forensic genetics not only to understand the underlying models to infer relatedness but also to fully explore the DNA technologies and data used in IGG. This review brings together many of the topics and examines their effectiveness and operational limits, while suggesting future directions for their forensic validation. We further investigated the methods used by the major direct-to-consumer (DTC) genetic ancestry testing companies as well as submitting a questionnaire where providers of forensic genetic genealogy summarized their operation/ services. Although most of the DTC market, and genetic genealogy in general, has undisclosed, proprietary algorithms we review the current knowledge where information has been discussed and published more openly.
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| 4. |
- Loreille, Odile, et al.
(författare)
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Improved DNA Extraction and Illumina Sequencing of DNA Recovered from Aged Rootless Hair Shafts Found in Relics Associated with the Romanov Family.
- 2022
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Ingår i: Genes. - : MDPI AG. - 2073-4425. ; 13:2
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 5. |
- Mostad, Petter, 1964, et al.
(författare)
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Improved computations for relationship inference using low-coverage sequencing data
- 2023
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Ingår i: BMC Bioinformatics. - : Springer Science and Business Media LLC. - 1471-2105. ; 24:1
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Tidskriftsartikel (refereegranskat)abstract
- Pedigree inference, for example determining whether two persons are second cousins or unrelated, can be done by comparing their genotypes at a selection of genetic markers. When the data for one or more of the persons is from low-coverage next generation sequencing (lcNGS), currently available computational methods either ignore genetic linkage or do not take advantage of the probabilistic nature of lcNGS data, relying instead on first estimating the genotype. We provide a method and software (see familias.name/lcNGS) bridging the above gap. Simulations indicate how our results are considerably more accurate compared to some previously available alternatives. Our method, utilizing a version of the Lander-Green algorithm, uses a group of symmetries to speed up calculations. This group may be of further interest in other calculations involving linked loci.
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| 6. |
- Phillips, C., et al.
(författare)
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A compilation of tri-allelic SNPs from 1000 Genomes and use of the most polymorphic loci for a large-scale human identification panel
- 2020
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Ingår i: Forensic Science International. - : ELSEVIER IRELAND LTD. - 1872-4973 .- 1878-0326. ; 46
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Tidskriftsartikel (refereegranskat)abstract
- In a directed search of 1000 Genomes Phase III variation data, 271,934 tri-allelic single nucleotide polymorphisms (SNPs) were identified amongst the genotypes of 2,504 individuals from 26 populations. The majority of tri-allelic SNPs have three nucleotide substitution-based alleles at the same position, while a much smaller proportion, which we did not compile, have a nucleotide insertion/deletion plus substitution alleles. SNPs with three alleles have higher discrimination power than binary loci but keep the same characteristic of optimum amplification of the fragmented DNA found in highly degraded forensic samples. Although most of the tri-allelic SNPs identified had one or two alleles at low frequencies, often single observations, we present a full compilation of the genome positions, rs-numbers and genotypes of all tri-allelic SNPs detected by the 1000 Genomes project from the more detailed analyses it applied to Phase III sequence data. A total of 8,705 tri-allelic SNPs had overall heterozygosities (averaged across all 1000 Genomes populations) higher than the binary SNP maximum value of 0.5. Of these, 1,637 displayed the highest average heterozygosity values of 0.6-0.666. The most informative tri-allelic SNPs we identified were used to construct a large-scale human identification panel for massively parallel sequencing, designed for the identification of missing persons. The large-scale MPS identification panel comprised: 1,241 autosomal tri-allelic SNPs and 29 X tri-allelic SNPs (plus 46 microhaplotypes adapted for genotyping from reduced length sequences). Allele frequency estimates are detailed for African, European, South Asian and East Asian population groups plus the Peruvian population sampled by 1000 Genomes for the 1,270 tri-allelic SNPs of the final MPS panel. We describe the selection criteria, kinship simulation experiments and genomic analyses used to select the tri-allelic SNP components of the panel. Approximately 5 % of the tri-allelic SNPs selected for the large-scale MPS identification panel gave three-genotype patterns in single individual samples or discordant genotypes for genomic control DNAs. A likely explanation for some of these unreliably genotyped loci is that they map to multiple sites in the genome - high-lighting the need for caution and detailed scrutiny of multiple-allele variant data when designing future forensic SNP panels, as such patterns can arise from common structural variation in the genome, such as segmental duplications.
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| 7. |
- Sidstedt, Maja, et al.
(författare)
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Ultrasensitive sequencing of STR markers utilizing unique molecular identifiers and the SiMSen-Seq method
- 2024
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Ingår i: Forensic Science International: Genetics. - : Elsevier Ireland Ltd. - 1872-4973 .- 1878-0326. ; 71
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Tidskriftsartikel (refereegranskat)abstract
- Massively parallel sequencing (MPS) is increasingly applied in forensic short tandem repeat (STR) analysis. The presence of stutter artefacts and other PCR or sequencing errors in the MPS-STR data partly limits the detection of low DNA amounts, e.g., in complex mixtures. Unique molecular identifiers (UMIs) have been applied in several scientific fields to reduce noise in sequencing. UMIs consist of a stretch of random nucleotides, a unique barcode for each starting DNA molecule, that is incorporated in the DNA template using either ligation or PCR. The barcode is used to generate consensus reads, thus removing errors. The SiMSen-Seq (Simple, multiplexed, PCR-based barcoding of DNA for sensitive mutation detection using sequencing) method relies on PCR-based introduction of UMIs and includes a sophisticated hairpin design to reduce unspecific primer binding as well as PCR protocol adjustments to further optimize the reaction. In this study, SiMSen-Seq is applied to develop a proof-of-concept seven STR multiplex for MPS library preparation and an associated bioinformatics pipeline. Additionally, machine learning (ML) models were evaluated to further improve UMI allele calling. Overall, the seven STR multiplex resulted in complete detection and concordant alleles for 47 single-source samples at 1 ng input DNA as well as for low-template samples at 62.5 pg input DNA. For twelve challenging mixtures with minor contributions of 10 pg to 150 pg and ratios of 1–15% relative to the major donor, 99.2% of the expected alleles were detected by applying the UMIs in combination with an ML filter. The main impact of UMIs was a substantially lowered number of artefacts as well as reduced stutter ratios, which were generally below 5% of the parental allele. In conclusion, UMI-based STR sequencing opens new means for improved analysis of challenging crime scene samples including complex mixtures.
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| 8. |
- Soderberg, C., et al.
(författare)
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The importance of sample size with regard to the robustness of postmortem reference values
- 2020
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Ingår i: Forensic Science International. - : ELSEVIER IRELAND LTD. - 0379-0738 .- 1872-6283. ; 311
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Tidskriftsartikel (refereegranskat)abstract
- Evaluating postmortem toxicological results is a challenging task due to multiple factors affecting blood concentrations after death. In order to improve the diagnostic accuracy in cases of suspected fatal intoxication different compilations of postmortem reference drug concentrations are often used. However, it is not clear what constitutes a reliable postmortem reference value. The current study presents reference concentrations for 13 substances from seven substance groups according to a standardized protocol. The reference concentrations were gathered from 3767 autopsy cases and subdivided into intoxications by one substance only (Group A, n= 611), multi-substance intoxications (Group B, n = 1355) and postmortem controls, in which incapacitation by drugs were excluded (Group C, n = 1801). In particular, this study presents statistical information about the precision and conformity change with various sample sizes. Based on the present data >10 detections are usually needed, for the substances examined, to differentiate between intoxication cases and controls. Repeated samplings show that the median of small samples (N= <= 5) has a high variation (normalized interquartile range 138-75%) and that a high number of detections (N = >20) in each group are needed to reduce the variation. (C) 2020 The Author(s). Published by Elsevier B.V.
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| 9. |
- Staadig, Adam, et al.
(författare)
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Applying Unique Molecular Indices with an Extensive All-in-One Forensic SNP Panel for Improved Genotype Accuracy and Sensitivity
- 2023
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Ingår i: Genes. - : MDPI AG. - 2073-4425. ; 14:4
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Tidskriftsartikel (refereegranskat)abstract
- One of the major challenges in forensic genetics is being able to detect very small amounts of DNA. Massively parallel sequencing (MPS) enables sensitive detection; however, genotype errors may exist and could interfere with the interpretation. Common errors in MPS-based analysis are often induced during PCR or sequencing. Unique molecular indices (UMIs) are short random nucleotide sequences ligated to each template molecule prior to amplification. Applying UMIs can improve the limit of detection by enabling accurate counting of initial template molecules and removal of erroneous data. In this study, we applied the FORCE panel, which includes ~5500 SNPs, with a QIAseq Targeted DNA Custom Panel (Qiagen), including UMIs. Our main objective was to investigate whether UMIs can enhance the sensitivity and accuracy of forensic genotyping and to evaluate the overall assay performance. We analyzed the data both with and without the UMI information, and the results showed that both genotype accuracy and sensitivity were improved when applying UMIs. The results showed very high genotype accuracies (>99%) for both reference DNA and challenging samples, down to 125 pg. To conclude, we show successful assay performance for several forensic applications and improvements in forensic genotyping when applying UMIs.
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| 10. |
- Staadig, Adam, et al.
(författare)
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Evaluation of microhaplotypes in forensic kinship analysis from a Swedish population perspective
- 2021
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Ingår i: International journal of legal medicine. - : SPRINGER. - 0937-9827 .- 1437-1596. ; 135:4, s. 1151-1160
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Tidskriftsartikel (refereegranskat)abstract
- The development of massively parallel sequencing (MPS) technology has enabled the discovery of several new types of forensic markers where microhaplotypes are one of these promising novel genetic markers. Microhaplotypes are, commonly, less than 300 nucleotides in length and consist of two or more closely linked single-nucleotide polymorphisms (SNPs). In this study, we have examined a custom-made QIAseq Microhaplotype panel (Qiagen), including 45 different microhaplotype loci. DNA libraries were prepared according to the GeneRead DNAseq Targeted Panels V2 library preparation workflow (Qiagen) and sequenced on a MiSeq FGx instrument (Verogen). We evaluated the performance of the panel based on 75 samples of Swedish origin and haplotype frequencies were established. We performed sensitivity studies and could detect haplotypes at input amounts down to 0.8 ng. We also studied mixture samples with two contributors for which haplotypes, for the minor contributor, were detectable down to the level of 1:100. Furthermore, we executed kinship simulations to evaluate the usefulness of this panel in kinship analysis. The results showed that both paternity and full sibling cases can clearly be solved. When simulating a half sibling versus unrelated case scenario, there were, however, some overlap of the likelihood ratio distributions potentially resulting in inconclusiveness. To conclude, the results of this initial study are promising for further implementation of this microhaplotype assay into the forensic field, although we noticed some primer design issues that could be optimized, which possibly would increase the power of the assay.
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