| 1. |
- Junker, Klara, et al.
(författare)
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Phenotype prediction accuracy – A Swedish perspective
- 2019
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Ingår i: Forensic Science International: Genetics Supplement Series. - : Elsevier BV. - 1875-1768 .- 1875-175X. ; 7:1, s. 384-386
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Tidskriftsartikel (refereegranskat)abstract
- 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 ≥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.
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| 2. |
- Kling, Daniel, et al.
(författare)
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Kinship inference for males with identical Y-STR profiles using whole genome SNP data provides a deeper understanding about the level of coancestry in the Swedish male population
- 2017
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Ingår i: Forensic Science International. - : Elsevier BV. - 1875-1768 .- 1875-175X. ; 6, s. e393-e394
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- 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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| 4. |
- Sidstedt, Maja, et al.
(författare)
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Assessing the GeneRead SNP panel for analysis of low-template and PCR-inhibitory samples
- 2017
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Ingår i: Forensic Science International: Genetics Supplement Series. - : Elsevier BV. - 1875-1768 .- 1875-175X. ; 6, s. 267-269
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 5. |
- Tillmar, Andreas, 1980-
(författare)
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Populations and Statistics in Forensic Genetics
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- DNA has become a powerful forensic tool for solving cases such as linking a suspect to a crime scene, resolving biological relationship issues and identifying disaster victims. Traditionally, DNA investigations mainly involve two steps; the establishment of DNA profiles from biological samples and the interpreta-tion of the evidential weight given by theses DNA profiles. This thesis deals with the latter, with focus on models for assessing the weight of evidence and the study of parameters affecting these probability figures.In order to calculate the correct representative weight of DNA evidence, prior knowledge about the DNA markers for a relevant population sample is required. Important properties that should be studied are, for example, how frequently certain DNA-variants (i.e. alleles) occur in the population, the differences in such frequencies between subpopulations, expected inheritance patterns of the DNA markers within a family and the forensic efficiency of the DNA markers in casework.In this thesis we aimed to study important population genetic parameters that influence the weight of evidence given by a DNA-analysis, as well as models for proper consideration of such parameters when calculating the weight of evi-dence in relationship testing.We have established a Swedish frequency database for mitochondrial DNA haplotypes and a haplotype frequency database for markers located on the X-chromosome. Furthermore, mtDNA haplotype frequencies were used to study the genetic variation within Sweden, and between Swedish and other European populations. No genetic substructure was found in Sweden, but strong similari-ties with other western European populations were observed.Genetic properties such as linkage and linkage disequilibrium could be im-portant when using X-chromosomal markers in relationship testing. This was true for the set of markers that we studied. In order to account for this, we pro-posed a model for how to take linkage and linkage disequilibrium into account when calculating the weight of evidence provided by X-chromosomal analysis.Finally, we investigated the risk of erroneous decisions when using DNA in-vestigations for family reunification. We showed that the risk is increased due to uncertainties regarding population allele frequencies, consanguinity and compet-ing close relationship between the tested individuals. Additional information and the use of a refined model for the alternative hypotheses reduced the risk of making erroneous decisions.In summary, as a result of the work on this thesis, we can use mitochondrial DNA and X-chromosome markers in order to resolve complex relationship in-vestigations. Moreover, the reliability of likelihood estimates has been increased by the development of models and the study of relevant parameters affecting probability calculations.
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| 6. |
- Tillmar, Andreas, 1980-, et al.
(författare)
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Using X-chromosomal markers in relationship testing: How to calculate likelihood ratios taking linkage and linkage disequilibrium into account
- 2011
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Ingår i: Forensic Science International. - : Elsevier. - 1872-4973 .- 1878-0326. ; 5:5, s. 506-511
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Tidskriftsartikel (refereegranskat)abstract
- X-chromosomal markers in forensic genetics have become more widely used during the recent years, particularly for relationship testing. Linkage and linkage disequilibrium (LD) must typically be accounted for when using close X-chromosomal markers. Thus, when producing the weight-of-evidence, given by a DNA-analysis with markers that are linked, the normally used product rule is invalid. Here we present an efficient model for calculating likelihood ratio (LR) with markers on the X-chromosome which are linked and in LD. Furthermore, the model was applied on several cases based on data from the eight X-chromosomal loci included in the Mentype® Argus X-8 (Biotype). Using a simulation approach we showed that the use of X-chromosome data can offer valuable information for choosing between the alternatives in each of the cases we studied, and that the LR can be high in several cases. We demonstrated that when linkage and LD were disregarded, as opposed to taken into account, the difference in calculated LR could be considerable. When these differences were large, the estimated haplotype frequencies often had a strong impact and we present a method to estimate haplotype frequencies. Our conclusion is that linkage and LD should be accounted for when using the tested set of markers, and the presented model is an efficient way of doing so.
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