| 1. |
- Kling, Daniel, et al.
(författare)
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Familias 3-Extensions and new functionality
- 2014
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Ingår i: Forensic Science International. - : Elsevier. - 1872-4973 .- 1878-0326. ; 13, s. 121-127
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Tidskriftsartikel (refereegranskat)abstract
- In relationship testing the aim is to determine the most probable pedigree structure given genetic marker data for a set of persons. Disaster Victim Identification (DVI) based on DNA data from presumed relatives of the missing persons can be considered to be a collection of relationship problems. Forensic calculations in investigative mode address questions like "How many markers and reference persons are needed? Such questions can be answered by simulations. Mutations, deviations from Hardy-Weinberg Equilibrium (or more generally, accounting for population substructure) and silent alleles cannot be ignored when evaluating forensic evidence in case work. With the advent of new markers, so called microvariants have become more common. Previous mutation models are no longer appropriate and a new model is proposed. This paper describes methods designed to deal with DVI problems and a new simulation model to study distribution of likelihoods. There are softwares available, addressing similar problems. However, for some problems including DVI, we are not aware of freely available validated software. The Familias software has long been widely used by forensic laboratories worldwide to compute likelihoods in relationship scenarios, though previous versions have lacked desired functionality, such as the above mentioned. The extensions as well as some other novel features have been implemented in the new version, freely available at www.familias.no. The implementation and validation are briefly mentioned leaving complete details to Supplementary sections.
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| 2. |
- Tillmar, Andreas O, et al.
(författare)
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A universal method for species identification of mammals utilizing next generation sequencing for the analysis of DNA mixtures
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 8:12, s. e83761-
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Tidskriftsartikel (refereegranskat)abstract
- Species identification can be interesting in a wide range of areas, for example, in forensic applications, food monitoring and in archeology. The vast majority of existing DNA typing methods developed for species determination, mainly focuses on a single species source. There are, however, many instances where all species from mixed sources need to be determined, even when the species in minority constitutes less than 1 % of the sample. The introduction of next generation sequencing opens new possibilities for such challenging samples. In this study we present a universal deep sequencing method using 454 GS Junior sequencing of a target on the mitochondrial gene 16S rRNA. The method was designed through phylogenetic analyses of DNA reference sequences from more than 300 mammal species. Experiments were performed on artificial species-species mixture samples in order to verify the method's robustness and its ability to detect all species within a mixture. The method was also tested on samples from authentic forensic casework. The results showed to be promising, discriminating over 99.9 % of mammal species and the ability to detect multiple donors within a mixture and also to detect minor components as low as 1 % of a mixed sample.
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| 3. |
- Tillmar, Andreas O., et al.
(författare)
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Choosing supplementary markers in forensic casework
- 2014
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Ingår i: Forensic Science International-Genetics. - : Elsevier BV. - 1872-4973 .- 1878-0326. ; 13, s. 128-133
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Tidskriftsartikel (refereegranskat)abstract
- The vast majority of human familial identifications based on DNA end up with a well founded conclusion, normally using a standard set of genetic short tandem repeat (STR) loci. There are, however, a proportion of cases that show ambiguous results. For such occasions a number of different supplementary markers could be typed in order to gain further information. There are numerous markers available for such supplementary DNA typing, including STRs, deletion and insertion polymorphisms (DIPs), and single nucleotide polymorphisms (SNPs). The purpose of this work was to describe a precise method for decision making, aiming to aid the comparison of different sets of markers for different case scenarios in order to find the most efficient set for routine casework. Comparisons are based on a particular function relating the expected additional value of information from new data to the amount of information already obtained from initial data. The function can be computed approximately by approximating likelihood-based error rates using simulation. In this paper we focused on paternity investigations, more specifically the use of supplementary markers in cases where a smaller number of genetic inconsistencies make the matter inconclusive. We applied the method to a comparison of three different kits: Investigator HDplex (STRs), Investigator DIPplex (DIPs), and the SNPforID-plex (SNPs) to study their efficiencies in gaining information in different case scenarios involving various alternative relationships between the tested man and the tested child. We show that the Investigator HDplex was the most efficient set of supplementary markers for the standard paternity case. However, for paternity cases with a close relative being the alternative father, the Investigator HDplex and the SNPforID-plex showed similar patterns in their ability to deliver a well-founded conclusion. The Investigator DIPplex was the least efficient set.
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| 4. |
- Tillmar, Andreas O, et al.
(författare)
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Genetic variation of 15 autosomal STR loci in a Somali population
- 2009
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Ingår i: Forensic Science International. - : Elsevier. - 1872-4973 .- 1878-0326. ; 4:1, s. E17-E18
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Tidskriftsartikel (refereegranskat)abstract
- Allele frequencies for 15 autosomal STR loci included in the AmpFlSTR Identifiler kit (CSF1PO, D13S317, D16S539, D18S51, D19S433, D21S11, D2S1338, D3S1358, D5S818, D7S820, D8S1179, FGA, TH01, TPOX, VWA) were obtained from the analysis of 404 individuals with Somali origin. The overall match probability for the 15 studied loci was 1 in 1.18 X 10(17) and the combined power of exclusion was 0.999997676. Deviation from Hardy-Weinberg equilibrium was observed for locus D2S1338 after correction for multiple testing. When comparing allele frequencies with five other African populations (Karamoja (Uganda), Mozambique, Tanzania and two other Somali population sample sets), only the Somali populations did not show significant differences for any of the tested loci.
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