| 1. |
- Hedman, Johannes, et al.
(författare)
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A fast analysis system for forensic DNA reference samples
- 2008
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Ingår i: Forensic Science International: Genetics. - : Elsevier BV. - 1878-0326 .- 1872-4973. ; 2:3, s. 184-189
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Tidskriftsartikel (refereegranskat)abstract
- On January 1st, 2006, the Swedish legislation on obtaining DNA reference samples from Suspects and the recording of DNA profiles in databases was changed. As a result the number of samples analysed at the Swedish National Laboratory of Forensic Science (SKL) increased from about 4500 in 2005 to more than 25,000 in 2006. To meet this challenge, SKL launched a flew analysis system to create an unbroken chain, from sampling to incorporation of a profile in the national DNA database and subsequent automatic generation of digitally signed hit reports. The system integrates logistics, digital data transfer, new functions in LIMS (ForumDNA Version 4, Ida Infront AB) and laboratory automation. Buccal swab samples are secured on a FTA (R) card attached to an identity form, which is barcoded with a unique sample ID. After sampling, the police officer sends a digital request to SKL. The sample is automatically registered in LIMS and processed on delivery. The resulting DNA profiles are automatically classified according to quality using a custom-made expert system. Building the evaluation around mathematical rules makes it reproducible, standardised and minimises manual work and clerk errors. All samples are run in duplicate and the two profiles are compared within LIMS before incorporation in the database. In the first year of operation, the median time for completion of an analysis was 3 days, measured from delivery of the sample to incorporation of the profile in the national DNA database. In spite of the dramatic increase in the number of reference samples there was no backlog. (C) 2008 Elsevier Ireland Ltd. All rights reserved.
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| 2. |
- Hedman, J., et al.
(författare)
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Applying a customised DNA polymerase blend in forensic DNA profiling
- 2011
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Ingår i: Book of Abstracts. ; , s. 161-
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Konferensbidrag (refereegranskat)abstract
- Crime scene stains often contain extraneous compounds that may interfere with PCR-based DNA analysis,resulting in partial or negative/blank DNA profiles. Extensive DNA purification may remove PCR inhibitors, butinvolve a risk of DNA loss and introduction of contaminations. Customising the chemical content of the PCRreaction is a strategy that may increase PCR inhibitor tolerance without manipulating the sample. Previously wehave shown that crime scene stain analysis can be significantly improved by replacing the commonly used DNApolymerase AmpliTaq Gold with either individual alternative DNA polymerases or a blend of such enzymes [1,2].Here we present the validation of AmpFℓSTR SGM Plus with a modified PCR chemistry for routine casework,applying a 1:1 blend of the DNA polymerases ExTaq Hot Start and PicoMaxx High Fidelity. Allele callings areidentical to standard analysis, and stutters sizes and balance values are indistinguishable. The modified chemistryprovides increased resistance to PCR inhibitors, resulting in an elevated number of detected alleles for crimescene stains of both blood and secretion/saliva. Additionally, the detection limit is improved.[1] Hedman, J., Nordgaard, A., Rasmusson, B., Ansell, R. and Rådström, P. (2009) Improved forensic DNA analysis through the use of alternativeDNA polymerases and statistical modeling of DNA profiles. Biotechniques, 47, 951-958.[2] Hedman, J., Nordgaard, A., Dufva, C., Rasmusson, B., Ansell, R. and Rådström, P. (2010) Synergy between
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| 3. |
- Hedman, J., et al.
(författare)
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Applying a PCR inhibitor tolerant DNA polymerase blend in forensic DNA profiling
- 2011
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Ingår i: Forensic Science International: Genetics, Supplement Series. - : Elsevier. - 1875-1768. ; 3:1, s. e349-e350
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Tidskriftsartikel (refereegranskat)abstract
- Crime scene samples often contain extraneous compounds that may interfere with PCR-based DNA analysis, resulting in imbalanced, partial or blank/negative DNA profiles. Customising the chemical content of the PCR reaction is a strategy that may increase PCR inhibitor tolerance without manipulating the sample. We have validated a modified version of AmpFlSTR SGM Plus, replacing AmpliTaq Gold DNA polymerase with a customised blend of two alternative polymerases, ExTaq Hot Start and PicoMaxx High Fidelity. Allele calls are identical to standard analysis. Stutter sizes and balance values are indistinguishable. The modified chemistry provides increased resistance to PCR inhibitors, resulting in an elevated number of detected alleles for various problematic crime scene samples.
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| 4. |
- Jansson, Linda, et al.
(författare)
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Factors affecting DNA recovery from cartridge cases
- 2020
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Ingår i: Forensic Science International: Genetics. - : Elsevier BV. - 1872-4973 .- 1878-0326. ; 48
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Tidskriftsartikel (refereegranskat)abstract
- Cartridge cases are often the sole items left behind after a shooting incident and DNA traces from these can identify persons connected to the shooting. However, the chance of retrieving usable DNA profiles from cartridge cases is limited, due to the low amounts of deposited DNA and subsequent DNA loss associated with the firing process. In the current study, we set out to increase the DNA recovery from cartridge cases and cartridges by evaluating different swab types and detergents used for trace collection. A protocol applying nylon-flocked swabs instead of cotton swabs was implemented in casework at the Swedish National Forensic Centre (NFC), increasing DNA yield. The number of samples providing a DNA concentration ≥ 0.001 ng/μL (the in-house cut-off for processing low-template samples) increased from 11.1 to 28.6 % for cartridge cases and from 16.0 to 43.3 % for cartridges. There was also a substantial increase in mixed STR profiles, too complex to use for comparisons. Thus, it was not possible to take the full advantage of the elevated DNA yield provided by nylon-flocked swabs. The number of usable STR profiles increased from 5.0 to 8.0 % for cartridge cases and remained unchanged for cartridges. Controlled studies were performed to assess the impact on the DNA recovery from different persons handling the ammunition, different material and size of the cartridge cases, and the type of firearm used. These studies reflected an ideal situation, where all cartridges were extensively handled and loaded without gloves, thus providing a higher expected DNA yield compared to most casework samples. The total peak height differed by up to a factor of ∼50 when 20 different persons handled cartridges prior to shooting. By evaluating eleven combinations of different firearms and ammunition, it was found that the casing material and type of firearm also have a substantial impact on DNA yield.
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| 5. |
- Aarts, B., et al.
(författare)
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DNActivity: International cooperation in activity level interpretation of forensic DNA evidence.
- 2015
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Ingår i: Abstract book, 7<sup>th</sup> European Academy of Forensic Science, EAFS, Prag, Tjeckien, 2015.. ; , s. 555-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Questions posed to expert witnesses by the legal community and the courts are expanding to include not just those relating to source level (i.e. ‘who is the donor of the trace?’) but also those relating to activitity level (i.e. ‘how did the DNA get there?’). The answers to these questions are usually formulated as the probability of the evidence under alternative scenarios. As activity level questions are part of investigative and legal considerations it is of paramount importance that expert witnesses are provided with knowledge and tools to address these questions.To answer such questions within a probabilistic framework, empirical data is needed to estimate probabilities of transfer, persistence and recovery of DNA as well as background levels of DNA on everyday objects. There is a paucity of empirical data on these topics, but the number of studies is increasing both through in-house experiments and experimental data published in international scientific journals.Laboratories that conduct such studies all use different experimental setups, trace recovery strategies and techniques and DNA analysis systems and equipment. It is essential for the forensic genetics community in general to establish whether the data generated by different labs are in concordance, and can therefore be readily used by the forensic community.Moreover, if existing data and data generated from future experiments are made available to the (forensic) community, knowledge is needed on the key factors that underlie potential interlaboratory variation.The aims and objectives of this ENFSI Monopoly 2013 project are to conduct a study of methodologies and data from different laboratories and to assess the comparability of the scientific data on transfer, persistence and recovery of DNA. This comparison will allow us to identify key factors that underlie potential variation. This information will be used to setup guidelines to enable sharing and database-storage of relevant scientificdata. This will improve the ability of forensic scientists and other professionals of the Criminal Justice System to give evidence-based answers to questions that relate to the activity level of the crime under investigation.
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| 6. |
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| 7. |
- Albinsson, L., et al.
(författare)
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Mixed DNA profiles from single-donors
- 2015
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Ingår i: Abstract book, 7<sup>th</sup> European Academy of Forensic Science, EAFS, Prag, Tjeckien, 2015. ; , s. 538-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Mosaicism and chimerism in individuals can complicate the interpretation and even lead to misinterpretation of DNA profiles in forensic casework. If a person has different DNA profiles in different tissue types, i.e. a true chimaera, wrongful exclusions can be made. Additionally, mixed chimaeras can have DNA profiles that may be mistaken for mixtures. We have set-up automatic DNA databasing processes to handle atypical single-donor DNA profiles, i.e. profiles having one or several “extra” alleles.Studying all reference samples analysed at NFC from 2006 until spring 2014, 2‰ of the samples showed atypical DNA profiles. To be able to set routines for handling these DNA profiles, each one was manually searched in CODIS with adjusted settings, to evaluate the frequency of false-positive hits. To tag these profiles in LIMS a new result status was implemented. Additionally, all such DNA profiles must be confirmed by analysing at least two discrete samples. In LIMS, the results are manually recorded to compose of all alleles from the samples from a suspect, i.e. containing most possible genetic information. LIMS automatically categorises the atypical DNA profiles with a special CODIS index, called “Multi-allelic offender”. The first time an atypical profile is searched, the matches are manually investigated. If a match is false, its disposition will be set to “no match” to prevent this from occurring in future searches. Automatic searches will then be performed in every day routine with moderate stringency, allowing the atypical DNA profile to match either a genotype or a mixture. If the match is true, a match-report will be created and sent to the police from the LIMS.
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| 8. |
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| 9. |
- Albinsson, Linda, et al.
(författare)
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SKL byter DNA-kit
- 2011
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Ingår i: Kriminalteknik. - Linköping : SKL. ; :1, s. 4-5
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 10. |
- Albinsson, Linda, et al.
(författare)
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Swedish population data and concordance for the kits PowerPlexÒ ESX 16 System, PowerPlexÒ ESI 16 System, AmpFlSTRÒ NGMTM, AmpFlSTRÒ SGM PlusTM and Investigator ESSplex
- 2011
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Ingår i: Forensic Science International. - Clare, Irland : Elsevier. - 1872-4973 .- 1878-0326. ; 5:3, s. e89-e92
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The European Standard Set of loci (ESS) has been extended with five additional short tandem repeat (STR) loci following the recommendations of the European Network of Forensic Science Institutes (ENFSI) and the European DNA Profiling Group (EDNAP) to increase the number of loci routinely used by the European forensic community. Subsequently, a new extended Swedish population database, based on 425 individuals, has been assembled using the new STR multiplex kits commercially available.Allele frequencies and statistical parameters of forensic interest for 15 autosomal STR loci (D3S1358, TH01, D21S11, D18S51, D10S1248, D1S1656, D2S1338, D16S539, D22S1045, vWA, D8S1179, FGA, D2S441, D12S391 and D19S433) were obtained from the analysis of the PowerPlex® ESX 16 System kit (Promega Corporation, USA). According to the data no evidence of deviations from Hardy–Weinberg equilibrium was found. The observed heterozygosity varies between 0.755 (TH01) and 0.892 (D1S1656). The power of discrimination was smallest for D22S1045 (0.869) and largest for D1S1656 (0.982) while the power of exclusion was smallest for TH01 (0.518) and largest for D1S1656 (0.778).A concordance study was performed on the five amplification systems: PowerPlex® ESX 16 System, PowerPlex® ESI 16 System (Promega Corporation, USA), AmpFlSTR® NGM™, AmpFlSTR® SGM Plus™ (Applied Biosystems, USA) and Investigator ESSplex (Qiagen, Germany) to reveal null alleles and other divergences between the kits. For the 425 DNA profiles included, AmpFlSTR® NGM™ revealed two null alleles, AmpFlSTR® SGM Plus™ revealed one, and Investigator ESSplex revealed a micro-variant, while the rest of the alleles showed full concordance between the kits tested.
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