Evaluating the use of hypoxia sensitive markers for body fluid stain age prediction |
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| Institution: | 1. School of Applied Sciences, University of Huddersfield, Queensgate, Huddersfield, West Yorkshire, HD1 3DH, United Kingdom;2. Department of Criminal Justice and Forensic Science, School of Law, Policing and Forensics, Staffordshire University, Leek Road, Stoke-on-Trent, Staffordshire, ST4 2DF, United Kingdom;1. Department of Security and Crime Science, University College London, 35 Tavistock Square, London WC1H 9EZ, United Kingdom;2. Centre for the Forensic Sciences, University College London, 35 Tavistock Square, London WC1H 9EZ, United Kingdom;3. Department of Medical Physics & Biomedical Engineering, University College London, Gower Street, London WC1E 6BT, United Kingdom;4. School of Applied Science, London South Bank University, 103 Borough Road, London SE1 0AA, United Kingdom;5. Institute for Sustainable Heritage, University College London, Central House, London WC1E 0NN, United Kingdom;1. Institute of Legal Medicine, University of Leipzig, Johannisallee 28, D-04103 Leipzig, Germany;2. University of Applied Sciences – Forensic Science Investigation Lab (FoSIL), Technikumplatz 17, D-09648 Mittweida, Germany;3. Institute of Legal Medicine, Department of Forensic Genetics, Charité Berlin, Augustenburger Platz 1, D-13353 Berlin, Germany;1. Department of Genetic Identification, Erasmus MC University Medical Centre Rotterdam, Rotterdam, The Netherlands;2. EaStCHEM School of Chemistry, Biomedical Sciences Research Complex and Centre of Magnetic Resonance, University of St. Andrews, St. Andrews, United Kingdom;3. Centre for Chronobiology, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom;4. CNAG–CRG, Centro Nacional de Análisis Genómico, Parc Científic de Barcelona—Torre I, Barcelona, Spain;1. Vocational School of Health Services, Alt?nba? University, Istanbul, Turkey;2. Department of Molecular Biology and Genetics, Faculty of Arts and Science, Y?ld?z Technical University, ?stanbul, Turkey;3. Department of Forensic Sciences, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpa?a, Istanbul, Turkey |
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| Abstract: | To augment DNA profiling and body fluid identification techniques efforts are being made to increase the amount of information available from a crime scene stain, which includes efforts to identify externally visible characteristics through phenotypic analysis. A key question surrounding crime scene stains is the length of time between deposition of the stain and its subsequent recovery, in that is the stain recovered related to the incident in question or from a previously deposited stain number of weeks earlier? The inability to answer this fundamental question has a detrimental effect upon the successful completion of a criminal investigation. Once a body fluid leaves the body, the oxygen concentration in the environment changes; therefore, it may be that this change could cause a change in the expression of hypoxia-sensitive biomarkers. Here, a range of bloodstains, liquid saliva and liquid semen samples were collected at 0 days, 7 days, 14 days, 21 days and 28 days of degrading at room temperature (19–22 °C), before undergoing total RNA extraction and cDNA synthesis. Blood was recovered from filter paper with 3 mm2, with saliva and semen being left in their tubes and swabbed at the appropriate times. All samples then underwent quantitative PCR targeting Vascular Endothelial Growth Factor A (VEGFA) and Hypoxia-Inducible Factor 1 Alpha (HIF1A), with B-Actin (ACTB) as a reference gene. A range of linear and quadratic correlation values was obtained from the qPCR data and used to develop a predictive model with a mean absolute deviation (MAD) of 4.2, 2.1, and 5 days for blood, saliva, and semen respectively. Blind testing indicated that a stain age prediction model based upon VEGFA with ACTB as a reference gene could be used on samples up to four weeks old with a margin of error ranging from 2 days through to 5 days. While a sizeable potential time frame exists using this model; this represents a significant step towards the target of having an accurate stain age prediction model. |
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| Keywords: | Forensic genetics Hypoxia Stain age prediction qPCR RNA |
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