Prognoses on DNA-based identification success rates of altered human remains using capillary electrophoresis and Next Generation Sequencing technologies

Senst, Alina. Prognoses on DNA-based identification success rates of altered human remains using capillary electrophoresis and Next Generation Sequencing technologies. 2022, Doctoral Thesis, University of Basel, Faculty of Medicine.


Official URL: https://edoc.unibas.ch/89208/

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The DNA-based identification success of altered human remains relies on the condition of the collected tissue sample and the associated DNA quantity and quality. Due to tissue-specific differences in post-mortem DNA stability, sampling of the best-suited biological material is essential for successful and rapid identification. However, a large variety and partly contradicting recommendations on optimal material have been published so far. The observed insecurity in sampling strategies revealed the need for a broad and systematic approach in predicting short tandem repeat (STR) genotyping success rates in a wide range of tissue types. Therefore, the overarching aim of this thesis was to improve the DNA-based identification success of altered corpses by presenting novel recommendations and guidance for optimal tissue sampling according to the condition of the body.
First, the current situation of identification processes in forensics casework was assessed by a retrospective study on the identification success of 402 altered human corpses over seven years (project I). The evaluation of medical as well as genetic reports revealed an increase in the examination of highly and profoundly decomposed corpses and challenges in molecular analyses of degraded and inhibited samples from altered remains. By comparing the number of successive and parallel PCR amplifications, the most unpredictable typing success and highest number of additional analyses were observed in muscle and bone samples. A comparison with previously published studies highlighted the challenges and insecurity in tissue sampling and the need for standardized guidelines.
Furthermore, during project II, the reliability of novel DNA sequencing methods was assessed by validating the MiSeq FGx system for Next Generation Sequencing (NGS) of casework samples and optimizing the sequencing workflow for samples of altered remains. The extensive evaluation of sensitivity, concordance to currently used methods and reproducibility, among others, displayed the technology as robust and implementable in forensic routine casework. Additionally, the applicability of phenotype and biogeographic ancestry prediction was demonstrated in challenging samples of altered corpses. However, as the optimization results revealed, an additional PCR purification step, an increased pooling volume and a reduction of adapter volumes for DNA input concentrations ≥ 31.2 pg is recommended for sequencing highly degraded and inhibited samples.
Finally, based on the outcomes of projects I and II, the multicentre study concludes with the presentation of novel recommendations on alteration-specific optimal tissue types for first-attempt identification of altered human remains in project III. By providing an easy and rapid scoring system, a precise assessment of the corpse alteration progress is enabled. Furthermore, the systematic approach included the comparison of DNA quantity, integrity and resulting STR profile completeness in an exceptional high number of 1698 DNA extracts from 949 samples of 19 different tissue types. Thereby, standard capillary electrophoresis as well as forthcoming NGS methods were used and the impact of DNA extraction methods was assessed. The final and first-time prognoses on genotyping success of a wide range of tissues separated for two DNA extraction methods (purifying and non-purifying) and two sets of STR loci (22 loci and 16 loci of the extended European Standard Set) provide guidance that improves the first-attempt DNA-based identification success of altered corpses.
Advisors:Scheurer, Eva and Cichon, Sven and Anslinger, Katja and Schulz, Iris
Faculties and Departments:03 Faculty of Medicine > Departement Biomedical Engineering > Imaging and Computational Modelling > Forensic Medicine (Scheurer)
UniBasel Contributors:Scheurer, Eva and Cichon, Sven
Item Type:Thesis
Thesis Subtype:Doctoral Thesis
Thesis no:14854
Thesis status:Complete
Number of Pages:128
Identification Number:
  • urn: urn:nbn:ch:bel-bau-diss148542
edoc DOI:
Last Modified:23 Nov 2022 05:30
Deposited On:22 Nov 2022 09:27

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