Poster Presentation Australian Society for Medical Research Annual Scientific Meeting 2016

  Comparison of DNA Extraction Methods in Touch DNA Samples (#146)

Jamie-Lee Thompson 1 , Kevin Ashton 1
  1. Bond University, Robina, QLD, Australia

Introduction/Aim: DNA extraction from touch samples produces highly variable quantities. Growing evidence suggests DNA found in these samples comes from epithelial cells, but also from cell-free DNA (cfDNA) as a result of keratinisation. It is unknown if cfDNA can be isolated and whether it is too fragmented to be used in DNA profiling. A multiplex PCR of two different sized PCR products can be used to assess DNA fragmentation. The ratio produced between the two products indicates whether the DNA is fragmented below the size required for reliable DNA profiling. The aim of this study was to use the degradation assay to compare between traditional DNA extraction methods (DNA Investigator kit), a new single-step DNA extraction method (Fingerprint DNA Finder kit), and cell-free DNA collection (Microcon columns).


Methods: Touch samples were collected from fingerprints left on drinking glasses. DNA was then isolated by each of the three different DNA isolation methods (DNA investigator, FDF and Microcon columns). Comparison of the different methods was assessed using the multiplex degradation assay, which measures both quantity and quality of the sample.


Results: Preliminary results show the DNA Investigator kit produces an average yield of 790pg, while the FDF kit only produces a yield of 470pg, although this result is not statistically significant (P>0.05). The cfDNA isolation method produces an average DNA yield of 100pg; enough DNA to obtain a complete DNA profile, however a significantly smaller yield compared with the DNA Investigator kit.  


Conclusion: Although cfDNA isolation can produce enough DNA for a complete profile, and saves time and money, the yield cannot be compared with the DNA Investigator kit, which produces significantly more DNA. Likewise, the DNA Investigator kit produces a greater yield than the FDF kit, proving it is the most effective DNA extraction method for touch samples.

  1. Quinones, I., & Daniel, B. (2012). Cell free DNA as a component of forensic evidence recovered from touched surfaces. Forensic Science International: Genetics, 6(1), 26-30.
  2. Hughes-Stamm, S., J. Ashton, K., & van Daal, A. (2010). Assessment of DNA degradation and the genotyping success of highly degraded samples. International Journal of Legal Medicine, 125(3), 341-348.