Biological evidence of the future: the use of sequencing in forensic DNA analysis
About Rebecca Richards
Rebecca Richards is a doctoral student in the Forensic Science Programme at the University of Auckland. Her research focuses on the development and optimisation of DNA methylation markers for forensic applications, specifically identical twin differentiation and chronological age estimation. Rebecca is also a senior technician in the Forensic Biology Group at the Institute of Environmental Science and Research (ESR), a Crown Research Institute which provides forensic services to the New Zealand Police. In addition, she is running point for the MinION research currently being undertaken at ESR and is involved in the wider validation of DNA sequencing for forensic use.
Forensic DNA profiling uses short tandem repeat (STR) analysis for human identification purposes, i.e. to establish a link between biological evidence and an individual. This technique is currently limited to assessing the length of STR alleles via capillary electrophoresis and relies on the comparison to a reference DNA profile. The advent of DNA sequencing has revolutionised the field of forensic genetics. Alleles with the same length but a different sequence can be distinguished, providing additional discrimination between individuals which can greatly aid in DNA mixture interpretation. Rare sequence mutations can be identified to differentiate identical twins, who cannot be told apart using conventional DNA profiling. Using sequencing, scientists have also begun to harness intelligence-based information that a biological sample can provide which could be of use in an investigation. The analysis of single nucleotide polymorphisms (SNPs) offers new opportunities in the form of forensic DNA phenotyping and forensic epigenetics. Prediction of eye, hair and skin colour, as well as bio-geographic ancestry and chronological age estimations of an unknown individual are all now possible. The introduction of nanopore sequencing technology has the potential to transform the field of forensic genetics even further. The portability and real-time capability of the MinION could shift analysis out of the lab into the field, greatly reducing cost and turnaround time which are critical in an investigation. Research into the feasibility of this technology for forensic applications is currently underway. Sequencing has not only changed the field of forensic genetics, but also has changed the way biological evidence is approached and could be used in investigations which has had a wide-reaching effect in enforcement, legal, governmental and judicial fields. Although not routinely used in forensic casework at present, many forensic laboratories around the world are currently validating sequencing technologies with the expectation that this will be the biological evidence of the future.