Assessing the impact of common forensic presumptive tests on the ability to obtain results using a novel rapid DNA platform

Abstract

The rise of DNA evidence to the forefront of forensic science has led to high sample numbers being submitted for profiling by investigators to casework laboratories: bottleneck effects are often seen resulting in slow turnaround times and sample backlog. The ParaDNA® Screening and IntelligenceTests have been designed to guide investigators on the viability of potential sources of DNA allowing them to determine which samples should be sent for full DNA analysis. Both tests are designed to augment the arsenal of available forensic tests for end users and be used concurrently to those commonly available. Therefore, assessing the impact that common forensic tests have on such novel technology is important to measure. The systems were tested against various potential inhibitors to which samples may be exposed as part of the investigative process. Presumptive test agents for biological materials (blood, semen and saliva) and those used as fingerprint enhancement agents were both used. The Screening Test showed a drop in performance following application of aluminium powder and cyanoacrylate (CNA) on fingerprints samples; however this drop in performance was not replicated with high template DNA. No significant effect was observed for any agent using the Intelligence Test. Therefore, both tests stand up well to the chemical agents applied and can be used by investigators with confidence that system performance will be maintained.

A review of direct polymerase chain reaction of DNA and RNA for forensic purposes

“…This could account for the reduced quality of the profiles obtained. Another study demonstrated no effect from presumptive tests on the resulting profile (Donachie et al, ).…”

“…There is some concern over the effect of common presumptive and enhancement tests on direct PCR reactions (Donachie et al, 2015). One study has been completed that showed some negative effects on the resulting profiles, for example, when using the Kastle-Meyer and leucomalachite green tests (Thanakiatkrai, Raham, Pradutkanchana, Sotthibandhu, & Kitpipit, 2017).…”

A Systematic Review on Commercially Available Integrated Systems for Forensic DNA Analysis

“…Donachie et al concluded that the ParaDNA system could be used as a presumptive test for samples with medium to high template DNA present, such as blood, saliva, and semen stains. For low template samples, such as touch DNA (e.g., single fingerprints), the success rate was too low [ 43 ].…”

Field-based detection of biological samples for forensic analysis: Established techniques, novel tools, and future innovations

“…The screening test is able to obtain a gender result in >80% of samples with a sufficient presence of DNA (>62.5 pg), though is more sensitive to male samples than female due to software reporting a male result whenever a Y target is amplified [69]. There has also been some assessment of whether the assay interferes with existing forensic processes with research demonstrating that pre-treatment of samples with Phadebas and luminol/Bluestar® did not impact the ability of ParaDNA to reliably screen these samples for DNA [72]. However, despite the ease of use and portability, the ParaDNA screening test is intended to augment the existing processes of sample submission and case management, and not designed to replace existing tools [73] meaning that costs savings may be more difficult to identify.…”