Developmental Validation of the ParaDNA® Screening System - A presumptive test for the detection of DNA on forensic evidence items

Abstract

Current assessment of whether a forensic evidence item should be submitted for STR profiling is largely based on the personal experience of the Crime Scene Investigator (CSI) and the submissions policy of the law enforcement authority involved. While there are chemical tests that can infer the presence of DNA through the detection of biological stains, the process remains mostly subjective and leads to many samples being submitted that give no profile or not being submitted although DNA is present. The ParaDNA(®) Screening System was developed to address this issue. It consists of a sampling device, pre-loaded reaction plates and detection instrument. The test uses direct PCR with fluorescent HyBeacon™ detection of PCR amplicons to identify the presence and relative amount of DNA on an evidence item and also provides a gender identification result in approximately 75 minutes. This simple-to-use design allows objective data to be acquired by both DNA analyst and non-specialist personnel, to enable a more informed submission decision to be made. The developmental validation study described here tested the sensitivity, reproducibility, accuracy, inhibitor tolerance, and performance of the ParaDNA Screening System on a range of mock evidence items. The data collected demonstrates that the ParaDNA Screening System identifies the presence of DNA on a variety of evidence items including blood, saliva and touch DNA items.

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

“…This study did not assess the downstream STR success rate of the mock evidence items although data generated during the development of the ParaDNA technology shows there was no measurable impact in the quantification results between samples that underwent ParaDNA treatment and those that did not [5,7,16]. In these studies, mock evidence items did not undergo any form of presumptive testing; i.e.…”

“…Practitioners wanting to use the technology on touch DNA items, such as single finger-prints, may want to consider the success rate of the untreated samples as published in the developmental validation study of both tests [5,7] and also assess the impact of their own in-house practices on any results derived. Further work in this area should look to assess additional pre-treatments.…”

“…Recently, there have been a number of rapid DNA profiling and detection platforms released that allow the analyses and prioritisation of items by non-expert users outside the traditional laboratory setting [5][6][7][8][9]. The development and release of novel technology into the forensic arena is both carefully controlled and monitored [10].…”

“…For example, all rapid DNA systems look to combine the three current stand-alone processes of DNA extraction, PCR and STR detection steps [e.g. [5][6][7][8][9]. The move out of the laboratory brings additional risks as samples get processed earlier after collection and the boundaries between forensic processes begin to merge [10].…”

Species detection using HyBeacon ® probe technology: Working towards rapid onsite testing in non-human forensic and food authentication applications

“…There are a large number of recently launched portable devices that allow testing of forensic samples outside the laboratory. Many of these systems are based on familiar laboratory platforms, either utilising capillary electrophoresis (CE) based detection [22], microarray [23] or utilise melt curve detection of PCR amplicons [24,25].…”