Comparison between various DNA sterilization procedures applied in forensic analysis

Noora R Al-Snan,Najib M Alraimi

doi:10.1186/s41935-022-00265-7

Abstract

BackgroundThe advanced sensitive STR kits applied in forensic DNA typing techniques can cause challenging issues when evidence samples are contaminated with minute quantities of DNA from another source such as forensic analysts or crime scene examiners.ResultsIn this study, laboratory air and surfaces, gloves, tools, and equipment were evaluated as potential sources of contaminating DNA. Different sterilization methods were tested for their ability to efficiently eliminate DNA in a sample. Inactivation methods included 10% bleach, ethanol, UV light, and DNA-ExitusPlus IF. Exposure to the different inactivation protocols for varying periods of time was performed in two lab settings: low template DNA and DNA database labs. Surfaces were swabbed and any adhering DNA was quantified using HID real-time PCR. Results were detected using HID Real-Time PCR Analysis Software v1.2 and GeneMapper ID-X Software v1.4.ConclusionsIt was concluded that most of the DNA decontamination methods are not suitable for highly sensitive and precision STR kits such as GlobalFiler PCR Amplification Kit. The most suitable tested method was using DNA-ExitusPlus IF with the incubation time increased from 10 to 15 min.

Highlights

The advanced sensitive STR kits applied in forensic DNA typing techniques can cause challenging issues when evidence samples are contaminated with minute quantities of DNA from another source such as forensic analysts or crime scene examiners
DNA quantification The results obtained from the Human identification (HID) Real-Time PCR Analysis Software v1.2 displayed the amount of DNA using the small autosomal (SA) human target available in the Quantifiler HP DNA Quantification Kit (Thermo Fisher Scientific, Inc., Waltham, MA, USA)
SA consists of relatively short amplicons (75 to 80 bases) to improve the detection of degraded Genomic DNA (gDNA)

Summary

Introduction

The advanced sensitive STR kits applied in forensic DNA typing techniques can cause challenging issues when evidence samples are contaminated with minute quantities of DNA from another source such as forensic analysts or crime scene examiners. Forensic casework subjected to DNA analysis is common in crime laboratories and is used to make crucial decisions in intelligence and justice. Errors such as DNA transfer and contamination may occur, and they can have serious consequences (Kloosterman et al 2014). Some of these procedures are wellsuited to the laboratory setting These include (1) staff awareness about contamination; (2) the proper use of personal protective equipment (PPE); (3) limiting access to the laboratory working area; (4) effective cleaning and sterilization of all equipment and laboratory zones (Arena 2010); (5) physical separations between offices, laboratories, or storage facilities to reduce DNA contamination; and (6) the distribution of specific activities (e.g., trace collection) among different people to disrupt contamination chains With the use of the PCR technique, which has become a powerful and very sensitive tool in a wide range of research, false-positive PCR results due to various types of contamination are detected (Preuße-Prange et al 2009)

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Results

Discussion

Conclusion