Literature Review: Evaluation of the Effect of Swab Type and DNA Isolation Protocol on the Success of Touch DNA Genetic Profiling

Abstract

Touch DNA, trace DNA transferred upon contact with a surface is often very low in quantity and susceptible to degradation, making the success of Short Tandem Repeats (STR) profiling highly dependent on the collection method (swab type and technique) and DNA isolation protocol. A variety of collection devices (cotton, rayon, flocked/nylon, foam, microFLOQ) and isolation approaches (spin-column/silica, magnetic-bead, organic/phenol-chloroform; direct/LCN workflows) have been reported to produce different results on different substrates and sample conditions. Assess comparative evidence regarding the influence of swab type and DNA isolation protocol on the quality and efficacy of genetic profiling in touch DNA samples; identify best practices and research gaps for forensic/biomedical applications. The journal search identified 10 journals that met the specified inclusion criteria. The studies used case-control and cohort study designs. While some differences in the results were found for each study, they nevertheless shared similarities in the DNA isolation methods used for tracking and touch DNA. Based on the review results, it can be concluded that swab selection (type, material) and sampling techniques (swabbing, tape lifting, micromanipulation) are very important, especially for difficult surfaces such as metal or rough surfaces. Sample pre-processing (handling, storage, surface cleaning, contamination prevention) must be optimized to minimize DNA loss.