Trace DNA and its implication in obtaining genetic profiles. Bibliographic review

Abstract

Introduction: The increase in the sensitivity of the techniques used has made it possible to obtain genetic profiles from DNA traces that have been deposited through contact before, during or after the commission of the investigated acts. On the other hand, accidental contamination of biological evidence, with the consequent misinterpretation of genetic results, has important consequences in the judicial process. Due to this, minimizing the contamination that can be generated during some of the phases of collection or genetic analysis, as well as the detection of these events, is a priority for forensic laboratories. Objective: analyze the available bibliography regarding DNA traces, the different types of transfer and contamination that can be obtained in evidence. Methodology: the search was carried out in PubMed, from the National Institute of Health (NIH), and Google Scholar using the keywords touch DNA, DNA transfer, Contamination, Traces, DNA-TTPR, DNA persistence, Contaminated genetic profiles. The search was carried out in both Spanish and English. Results: More than 500 papers related to the topic proposed in this review were found. The selection criteria were the number of citations, the approach and the impact of the papers. Seventy articles were analyzed in which the composition of the contact samples and the origin of the genetic material they contain were evaluated. In addition, the collection methodologies, analysis of these samples, the importance of DNA transfer and contamination in different possible scenarios. Conclusions: there is a risk of DNA transfer that can lead to erroneous results, therefore it is important to ensure that practice procedures are updated and adequate training is provided to ensure that police and evidence collectors are aware of the risks of contamination and the different mechanisms of transferring genetic material.