Efficiency of Casework Direct Kit for extraction of touch DNA samples obtained from cars steering wheels

Author(s)

Fridman, Cintia ^[1] ; Goncalves, Fernanda T. ^[1] ; Francisco, Daniela O. ^[1]

Affiliation

^[1] Univ Sao Paulo, Fac Med FMUSP, Dept Med Legal Et Med & Med Social & Trabalho, Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: FORENSIC SCIENCE INTERNATIONAL GENETICS SUPPLEMENT SERIES; v. 7, n. 1, p. 16-18, DEC 2019.
• Web of Science Citations: 0

Abstract

Analysis of STR profiles obtained from touch DNA has been very useful to the elucidation of crimes. Extraction method may be determinant for the recovery of genetic material collected from different surfaces. Vehicle theft is one of the most common crimes in Sao Paulo city, Brazil, but collection of biological traces in car steering wheels is not considered, because of the belief that profiles generated won't be able to identify the thief, only the owner. This study aimed to analyze the efficacy of extraction methods for obtaining DNA profiles in samples collected from steering wheels. Eight criminal acts were simulated with 2 different individuals each (mixture of victim and thief), in duplicate, in order to compare two extraction methods: DNA IQ (TM) and Casework Direct Kit (both Promega Corporation). Genetic material was collected by double swab method and quantified by Quantifiler (TM) Trio (ThermoFisher Scientific). Amplification was conducted with PowerPlex (R) Fusion System (Promega). It was possible to obtain STR profiles for all experiments. The mixtures were compared with reference profiles to evaluated how many alleles of each donor were observed. Samples extracted with Casework Direct Kit obtained STR profiles with higher averages of alleles for primary and secondary donors (88.7% and 59.9%, respectively) than those extracted with DNA IQ (TM) (60.4% and 38.1%, respectively). This could be explained by the differences established in the protocols of both methods, since DNA IQ (TM) is based on successive washes and can result in loss of DNA, whereas Casework Direct Kit minimizes this problem. We concluded that Casework Direct Kit was more efficient for processing touch DNA samples than DNA IQ (TM). (AU)

• FAPESP's process: 17/06484-0 - Study of transfer DNA in simulated situations for forensic purposes
• Grantee: Daniela de Oliveira Francisco
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 16/14355-3 - Study of touch DNA in simulated situations for forensic purposes.
• Grantee: Fernanda de Toledo Gonçalves
• Support Opportunities: Regular Research Grants