NCJ Number
246393
Journal
Forensic Science International: Genetics Volume: 7 Issue: 3 Dated: May 2013 Pages: 392-396
Date Published
May 2013
Length
5 pages
Annotation
The goal of this study was to compare two commonly used methods for the surface decontamination of human hair shafts, and to evaluate the use of a duplex real-time qPCR assay to assess decontamination effectiveness for the purpose of mitochondrial DNA typing.
Abstract
Hair shafts of known mitochondrial DNA haplotype were coated with undiluted saliva, semen or blood, each of known mitochondrial haplotype distinct from the test hair. Surface decontamination was conducted by enzymatic treatment with Terg-a-zyme and by chemical treatment with dilutions of sodium hypochlorite (NaClO, bleach). Following DNA extraction, a duplex (nuclear and mitochondrial DNA) real-time qPCR assay was used to quantify mitochondrial DNA and to test for surface contamination by quantifying the exogenous nuclear DNA not removed from the hair shaft. The NaClO treatment was found to be more effective for removing surface contamination than the Terg-a-zyme treatment, and it was procedurally simpler to implement, resulting in a significant savings of sample processing time. Exposure to 3 percent NaClO for up to 2 minutes had no detrimental effect on quantity or typing of the mitochondrial DNA belonging to the hair. In addition, the researchers demonstrated that the duplex real-time PCR assay is a convenient early-warning diagnostic method for the detection of the presence of external DNA contamination, providing an assessment of the purity of the sample prior to embarking on further analysis by more laborious mitochondrial DNA typing methods. (Published Abstract)