NCJ Number
240065
Journal
Forensic Science International: Genetics Volume: 6 Issue: 5 Dated: September 2012 Pages: 565-577
Date Published
September 2012
Length
13 pages
Annotation
This article describes the development of a single multiplex mRNA-based system for the discrimination of the most common forensic body fluids as well as skin cells.
Abstract
In current forensic practice, information about the possible biological origin of forensic traces is mostly determined using protein-based presumptive testing. Recently, messenger RNA-profiling has emerged as an alternative strategy to examine the biological origin. A DNA/RNA co-isolation protocol was established that results in DNA yields equivalent to our standard in-house validated DNA extraction procedure which uses silica-based columns. An endpoint RT-PCR assay was developed that simultaneously amplifies 19 (m)RNA markers. This multiplex assay analyses three housekeeping, three blood, two saliva, two semen, two menstrual secretion, two vaginal mucosa, three general mucosa and two skin markers. The assay has good sensitivity as full RNA profiles for blood, semen, and saliva were obtained when using greater than 0.05 uL body fluid starting material whereas full DNA profiles were obtained with greater than 0.1 uL. The authors investigated the specificity of the markers by analyzing 15 different sets of each type of body fluid and skin with each set consisting of 8 individuals. Since skin markers have not been incorporated in multiplex endpoint PCR assays previously, the authors analyzed these markers in more detail. Interestingly, both skin markers gave a positive result in samplings of the hands, feet, back and lips but negative in tongue samplings. Positive identification (regarding both DNA- and RNA-profiling) was obtained for specimens stored for many years, e.g. blood (28 years-old), semen (28 years-old), saliva (6 years-old), skin (10 years-old) and menstrual secretion (4 years-old). The described approach of combined DNA- and RNA-profiling of body fluids and contact traces assists in the interpretation of forensic stains by providing information about not only the donor(s) that contributed to the stain but also by indicating which cell types are present. (Published Abstract)