Fluids Identification by Expression Analysis of Tissue-Specific mRNAs Following PCR

Human body fluids such as blood, semen and saliva represent the most common source of biological material discover at a crime scene. Hence one of the requirements for a crime scene is the timely and accurate diagnosis of biological fluids at the site of the crime. The purpose of this study was to use molecular methods, based on tissue-specific mRNA expression, in order to determine the possibility of identifying body fluids and creating a practical protocol.

Biological fluids (blood, semen and saliva) were collected as fresh and dried in vials and dried on paper at intervals of one and five months. After selecting the appropriate markers for each sample, the conditions and protocols for RNA extraction and PCR conditions for these markers were optimized. This assay was further validated with real casework samples and Crime scene samples.

Our results showed the protocols are appropriate in quantitative and qualitative terms for downstream processes. Also, PCR results confirmed that even after five months, RNA could be recovered from the dry surfaces and used well to detect fluids with PCR.

Here, we optimized RNA extraction conditions and PCR for forensic purposes and provided a general and practical outlook on the possibilities, techniques and the cost of doing the work. Eventually the results of this research support the potential use of mRNA profiling as an alternative to conventional serological tests.