Messenger RNA profiling: a novel method for body fluid identification by real-time PCR

Conventional methods for the identification of different body fluids like blood, semen and saliva from biological stains involve immunological or enzymatic detection of certain proteins. In this study, we investigated potential RNA markers with the aim of developing Real-Time polymerase chain reaction (PCR) based methods to allow differentiation between several body fluids. Total RNA samples from artificially stained swabs and from various pieces of evidence from case work were extracted, amplified and analyzed with several RNA markers. Three assays detecting the body fluids of interest were selected: hemoglobin-alpha locus 1 (HBA), kallikrein 3 (KLK) and mucin 4 (MUC). With this approach, we demonstrate that specific Real-Time PCR assays are useful in identifying the source of the biological stain. Furthermore, RNA profiling of various body fluids was even possible on samples stored over a long period of time at ambient temperature. The stability and sensitivity of the applied method outlines a novel application for Real-Time PCR within the forensic field.