Developmental validation of the ParaDNA® Body Fluid ID System-A rapid multiplex mRNA-profiling system for the forensic identification of body fluids.

Identifying the biological origin of forensic traces can provide crucial evidence to aid criminal investigations. Current forensic practice for the identification of body fluids mostly uses protein-based presumptive tests. Such tests cannot identify all of the forensically relevant fluids and have issues of cross-reactivity. More recently, messenger RNA methods have been developed that have expanded the range of body fluids that can be positively identified. However, these methods are slow and require expert scientists to run the processes and interpret the results. The ParaDNA® Body Fluid ID System has been designed to provide a simple, fast and robust way to identify forensically relevant body fluids in a lab or field-deployable manner. The system can analyse and detect mRNA targets for six different body fluids: vaginal fluid, seminal fluid, sperm cells, saliva, menstrual blood and peripheral blood. Utilising the ParaDNA Sample Collector and instruments, minimal training is required to enable both forensic scientists and non-specialist personnel to analyse biological samples directly, without prior sample processing, in approximately 90 min. The developmental validation studies described here were designed to address requirements of end users, based on the Scientific Working Group on DNA Analysis Methods (SWGDAM) guidelines, and tested the sensitivity, reproducibility, accuracy, inhibitor tolerance, and performance of the ParaDNA Body Fluid ID System on a range of mock evidence items. The data collected demonstrate that the Body Fluid ID System can automatically determine the presence of specific body fluid mRNA markers in single-source and mixed samples on multiple substrate types and body fluids could be identified with as little as 0.05ng total RNA and 1μl of the relevant fluid. Results can either be used to support confirmation of source from previously obtained STR DNA profiling results or to improve sample success rates by making better informed evidential submissions.