Performing Body Fluid Identification using a MicroRNA Multiplex with Capillary Electrophoresis

MicroRNAs have a potential to be ideal forensic markers due to their small size (~22nt), high abundance per cell, and sensitive and specific PCR-based detection. Thousands of microRNAs are present in biological material and they are rich in information due to their tightly regulated expression, and can therefore be used for body fluid identification (BFID). Their advantageous properties increase the chances of successful analysis from challenged crime scene samples. In addition, it has been demonstrated that informative microRNA expression levels can be obtained from common DNA extracts. Following an earlier pilot project on a single stream process with the integration of microRNA analysis into a DNA profiling multiplex, progress on this line of research is now presented. A panel of 8 microRNAs (hsa-miR-10a, -16a, -135a, -142, -203a, -205, -451a and -1260b) has been identified to allow differentiation between blood, saliva, semen and vaginal material. Here the analysis of the endogenous control (SNORD44) and the BFID markers using capillary electrophoresis on ABI’s 3130 genetic analyser is presented in singleand multiplex, and the effects of combining their analysis with genomic DNA human identification STR markers in a single reaction are explored. The markers are reverse transcribed using a multiplex stem-loop reverse transcription, followed by multiplex PCR with labelled primers for the cDNA and genomic DNA markers simultaneously. Future work will include the incorporation of the
additional body fluid specific markers, working towards a single reaction that can provide a DNA profile and body fluid identification on single source and mixed samples.