1 Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health and Medical Sciences, Københavns Universitet2 RI ledelse, Department of Forensic Medicine, Faculty of Health and Medical Sciences, Københavns Universitet3 Institut for Uddannelse og Pædagogik (DPU) - Forskningsprogrammet Fagdidaktik4 unknown5 Department of Mechanical Engineering6 Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health and Medical Sciences, Københavns Universitet7 RI ledelse, Department of Forensic Medicine, Faculty of Health and Medical Sciences, Københavns Universitet
A third collaborative exercise on RNA/DNA co-analysis for body fluid identification and STR profiling was organized by the European DNA Profiling Group (EDNAP). Twenty saliva and semen stains, four dilution series (10-0.01 µl saliva, 5-0.01 µl semen) and, optionally, bona fide or mock casework samples of human or non-human origin were analyzed by 20 participating laboratories using an RNA extraction or RNA/DNA co-extraction method. Two novel mRNA multiplexes were used: a saliva triplex (HTN3, STATH and MUC7) and a semen pentaplex (PRM1, PRM2, PSA, SEMG1 and TGM4). The laboratories used different chemistries and instrumentation and a majority (16/20) were able to successfully isolate and detect mRNA in dried stains. The simultaneous extraction of RNA and DNA from individual stains not only permitted a confirmation of the presence of saliva/semen (i.e. tissue/fluid source of origin), but allowed an STR profile of the stain donor to be obtained as well. The method proved to be reproducible and sensitive, with as little as 0.05 µl saliva or semen, using different analysis strategies. Additionally, we demonstrated the ability to positively identify the presence of saliva and semen, as well as obtain high quality DNA profiles, from old and compromised casework samples. The results of this collaborative exercise involving an RNA/DNA co-extraction strategy support the potential use of an mRNA based system for the identification of saliva and semen in forensic casework that is compatible with current DNA analysis methodologies.