In current forensic practice, information about the possible biological origin of forensic traces is mostly determined using protein-based presumptive testing. Recently, messenger RNA-profiling has emerged as an alternative strategy to examine the biological origin. This research have evaluated seven mRNA markers by Real time PCR for their specific identification of three human body fluid stains (blood, saliva and semen) and skin swabs of forensic interest, analyzing one blood (GlycoA), two saliva (HTN3 and STATH), two semen (PRM2 AND TGM4) and two skin (LOR and CDSN) markers. The peripheral blood specific marker GlycoA was found in blood and all other samples but there was high over-expression in blood samples compared to saliva, semen and skin samples by mean 7.51 folds which allows differentiation between blood and non blood samples. The two mRNA markers of saliva HTN3 and STATH are highly specific for saliva identification. The semen markers TGM4 and PRM2 exhibited high expression levels in semen and seminal fluid but TGM4 appeared more specific than PRM2 as it expressed only in semen samples while PRM2 appeared more sensitive than TGM4 as it is expressed in samples that containing little amount of RNA. So it should be used together for semen identification to decrease the probability of misidentifying semen. According to skin markers LOR and CDSN, CDSN appeared more specific than LOR and detected only in skin samples, however the gene marker LOR exhibited high over expression in skin samples compared to non skin samples by mean 3.39 folds and in mixtures contained skin by mean 2.1 folds higher than mixture did not contain skin samples, and that absolutely allows differentiation between skin and non skin samples. Thus both should not be used alone, but concomitant with each other. mRNA analysis is an effective methodology for body fluids and skin identification, amplification of markers in non-target samples that observed in this study made the identification of most of the body fluids based on the presence of one or two markers unreliable and we need to use more markers. |
