Impact of Semen/Vaginal Fluid Mixture on the Expression of miR891a and miR124a in Dried Sexual Stains

Background Identification of sexual assault samples is of great importance in the sexual crimes forensic studies. Currently employed routine methods are insufficient. Advances in mRNA markers have been developing and with increasing evidence for the tissue-specificity of microRNAs, short length of 1823 bp, which overcome the degradation properties of mRNA. Aim of the work to investigate the impact of mixing semen and vaginal stains on the expression of miR891a and miR124a as biomarkers in dried forensic stains. Methods MiR-891a and miR-124a expression levels were measured in semen, vaginal fluid stains as well as their mixture using a quantitative Real- time PCR technique. RUN6b was used as an internal reference gene for normalization of targets gene, the sensitivity and detection capability were evaluated. Results The expression level of miR891a was significantly high in dried semen, although it was undetectable in dried vaginal stains, the same results were detected for miR124a in dried vaginal stains. Both miRNAs targets were detected in dried mixed semen/ vaginal stains with high sensitivity. Conclusions mixture of semen and vaginal stains doesnt alter miRNAs expression levels with good stability over six months duration.