Estimation of the time of death through the analysis of clock miRNAs expression in blood and vitreous humor

Estimation of the time since death is a practical task in daily forensic casework but available methods lack reliability especially in complex deaths and after long PM period. MirRNA analysis should be ideally an useful ancillary tool as it proved to be sensitive in forensics especially for body fluid identification. Here we analyzed 10 miRNAs with a supposed role in circadian rhythms through an RT-qPCR assay in postmortem samples of blood (n = 12) and vitreous humor (n = 12) from individuals died in the day or at night, in order to find those with an oscillating pattern of variation. The expression stability of four endogenous controls was also tested to find the most suitable for normalization.SNORD95 proved to be the best and was used in both body fluids. Four miRNAs showed significant differential expression between individuals died at daytime and at nighttime, mir-106b and mir-96 in vitreal samples and mir-142-5p and mir-219 in blood. Results are preliminary and limited to the small sample set. Future studies on more samples and with additional markers are needed to further elucidate the role of miRNA profiling in postmortem contexts and how useful they would be as “chronobiomarkers” for time of death determination