Postmortem interval (PMI) determination by profiling of HAF mRNA degradation using RT-qPCR

Abstract

Postmortem interval (PMI) determination, helping exclude or confirm suspects, plays a key role in forensic cases. Recent years, degradation of mRNA has shown potentiality to determine time of death and be allowed to obtain a considerable time since death. In our study, we aimed to find an mRNA marker to assess PMI with accuracy. We performed hypoxia associated factor (HAF) mRNA degradation in 48h after death within 29 time points in mouse brain to seek a more precise time of PMI determination. Caspase-3 DNA was carried out as normalization of HAF mRNA degradation. Nucleic acids were extracted by commercial kits and relative quantitive PCR was used to detect expression level of HAF mRNA and Caspase-3 DNA. Through analyzed profiling of HAF mRNA degradation, we acquired a statistical model between 48h PMI and mRNA degradation. Then we found that abundance of 105bp HAF mRNA fragment was increased in 48h. Interestingly, in the first 4h after death, PMI was well correlated with HAF mRNA degradation in mouse brain. We believe these results indicate that HAF mRNA was a suitable marker for PMI determination in early time since death and the statistical model of it can become a useful tool in forensic practice.