Quantification of mRNA degradation as possible indicator of postmortem interval--a pilot study

Postmortem RNA degradation is a complex process which has not been studied systematically up to now. RNA, in contrast to DNA, is degraded in vivo to control translation and is believed to be less stable than DNA in vitro and postmortem due to ubiquitously present ribonucleases. Quantification of the fragmentation level of human mRNA might be a tool for determination for the time since death. We have developed a method for quantitating mRNA degradation by multiplex-RT-PCR coupled to laser-induced fluorescence capillary electrophoresis. The study included whole blood samples from living individuals and postmortem blood and brain samples which were stored refrigerated for up to 5 days. It could be shown that RNA degradation is significantly correlated with the storage interval of blood samples taken from living individuals and with the postmortem interval (PMI) in autopsy cases. This technique might become a parameter for the assessment of RNA quality in postmortem samples used for diagnosis and research and for the determination of the PMI. However, rather large confidence intervals have to be considered so that the use of this method in forensic casework requires further research.