Recently, several authors described the observation that RNA degradation does not correlate with the postmortem interval (PMI), but rather with other parameters like environmental impact and the circumstances of death. Therefore, the question arose if the analysis of gene expression could be a valuable tool in forensic genetics to contribute to the determination of the cause of death. In our study, six human tissues obtained from six individuals with PMI varying between 15 and 118 h were used for total RNA extraction. Quantification was performed using a GAPDH real-time assay, and the quality of mRNA was checked by amplification of different fragment lengths of the GAPDH transcript. In our set of samples, nearly all tissues in all PMI revealed satisfactory results, while skeletal muscle, followed by brain and heart, gave the best results. No correlation between PMI and RNA degradation could be detected, as very good results were observed for all tissues from the individual with the longest PMI. The highly promising results obtained in this study raise hopes that in the near future several fields of forensic investigation may profit from additional information about gene expression patterns and their correlation with pathological findings.
Supplementary Table 1Sequences of the forward primers (in 5′-3′ orientation) for the amplification of different lengths of the GAPDH transcript. For all amplicons, the same reverse primer (5′-tgccctgtagaaattcgttg-3′) was used. The different forward primers were chosen to span at least one exon/exon boundary. E/E Exon/Exon boundary according to GenBank NM002046 (mRNA) and J04038 (genomic sequence) (DOC 29 kb)
Supplementary Fig. 1a Example of the real-time PCR results of the GAPDH assay using RNA extracted from muscle tissue of the individuals A–E (according to Table 2). b Example of a denaturing agarose gel electrophoresis using RNA extracted from skeletal muscle of individual A. The band representing 28s ribosomal RNA is stronger than the one representing 18s ribosomal RNA indicating a high quality of the extracted RNA (DOC 96 kb)