How to combine the exigencies of histopathological and forensic-genetic investigation: a preliminary study on the use of medicolegal FFPE samples for DNA analysis

In forensic autopsies, tissue samples are routinely collected, fixed in formalin, and embedded in paraffin (FFPE) to ensure long-term preservation for histological examination. In some cases, these specimens may represent the only remaining biological material available for postmortem genetic analysis. However, the use of FFPE samples in forensic genetics poses significant challenges, as formalin fixation compromises DNA integrity and reduces the likelihood of obtaining complete genetic profiles. Moreover, relatively few experimental studies in the scientific literature have addressed the integration of forensic pathology requirements with those of forensic genetics. To address this gap, we designed a pilot study to systematically evaluate the impact of formalin fixation time on genetic analysis outcomes. FFPE liver and lung samples from 11 individuals undergoing forensic autopsy were examined. Fixation times ranged from 3 to 33 days, and three sections from each FFPE block were used for DNA extraction. Femoral blood samples collected during autopsy were analyzed in parallel as reference samples. DNA extraction was performed using the QIA amp DNA Mini Kit. Genomic DNA was amplified using the Power Plex Fusion 6 C System, and analysis was performed on the GeoStudio Genetic Analyzer for HID. Preliminary results indicate that complete genetic profiles can be obtained after fixation for up to 11 days, with a progressive decrease in correctly typed alleles as fixation time increases. Overall, the study experimentally demonstrates a correlation between DNA degradation, as reflected in the quality of genetic profiles, and the duration of formalin fixation.