LAUSR

Background/Objectives: Formalin-fixed paraffin-embedded (FFPE) tissues are sometimes the only DNA source for forensic applications. The quantity and integrity of the DNA extracted from these samples depend on multiple factors. In this work, we analyzed, for the first time, whether Masson’s trichrome (MT) staining alters the results of genetic profiles obtained from DNA extracted from FFPE tissue sections. Methods: Three pairs of sections from the year 2024 and three pairs from the year 2001 were analyzed. Each pair consisted of serial sections, one stained with hematoxylin and eosin and the other with MT. DNA was extracted using the PrepFiler Express BTA™ Forensic DNA Extraction Kit and quantified by real-time PCR using the Quantifiler™ HP DNA Quantification Kit. DNA samples were processed for short tandem repeat (STR) profiling using the GlobalFiler™ PCR Amplification Kit. The amplified alleles were separated and analyzed using an ABI PRISM® 3500 genetic analyzer. Results: All MT-stained samples showed deficiency in most or all of the parameters assessed: DNA yield, degradation index, number of alleles detected, random match probability value, and intensity of the electropherogram peaks. In fact, DNA could not even be quantified in the samples processed in 2001. Conclusions: These results could be due to the large number of acids used in MT staining, which cause chemical modification and hydrolysis of DNA, affecting the success of PCR-based methods used subsequently. In conclusion, DNA obtained from MT-stained FFPE tissue sections may be highly degraded and should therefore be used with great caution in forensic settings.