Formalin fixed histological specimens in DNA profiling of cadavers

Abstract

Collection of tissue samples for archiving is not a routine practice at each autopsy. This step may be omitted on purpose (e.g. identification of the corpse by DNA is not needed) or omitted by the pathologist. Tissue samples for pathological examination are commonly excised at the autopsy and frequently offer the only biological material available for DNA analysis.The objective of this study was evaluation of formalin fixed paraffin embedded (FFPE) tissue specimens as a potential source of DNA templates for kinship analysis, depending on a tissue type and a fixation method.The study material comprised of 10 sets of five FFPE specimens of cadaver tissue (a total of 50 samples) with no signs of decomposition – an archival material of the Department of Forensic Medicine, Medical University of Warsaw: three sets dating 2001 and three sets dating 2010 - fixed with 10% formaldehyde, four sets dating 2018 - fixed with buffered formaldehyde.DNA was extracted using Maxwell® 16 Forensic Instrument (Promega). PowerQuant System (Promega) 7500 Real-Time PCR System (Applied Biosystems) were used for DNA quantitation and integrity assessment. DNA templates were amplified with use of PowerPlex Fusion6C (Promega) and genotyped in 3500XL Genetic Analyzer.Based on our data, DNA degradation in 10% formaldehyde-fixed tissues increased, while the specimens fixed with buffered formaldehyde yielded good quality DNA. Based on DNA quantitation results and saturation of the PowerPlex Fusion6C profiles, the lung tissue and the brain tissue were the best sources of DNA templates out of all the specimens investigated regardless of the fixative used.