Comparative analysis of DNA extraction processes for DNA-based identification from putrefied bodies in forensic routine work.

Identification of putrefied bodies is an important and common task in forensic routine. Usually, the identification of deceased is done by visual recognition, fingerprints, physical distinguishing marks (e.g. tattoos, scars and surgical implants) and/or dental examination. However, if morphologic characteristics are not recognizable, due to advanced putrefaction of the corpse, or recent medical records are not available, the DNA-based identification is favored. Thus, in order to find another reliable procedure for DNA extraction of putrefied samples regarding tissue selection, costs and time, two commercial forensic kits were compared: DNeasy® Blood & Tissue kit and SwabSolution™ kit. Both kits were used for DNA extraction from five soft tissues (brain, aorta, liver, kidney and psoas major muscle) and nails (finger- and toenail) obtained during the medicolegal autopsy of 20 putrefied corpses. DNeasy® Blood & Tissue kit was by quantitative comparison mostly superior to SwabSolution™ kit: it yielded more DNA of better quality (i.e. less degraded and inhibited). However, the qualitative results (DNA profiles) of both extraction procedures were similar. Among the analyzed tissue types, nails were proved as the most suitable for DNA-based identification of putrefied bodies.