Genetic identification of highly putrefied bodies using DNA from soft tissues

Abstract

The identification of putrefied bodies is a common task in forensic routine work. The deceased are usually identified by dental records, fingerprinting, or--in cases where no such data are available--DNA analysis. However, with progressive putrefaction, DNA integrity is rapidly decreasing. Genetic analysis may then be greatly impaired, if not impossible. The aim of our study was to establish an efficient procedure to successfully extract and amplify DNA from soft tissues of bodies in different stages of putrefaction. Soft tissues-unlike teeth or bones-usually allow the application of fast and easy-to-use extraction protocols. DNA was extracted from different tissues (aorta, kidney, liver, and skeletal muscle) taken at autopsy using a commercially available DNA extraction kit, and DNA quality and quantity were controlled by agarose gel electrophoresis and real-time polymerase chain reaction (PCR). Presence of mitochondrial DNA was tested using a highly sensitive duplex PCR. Short tandem repeat analysis was done using the AmpFlSTR Identifiler kit. Additionally, mitochondrial DNA sequencing was performed. After DNA extraction from at least two different tissues-preferably the kidney and the aorta-with the extraction kit based on the Nucleobond method, a successful amplification of at least eight loci was possible in 17 out of 18 cases, and 12 or more loci could be amplified in 15 cases.