DNA extraction and purification from archival material: Revisiting the standard operating procedure

Abstract

Forensic evidence from tissues embedded in paraffin archived for long periods and safeguarded in Pathology Institutes are, in some cases, the only sample available for DNA analysis. However, recovering DNA from this material can be challenging. The aim of this study is to evaluate methods of extraction and purification of DNA, using biological archival materials, in order to determine a protocol that is easy use and efficiency to adapt to the Institute of Research and Expertise in Forensic Genetics (IPPGF). Twenty-two samples from cadaver tissues included in paraffin blocks were submitted to two pre-treatments: deparaffinization using xylene and heating in microwave. After that, four methods were used for DNA extraction: phenol–chloroform–isoamyl alcohol (PCI), Chelex 100®, Purification on membranes (NucleoSpin) and the Resin purification method (DNA IQ). The quality and quantity of the DNA extracted was compared using RT-PCR. Additionally, PCR reactions were performed using the MiniFiler™ Kit. The methodology that presented better DNA recovery and more loci amplified in relation to the age of the tissues and also for the different tissues embedded in paraffin was PCI. These results reinforce and validate the maintenance of Standard Operating Procedure based on PCI used in IPPGF.