Semi-quantitative PCR Analysis of DNA Degradation

Natural variables, including environmental conditions and post-mortem interval (PMI), affect the course of tissue decay in forensic and archaeological contexts. Compared with soft tissue, skeletal materials provide longer protection against DNA degradation. However environmental factors, including temperature and humidity, may affect the longevity of DNA survival in bone structure. In this study we describe the development of a semi-quantitative multiplex PCR based method to assess the level of DNA degradation with applications in analysis of forensic specimens. The assay was then applied to assess DNA survival in rib bone samples taken from 12 corpses in the mortuary. Samples were de-fleshed and stored in two different environmental conditions, including ambient conditions and underground burial from 103 to 445 days. Bone DNA was extracted and then assessed by the optimized semi-quantitative PCR and capillary electrophoresis of three products from the human mitochondrial DNA. The results show DNA survived for longer periods in samples stored in ambient conditions compared with underground burial conditions. There was no correlation found between the level of DNA degradation and PMI in our samples. Results also confirm that post-mortem alteration to DNA in skeletal tissues can occur very soon after death, with direct implications to the forensic industry.