Forensic DNA typing of human nails at various stages of decomposition

Forensic scientists often face the problem of extracting and typing human DNA from degraded materials such as muscle and bones from decomposed bodies. Bone samples are particularly difficult and time consuming to be analyzed and other body tissues suffer from rapid deterioration. Nails are a well-known source of DNA and their composition makes them less predisposed to decomposition compared to other soft tissues. With the aim of evaluating the usefulness of DNA extracted from aged human nails we analyzed nails taken either from exhumed and partially skeletonised bodies or from nail clippings stored at room temperature for 10-12 years. The adopted DNA extraction procedures yielded enough DNA for reliable PCR results even when no results were obtained either from soft or bone tissues. This study confirms the usefulness of nails as a source of DNA even in cases when PCR failed to amplify DNA extracted from bones