Optimisation of an Automated DNA Extraction Method for Bone and Teeth Samples and Applicability to Two Forensic Cases

Abstract

Bones and teeth are highly challenging sources of DNA in forensic science and human remains identification, requiring multiple laborious processing steps. In this study, we compared an organic phenol–chloroform method to the QIAamp® DNA Investigator and PrepFiler Express BTA™ methods in order to identify the most efficient automated DNA extraction method for bones and teeth. Results from individual tooth powder replicates showed that the PrepFiler Express BTA™ method extracted the highest yields of DNA per mg of tooth powder, returning a minimum of 20/21 PowerPlex® 21 loci. Samples extracted using the organic extraction or QIAamp® DNA Investigator methods produced PowerPlex® 21 profiles displaying a ski-slope morphology. The improved DNA quality and yield from the PrepFiler Express BTA™ method was verified using aged samples, where higher DNA yields per mg of powder and more informative profiles were obtained. Furthermore, the PrepFiler Express BTA™ method subsequently provided useful DNA profiles for two forensic cases involving degraded bone samples. Overall, this study showed that the PrepFiler Express BTA™ chemistry is a reliable and robust method for DNA extraction from bone and teeth samples, and will allow larger numbers of samples to be efficiently extracted in the event of a Disaster Victim Identification event.