High efficiency DNA extraction from bone by total demineralization

In historical cases, missing persons' identification, mass disasters, and ancient DNA investigations, bone and teeth samples are often the only, and almost always the best, biological material available for DNA typing. This is because of the physical and chemical barrier that the protein:mineral matrix of bone poses to environmental deterioration and biological attack. Most bone extraction protocols utilized in the forensic community involve an incubation period of bone powder in extraction buffer for proteinase digestion, followed by the collection of the supernatant, and the disposal of large quantities of undissolved bone powder. Here we present an extremely efficient protocol for recovery of DNA by complete demineralization, resulting in full physical dissolution of the bone sample. This is performed in a manner that retains and concentrates all the reagent volume, for complete DNA recovery. For our study, we selected 14 challenging bone samples. The bones were extracted side-by-side with our new demineralization protocol and the standard extraction protocol in use at AFDIL. A real-time quantification assay based on the amplification of a 143 bp mtDNA fragment showed that this new demineralization protocol significantly enhances the quantity of DNA that can be extracted and amplified from degraded skeletal remains. We have used this technique to successfully recover authentic DNA sequences from extremely challenging samples that failed repeatedly using the standard protocol.