Simplified, rapid DNA extraction protocol for STR typing from bones

Abstract

Bones are one of the body parts most tolerant towards various environmental conditions, especially as unidentified remains found in several circumstances: mass disaster, terrorism, war, and plague. Typically, the most complex and time-consuming part of the STR typing process is DNA extraction, with many different methods developed, such as organic extraction, total demineralization (TD), and silica-based column extraction. These protocols may take more than a day to complete. In such events where time is of the essence for human identification of the remains, a simple and fast but effective method is required. This study aimed to develop a simplified and rapid DNA extraction protocol from bone samples. Two bone types (fresh femur and tibia) were incubated in a buffer of SLS, EDTA, proteinase K, and DTT. We also evaluated extraction from different amounts of bone powder. Comparison was done for the developed method against standard total demineralisation protocol. Quantity of DNA extracted was slightly lower for the developed protocol compared to TD, however this did not affect STR typing and profile interpretability. DNA extraction was also possible from merely 0.1 g of bone. The developed method used significantly shorter incubation time and processing steps. Our final protocol only required two hours of incubation and 0.1 g of bone powder. STR typing results gave full profiles. The rapid protocol could be used when there is an urgent need of STR typing for human identification or when the sample amount is limited with a significant reduction in cost and time for investigation.