Optimization of dried stain co-extraction methods for efficient recovery of high quality DNA and RNA for forensic analysis

A requirement for the routine implementation of mRNA profiling methods is the ability to co-extract RNA and DNA from the same biological stain. While methodologies exist for the co-isolation of DNA and RNA from biological material, few studies include a thorough evaluation of these methods for use with forensic samples. Frequently, modifications to standard methods need to be implemented in order to accommodate the challenging nature of forensic biological samples. We therefore evaluated several co-extraction methods for ease of use and ability to recover DNA and RNA of sufficient quantity and quality for forensic analysis. From the five methods evaluated, two methods were selected for subsequent optimization (NCFS organic co-extraction and the Qiagen AllPrep DNA/RNA Mini kit). Modification of the incubation temperature and time and the inclusion of additional purification steps were found to improve the efficacy of nucleic acid recovery.