Holmes AS, Roman MG, Hughes-Stamm S (2018) In-field collection and preservation of decomposing human tissues to facilitate rapid purification and STR typing. Forensic Science International: Genetics 36: 124-129. https://doi.org/10.1016/j.fsigen.2018.06.015
For forensic cases in which refrigeration of human remains is not feasible, such as during a mass disaster or in rural forensic casework, collection and preservation are critical to ensuring sufficient quantity and quality of DNA. Researchers Holmes, Roman and Hughes-Stamm set out to examine two simple in-field collection and preservation methods for decomposing human tissues.
These methods were tested for their ability to facilitate more direct and faster processing of DNA from preserved tissues or DNA leached into the surrounding TENT preservative solution for STR typing. Pre-PCR methods tested in this study included a quick lysis of FTA® Elute Cards, silica-based purification (QIAquick®), enzyme-based extractions (PDQeX), and simple dilution of liquid preservative. The traditional DNA analysis pipeline, which includes DNA extraction and quantification, is compared to an alternate direct PCR method, thereby allowing the elimination of these two time-consuming and costly steps.
The results showed that MicroGEM’s PDQeX Nucleic Acid Extractor provided the most complete STR profiles in under 20 minutes. The study indicates that modified TENT preservative and FTA® Elute Cards both preserved DNA from relatively fresh tissue for up to six months at room temperature. However, mostly partial profiles were produced from decomposed tissues (day 6 – day 14 in this study) when stored for up to six months compared to when tissues were processed immediately following collection.
Overall, the modified TENT preservative produced higher DNA concentrations and more successful STR results than FTA® Elute Cards. In addition, the PDQeX generated the most successful STR typing results from the decomposed tissues stored in TENT for up to six months at room temperature. The direct PCR method used in this study generated comparable STR results to the traditional DNA analysis approach, warranting further investigation of direct PCR methods for forensic casework type samples.
PDQeX forensicGEM Universal was used as the enzyme reagent in this study.
Read about the study here.