High DNA yield from metatarsal and metacarpal bones from Slovenian Second World War skeletal remains

DNA yield varies by anatomical region, and the selection of bone types that yield maximum recovery of DNA is important to maximize the success of human identification of skeletal remains. The goal of our study was to explore inter- and intra-individual variation in DNA content by measuring nuclear DNA quantity and quality and autosomal STR typing success to determine the most promising skeletal elements for bone sampling. To exclude the influence of taphonomic issues as much as possible, three complete male skeletons from a single Second World War mass grave were examined and all representative skeletal element types of the human body were analyzed. Forty-eight different types of bones from the head, torso, arm, leg, hand, and foot were sampled from each skeleton, 144 bones altogether. The samples were cleaned, and half a gram of bone powder was decalcified using a full demineralization extraction method. The DNA was purified in a Biorobot EZ1 (Qiagen). DNA content and rates of DNA degradation were determined with the PowerQuant (Promega), and the Investigator ESSplex SE QS (Qiagen) was used for STR typing. The highest-yielding bones mostly produced the most complete STR profiles. Among the skeletal elements containing on average the most DNA and producing the most complete profiles in all three skeletons examined were metacarpals, metatarsals, and the petrous portion of the temporal bone. Metatarsals and metacarpals can easily be sampled without using a saw, thus reducing potential DNA contamination. Skeletons from the Second World War can be used as a model for poorly preserved skeletal remains, and the results of the investigation can be applied for genetic identification of highly degraded skeletal remains in routine forensic casework. Although the research was limited to only three skeletons found in a unique mass grave, the data obtained could contribute to sampling strategies for identifying old skeletal remains. More Second World War skeletons will be analyzed in the future to investigate inter-bone variation in the preservation of DNA.