Intra-bone nuclear DNA variability and STR typing success in Second World War first ribs

DNA sampling and typing are used for identifying missing persons or war victims. In recent forensic studies, little focus has been placed on determining intra-bone variability within a single skeletal element. When dealing with aged human bones, complete skeletal remains are rarely present. In cases in which only the torso is available, studies have shown that ribs are one of the most appropriate samples, but intra-bone variability has not yet been studied. A higher degree of remodeling was found to contribute to higher DNA yield in the parts of the skeletal element where the most strain is concentrated. This study explores intra-bone variability in proximal, middle, and distal parts of the first human rib by determining the quantity and quality of DNA using the PowerQuant System (Promega) and autosomal STR typing success using the PowerPlex ESI 17 Fast System (Promega). Thirty first ribs from a single Second World War mass grave were sampled. No variation in DNA degradation was observed across the individual rib. The highest quantity of DNA was measured in the proximal part of the first rib, and in all ribs except three, full or almost full genetic profiles were obtained. Thus, when only the torso is present in archaeological or medico-legal cases, first ribs are recommended to be collected if possible, and the proximal or vertebral ends should be sampled for genetic analysis.