Comparison of DNA yield after long-term storage of Second World War bone samples

Abstract

Sample storage is of paramount importance in forensic genetics laboratories since only optimal storage enables successful recovery of DNA from old bones that contain very low amount of severely degraded DNA. When identification of missing persons from skeletal remains is completed, bone sample is routinely stored at -20°C for long-term storage for retesting in future, if necessary. After molecular genetic analyses of Slovenian Second World War (WWII) victims, small fragments of femurs were stored at -20°C. Reduction in DNA recovery has been observed in frozen liquid DNA extracts by some authors and the goal of our study was to explore how freezing of bone samples affects the preservation of DNA. To achieve this goal, the difference in DNA yield in extracts obtained from WWII bones analyzed in 2009 (data from published paper) and DNA yield in extracts obtained from the same bones (piece sampled next to the one used in 2009) taken out of the freezer after long-term storage on -20°C for 10 years was examined, using the same extraction method and the same quantification kit. Up to 100 ng DNA/g of bone powder was obtained from 57 WWII femurs and up to 31 ng DNA/g of bone powder from the same femurs investigated after long-term storage in this study. 0,5 g of bone powder was decalcified using full demineralization extraction method. The DNA was purified in a Biorobot EZ1 device (Qiagen) and DNA quantity determined with the Human Quantifiler kit (TFS). Statistical analysis showed significant difference in DNA yield in extracts obtained from WWII bones in 2009 and extracts obtained from the same bones stored at -20°C after 10 years. As reported for frozen liquid DNA extracts, reduction in recovery of DNA was confirmed for frozen bone samples as well.

Genealogy: The Tree Where History Meets Genetics

“…According to Johnson and Paul (2016), the archaeological studies of kinship reflect the growing interest in understanding what the concept of "family" has meant throughout history and if human beings have followed the same rituals and concepts in distinct periods. Alternatively, in cases of soldiers whose identification is not known given the time passed after their deaths, or of victims of war crimes and torture, the application of DNA analysis acquires a leading role (Hummel 2003;Zupanič Pajnič et al 2016;Friš et al 2019;Gomes et al 2019;Obal et al 2019;Palomo-Díez et al 2019;Marshall et al 2020).…”