Bulletins of Natural and Applied Sciences
Vol. 3(2):55-69
Analysis of the effect of various evidence tampering agents on DNA and gender predicting genes (SOX9/FOXL2) in human blood samples
Onyekachi Ogbonnaya Iroanya, Menereobong Akpan, Tawakalt Ajoke Fagbayi, Tochukwu Frank Egwuatu Department of Cell Biology and Genetics, Faculty of Life Science, University of Lagos, Akoka, Lagos, Nigeria
ABSTRACT
DNA evidence plays a critical role in forensic science, providing precise identification in criminal investigations. However, intentional tampering using chemical agents such as acids, bleach, and fuel can degrade DNA and affect forensic conclusions. This study examines the impact of these chemical agents on the integrity of DNA and the detectability of gender-determining genes, SOX9 and FOXL2, in human blood samples. Human blood samples (n=50) were analyzed under four experimental conditions. The same set of 50 samples were independently treated with bleach, acid (HCl) and fuel (petrol), while untreated aliquots of the same 50 samples served as controls and were stored under controlled conditions before DNA extraction using the salting-out method. DNA concentration and purity were assessed using a Nanodrop spectrophotometer, and polymerase chain reaction (PCR) was performed to amplify SOX9 and FOXL2 genes. Gel electrophoresis was used to determine the extent of DNA damage. Results indicate that acid treatment caused the most severe degradation, significantly reducing mean DNA concentration by ~94.9% with the lowest mean concentration (27.24ng/μl), and inhibiting PCR amplification. Bleach exposure led to oxidative DNA damage, resulting in inconsistent purity levels, while fuel (petrol) treatment caused moderate degradation, with partial loss of amplifiable DNA. The study highlights the vulnerability of forensic DNA to chemical tampering and the differential impact on specific genetic markers. The need for enhanced forensic methods to identify and retrieve damaged genetic material is highlighted by these findings. Alternative recovery techniques and the impact of additional chemical agents on the integrity of forensic DNA should be investigated in future studies.
