Directed Research Project
Susan A. Greenspoon
Touch DNA samples are low templates and often are mixtures, making them typically one of the most difficult types of evidence to interpret. Short tandem repeat analysis is a standard method to estimate the number of contributors and DNA yield for each contributor; however, there are some limitations. Applying a non-destructive pre-DNA analysis technique that provides information about the touch DNA may improve the casework process. Antibody probes to hormones such as testosterone and dihydrotestosterone (DHT), and proteins including cytokeratins (CK) inside epidermal cells, have been demonstrated to produce a personalized signature for human touch cell populations. Testosterone, DHT, and CKs are highly expressed in epithelial cells and have high stability, making them to act as markers for the differentiation of cell populations. In this study, anti-testosterone and anti-DHT and anti-CK binding efficacy among humans was evaluated using swabs of epithelial cells collected directly from each volunteer’s hands and analyzed with flow cytometry. The results demonstrated that anti-testosterone and anti-DHT, and anti-CK could distinguish between single sources touch samples or mixtures comprised of more than one person. The order of touching an item was predicted by antibody staining intensity as well as a correlation between fluorescent signal intensity and DNA content. The quantitation data showed that the DNA amount correlated with the shift in fluorescence in histograms. We concluded that antibody hybridization targeting the testosterone/DHT and CK targets has the potential to serve as a non-destructive technique prior to STR analysis to enhance the probative value of biological evidence.
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VCU Master of Science in Forensic Science Directed Research Projects
Date of Submission
Available for download on Thursday, May 02, 2024