DOI
https://doi.org/10.25772/dsd8-qw41
Defense Date
2021
Document Type
Directed Research Project
First Advisor
Dr. Sarah Williams
Second Advisor
Dr. Edward Boone
Third Advisor
Dr. Catherine Connon
Abstract
DNA profiles do not provide as much evidentiary value when either all known samples can be excluded or when there is no known suspect. DNA phenotyping is a technique used for investigative purposes to predict externally visible characteristics (EVCs) based on specific markers found in the genome. Most phenotyping panels are currently restricted to markers stable over a lifetime within an individual and are not able to predict environmental or metabolic impacts on EVCs. It is known that miRNA expression levels change due to environmental and metabolic factors, such as BMI, and research has proven associations between circulating plasma miRNAs and BMI. In this project, 25 dried whole blood swabs were prepared from individuals with varying BMI values. To accommodate the typical forensic casework protocol, a DNA extraction method (QIAamp DNA Investigator Kit) was utilized followed by a cDNA synthesis reaction. Fifteen candidate miRNAs were examined for their expression levels and analyzed against both BMI and weight. It was found that the calculated change in quantification cycle from stable miRNA expression, or DCq, of miR-486-5p and miR-885-5p both individually showed negative associations with BMI. The DCq of miR-486-5p additionally showed a negative association with weight, along with the DCq of let-7i-5p and the Cq of miR-194-5p. The observed associations were found to be weak, but it is proposed that this is mostly due to the small sample size of this study. However, the data collected in this study, when analyzed using predictive models, was shown to have some success with a classification and regression tree analysis and a high level of success when utilizing a support vector machine model. This research demonstrates the possibility of adding environmentally impacted EVCs into current phenotyping panels. Recommendations for future work include the testing of additional markers and the use of a larger set of samples from the population.
Rights
© The Author(s)
Is Part Of
VCU Master of Science in Forensic Science Directed Research Projects
Date of Submission
4-29-2021