Defense Date
2023
Document Type
Directed Research Project
First Advisor
Sarah Seashols-Williams
Second Advisor
Baneshwar Singh
Third Advisor
Carolyn Lewis
Abstract
Body fluid identification is one of the first and most fundamental steps in the forensic DNA workflow. It allows analysts to determine where a sample might exist on an item of evidence, as well as the type of sample that they are dealing with. However, current serological methods have been documented to produce false or inaccurate results in some cases, and may consume large amounts of sample during processing. Molecular methods, such as the use of microRNA and microbial profiles have been introduced as a means to increase specificity of testing, and have even been combined into a singular assay to increase accuracy and decrease sample consumption. A previous assay created in the Williams laboratory combined three microbial targets with two miRNA targets into a multiplex RT-qPCR reaction. This project aimed to incorporate additional miRNA markers into the previously developed assay to improve upon the separation of menstrual blood from other forensic body fluids. A single-plex reverse transcription RT-qPCR reaction was used to validate two new miRNA targets, miR-451a and miR-21-5p, in addition to the three microRNA targets that had been previously evaluated in the combined assay. miR-451a and miR-891a proved to be useful markers for the purposes of body fluid identification. A classification regression tree (CART) model created using these two markers was able to distinguish between blood, vaginal fluid, and seminal fluid with an overall accuracy rate of 86.7%. The CART model was unable to classify menstrual blood samples using only the data from the proposed miRNA targets, but it is possible these samples could be identified with the addition of bacterial information into the model. With the exception of the menstrual blood samples, the two miRNA targets were able to successfully separate blood, semen, and vaginal fluid samples with a high rate of accuracy, establishing them as useful miRNA markers to be incorporated into the combined microbial/miRNA qPCR assay before transitioning to Next Generation Sequencing.
Rights
© The Author(s)
Is Part Of
VCU Master of Science in Forensic Science Directed Research Projects
Date of Submission
5-5-2023