Identification of nasal mucosa markers for forensic mRNA body fluid determination

Biological fluids are commonly encountered as a form of evidence within forensic science, and can often provide important information relating to events which may have occurred. Over the years, significant advancements have been made with DNA profiling techniques, allowing for links to be made between an individual and cellular material recovered from a crime scene. While this DNA analysis can aid in linking an individual to a crime, it can often be beneficial to also determine the body fluid source of the DNA obtained from the sample in question for case context. One increasing area within the forensic field is the use of mRNA profiling for the identification of body fluids. The analysis of gene expression patterns can give information on cell function, and ultimately the body fluid source of the DNA in a sample. Over time this has led to the development of mRNA reverse transcriptase PCR assays to detect body fluid specific RNA transcripts for casework. During the use of these techniques nasal mucosa has been observed to give rise to false positive results. We report here on the identification of promising markers using RNA sequencing for the detection of nasal mucosa, with the aim to incorporate these markers into existing assays to assist in the identification of nasal mucosa and to assist in the interpretation of possible false positive results.