Estimating time since deposition using quantification of RNA degradation in body fluid-specific markers

• Published in: Forensic science international Vol. 298; pp. 58 - 63
• Main Authors: Alshehhi, Suaad, Haddrill, Penelope R.
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 01.05.2019; Elsevier Limited
• Subjects: Age; Age determination; Aging; Aging (natural); ambient temperature; animal tissues; Autopsy; Biological properties; Biological samples; Body fluid identification; Body fluids; Chronology; Crime; Criminal investigations; Degradation; Deoxyribonucleic acid; Deposition; DNA; Efficiency; Estimation; Fluids; Forensic science; Forensic sciences; Gene expression; genes; Markers; messenger RNA; Methods; microRNA; MicroRNAs; miRNA; mRNA; RER; reverse transcriptase polymerase chain reaction; Reverse transcription; Ribonucleic acid; RNA; Saliva; Semen; Stains & staining; Statistical analysis; Time since deposition; Values; United Kingdom > UK; Dubai United Arab Emirates; United Arab Emirates; Time since deposition; microRNA; mRNA; Body fluid identification; RER
• ISSN: 0379-0738; 1872-6283; 1872-6283
• DOI: 10.1016/j.forsciint.2019.02.046

•Each RNA marker has a unique pattern of degradation behavior.•microRNA markers remained stable in aged saliva and semen samples.•RERs of body fluid-specific markers significantly correlated with ageing points.•RERs of RNA markers can potentially be used to estimate time since deposition. The first appearance of ribonucleic acid (RNA) in forensic science research was in 1984 in the study of post-mortem tissues. Since then, many studies have explored the role of gene expression and its potential applications in forensic science. The two main RNA molecules that have been subject to increasing interest in the forensic science community are messenger RNA (mRNA) and microRNA (miRNA). Identification of body fluid type and estimating the time since deposition can be of immense value to criminal investigations. Determining the time since deposition or age of a biological stain can help to indicate either when a crime happened, or whether the biological evidence was deposited before/after a known crime event, in order for samples to be excluded. The research presented here has used reverse transcription quantitative PCR to examine the relative expression ratio (RER) in two types of body fluid-specific markers (saliva and semen), to develop a method to estimate the age of biological stains. mRNA and miRNA markers specific to saliva and semen, along with three reference genes were selected. Biological samples from 20 participants were stored in a dark dry place at room temperature to simulate natural ageing. A series of desired ageing points were set and total RNA was extracted when samples reached each desired point. The degradation behaviour of each RNA marker was analysed, showing that they exhibited unique degradation profiles across a one-year storage interval for saliva and semen samples, where miRNAs and the U6 reference gene were shown to have high stability. The RERs exhibit a non-linear relationship with body fluid stain age and can be considered as a potential method for body fluid stain age estimation, hence the time since deposition.