Body-Fluid-Specific Transcripts
Definition
RNA markers expressed only in one fluid: HBB for blood, STATH for saliva, PRM1 for semen, MUC4 for vaginal fluid, MMP7 for menstrual blood.
- Blood marker
- HBB (haemoglobin beta)
- Saliva marker
- STATH (statherin)
- Semen marker
- PRM1 (protamine 1)
- Vaginal fluid marker
- MUC4 (mucin 4)
- Menstrual blood marker
- MMP7 (matrix metalloproteinase 7)
Common questions
Why use mRNA markers instead of just presumptive chemical tests?+
Presumptive tests such as Kastle-Meyer or acid phosphatase indicate a category of stain but can cross-react with non-target substances. Fluid-specific transcripts are expressed mainly in the tissue of origin, so a positive result narrows the source with more specificity than a colour-change presumptive test.
How stable is mRNA in old or degraded bloodstains?+
RNA degrades faster than DNA under most storage conditions, but validated protocols have recovered informative fluid-specific transcripts from stains stored for years, because short, stable regions of these markers are targeted rather than full-length transcripts. Degradation still lowers success rates as sample age and exposure increase.
Related terms
- Biogeographic Ancestry Inference (BGA)
- Statistical assignment of a donor to continental ancestry groups using Ancestry-Informative SNPs (AIMs). Distinct from racial categorisation.
- Deconvolution
- A computational technique that estimates the PSF and inverts its effect to recover a sharper image. The quality depends entirely on how...
- Externally Visible Characteristics (EVCs)
- Traits a witness could see: eye, hair, skin colour, freckling, hair shape, height. The EU-funded VISAGE consortium targets this set.
- Forensic DNA Phenotyping (FDP)
- Prediction of externally visible characteristics, ancestry and age of an unknown donor from SNP genotypes. Investigative lead, not identification.
- HIrisPlex-S
- A 41-SNP externally visible characteristics (EVC) panel for simultaneous prediction of eye, hair, and skin colour, developed at Erasmus MC Rotterdam by...
- mRNA / miRNA
- Messenger and micro RNA. Forensic RNA profiling uses tissue-specific transcripts of both classes to identify body fluids.
- Parabon Snapshot
- A commercial DNA phenotyping service (Parabon NanoLabs, Virginia, US) that genotypes thousands of SNPs from a crime-scene sample and uses machine learning...
- SNP
- Single Nucleotide Polymorphism. A one-base variant at a defined position. FDP uses SNP panels, not STRs.