Inter-Individual Variability
Definition
Differences in RNA degradation rate between different donors' blood, arising from variation in RNase activity, blood cell composition, and haematological status. One of the primary barriers to building a universal RNA ageing model.
- Field
- RNA-based stain age estimation
- Sources
- RNase activity, blood cell composition, haematological status
- Consequence
- Barrier to a universal RNA ageing model
- Target molecules
- mRNA and microRNA
Common questions
Why does RNase activity differ enough between donors to matter forensically?+
Circulating and cellular RNase levels vary with individual physiology, health status, and even time of day, so two blood stains of the same true age from different donors can show different degrees of RNA degradation, making a single universal decay curve unreliable.
How do researchers try to work around inter-individual variability in RNA ageing models?+
Approaches include using ratios between multiple RNA markers that degrade at correlated rates within the same donor, or building donor-calibrated models, rather than relying on the absolute degradation level of a single marker.
Related terms
- Degradation Index
- A ratio or combination of RNA abundance measurements designed to capture the state of degradation of a sample. Often calculated as the...
- microRNA (miRNA)
- Small non-coding RNA molecules of approximately 18-24 nucleotides that regulate gene expression post-transcriptionally. Abundant in blood cells, relatively resistant to degradation compared...
- mRNA (Messenger RNA)
- Transcripts encoding proteins, synthesised in the nucleus from DNA templates and translated by ribosomes. mRNA molecules vary greatly in length (hundreds to...
- RNase
- Ribonuclease enzymes that cleave RNA phosphodiester bonds. Present in blood plasma (RNase A family) and released from cells on death. The activity...
- RT-qPCR
- Reverse-transcription quantitative PCR: a two-step assay in which RNA is first converted to complementary DNA (cDNA) by reverse transcriptase, then amplified and...