Glossary · Biology
Epigenetic clock
In short
An epigenetic clock estimates a biological age from chemical marks on the genome, the methylations. If it differs from chronological age, this is taken as a sign of faster or slower ageing.
Methylation at certain sites of the DNA changes fairly regularly with age. The first clocks, such as Steve Horvath’s from 2013, were trained to predict chronological age. Newer clocks such as PhenoAge, GrimAge and DunedinPACE are geared more towards disease and mortality.
For research they are an important tool. As a personal measurement they have limits: results differ between clocks and measurements, and whether a younger reading on the clock also means less disease has not been shown. That makes the clock a surrogate marker.
What the test can do in detail, how precisely it measures for you and what it costs is covered on the topic page Epigenetic age test.
The clock measures methylation — whether it measures ageing is the open question.
Where this comes up in the fact checks
- Therapeutic plasma exchange – The epigenetic ageing clocks went down after three sessions; after six, no difference from the sham treatment was measurable any more.
- Prevention, epigenetics & genetics – Prevention services derive a personal biological age from methylation patterns.
Sources
Related terms: Biomarker · Surrogate marker
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