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Aging & age metrics

Epigenetic clock

An algorithm that predicts biological age from DNA methylation patterns

A clock face made of methylation marks on a DNA helix — the epigenetic clock

Epigenetic clocks are mathematical models that estimate biological age from the level of DNA methylation at hundreds of specific sites in the genome (CpG sites). With age the methylation pattern changes in a regular way, and from it one can predict age to within a few years.

These are among the strongest known biomarkers of aging: the gap between epigenetic and calendar age is linked to the risk of disease and death.

How epigenetic clocks work

With age the level of DNA methylation at certain points in the genome (CpG sites) changes in a regular way. A machine-learning algorithm selects a set of such sites and converts their methylation into an "age" in years. The first clocks were Horvath's (2013, 353 CpG sites, working across different tissues) and Hannum's (2013, 71 sites, blood).

Generations of clocks

First-generation clocks (DNAm age) were trained to predict calendar age. The second generation — PhenoAge and GrimAge — were trained on health and mortality measures, so they predict disease better. DunedinPACE estimates not age but the pace of aging.

What is proven and what is not

Epigenetic clocks are among the strongest predictors of mortality and age-related diseases. But for now this is a research tool: the result depends on the laboratory and tissue type, and there is not enough evidence that "rejuvenating" the clock readings by itself extends a person's life.

Calculate using this marker

Calculators where Epigenetic clocks is used directly:

PhenoAge (Levine) Nine blood markers — the formula from Morgan Levine et al., 2018 Open Biological Age Estimate A quick estimate from height, weight, and body measurements — no labs needed Open

Frequently asked questions

Where can I get a test for epigenetic age?

Some commercial laboratories offer it from a blood or saliva sample (DNA methylation analysis). Keep in mind that the methods differ and the results are still considered largely research-grade.

Can epigenetic clocks be "rejuvenated"?

In some studies a healthy lifestyle and certain interventions are associated with younger readings. But a causal link with life extension in humans has not yet been proven.

Related terms

DNA methylation Chemical marks on DNA — the molecular "clock" of biological age Epigenetics The science of how lifestyle and environment control gene activity DNAm Age DNA methylation age — an estimate from epigenetic clocks PhenoAge Phenotypic biological age from 9 blood markers GrimAge A second-generation epigenetic clock — the best predictor of mortality and disease DunedinPACE An epigenetic measure of the pace of aging: how many biological years the body ages per calendar year Biological age The body's real age, independent of the passport age Biomarker of aging A measurable indicator that reflects the body’s biological age

Sources

  1. Wikipedia — Epigenetic clock
  2. Levine et al. An epigenetic biomarker of aging (Aging, 2018)
  3. Lu et al. DNA methylation GrimAge predicts lifespan (Aging, 2019)
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This content is educational and does not replace consultation with a physician. Reference ranges may vary depending on the laboratory and method — rely on the ranges stated on your own test report.
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