Epigenetic Clock

Definition

An epigenetic clock is a model that estimates age-related biological patterns from epigenetic data, most commonly DNA methylation measurements at selected sites across the genome. These models are called clocks because their predictions often correlate strongly with chronological age, although different clocks may be trained to estimate chronological age, mortality risk, healthspan-related risk, or the pace of ageing. [1] [2] [3] [4]

Why It Matters in Ageing Research

Epigenetic clocks matter because they give researchers a way to measure ageing-related molecular patterns before late outcomes such as disease, disability, or death occur. They are used to compare individuals, tissues, exposures, and interventions, but an epigenetic clock reading should be interpreted in the context of the specific clock, tissue type, population, and study design. [3] [4] [5] [6]

Common Confusion

• An epigenetic clock is not a literal measure of how many years a person has left to live.
• Different clocks are not interchangeable, because they can be trained on different outcomes.
• A younger or older clock result is not a diagnosis on its own.

Related Reading

• Epigenetic Clocks
• What Is a Biomarker of Ageing?
• Chronological vs Biological Age
• Epigenetic Age
• Biological Age
• Biomarker

References

1. Horvath, S. (2013). DNA methylation age of human tissues and cell types. https://pubmed.ncbi.nlm.nih.gov/24138928/
2. Hannum, G., et al. (2013). Genome-wide methylation profiles reveal quantitative views of human aging rates. https://pubmed.ncbi.nlm.nih.gov/23177740/
3. Levine, M. E., et al. (2018). An epigenetic biomarker of aging for lifespan and healthspan. https://pubmed.ncbi.nlm.nih.gov/29676998/
4. Belsky, D. W., et al. (2022). DunedinPACE, a DNA methylation biomarker of the pace of aging. https://pubmed.ncbi.nlm.nih.gov/35029144/
5. Bell, C. G., et al. (2019). DNA methylation aging clocks: Challenges and recommendations. https://pmc.ncbi.nlm.nih.gov/articles/PMC6876109/
6. Levine, M. E. (2020). Assessment of epigenetic clocks as biomarkers of aging in basic and population research. https://pmc.ncbi.nlm.nih.gov/articles/PMC7328198/