DNA Methylation

Definition

DNA methylation is an epigenetic modification in which a methyl group is added to DNA, most commonly at cytosine bases in CpG sites. It helps regulate gene activity, genome stability, cell identity, and developmental programmes without changing the underlying DNA sequence. [1] [2] [3]

Why It Matters in Ageing Research

DNA methylation matters because methylation patterns change across the life course and are widely used to build epigenetic clocks. These clocks can estimate chronological age, mortality risk, healthspan- related risk, or pace of ageing depending on how they are trained. DNA methylation is therefore central to biological-age research, although methylation-based estimates should not be treated as a complete measure of ageing by themselves. [4] [5] [6]

Common Confusion

• DNA methylation is not a mutation; it changes gene regulation rather than the DNA sequence itself.
• DNA methylation is not always harmful or always beneficial; its effects depend on genomic location and biological context.
• DNA methylation data can be used to estimate epigenetic age, but DNA methylation and epigenetic age are not the same thing.

Related Reading

• Epigenetic Clocks
• Epigenetic Age
• Epigenetics
• Biological Age

References

1. Moore, L. D., Le, T., & Fan, G. (2013). DNA methylation and its basic function. https://doi.org/10.1038/npp.2012.112
2. Bird, A. (2002). DNA methylation patterns and epigenetic memory. https://doi.org/10.1101/gad.947102
3. Jones, P. A. (2012). Functions of DNA methylation: islands, start sites, gene bodies and beyond. https://doi.org/10.1038/nrg3230
4. Horvath, S. (2013). DNA methylation age of human tissues and cell types. https://doi.org/10.1186/gb-2013-14-10-r115
5. Horvath, S., & Raj, K. (2018). DNA methylation-based biomarkers and the epigenetic clock theory of ageing. https://doi.org/10.1038/s41576-018-0004-3
6. Levine, M. E., et al. (2018). An epigenetic biomarker of aging for lifespan and healthspan. https://doi.org/10.18632/aging.101414