Epigenetic drift

Epigenetic drift" refers to the "gradual deviation" of the epigenetic patterns of individual cells or individuals from their original state without the underlying DNA sequence changing. In the course of life, it can contribute to altered gene activity and increased susceptibility to disease.

Epigenetic drift mainly affects DNA methylation: methylation is copied with every cell division, but not always perfectly. Histone modifications can also be affected.

Properties:

• Stochastic: The changes occur randomly, not through targeted adaptation.
• Accumulative: They increase with age.

Significance and consequences:

• Ageing: Epigenetic drift is a major reason why cells exhibit different methylation profiles with age. This is the basis for so-called epigenetic clocks, which estimate biological age.
• Diseases: Epigenetic drift can lead to misregulation of genes. There is an increased risk of cancer because tumor suppressor genes or DNA repair genes can be falsely silenced or activated.
• Variability between individuals: Even genetically identical twins show significant differences in the epigenome over time - a classic example of epigenetic drift.

1. Zheng SC et al.(2016) Epigenetic drift, epigenetic clocks and cancer risk. Epigenomics 8:705-719