Epigenetic clocks measure DNA methylation of sites on the genome that are patterned in much the same way in every individual of a given age. DNA methylation is an epigenetic marker that serves to regulate the production of protein from a specific gene. A range of different clocks have been constructed based on weighted assessments of methylation at various points on the genome, and the best of them can measure age quite accurately, to within a few years.
The clocks were built by working backwards from DNA methylation and age data, and it was discovered along the way that people with methylation patterns characteristic of an older age have a worse prognosis for age-related disease and mortality, or have a greater tendency to already exhibit age-related diseases. It is unclear, however, as to what exactly epigenetic clocks really are measuring. Which of the underlying forms of damage and consequent dysfunction, outlined in the SENS rejuvenation research proposals, lead to these DNA methylation changes? Some of them? All of them? No-one can presently say, and that is a challenge if the research community is to use epigenetic clocks to assess potential rejuvenation therapies.
The development of