With billions of dollars flooding into longevity, what role will epigenetic clocks play in measuring and intervening in aging?
In Horvath’s case, he found that the action of 353 sites, considered together, yielded an exceptionally accurate test for chronological age. Using data from 8,000 samples from 82 DNA methylation datasets compiled by other researchers, Horvath examined patterns of methylation across 51 tissue and cell types. With those datasets, Horvath developed a biomarker-based clock for aging, then proved its accuracy. In practice, any two 25-year-olds would have the same chronological age, but the Horvath clock might put one at 20 and another at 30, based on individual DNA methylation patterns. The implication, if yet unproven, is obvious: People aging faster could die younger and have less healthy lives.