Epigenetic clock
biochemical test
An epigenetic clock is an analytical method used as a biomarker of aging to estimate "biological age." The method relies on age-related modifications to DNA that occur over time and regulate how genes are expressed. Many epigenetic clocks are based on the analysis of DNA methylation, measuring the accumulation of methyl groups to CpG regions of DNA molecules. More recently, new epigenetic clocks have been developed based on the histone code, chromatin accessibility and nucleosome positioning.
History
The strong correlation between aging and DNA methylation levels has been known since the late 1960s. A vast literature describes sets of CpGs whose DNA methylation levels correlate with age. The first robust demonstration that DNA methylation levels in saliva could generate age predictors with an average accuracy of 5.2 years was published by a UCLA team including Sven Bocklandt, Steve Horvath, and Eric Vilain in 2011 (Bocklandt et al. 2011). The laboratories of Trey Ideker and Kang Zhang at the University of California, San Diego published the Hannum epigenetic clock (Hannum 2013), which consisted of 71 markers that accurately estimate age based on blood methylation levels. The first multi-tissue epigenetic clock, Horvath's epigenetic clock, was developed by Steve Horvath, a professor of human genetics and biostatistics at UCLA (Horvath 2013). Horvath spent over 4 years collecting publicly available Illumina DNA methylation data and identifying suitable statistical methods.
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This entry incorporates text from “Epigenetic clock” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.