An epigenetic clock for kids

Epigenetic clocks use DNA methylation to measure biological age. Differences between biological age and actual chronological age can reflect health issues. Such clocks are constructed by measuring DNA methylation at multiple sites and correlating that with the known age. The most popular method of estimating DNA methylation age has a median difference between biological and chronological ages of up to 3.5 years. That’s a relatively small difference for adults but a huge one for children. Now Steve Horvath of the University of California, Los Angeles; Michael S. Kobor of the University of British Columbia; and coworkers have developed an estimator of DNA methylation age specific to children (Proc. Natl. Acad. Sci. U.S.A. 2019, DOI: 10.1073/pnas.1820843116). The researchers used a collection of cheek cells from individuals 0–20 years old. Data from 94 DNA methylation sites in 1,032 samples were used to construct the model, and 689 samples were a test set.