A new test reads chemical tags on DNA to track aging and treatment

Your DNA is not the whole story of aging. Above it sits another layer that decides which genes are silenced and which are expressed, and that layer changes as you get older.

That is how Bilal Karoui, the French founder of the longevity startup AK Labs, explains epigenetics. His company focuses on one slice of it called methylation, chemical tags that attach to DNA and, as Karoui puts it, "switch certain genes on and off." The pattern of those tags shifts with aging, and it also shifts when a person responds to a treatment.

Reading the pattern is the business. Karoui says his team has its own method to read methylation signals at very high resolution and at very low cost. The test is sample agnostic, meaning it can work from different sample types, rather than requiring one specific tissue.

What the readout gives is not your birthday age. It is a comparison. Scientists look at the methylation pattern and find the age group it most resembles, so a person might carry a methylation pattern typical of a 45-year-old on one marker and 55 on another. For consumers, Karoui says the value is mostly in trends over time, the kind of nudge that encourages better sleep or diet, since single scores can be gamed and can feel disconnected from how someone actually feels.

The bigger use, he says, is in drug development. His company is paid to generate this kind of data for research on aging and for quality control in cell therapy, where makers need to know if a batch is potent, meaning the cells still work as intended, if it is what they think it is, and if it matches the next batch. The work often involves large patient groups, sometimes hundreds or thousands of people, because researchers want to see how methylation patterns change with age across a cohort and how they change when a drug works.

That data is then used to build models for drug discovery, to help choose the right patients for clinical trials, and to check consistency in manufacturing.