What is DNA methylation?

What is methylation and how can it help us estimate a dog's age

DNA methylation is one type of epigenetic modification. It doesn’t change the DNA, but it can affect which genes are turned on and off, and when. 

Methylation refers to a methyl group (one carbon atom and three hydrogen atoms, or CH3) that can be attached to a DNA strand. Our DNA is made up of four letters—A, C, T, and G. Most methylation occurs on letter C, although A can also be methylated. (Learn more about these four letters and how DNA works.)

In the diagram below, the yellow marks are methyl groups that attach to the sides of the DNA strand. These methylation sites are not permanently attached. They can be added or removed over time.

Methylation is a normal process that happens in your cells (and your dog’s cells). It acts as a stop sign, telling genes when to turn on and when to turn off. Even though these methyl groups are tiny molecules, they physically block proteins from accessing the DNA. If there is a high level of methylation, then it becomes harder for proteins to “read” the DNA, so that gene is turned “off.” If the methylation is removed, the DNA becomes open and accessible, so that gene can turn back “on” again.

For more information, check out our blog: The Science of Dog DNA Methylation and Age