Smoking affects over 7000 genes and may leave some permanent epigenetic marks even after cessation, according to a new study
We all know smoking is bad for you. It raises disease risk across the board and increases mutation rate, but it also leaves telltale signs on your DNA through epigenetic marks. After analysing and reviewing blood data from almost 16,000 people from 16 studies, a team of researchers discovered that most genes recovered to 'normal' within 5 years of quitting. However, some appeared to remain altered, even 30 years after ending the habit.
"Although this emphasizes the long-term residual effects of smoking, the good news is the sooner you can stop smoking, the better off you are. We could use this type of data to estimate people's previous smoking. No one says they smoke when they don't, but they say they don't smoke when they do, so we could use these signals to find that out"
One of the ways your body regulates gene expression is through DNA methylation, which essentially involves adding a methyl group to DNA to affect its translation. This can be done either directly to DNA, or to the histone proteins the DNA is bound to. When the researchers compared DNA methylation sites in current smokers, previous smokers, and non-smokers, they found that smoking causes characteristic changes in over 7000 genes. A few changes persisted years after stopping, which suggests some of the effects of smoking may be permanent in at least some individuals.
"Smoking has such a wide array of effects, it's not especially surprising to hear its epigenetic effects. The message here is that smoking has an enormous, widespread impact on your genes. Most of it is reversible, but some is not. So if you smoke, you're going to alter your genetic makeup in a way that's not totally reversible"
While it isn't clear whether all of these changes are necessarily negative, as some could be responsive changes to limit damage for example, the study serves as an additional stark warning, especially to nonchalant young smokers.
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