Today, most people know that smoking can lead to bad health, and that second-hand smoke can affect more people than the smoker. A study found that smoking can have an impact on on a person’s genetics. Those altered genes can be passed down from one generation to the next.
The study was titled “Epigenetic Signatures of Cigarette Smoking” and was published in Circulation: Cardiovascular Genetics. Epigenetic means “above” or “on top of” genetics. It refers to external modifications to DNA that turn genes “on” or “off”. These modifications affect how cells “read” genes.
One type of epigenetic change is called DNA methylation. It means there has been an addition of a methyl group, or a “chemical gap” to part of the DNA molecule. It prevents certain genes from being expressed.
In the study, researchers tried to comprehensively determine the association between smoking and DNA methylation. They took around 16,000 blood samples from the people who participated in the study. The people in the study included smokers, former smokers, and nonsmokers. There were 16 groups of participants.
The researchers determined the difference between gene changes in smokers and non-smokers by analyzing the blood samples and searching genomes for sites that had methyl groups attached. They found more than 2,600 sites that were statistically different between smokers and non-smokers. It came out to more than 7,000 genes, equaling one-third of known human genes.
The researchers found that people who had quit smoking within five years had those particular sites return to levels similar to those in people who had never smoked. But, some of the surface gene changes persisted 30 years after quitting.
The conclusion of the researchers was that genes the changes in the genes of smokers sticks around even after the person stops smoking. They noted that “DNA methylation leaves a long-term signature of smoking exposure and is one potential mechanism by which tobacco exposure predisposes to adverse health outcomes, such as cancers, osteoporosis, lung, and cardiovascular disorders.”
They concluded: “Cigarette smoking has a broad impact on genome-wide methylation that, at many loci, persists many years after smoking cessation. Many of the differently methylated genes were novel genes with respect to biologic effects of smoking, and might represent therapeutic targets for prevention or treatment of tobacco-related diseases. Methylation at these sites could also serve as sensitive and stable biomarkers of lifetime exposure to tobacco smoke.”
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