Smoking may affect DNA methylation more than 3 decades despite quitting smoking cigarette

Emobileclinic Researchers Corner 

The American Heart Association Journal of Circulation: Cardiovascular Genetic has recently published the finding of recent research which found that some DNA methylation sites still remain active even after 3 decades of stopping smoking.
DNA methylation deals with how cells regulate gene activity and controls the function of genes. Scientists have discovered that DNA methylation could show the smoking history of a person, thereby creating targeted new therapies for smoking related diseases.
“These results are important because methylation, as one of the mechanisms of the regulation of gene expression, affects what genes are turned on, which has implications for the development of smoking-related diseases,” says Dr. Stephanie J. London, last author and deputy chief of the Epidemiology Branch at the National Institute of Environmental Health Sciences – part of the National Institutes of Health.
According to Dr Stephanie J. London, she noted the importance of their study “that even after someone stops smoking, we still see the effects of smoking on their DNA”.

Previous research has identified genes linked with smoking and influences the development of smoking related diseases. Smoking of Cigarette is a vital modifier of DNA methylation.

DNA methylation has also revealed a strong link between smoking and cancer as well as prenatal cigarette smoke exposure and the development of chronic diseases in adults.

With the decline in the rates of cigarette smokers across the world owing to legislations and campaigns against smoking, findings have shown that ex-smokers still have significant and higher risk of smoking related diseases such as stroke, some cancers and chronic obstructive pulmonary disease in the long run.

In carrying out the study, the team collected and examined blood samples of 16,000 participants from 16 groups included in the Cohorts for Heart and Aging Research in Genetic Epidemiology (CHARGE) Consortium, including a group from the Framingham Heart Study that researchers have followed-up since 1971.
The team found that DNA methylation sites related to smoking were linked to more than 7,000 genes – accounting for one third of known human genes after comparing with lifelong nonsmokers.
Investigators indicate that the long-term DNA methylation sites may emphasize genes that could put former smokers at risk of developing certain diseases years, even decades after quitting. This discovery could lead to researchers developing biomarkers to assess smoking history, which may result in new treatments emerging that could potentially target the methylation sites.
According to Roby Joehanes of the Harvard Medical School, “the encouraging news is that once you stop smoking, the majority of DNA methylation signals return to never smoker levels after 5 years, which means your body is trying to heal itself of the harmful impacts of tobacco smoking”.