Study: Smoking Can Cause DNA Damage Even Years After Quitting


New findings suggest that smoking can leave a mark in a person’s DNA that can stay there even after quitting the habit. This indicates that the effects of smoking can still linger even after one breaks the habit. The results of the study was recently included in Circulation: Cardiovascular Genetics, a journal of the American Heart Association.
Researchers found out that smoking leaves its footprint on the human genome by way of DNA methylation. This is the process that allows cells to control gene activity. The findings suggest that studying the process can be an important sign that can reveal a person’s smoking history. It can also provide researchers with potential targets for therapies for disorders related to smoking.
According to Stephanie J. London, M.D., Dr.P.H., a deputy chief of the Epidemiology Branch at the National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina and last author of the said study, “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. Equally important is our finding that even after someone stops smoking, we still see the effects of smoking on their DNA.”
The researchers conducted a meta-analysis of data using the blood samples taken from about 16,000 participants from the 16 groups that comprise the Cohorts for Heart and Aging Research in Genetic Epidemiology (CHARGE) Consortium. The study also included a group from the Framingham Heart Study, which many researchers have been following since 1971. The researchers compared data from the DNA methylation sites in current and former smokers to those taken from non-smokers.
The researchers findings included identifying smoking-associated DNA methylation sites that were associated with more than 7,000 genes, which accounts for one-third of currently known human genes. The researchers also found out that a majority of DNA methylation sites among smokers who kicked the habit returned to levels known to that of non-smokers only after five years from when they quite smoking. However, the researchers also noticed that there were some DNA methylation sites associated with smoking that persisted even 30 years after smokers have stopped the habit. Those methylation sites were also linked to genes associated with diseases caused by smoking such as certain cancers and cardiovascular diseases.
The researchers suggest that these long-term methylation sites associated with smoking can be further studied for the development of biomarkers when evaluating a person’s smoking history as well as a potential target for developing new treatments for diseases that arise as a result of smoking.
Source: American Heart Association. “Smoking has a very broad, long-lasting impact on the human genome.” ScienceDaily. ScienceDaily, 21 September 2016. <>


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