Smoking has long-term impacts on DNA, says study

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It is known that smoking harms the body in various ways. It can cause lung disease by damaging the airways and the small air sacs in lungs. It can also increase risks of cancers and cardiovascular disorders.

Now an international research provides a new reason to quit smoking: cigarette smoking can have a long-term impact on genome, and this may be the reason why smoking is so harmful.

The paper “Epigenetic Signatures of Cigarette Smoking” is recently published in Circulation: Cardiovascular Genetics. Scientists from the USA, the UK, The Netherlands, and Australia worked together to conduct the research.

In the study, researchers focused on DNA methylation, a mechanism used by cells to control gene expression. Basically, it is epigenetic tool that can fix genes in the “off” position.

To fully understand the relation between cigarette smoking and DNA methylation, researchers conducted a meta-analysis of genome-wide DNA methylation samples.

The 15,907 blood derived DNA samples were collected from participants in 16 cohort studies. Among them, 2433 people were current smokers, 6518 were former smokers, and 6956 never smoked.

Compared with people who never smoked, current smokers showed different DNA methylation. Genes related to the changes were enriched for associations with several smoking-related traits, such as cancers, inflammatory diseases, and heart diseases.

Compared with non-smokers, former smokers showed different DNA methylation too. Some changes found in the current smokers were also found in the former smokers, including a pattern of persistent altered methylation (the change was reduced after quitting smoking).

Researchers suggest that cigarette smoking have a broad impact on DNA methylation at numerous sites, and that the impact can persist many years after smoking cessation. Many methylated genes were new genes, and they appear due to biological effects of smoking.

These new genes may represent targets for prevention and treatment of smoking-related diseases. In addition, DNA methylation at these sites may provide stable biomarkers of tobacco smoking.

Citation: Joehanes R, et al. (2016). Epigenetic signatures of cigarette smoking. Circulation: Cardiovascular Genetics. doi: 10.1161/circgenetics.116.001506
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