By Maggie Fox(NBC NEWS):
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Smoking changes DNA in clear patterns,researchers Tuesday.Most of the damage fades over time,they found but not all of it..Their study of 16,000 people found that while most of genetic footprints left by smoking fade after five years if people quit,some appear to stay there forever. Th marks are made in process called methylation,which is an alteration of DNA that can inactivete a gene or change how it functions.. .."Our study has found compelling evidence that smoking has along-lasting impact that can last more than 30 years".
Said Roby Joehanes of Hebrew SenioorLife and 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."
The team examined blood samples given by 16,000 people taking part in various studies going back to 1971.In all the studies,people have given blood samples and filled out questionnaires about smoking,diet,lifestyle and their health histories.They found smokers had pattern of methylation changes affecting more than 7,000 genes, or one-third of know link to heart disease and cancers known human genes. Many of the genes had known to be caused by smoking.
Among quitters , most of these changes reverted to patterns seen in people who never smoked after about five years, the team reported in the American heart association journal .....
But smoking-related changes in 19 genes, including the TIAM2 gene linked to lymphoma, lasted 30 years,the team found "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-diseases,"said Dr. Stephanie London of the National Institute of Environmental Health Sciences,who directed the team .."Equally important is our finding that even after someone stop smoking ,we still see the effects of smoking on their DNA ."
Some of the affected genes had not been associated with the damage caused by smoking before .It might be possible to use them as markers to see who is at risk of smoke-related diseases in the future they might also be targets for new drugs to treat the damage done by cigarette smoke, the researchers said. Smoke is the biggest cause of preventable illness,killing more than 480,000 Americans every year,according to the center for disease control and prevention. Globally ,it kills about 6 million people a year through cancer,heart disease,lung disease and other ills.
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