Links between genes and smoking confirmed
(17 March 2009: VIDYYA MEDICAL NEWS SERVICE) -- Early evidence that genes may influence a person’s use of tobacco came years ago from studies of twins. More recently, genome-wide association studies (GWAS) have explored links between genes and aspects of smoking behavior, such as the age of initiation and the amount of cigarettes smoked per day.
Building on this work, researchers have now tested associations between genes and seven key events across the spectrum of smoking behavior, from initiation through the development of dependency and health outcomes. DNA from 4,600 individuals, including 2,600 smokers, was analyzed using genome-wide and candidate gene approaches. For the candidate genes, several hundred previously identified genes suspected of playing a role were specifically evaluated.
The results confirm previous reports implicating nicotine receptor genes and genes involved in the dopamine system in the brain. In particular, a gene called MAOA, which helps break down dopamine, was strongly associated with the number of cigarettes smoked per day.
No specific chromosome regions achieved the genome-wide threshold of statistical significance, but the study provides a list of priority genes for further investigation. Reporting their findings online in PLoS One on February 27, Dr. Neil Caporaso of NCI’s Division of Cancer Epidemiology and Genetics and his colleagues said that the lack of genome-wide significant results suggests that common variants individually have at most a modest influence on smoking behavior.
“This was the first such study to look at a variety of smoking behaviors,” said Dr. Caporaso. “By identifying genes involved in smoking, we hope to develop more effective prevention and treatment strategies.” Two drugs used to help smokers quit, bupropion and varenicline, are likely to interact with targets related to genes that are associated with smoking behavior, he noted.
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