Genes may affect smoking addiction

Scientists have identified a number of genetic mutations that appear to be associated with the number of cigarettes people smoke a day, the chance of taking up smoking, and the ability of being able to quit smoking.

'This lends support to the idea that smoking is not just a question of will power alone, but that genetics plays a role in how much a person smokes and their ability to quit smoking', said Dr Helena Furberg from University of North Carolina, US, who was involved in the research. 'We hope that our findings will help pave the way for better treatments that will help people quit smoking'.

The study, which was published in Nature Genetics, looked at the DNA profiles of over 140,000 smokers and non-smokers. It was carried out by a large group of researchers from 23 institutions in a dozen countries.

The scientists found three gene variants in three different genetic regions associated with how many cigarettes someone smoked per day, two of which were close to genes known to influence nicotine metabolism. They also found a link between these three variants and the risk of lung cancer. However, they couldn't tell whether the genes affect smoking behaviour or whether they increase a person's vulnerability to the harmful effects of smoking, and said more work is needed to disentangle the causes and effects of the relationship.

DeCODE, an Icelandic company, are planning on incorporating the results into genetic tests to tell if people run the risk of becoming smokers. 'Smoking is bad for anyone's health', said Dr Kari Stefansson, chairman of the organisation and also one of the researchers in the study. 'It is even worse for some, and these discoveries continue to strengthen our ability to identify who those people are and give them a compelling reason to quit. We plan to incorporate these (variants) into our testing products to do that'.

Although smoking causes nine out of ten cases of lung cancer, only a small proportion of smokers actually develop the disease. The researchers note this is further evidence that an individual's genetic make-up plays a part.