More reasons to quit smoking

According to new research, there are certain genes in a smoker that make it difficult for them to cut down or quit the bad habit. This report from three studies published in the journal Nature Genetics mentions at least three different genetic mutations on chromosome 15 or changes that can increase the number of cigarettes smoked per day by an individual.

There are more that can initiate the habit of smoking and only one related to stopping the nicotine habit say researchers. There have been studies on this before with one of them reporting a single base pair change in a genetic code coding for an amino acid in the body protein. This was linked to nicotine dependence and lung cancer risk.

This new study includes more than 140 000 people from 23 institutions and dozens of countries and has confirmed two more single base pair change also known as single nucleotide polymorphism or SNP or snip linked to increased smoking. When this SNP was present, there was a small increase in smoking equivalent to about half a cigarette a day. However, they also meant a 10% increase in lung cancer risk, raising questions about their effect. One of these studies showed eight different mutations that are linked to taking up smoking and one linked to cessation.

An Icelandic company called deCODE that has a battery of genetic tests that detect risk factors was a part of this research and has now incorporated some of these gene mutations in their test battery.

Bad for all, even worse for some

Dr Kari Stefansson, executive chairman of deCODE and one of the researchers said, “Smoking is bad for anyone's health. It is even worse for some, and today's discoveries continue to strengthen our ability to identify who those people are and give them a compelling additional reason to quit….We plan to incorporate these SNPs into our testing products to do that. What we do not yet know is exactly how this additional risk is conferred. To some degree, these variants suggest that those for whom nicotine is more addictive are driven to smoke more, increasing their exposure to environmental risk. However, given the quite substantial corresponding increases in risk of lung cancer it may also be that they make people more susceptible to the noxious effects of tobacco smoke… What is clear is that these variants - which are all near genes that encode nicotine metabolising enzymes and receptors - are giving us a solid starting point for finding answers to advance personal and public health.” She added, “…so many things are predetermined in your genes but it doesn't provide you with any excuse it only provides you with an explanation. However, if you are genetically predisposed to smoking, you have more reasons not to begin to smoke. So rather than giving you excuses it gives you a reason.”

University of North Carolina Lineberger members Helena Furberg who was a part of this research said, “We hope that this work will allow researchers from multiple disciplines to develop a better understanding of the genetics of addiction and evaluate how drug-gene interactions could be used to create and tailor therapies to improve the rates of smoking cessation. More work needs to be done before these findings can be used to treat smokers who wish to quit. At this time, testing for these variants will not tell you anything meaningful about your risk of smoking or nicotine dependence. Of course, all smokers should be encouraged to quit regardless of their genetic make-up.”

The research was supported by a grant from the National Cancer Institute and multiple agencies. Statistical analyses were carried out on the Genetic Cluster Computer, which is supported by the Netherlands Scientific Organisation.