Smokers who find it hard to cut
down or quit may be able to blame their genes, new research suggests.
Scientists identified three genetic
mutations that increase the number of cigarettes people smoke a day.
And several genes appear to dictate
how likely you are to take up smoking and how easily you can quit.
Three separate studies collected
data from 140,000 people, with the results published in the journal Nature
A previous study two years ago
found a common single-letter change in the genetic code linked to nicotine
addiction and lung cancer risk.
This new research confirms this
discovery and also pinpoints two more genetic variants that seem to increase
cigarette consumption among smokers.
The new single-letter mutations,
known as single nucleotide polymorphisms or SNPs, lie in regions of the DNA
molecule containing genes believed to influence nicotine addiction.
In smokers, each copy of the
variants was associated with a small increase in smoking consumption equivalent
to about half a cigarette a day.
However they also conferred a 10
per cent increase in lung cancer risk, raising questions about their effect.
It is not clear whether the
variants simply drive people to smoke more, or increase susceptibility to
cancer as well.
The University of North Carolina,
Oxford University and Icelandic company deCODE were all involved in the