London, Feb 8 (IANS): Genes of some smokers may increase their risk up to 72 per cent of developing a deadly lung disease -- the third biggest killer in the world, researchers have found.

Although smoking is a strong risk factor for chronic obstructive pulmonary disease (COPD) -- a group of incurable lung ailments, including emphysema and chronic bronchitis which makes it difficult to breathe -- not all people affected by COPD are smokers and not all smokers develop the disease.

In the study, the researchers from the University of Leicester and University of Nottingham in Britain analysed 24 million genetic differences in 350,000 people from 13 countries to identify those who are at a higher risk of developing COPD.

The findings showed that those in the highest risk group were at 3.7 times the risk of developing COPD than those in the lowest risk group.

Because smokers are already at higher risk of developing COPD, this could mean that 72 of 100 smokers in this genetically high-risk group will develop COPD in later life, the researchers said.

"Given how common COPD is, we know surprisingly little about the reasons why one individual develops the condition whilst another does not," said Ian Hall, Professor at the University of Nottingham.

"The study of genetic variation between individuals provides a powerful way to understand these mechanisms which underlie disease risk, which in turn will provide a stimulus for drug development," Hall added.

In addition, by quitting smoking in early adulthood, COPD can be reduced in 5 out of 10 people at high genetic risk.

"As a result of this study, we can now better predict who will develop COPD -- opening up the possibility of using this information in prevention (such as for targeting smoking cessation services)," said Martin Tobin, Professor at the University of Leicester in Britain.