KEY POINTS:
A gene that significantly increases the risk of asthma in children has been discovered by British scientists who described it as the strongest link yet in the search to find a genetic basis for the condition.
Inheriting the gene raises the risk of developing asthma by 60 to 70 per cent - enough for researchers to believe that the discovery may eventually open the way to new treatments for the condition.
The Asthma and Respiratory Foundation of New Zealand says about 600,000 Kiwis have asthma. The problem affects one in four children and one in six adults.
A combination of genetic and environmental factors appears to trigger asthma attacks, which are linked with allergic reactions and over-active immune systems.
The breathing problems associated with asthma are caused by a narrowing of the airways in the lungs.
Exposure to house-dust mites or air pollutants are thought to be involved in triggering an asthma attack in people who were born with a genetic predisposition to developing the disorder. It is well established that asthma tends to run in families.
The latest study, published in the journal Nature, involved an analysis of the DNA of more than 2000 children to compare the genetic factors that are common among asthmatics but are absent from non-asthmatics.
The scientists found that mutations in a gene known as ORMDL3 on chromosome 17 are strongly associated with the risk of having asthma.
Professor William Cookson of Imperial College London's National Heart and Lung Institute said: "Our results have found the strongest genetic effect on asthma so far discovered. We do not yet know how ORMDL3 affects asthma susceptibility.
"Similar genes are found in primitive organisms such as yeast, so we suspect that ORMDL3 may be a component of quite ancient immune mechanisms. It does seem to be part of the allergic process. As its expression is increased in asthmatics, it may be possible to develop therapies against it, but this will take some time."
Miriam Moffatt, also of Imperial College London, said the study involved a large number of people from several countries and she was confident the researchers had found something "new and exciting" about childhood asthma. "These findings do not explain completely how asthma is caused, but they do provide a further part of the gene-environment jigsaw that makes up the disease.
"We are preparing bigger studies to find other genes of smaller effect and to relate these to environmental factors that protect against asthma. Our eventual aim is to prevent the disease in susceptible individuals."
The NZ foundation's medical director, Professor Robin Taylor, said: "There's no doubt we've identified the fact that if one of your parents has asthma, you're more likely to have asthma. But if it's a lot narrower than that, then it might be possible to identify children who are at risk of developing asthma, or to identify parents who are more likely to be parents of a susceptible child. One would have to say that [those tests] would be two, three, five years down the track."
Growing problem
* 600,000 New Zealanders have asthma.
* It affects one in four children and one in six adults.
* A gene has been identified as increasing the risk of asthma.
* Inheriting the gene raises the chances of developing asthma 60-70 per cent.
- INDEPENDENT
additional reporting: Errol Kiong
