Childhood asthma gene identified by scientists

Childhood asthma gene identified by scientists
By Steve Connor, Science Editor
Published: 05 July 2007
Independent UK

A gene that significantly increases the risk of asthma in children has been discovered by 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 between 60 and 70 per cent - enough for researchers to believe that the discovery may eventually open the way to new treatments for the condition.

Asthma is one of the fastest growing childhood illnesses, with one in 10 children affected in Britain. More than five million people are being treated for asthma in the UK, of whom 1.1 million are under 16.

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 2,000 children to compare the genetic factors that are common among asthmatics but are absent from non-asthmatics.

The scientists found mutations in a gene known as ORMDL3 on chromosome 17 are strongly associated with the risk of having asthma, according to Professor William Cookson of Imperial College's National Heart and Lung Institute.

"Similar genes are found in primitive organisms such as yeast, so we suspect that ORMDL3 may be a component of quite ancient immune mechanisms," he said. "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."

Miriam Moffatt of Imperial College said the study involved people from several countries and she was confident the researchers had found something "new and exciting" about childhood asthma.

"These novel 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," Dr Moffatt said. "We are preparing even 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 be able to prevent the disease in susceptible individuals."

The scientists compared their findings from work on 2,000 children born in Germany with a study of 3,000 British subjects born in 1958 and who have been monitored up to the present day.

Raising the risk factor

* People with a family history of asthma are more likely to develop the condition than those with no family history

* The usual symptoms of asthma are wheezing, shortness of breath and tightness in the chest

* Many aspects of modern life, such as centrally heated houses with fitted carpets and a more hygienic environment, are believed to have contributed to the rise of asthma in recent decades

* Children of parents who smoke are more likely to have asthma than children of non-smokers