A massive genetic study of thousands of asthma sufferers may force a rethink of some commonly held beliefs about the disease.

Over 150 scientists from 19 countries teamed up to carry out a genome-wide association study on 10,365 people with asthma and 16,110 people without the respiratory condition. The GABRIEL Consortium identified a number of genetic differences associated with asthma, but the disease proved to be surprisingly ‘genetically heterogeneous’, they report in the New England Journal of Medicine.

“Asthma has often been considered a single disease, but our genetic findings suggest that childhood-onset asthma may differ biologically from asthma that is acquired in adult life,” says David Strachan, an epidemiologist at St Georges, University of London (press release). “The GABRIEL consortium is now investigating whether the causes of asthma differ between people with and without these newly discovered genetic variants.”

Although asthma is thought to be caused by both environmental and genetic factors, the team behind the new work found that many previously reported associations were not significant in their huge study. They also caution that the associations they did detect will not provide a useful genetic test to identify those likely to develop asthma, “no doubt because of variable environmental effects”.

There are more positive outputs from the trial, not least that the team believe they’ve established that the oft-noted link between asthma and allergies seems to be asthma causing allergies rather than the other way round. They also think some of the variations they identified could be targets for drug treatments.

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