An asthma gene has been discovered by British and American scientists which could lead to the development of more effective treatment.
The gene, now the subject of a patent application, is one of a growing number thought to play a role in the condition.
Between 30 and 50 genes believed to be associated with asthma have been identified by scientists.
The new find is the result of five years' work. It was made by a team at the University of Southampton's School of Medicine and two American companies which are together engaged in a £50 million project to pinpoint asthma genes.
Professor Stephen Holgate, who led the Southampton researchers, said: "The discovery of this gene is an important advance in our understanding of the genetic causes of asthma."
More than 300 volunteer families of asthma sufferers from the south coast of England were recruited to take part in the study. They provided extensive clinical information and DNA samples.
The American partners in the project are the Genome Therapeutics Corporation of Massachusetts and the Schering-Plough Corporation. They conducted a study of 110 families from the US and then used advanced computer technology to pinpoint the gene.
Professor Holgate's group is now looking at what role this gene has in the development of asthma. The gene has so far not been named because there is a patent application pending.
Asthma affects 3.4 million people in the UK alone. It is also the most common chronic childhood disease with latest estimates suggesting that one in seven youngsters under 15 years have symptoms needing treatment.
A spokeswoman for the National Asthma Campaign said: "Knowing about these genes is useful because it provides information about the disease and new targets for drugs."