The discovery of a defective gene linked to asthma could lead to earlier and better methods of diagnosis and treatment of the condition.

The discovery of a defective gene linked to asthma could lead to earlier and better methods of diagnosis and treatment of the condition.

The gene, which is called ADAM33, was found to be related to the development of over-responsive airways that are characteristic of asthma.

Professor Stephen Holgate, chief researcher on the study and director of respiratory cell and molecular biology at Southampton University, said: "Our research could lead to entirely new ways of diagnosing and treating asthma. This holds great promise for benefiting the huge numbers of people who suffer from this condition, one of the most prevalent chronic illnesses in children today. This is the first major novel gene to be identified in asthma from a whole genome scan as being a key component of this disease."

A team of scientists scanned the entire genetic make-up of 460 pairs of siblings in Britain and the United States.

Asthma charities responded positively to the finding. Donna Covey, the National Asthma Campaign's chief executive, said it would advance the early treatment of asthma and help to unravel the genetics of the illness. Ms Covey said: "The discovery will help us to understand why asthma might develop in the first place and its findings will enable the scientific community to push forward with further research. It could potentially enable better and earlier targeting of treatment for people with asthma.

"It also leads on to further questions such as how asthma genes interact with environmental and lifestyle factors."

She added that more research and funding was needed into the development of asthma in early life if continued progress was to be made.

The ailment currently affects one in five children as well as one in 10 adults in Britain. It is the most common long-term childhood illness, according to research compiled by the National Asthma Campaign and issued in May, which revealed the UK to have the highest rate in the world of severe wheezing among children aged 13 to 14.

Treatment for asthma costs the NHS an estimated £850m a year. The NHS has a £5m programme spanning five years, which is dedicated to research and development into asthma management.

An estimated eight million people in Britain have been diagnosed with the disease at some stage in their lives and the number of sufferers is increasing across the world. In 2000, GPS in Britain saw more than 18,000 cases a week related to asthma attacks, and there were nearly 74,000 emergency hospital admissions.

The symptomatic coughing, wheezing and shortness of breath in an asthma attack result from the over-contraction of airways in the lungs when stimulated by factors such as exercise, cold air, fumes and allergies. This process is known as bronchial hyper-responsiveness, or BHR. Scientists hope the discovery will lead to innovative approaches to asthma management and better prevention of BHR, allergic inflammation in the lungs.