An international study looking at DNA from over 26,000 people has identified several genetic variants that substantially increase susceptibility to asthma in the population.
The findings, published in the New England Journal of Medicine, will help scientists to focus their efforts to develop better therapies for the illness.
The study, which was co-ordinated by researchers from Imperial College London, was performed by the GABRIEL consortium.
The researchers performed more than half a million genetic tests on each subject, covering all the genes in the human genome. The study pinpointed seven locations on the genome where differences in the genetic code were associated with asthma.
One in seven children in the UK suffers from asthma.
The study suggests that allergies are probably a consequence of asthma, rather than a cause of the disease.
The new variants linked to asthma were found in more than a third of children with asthma in the study. The gene with the strongest effect on children did not affect adults, and adult-onset asthma was more weakly linked to other genetic differences, suggesting that it may differ biologically from childhood-onset asthma.
Childhood asthma, which affects boys more than girls and can persist throughout life, is often linked to allergies, and it has been assumed that these can trigger the condition.
Professor Miriam Moffatt, Professor of Human Genetics at Imperial College London and one of the study’s leaders, said: “As a result of genetic studies we now know that allergies may develop as a result of defects of the lining of the airways in asthma. This does not mean that allergies are not important, but it does mean that concentrating therapies only on allergy will not effectively treat the whole disease.”
Professor David Strachan, Professor of Epidemiology at St Georges, University of London, who also co-authored the study, said: “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. The GABRIEL consortium is now investigating whether the causes of asthma differ between people with and without these newly discovered genetic variants.”
The study was primarily funded by the European Commission, the French Ministry for Higher Education and Research, the charity Asthma UK and the Wellcome Trust.
Source: Imperial College London, UK