Gene may explain why asthma inhalers don't work for some children

One million children in the UK suffer from asthma, yet it last week transpired that one in ten of these might not be responding as expected to existing treatment. A collaboration between Professor Somnath Mukhopadhyay, of the University of Brighton, and Professor Colin Palmer, of the University of Dundee, has found that a common gene variant in children renders the blue 'Ventolin' inhalers - containing the drug Salbutamol - ineffective in warding of asthma attacks. The work was published in the Journal of Allergy and Clinical Immunology.

Previous work had identified a single change in the ADRB2 gene, called Arg16, which predisposes carriers to acute episodes of asthma. This gene encodes the receptor to which Salbutamol binds. For this study, researchers were interested in how this phenomenon might be affected by daily use of 'long-acting bronchodilator' drugs, like in the Ventolin inhalers.

A cohort of 1,182 children and young people between the ages of three and 22 from Tayside, Scotland, were screened for their genetic make-up at the ADRB2 locus. All the children routinely used a Ventolin inhaler as well as a second inhaler for controlling the severity of asthma attacks. Researchers found that for each copy of the Arg16 change, children were 30 per cent more likely to suffer an asthma attack. The difference was only evident when using Ventolin inhalers on a daily basis.

'Our study shows that common gene changes may predict the children with asthma who will have a worsening of symptoms with this commonly used medicine', said Professor Mukhopadhyay. 'We need to find out if alternative reliever medication will provide better asthma control in these children'.

Some 350,000 asthmatic children are thought to contain one copy of Arg16, whilst 130,000 carry two copies. Thus the finding will have important repercussions for the methods of treatment for nearly one in two such children. The wide use of bronchodilators means that the findings may warrant a change in the methods of treating such children. Other relieving drugs like Ipratropium work via a different mechanism to Salbutamol, such that they should be unhindered by the Arg16 variant. The authors stress that children should continue with their current treatments until alternative therapies are devised. Furthermore, the authors of the paper suggested that, in the future, children might be screened for such variants via a saliva sample, in order to optimise effective treatments on an individual basis.