Thousands of asthmatic children may get little or no benefit from the most popular inhaler because they carry a particular gene mutation, researchers say.

While most children can control the condition by using a blue Ventolin inhaler, as many as one in ten are believed to have inherited a double copy of a gene that impairs the effects of the medicine.

Children and young adults with two variant copies of the gene known as Arg16, inherited from each of their parents, are more than 30pc more likely to suffer asthma attacks if they use their inhaler daily, compared with those without the gene.

Even children with a single copy of the variant gene have an increased risk of asthma attacks if they use the inhaler.

But the researchers said that there was no need for youngsters to switch inhalers until further research could verify the findings.

Wheezing

The team from the Brighton and Sussex Medical School and the University of Dundee studied 1,182 children and young people with asthma, aged three to 22.

All were using Ventolin, also known as salbutamol, to relieve symptoms such as coughing and wheezing but were also on a second inhaler, such as a steroid, to control their condition.

The study found that 70pc of children with a double copy of the gene had asthma attacks compared with 45pc of those without the mutated form.

Up to 40pc of asthma sufferers with a single copy of the Arg16 variant would also suffer a "degree of interference" to the medicine's effect.

Professor Somnath Mukhopadhyay, of Brighton, a joint author of the research, said that poorly controlled asthma was a major cause of hospital stays in children.

The genetic mutation means that salbutamol cannot bind to a receptor in the body that it needs to work. People with the variant were less sensitive to the drug the more frequently it was used, the researchers said.

Professor Mukhopadhyay called for further research, but said that in future children might be screened using a saliva test to see if they carried the Arg16 variant, with a view to offering them alternative treatments.

But he added that in the meantime young people should continue using Ventolin, "an effective 'reliever' treatment in most children".

Professor Colin Palmer, of Dundee, said that the findings could be a step to personalised medicine, where genetic information might lead to more effective use of treatment.

hnews@herald.ie

- David Rose