Genes may help detect which youngsters may grow out of childhood asthma, and which youngsters won't, a new study claims.
Asthma is one of the commonest disorders among children in developed countries and is spreading fast in emerging economies.
Roughly half of children with asthma will emerge from it by the time they become young adults -- but until now, no-one knows how to determine who will be the lucky ones.
The new research, published in The Lancet Respiratory Medicine Journal, marks a first step towards a predictive test.
Researchers in the United States put together a risk score derived from 15 genetic variants that are closely associated with asthma.
They tested this model on data from a highly-regarded, long-running study in New Zealand, in which 880 people have been tracked for health since their birth 40 years ago.
Those whose DNA carried most risk variants were more than a third likelier to develop asthma earlier in life and to have asthma that persisted into adulthood than those at low genetic risk.
A higher score also meant they were likelier to be prone to asthma-related allergic reactions and impaired lung function. They were also likelier to miss school or work than counterparts with a lower genetic risk.
The test is an initial foray into a complex disease believed to have environmental and genetic factors, and for which more risk variants are likely to emerge.
It could unlock better understanding of the biology of asthma, notably how pollution and genes interact.
But it would have to be refined and widened to make it usable in routine medical practice.
"As additional risk genes are discovered, the value of genetic assessments is likely to improve. But our predictions are not sufficiently sensitive or specific to support their use in routine clinical practice," said study leader Daniel Belsky from Duke University, in Durham, North Carolina.