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Asthma hope in gene find

New Delhi, Nov. 17: Scientists have identified a previously unknown gene that appears to increase the risk of severe asthma in young children, opening a window of opportunity to decipher a form of illness that has been hard to treat.

Researchers collaborating out of institutions in Europe and the US have found that children between two and six years who have a specific version of a gene called CDHR3 are susceptible to severe exacerbation of asthma.

Their study, published today in the journal Nature Genetics, supports the idea that asthma is not a single disease but an illness with several subtypes and multiple genetic components that will need to be unravelled piecemeal.

“Early childhood asthma is currently a black box about which we know very little,” Klaus Bonnelykke, a paediatric pulmonologist and the study’s lead researcher at the University of Copenhagen, Denmark, told The Telegraph. “As a consequence, we can’t prevent the disease, and (current) treatments are inadequate.”

While earlier studies had implicated four genes associated with the risk of asthma, Bonnelykke said, the CDHR3 gene’s link with severe asthma in young children is stronger than that of any of those four genes.

Bonnelykke and his colleagues analysed the genetic makeup of 1,100 children in Denmark and England, followed up from birth up to six years of age, and found that children who had one copy of the CDHR3 risk variant had 70 per cent increased risk of being hospitalised for asthma.

Children who had two copies of this gene had a threefold higher risk for asthma hospitalisation compared with children who had no copies of the risk variant version of the gene.

“Genetics seems to play a strong role for children with the most severe disease,” Bonnelykke said.

He cautioned that the finding had no immediate clinical implications. “We will only learn to prevent and treat early childhood asthma by understanding the mechanisms involved and, in this process, genetics is a first step.”

Scientists are yet to understand how CDHR3, which is expressed in the lungs, actually increases the risk of asthma.

“We speculate that this gene plays a role in the lungs and might be involved in the response to viral infections,” Bonnelykke said. “The majority of severe asthma exacerbations in early life are triggered by viral infections.”

Future research focused on understanding the role of CDHR3 in the development or exacerbation of asthma could, the researchers wrote in their paper, help improve the treatment for asthma.