Scientists in the United States found the first evidence of a genetic variation that can worsen a chronic lung disease in conjunction with passive smoking, according to a study released Tuesday.
Researchers at Johns Hopkins University found "one gene variation that can weaken lung function as well as shorten the lifespan of those affected by cystic fibrosis and also are exposed to secondhand smoke," a summary of the study said.
"It's always been suspected that secondhand smoke is detrimental to lung disease patients, and now we have a handle on one specific gene that clearly makes it worse for those with cystic fibrosis," said Garry Cutting, one of the study's authors quoted in the report.
Cystic fibrosis causes excess mucus that makes a sufferer prone to fatal lung infections.
A six-year study of more than 800 patients found that while those exposed to secondhand smoke at home suffered more lung damage, those with mutations of the TGFbeta1 gene, which affects cystic fibrosis, fared worst of all.
"We're really surprised that such a small genetic change can double the negative effects of secondhand smoke on lung function in these patients," Cutter said.
The report is published in the Journal of the American Medical Association.