So what does the MUC5B gene do in the body? It is involved with mucus production it codes for it, in fact -- and is expressed in the air sacs deep within the lungs.
In people with the variant who had pulmonary fibrosis, expression of the MUC5B protein was 14.1 times higher than in those without lung disease. The protein produced by MUC5B was also found at higher concentrations in the injured sections.
Though pulmonary fibrosis was believed to be a problem with the lung tissue itself, the new research suggests that pulmonary fibrosis is actually a problem of the airways, Schwartz said.
That could open the door to new treatment possibilities, including inhaled medications, he said.
"We don't have an effective treatment for the disease, and we don't have an effective treatment because we've been focusing on the wrong target," Schwartz said. "This discovery will help us focus on the right target and develop or try treatments that are directed at the mucus in the lung and the repair process in the lung associated with excessive mucus production.
The research is reported in the April 21 issue of the New England Journal of Medicine.
Dr. Marylyn Glassberg, an associate professor of medicine and surgery and director of the Interstitial Lung Disease Program at the University of Miami Miller School of Medicine, said that the researchers have found a strong association, but they haven't proven causality.
"They make a strong case that this could be a very important contributor in terms of the development of the disease," Glassberg said.
But the findings do not explain why about 9 percent of people without lung disease have the variant but not the disease or what triggers the disease in those who get it.
It's likely that other genes, illnesses or environmental factors play a role, Glassberg said. Conditions such as lupus and scleroderma are risk factors for the disease, as is smoking and air
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