"This is a very important study, but it's not causative," Glassberg said.
It's possible that too much MUC5B protein makes it increasingly difficult for the mucus in the lung to clear foreign particles, such as cigarette smoke, dust and air pollution or to repair itself when it's exposed to pollution and other irritants, Schwartz said.
Another theory is that the MUC5B polymorphism may result in the protein being produced in parts of the lung where it shouldn't be, so that it acts not as a protector but as a toxin.
Besides opening the door to other treatments, Schwartz said, the study's findings might also enable genetic testing of people who have the disease in their family.
In addition, researchers found that those who'd inherited one copy of the variant from their parents were seven to nine times more likely to have disease and those with two copies of the variant had up to a nearly 22-fold increased risk.
A genetic test for pulmonary fibrosis would be welcomed by many, such as Teresa Barnes, vice president of patient outreach and program support at the Coalition for Pulmonary Fibrosis. Her father was diagnosed with the disease in 2002 and died within two years. Within a few years, his sister and two other brothers also died of the disease.
"It's excruciating to watch," Barnes said. "Someone you love is suffocating. You can't make it go away. You can't stop it. You feel really helpless, and you feel really hopeless."
Barnes, who has a 7-month-old daughter, said she wonders if she or her daughter are destined to get the disease.
"It scares the life out of all of us," Barnes said. "If 100 percent of the generation before you died from something, believe me, you're afraid."
The Coalition for Pulmonary Fibrosis has more about pulmonary fibrosis.SOURCES: David Schwartz, M.D.,
All rights reserved