Dr Max Seibold and colleagues from the University of Colorado, studied genetic mutations in 492 patients with idiopathic pulmonary fibrosis.
They looked at expression of the MUC5B gene which has been linked to pulmonary fibrosis in previous studies.
Patients were compared with 322 controls. Those with a particular genetic mutation in the MUC5B gene were nine times more likely to have idiopathic pulmonary fibrosis than those who did not have the mutation.
Writing in the New England Journal of Medicine, the researchers said: 'A common polymorphism in the promoter of MUC5B is associated with familial interstitial pneumonia and idiopathic pulmonary fibrosis. Our findings suggest that dysregulated MUC5B expression in the lung may be involved in the pathogenesis of pulmonary fibrosis.'