Oct. 22 (UPI) -- A genetic connection exists between two deadly diseases involving lungs -- rheumatoid arthritis-associated interstitial and idiopathic pulmonary fibrosis.

Researchers studied 6,682 patients from the United States, France, China, Greece, Japan, Mexico and the Netherlands with rheumatoid arthritis, including those who did not have interstitial lung disease. The findings were published Saturday in the New England Journal of Medicine.


"By uncovering this link in the genetic background between these conditions, we now know that rheumatoid arthritis associated-interstitial lung disease and idiopathic pulmonary fibrosis have similar causes and may prove to have similar treatments," first author Dr. Joyce Lee, associate professor in the Department of Medicine at the University of Colorado School of Medicine, said in a press release.

Rheumatoid arthritis is an inflammatory and autoimmune disease. Most patients with RA suffer from pulmonary conditions known as interstitial lung disease, according to the Arthritis Foundation. The disease, which causes progressive scarring of lung tissue and lung impairment, is a leading cause of morbidity and mortality in patients with RA.

In idiopathic pulmonary fibrosis, the most common type of progressive lung fibrosis, it becomes hard to breath as scarring gets worse and lungs cannot take in enough oxygen. The average length of survival of patients with IPF is three to five years, according to the National Center for Advancing Translational Sciences.

The researchers analyzed data on 620 people with RA-ILD, 614 with RA without ILD and 5,448 people with neither condition.

The investigators found that a specific genetic characteristic, MUC5B promoter variant rs35705950, results in a marked increase production of mucus in the lung. It the strongest genetic risk factor for idiopathic pulmonary fibrosis and RA-interstitial lung disease.

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The genetic link was observed in at least 50 percent of patients with idiopathic pulmonary fibrosis and accounts for 30 percent of the risk of developing this disease.

"These findings will enable us to identify those with rheumatoid arthritis who are at risk of pulmonary fibrosis and design interventions to potentially prevent patients with rheumatoid arthritis from developing progressive pulmonary fibrosis," said senior author Dr. David Schwartz, chairman of the Department of Medicine at the CU School of Medicine.