Researchers at University of Texas have determined that a mutation in a gene known for its role in defending the lungs against invading pathogens is responsible for some inherited cases of a lethal lung disease affecting older adults.

The same mutation may also be associated with lung cancer, the researchers reported in the January 2009 issue of American Journal of Human Genetics.

This is the third gene that has been linked with idiopathic pulmonary fibrosis, or IPF. In the United States, about 200,000 patients have IPF, and about 40,000 patients die from the disease each year, according to the Pulmonary Fibrosis Foundation.

The disease typically strikes people in their 50s and older, causing severe scarring of the lungs. Death usually occurs within three years of diagnosis.

"We don't have any medicines to treat this disease," said Christine Garcia, the study's senior author. "If a patient is younger than 65, lung transplantation is an option, but most people who develop IPF are older than that."

The ultimate goal, Garcia said, is to find or develop a medication that can stem the progression of this pulmonary condition.

About one in 50 IPF patients have an inherited form of the disease. "We've been trying to identify the genes and genetic variants that underlie this familial form of the disease," Garcia said. "Now, we know there are multiple genes involved."

In 2007, Garcia's research team discovered that the mutations of gene TERC or TERT can cause IPF. In the current study, they focused on families that did not have TERC or TERT mutations. By scanning the entire human genome, they were led to mutations in a gene called SFTPA2. The protein produced by this gene, surfactant protein A2, is found in the fluid of the lungs and helps protect the organ from invading pathogens.

Many of the individuals in the families who carried this mutation had not only IPF but also lung cancer. It is known that people with IPF have a higher risk for developing lung cancer, and Garcia suspects that mutations in the SFTPA2 gene are associated with both IPF and lung cancer.

(Xinhua News Agency December 22, 2008)