Lung cancer and some inherited cases of a lethal lung disease might be caused by gene mutation, a new study said.

The mutated gene was previously found to help protect the lungs against toxins, scientists at the University of Texas Southwestern said in the study published in the January issue of the American Journal of Human Genetics.

In the study, the researchers found the mutations in the SFTPA2 gene in families with the inherited version of idiopathic pulmonary fibrosis, or IPF.

The SFTPA2 gene normally produces the surfactant protein A2 in the fluid of the lungs, and it helps protect the organ from invading pathogens, said the study.

IPF usually affects people age 50 and older, causing severe scarring of the lungs that results in about 40,000 deaths annually, according to the Pulmonary Fibrosis Foundation (PFF).

Currently about 200,000 people in the United States have been affected by the disease, said the PFF.

About one in 50 people with IPF have an inherited form of the disease, for which there is no cure beyond a lung transplant, said the study.

The reason why these gene mutations increase the risk for lung cancer or IPF remains unknown to scientists, the study said.

(Xinhua News Agency January 2, 2009)