THURSDAY, Feb. 6 (HealthScoutNews) -- American researchers have pinpointed a gene pathway that causes pulmonary hypertension. Pulmonary hypertension is a form of high blood pressure in the lungs. It kills about 1 percent of Americans each year. In this study, which appears in the Feb. 6 issue of The New England Journal of Medicine, researchers at the University of California, San Diego (UCSD) School of Medicine identified an overactive gene called angiopoietin-1 and the molecular events it triggers that lead to acquired cases of pulmonary hypertension. The study findings provide the first specific molecular targets for the development of therapies to deal with pulmonary hypertension. Currently, lung transplantation is the only treatment for most types of pulmonary hypertension, although some patients benefit from surgery to remove blood clots from their lungs. Angiopoietin-1 is normally involved in the growth of smooth muscle in developing blood vessels in embryos. However, the UCSD researchers found the gene can be inappropriately turned on in adulthood, leading to a molecular chain of events that result in muscle cell proliferation within the lining of the lung's blood vessels. As the walls of the lung blood vessels become thicker, the small lung arteries become narrowed and blocked. Most people with pulmonary hypertension develop the disease as the result of congenital heart defects, autoimmune disease, left-sided heart failure, blood clots in the lungs, drug interactions or vascular diseases. A few people inherit a rare form of pulmonary hypertension caused by a genetic mutation. More information Here's where you can learn more about pulmonary hypertension. SOURCE: University of California, San Diego, news release, Feb. 5, 2003 --Robert Preidt Copyright © 2003 ScoutNews, LLC. All rights reserved.