June 25 (HealthDay News) -- The high blood pressure drug losartan shows promise in treating Marfan syndrome, according to a small study by Johns Hopkins University researchers.

Marfan syndrome is a genetic disorder that affects connective tissue.

The clinical trial of 18 children with severe Marfan syndrome found that losartan slowed the enlargement of the aorta, the most life-threatening defect associated with the condition.

The patients' average rate of aortic enlargement before treatment was 3.5 millimeters in diameter per year. After treatment, it was less than half a millimeter per year.

The findings were published in the June 26 issue of the New England Journal of Medicine.

"This experience increases my belief that losartan holds great promise for treating Marfan syndrome. This would be the first therapy generated by basic research that revealed the molecular mechanism of this genetic disease," Dr. Harry Dietz, a professor in the McKusick-Nathans Institute of Genetic Medicine and director of the William S. Smilow Center for Marfan Syndrome Research at Hopkins, said in a prepared statement.

In previous research in mice with the same genetic defect that causes Marfan syndrome in humans, Dietz and colleagues found that excessive activity of the protein TGF-beta -- which is vital to cell growth and specialization -- causes many Marfan-related features.

When the mice were treated with losartan -- which is known to decrease TGF-beta activity -- the potentially deadly enlargement of the aorta was slowed or even halted.

A large, multicenter clinical trial of losartan for Marfan syndrome has been launched by the Pediatric Heart Network of the U.S. National Heart, Lung, and Blood Institute.

SOURCE: Johns Hopkins Medicine, news release, June 25, 2008