Researchers have produced mice that develop cystic fibrosis, a feat that some experts term a "major victory" in the quest to overcome this disabling disease.
Development of this mouse "model" of the disease, to be reported by North Carolina scientists in today's issue of the journal Science, should provide researchers with an invaluable tool in the search for new therapies for the disease, which usually is fatal by age 40.
"This is a dream come true for CF researchers," said Dr. Richard C. Boucher, a professor of medicine at the University of North Carolina at Chapel Hill School of Medicine and a member of the team that developed the mice.
"We now have an animal model in which we can test new therapies for cystic fibrosis in a fast, thorough and safe manner," he said.
Using genetic engineering techniques, the researchers inserted a faulty version of the gene that causes the disorder -- which was discovered only three years ago -- into mouse embryos. When the adults grown from the embryos mated, some of their offspring developed the symptoms of cystic fibrosis.
Cystic fibrosis is the most common fatal genetic defect in the United States, affecting an estimated 30,000 people.
"It should significantly speed our progress toward the ultimate cure" for the disease, said Robert K. Dresing, president of the Cystic Fibrosis Foundation.
"It's a pretty stunning development," said molecular geneticist Francis Collins of the University of Michigan, one of the discoverers of the cystic fibrosis gene.
Researchers have been in a frantic race to produce the CF mice ever since the gene was identified. At least five other groups have also been attempting to produce the animal model, and one of those is expected to report similar results in coming weeks.
Even though the technology for producing such "knockout" mice -- in which a key gene has been knocked out or replaced -- is well-known and widely available, the cystic fibrosis gene has proved particularly difficult to work with for reasons that are not yet clear. So molecular biologist Beverly Koller and pathologist Oliver Smithies were especially jubilant at producing the mice in their laboratories.
One in every 20 Americans, more than 12 million people, carry a copy of the defective gene that causes cystic fibrosis. The disorder occurs in approximately one in every 2,000 live births, with about 1,400 new cases being diagnosed each year.
Cystic fibrosis causes the production of an abnormally thick, sticky mucus that clogs the lungs and leads to life-threatening infections and lung damage. Similar mucus elsewhere obstructs parts of the pancreas, preventing enzymes necessary for digesting food from reaching the intestines.