Fibrosis

Cystic fibrosis is a genetic disease.

Tom has cystic fibrosis.

On Aug. 25, 1989, an 8-year-old girl with cystic fibrosis wrote in her journal that it was "the most best day" because scientists had "found a Jean for Cistik fibrosis."

"We hoped that the gene discovery would someday lead to effective treatments for children and adults with cystic fibrosis," Francis Collins wrote. "Now, 30 years later, that time has come."

Some 30,000 Americans have been diagnosed with cystic fibrosis, which causes thick mucus buildup in the patient's organs, affecting respiration and digestion.