About 30,000 Americans have cystic fibrosis, most of northern European heritage. Each year, about 2,500 are born with the disease.

Basics: Cystic fibrosis is a chronic, progressive and often fatal disease that produces thick mucus in the lungs and digestive tract. The body usually produces excess salt in sweat.

How it is transmitted: People must inherit a defective gene from both parents to develop the disease. About one in 30 people carry the defective gene without developing cystic fibrosis.

Symptoms: Thick accumulations of mucus in the intestines and lungs can cause malnutrition, frequent respiratory infections, breathing difficulties and eventually permanent lung damage. Loss of excessive salt can change the blood chemistry and cause heart damage or shock. In infants, the disease usually is identified quickly because of weight loss and related symptoms. Symptoms vary widely.

For more information

• Cystic Fibrosis Foundation, go to

• Mayo Clinic, go to