What is Cystic Fibrosis?

Cystic fibrosis is a genetic disease that varies widely in severity, but the most common type of CF is life-threatening. In people with CF, a defective gene causes a thick buildup of mucus in the lungs, pancreas and other organs. In the lungs, the mucus clogs the airways and traps bacteria, leading to infections, extensive lung damage and, eventually, respiratory failure. In the pancreas, the mucus prevents the release of digestive enzymes that allow the body to break down food and absorb vital nutrients.

Signs and Symptoms of CF

People with CF can have a variety of symptoms, including:

  •  Very salty-tasting skin
  • Persistent coughing, at times with phlegm
  • Frequent lung infections including pneumonia or bronchitis
  • Wheezing or shortness of breath
  • Poor growth or weight gain in spite of a good appetite
  • Frequent greasy, bulky stools or difficulty with bowel movements
  • Male infertility
Most CF patients now are diagnosed in the first month of life with a newborn screen, mandatory in California. These infants are healthy at the time of diagnosis, and management is focused on preventing the complications of CF.


People with CF have inherited two copies of the defective CF gene -- one from each parent.
People with only one copy of the defective CF gene are called carriers, but they do not have the disease. Each time two CF carriers have a child, the chances are:
  • 25 percent (1 in 4) the child will have CF
  • 50 percent (1 in 2) the child will be a carrier but will not have CF
  • 25 percent (1 in 4) the child will not be a carrier and will not have CF
The defective CF gene contains an abnormality called a mutation. There are more than 2,000 known mutations of the disease, but one mutation, 508delF, accounts for 60 percent or more of all defective CF genes. Many genetic tests only screen for the most common CF mutations, but the California Newborn CF Screen identifies almost all CF mutations.

In the United States:

  • About 30,000 people are living with cystic fibrosis (70,000 worldwide).
  • Approximately 1,000 new cases of CF are diagnosed each year.
  • Nearly half of the CF population is age 18 or older.


The California Newborn Screen identifies over 90 percent of infants with CF by 2 to 4 weeks of age, but it also identifies an equal number of babies who will not develop CF. In cooperation with the infant’s pediatrician, each infant is referred to an accredited CF center for further evaluation and diagnosis. At that visit a sweat test is done, which is a painless test that has been used for decades to identify people with CF. There are some additional tests done to separate infants with CF disease from those who might have risk for less serious problems or for no problems at all. The diagnosis may not be completely resolved with the first visit to the CF Center.

What to Expect

Because of tremendous advances in research and care, people with CF are living longer and longer, and their life goals and dreams have become like everyone else: attending college, pursuing careers, getting married and having kids. We fully expect that CF patients born now likely will have a normal lifespan and quality of life.

The UCSF Benioff Children’s Hospitals CF Center is a CF Foundation accredited care center that is staffed by experienced, dedicated healthcare professionals who provide outstanding cutting-edge care, and our CF patients and their families work closely with our CF Care Team to create effective individualized treatment plans.


North American Cystic Fibrosis Foundation
Cystic Fibrosis Research, Inc.
California Newborn Screening Program
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