Cystic fibrosis (CF) is an inherited disease that affects breathing and digestion. Advances in medical treatment have improved the outlook for affected children and adults. However, there is no cure. Most affected individuals survive into their 30s, though some die in childhood and others live to age 40 or beyond (1).

The abnormal gene that causes CF was discovered in 1989 (2). This discovery led to the development of a test, called a carrier screening test, that can help determine whether a couple is at increased risk of having a baby with CF. The test is routinely offered to couples who have a family history of CF. Many health care providers also make this test available to couples who are planning pregnancy or are pregnant. Couples must decide if testing is right for them.

What is cystic fibrosis?

CF is an inherited disease that affects the normal movement of salt (sodium chloride) into and out of certain cells, including those that line the lungs and pancreas. This results in thick, sticky mucus and other secretions.

The mucus clogs the lungs, causing breathing problems. It also provides a breeding ground for bacteria to grow. This leads to frequent lung infections, which eventually damage the lungs and contribute to early death.

Thick digestive fluids also may clog ducts leading from the pancreas to the small intestine. This prevents the fluids from reaching the small intestine, where they are needed to digest food. This can cause digestive problems and slow growth.

How common is CF?

About 30,000 children and adults in the United States have CF (1). The disease is most common in Caucasians, though all racial groups are affected.

What are the symptoms of CF?

The symptoms of CF vary and can range from mild to severe. Some common symptoms include:

  • Coughing or wheezing
  • Repeated lung infections, such as pneumonia and bronchitis
  • Shortness of breath
  • Poor growth, in spite of a big appetite
  • Intestinal blockage, called meconium ileus, in a newborn (caused by thickening of the greenish stool newborns usually pass in the first days of life)
  • Greasy, bulky stools
  • Infertility in affected males due to blockage or absence of the tube (vas deferens) that carries sperm out of the testicles

Many lung infections in individuals with CF are caused by a bacterium called Pseudomonas aeruginosa. This bacterium rarely causes problems in people who do not have cystic fibrosis. Antibiotics often cannot completely clear this bacterium from the lungs. These infections contribute to lung damage.

Most children with CF are well enough to exercise and attend school (3). Doctors recommend exercise in individuals with CF because it helps loosen mucus in the lungs and strengthens the heart and lungs.

How is CF diagnosed?

CF is diagnosed with a sweat test or with gene tests using a blood sample or saliva. Many children with CF are now diagnosed in the first six months of life (4). About 10 states routinely screen all newborns for CF, along with other disorders of body chemistry (5).

About 15 to 20 percent of newborns with CF have meconium ileus (4). When a baby has this symptom, the health care provider will recommend a gene test to diagnose or rule out CF. Some studies suggest that early diagnosis and treatment improve the growth of babies and children with CF (4).

Other children are not diagnosed until they begin to develop other symptoms, such as repeated lung infections or poor growth. Children with possible symptoms of CF usually are given a sweat test. This simple, painless test measures the amount of salt in the sweat. Individuals with CF have more salt in their sweat than unaffected individuals. In most cases, CF is diagnosed by 3 years of age (1). Some health care providers also recommend a gene test to confirm the diagnosis.

Both the gene test and the sweat test are accurate in diagnosing CF. However, neither can accurately predict how severe the child.s symptoms will be (1, 4).