Information found in this section is provided with consent of the March Of Dimes.

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

The abnormal gene that causes CF was discovered in 1989. This discovery led to the development of tests that can help determine whether or not couples carry an abnormal gene that can cause CF in their children. Testing usually is offered to couples with a family history of this disease, though now health care providers also are offering this test to couples without a family history of CF who are planning pregnancy or who are already pregnant. Couples will be better able to decide whether they want to have the carrier test if they understand the medical problems that CF can cause and what the tests can and cannot tell them.

What Is Cystic Fibrosis?

CF is an inherited disease caused by an abnormal protein that does not allow the normal passage of chloride (which, along with sodium, makes up salt) into and out of certain cells, including those that line the lungs and pancreas. As a result, these cells produce thick, sticky mucus and other secretions. The mucus clogs the lungs, causing breathing problems. Affected individuals also have frequent lung infections, which eventually damage the lungs and contribute to early death. The thickened digestive fluids made by the pancreas are prevented from reaching the small intestine, where they are needed to digest food.

Is CF Common?

About 30,000 children and adults in this country have CF, according to the Cystic Fibrosis Foundation. While all racial groups are affected, the disease is most common in caucasians.

What Are the Symptoms of CF?

The symptoms of CF vary, and some children and adults are less severely affected than others. Individuals with CF tend to cough and wheeze frequently. They may develop repeated lung infections, such as pneumonia. Many of these infections are caused by a bacterium called Pseudomonas aeruginosa, which rarely causes problems in healthy people.

Many, but not all, children and adults with CF have digestive problems due to blockage of digestive chemicals from the pancreas. Affected children often have a big appetite, but gain weight or grow slowly.

Some children with CF are well enough to attend school, participate in some exercise and recreational activities (though stamina is generally reduced), and go on to college and rewarding careers. Others, however, are too ill to attend school regularly.

How Is CF Diagnosed?

CF is diagnosed with a simple, painless test that measures the amount of salt in the sweat. Infants, children and adults with CF have more salt in their sweat than unaffected individuals. In many cases, CF is diagnosed when a child is between 2 and 4 years of age, following repeated lung infections and/or growth problems.

A few states have begun screening newborns for CF, along with other disorders of body chemistry routinely tested for soon after birth. Some studies suggest that early diagnosis and treatment improve the growth of babies and children with CF.

How Is CF Treated?

Children and adults with CF need close medical supervision throughout their lives. To improve growth, children with CF must eat a healthy, high-calorie diet supplemented with vitamins and, usually, medications that contain pancreatic enzymes (which the body needs to absorb nutrients from food). Some children must take about 25 vitamins and other pills each day.

Many children with CF also need daily respiratory therapy, which is done at home. For about 30 minutes once or twice a day, a parent or other caretaker claps the child on the back and chest, to help clear the mucus from the lungs.

There are a number of medications that can help affected individuals breath better and prevent infections. The medications recommended for a child or adult with CF will depend on the person’s symptoms and their severity. These medications include a mucus-thinning drug called Pulmozyme and an antibiotic called TOBI (tobramycin solution) that is inhaled in vapor form. One study also suggested that the anti-inflammatory drug ibuprofen, when given in high doses, can help prevent lung inflammation, which is common in individuals with CF, and can make breathing more difficult. When infections occur, they are treated at home or in the hospital with a number of antibiotics, which can be given orally, intravenously, or by inhalation.

Unfortunately, as the individual gets older, infections tend to get worse and more difficult to treat, and lung damage becomes more serious. Infection, and the resultant lung damage, is the leading cause of death in individuals with CF.

Can a Person Catch CF from Someone Who has It?

No. The disease is inherited and is not contagious. Genes come in pairs. To inherit CF, a child must receive two CF genes, one from each parent who “carries” a CF gene. A carrier has one normal gene and one abnormal gene in the pair, and is as healthy as a noncarrier.

How Is CF Inherited?

When both parents carry an abnormal CF gene, there is a 25 percent (one-in-four) chance that the child will have CF. There is a 50-50 (50 percent) chance that the child will be a carrier like the parents. There also is a 25 percent chance that the child will be free of the abnormal gene and neither be a carrier nor have the disease.

Each successive pregnancy has the same set of chances. If only one parent is a carrier, there is no chance that their children will have CF. However, there is a 50-50 chance of each child being a carrier.

Who Should Have the Carrier Screening Test?

The American College of Obstetricians and Gynecologists (ACOG) now recommends that the carrier screening test be available to all couples who are planning pregnancy or are pregnant. Many health care providers hand out printed material on the test for couples to read. Those who may be interested in testing can then discuss it further with their provider.

Health care providers are more likely to offer the test to couples considered at increased risk of having an affected child, including those with a family history of the disorder and those from racial/ethnic groups that have higher rates of CF.

Whether or not a couple chooses to take the carrier screening test is a personal decision. A couple must decide what is right for them after learning more about CF and discussing the test with their health care provider.

Who Is Most Likely to Be a Carrier?

According to the Cystic Fibrosis Foundation, one in 31 Americans — more than 10 million people — carry a gene for CF. Someone with a family history of CF is more likely to carry a CF gene than someone from an unaffected family. The risk also is increased in individuals of caucasian backgrounds. These individuals have a 1 in 29 chance of carrying the gene, compared to 1 in 46 for those of Hispanic background, 1 in 65 for African Americans, and 1 in 90 for Asian Americans.

What Happens if the Test Shows a Woman Is a Carrier?

The next step is to test her partner. A baby is not at risk of CF unless both parents carry the abnormal gene. Fortunately, this situation is fairly uncommon. In those of caucasian background, the chances that both partners carry the CF gene is only about 1 in 800; the risk is less in other groups.

It’s important to keep in mind, however, that the test is not 100 percent accurate. Scientists have discovered more than 900 different mutations (abnormalities) in the CF gene, and the test looks only for some of the most common of these. So even when the test shows that a person is not a carrier, a very small chance remains that he or she carries an abnormal gene.

What Happens if Both Parents Are Carriers?

A couple in which both partners are carriers should consider consulting a genetic counselor, who can discuss the risks to their future children. A genetic counselor also can discuss the option of prenatal testing (using amniocentesis or CVS) to diagnose or rule out CF in the fetus. As discussed above, each child of parents who both carry an abnormal CF gene has a 25 percent chance of inheriting CF. This means that in three out of four cases, the prenatal test will reveal that the fetus will not have CF. When the fetus is affected, parents can take the time before delivery to learn more about the disease and locate appropriate specialists. Prenatal testing cannot, however, tell how seriously affected the baby may be.

Is the March of Dimes Conducting Research on CF?

March of Dimes research grantees are conducting research aimed at improving understanding of the basic cellular defects in CF, as well as seeking to develop improved treatments for this disorder. One grantee is studying an enzyme that plays a key role in Pseudomonas aeruginosa lung infections, in order to develop drugs to improve treatment of this life-threatening infection. Another is attempting to develop a new type of gene therapy for cystic fibrosis that involves replacing or changing the disease-causing gene in certain cells of the body.

Other researchers, not associated with the March of Dimes, have recently completed a map of all the genes in Pseudomonas aeruginosa, which may eventually lead to development of new drug treatments, and possibly a vaccine to protect against it. Researchers also are exploring the possibility that excess acid in the lungs of those with CF may contribute to bacterial growth, and that treatment to reduce acidity may help prevent infections. A number of new drugs that aim to prevent or treat infections in those with CF are currently being tested.

Other Sources of Information on CF
Cystic Fibrosis Foundation
6931 Arlington Rd.
Bethesda, MD 20814
1-800-344-4823

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