An autosomal recessive disordered caused by faulty ion transport that results in respiratory, digestive, and reproductive complications.

Detailed Definition

that plugs the lungs and pancreas. There are about 30,000 people with CF in the US, making it one of the most common genetic disorders among the Caucasian population.

CF is inherited as an autosomal recessive disorder. This means that for two parents to have a child with CF, both parents must be carriers of one non-working gene. If both parents are carriers, then their child has a one-in-four (25%) chance of having CF, a one-in-two (50%) chance of being a carrier, and a one-in-four (25%) chance of being neither affected nor a carrier. These probabilities remain the same even if it is the couple’s second or third child. Carriers are of normal health and most often do not know they are carriers.

Common symptoms of CF include a long-lasting cough with increased phlegm, wheezing, sinus disease, and frequent lung infections. Pancreatic insufficiency, in which the many enzymes and secretions normally produced by the pancreas are defective or less concentrated, is another feature of CF. Failure to thrive, liver disease, recurrent pancreatitis, salt-loss syndromes, meconium ileus (a gastrointestinal condition), and certain vitamin deficiencies are also common with CF. The majority (98%) of males with CF is infertile due to congenital absence or atresia of the vas deferens. However, new technology provides opportunities for these men to father children.

Although almost two-thirds of people affected by CF are diagnosed before the age of 1 year, CF is highly variable. Many people have mild symptoms and are diagnosed in adulthood. People affected by CF usually look normal, although they are often thinner and slightly shorter than average.

Causes/Types

CF occurs when mutations are present in both copies of a person’s CF gene. The CF gene makes a protein that functions as a chloride channel in the cell membranes of epithelial cells (cells on the surface of the respiratory and digestive system tracts). This protein is called CF transmembrane conductance regulator (CFTR). When the CF gene is mutated, a defective chloride channel can be produced, leading to high sweat chloride levels and thick mucus in the lungs and pancreas. This causes the phenotype (physical expression) of CF.

Diagnosis

The sweat chloride test can make a diagnosis in a person suspected of having CF by measuring the amount of chloride in the person’s sweat.

CF DNA testing is a laboratory test that analyzes people’s DNA for a mutation in the CF gene that could lead to CF. This test is available to confirm a diagnosis, as well as to test for carriers. It can also be used for prenatal diagnosis on a fetus at risk for having CF by using chorionic villus sampling (CVS) or amniocentesis to acquire the necessary fetal cells for testing. However, because of the large number of mutations possible in the CF locus, this test is not always definitive.

Newborn screening by an immunoreactive trypsinogen (IRT) blood test is also practice in some states to test newborn babies for CF.

If you are an individual with a family history of CF, or if you have a reproductive partner with CF, you are eligible for testing. Also, if you or your reproductive partner is of Caucasian descent, and you are planning a pregnancy or are already pregnant, then CF testing should be considered.

Treatment/Services

There is no cure for CF, but treatments are currently being researched and are improving. Patients require daily chest therapy, medications, and periodic hospitalizations.

Other Information

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