Cystic fibrosis is a progressive, genetic disease that causes persistent lung infections and limits the ability to breathe over time.
In people with CF, mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause the CFTR protein to become dysfunctional. When the protein is not working correctly, it’s unable to help move chloride -- a component of salt -- to the cell surface. Without the chloride to attract water to the cell surface, the mucus in various organs becomes thick and sticky.
In the lungs, the mucus clogs the airways and traps germs, like bacteria, leading to infections, inflammation, respiratory failure, and other complications. For this reason, minimizing contact with germs is a top concern for people with CF.
In the pancreas, the buildup of mucus prevents the release of digestive enzymes that help the body absorb food and key nutrients, resulting in malnutrition and poor growth. In the liver, the thick mucus can block the bile duct, causing liver disease. In men, CF can affect their ability to have children.
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
Diagnosis and Genetics
Cystic fibrosis is a genetic disease. People with CF have inherited two copies of the defective CF gene -- one copy from each parent. Both parents must have at least one copy of the defective gene.
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 a slight abnormality called a mutation. There are more than 1,700 known mutations of the disease. Most genetic tests only screen for the most common CF mutations. Therefore, the test results may indicate a person who is a carrier of the CF gene is not a carrier.
Diagnosing cystic fibrosis is a multistep process, and should include a newborn screening, a sweat test, a genetic or carrier test, and a clinical evaluation at a CF Foundation-accredited care center. Although most people are diagnosed with CF by the age of 2, some are diagnosed as adults. A CF specialist can order a sweat test and recommend additional testing to confirm a CF diagnosis.
Read the CF Foundation’s clinical care guidelines for diagnosing CF.
According to the Cystic Fibrosis Foundation Patient Registry, in the United States:
More than 30,000 people are living with cystic fibrosis (more than 70,000 worldwide).
Approximately 1,000 new cases of CF are diagnosed each year.
More than 75 percent of people with CF are diagnosed by age 2.
More than half of the CF population is age 18 or older.
Dorothy Hansine Andersen
First described cystic fibrosis in 1938.