Reza Samad, MD, is a board-certified pulmonologist and assistant professor of medicine.
Cystic fibrosis (CF) is an inherited, life-threatening disorder that damages the lungs and digestive tract. It is caused by a defective gene that triggers the production of thickened mucus that clogs airways and blocks the secretion of digestive enzymes.
Symptoms are progressive and often severe, and they may include breathing problems, recurrent lung infections, poor growth, male infertility, and chronic inflammation of the pancreas, liver, kidneys, and heart.
CF can be diagnosed with blood tests, genetic screening, and a procedure known as a sweat chloride test. While there is no cure for CF, there are treatments that can improve both the length and quality of one's life.
Cystic fibrosis is caused by a mutation (a change in the DNA sequence) of the cystic fibrosis transmembrane receptor (CFTR) gene. A defect in this gene, of which there are more than 2,000 known mutations, results in the abnormal accumulation of thick, sticky mucus in the lungs and digestive system. Two copies of the mutated CFTR gene must be inherited in order to get the disease.
Every person has two copies of the cystic fibrosis transmembrane receptor (CFTR) gene. If a person inherits two copies of the mutated CFTR gene, one from each parent, they will have cystic fibrosis. This means that cystic fibrosis is inherited in an autosomal recessive pattern.
No. Cystic fibrosis is not a contagious disease. Therefore, the disease cannot be contracted by kissing, hugging, holding hands, or coming into contact with the blood or bodily fluids of an infected person. The only way to get cystic fibrosis is by inheriting two abnormal cystic fibrosis genes, one from each parent.
Cystic fibrosis affects about 30,000 people in the United States and 70,000 people worldwide. Even though the disease is rare, about 1 in 30 Americans is a carrier of the abnormal gene that causes cystic fibrosis.
Cystic fibrosis is a recessive disease. This means that in order to get cystic fibrosis, a person needs to inherit the abnormal gene from both parents. If a person gets the abnormal gene from only one parent, they will not have cystic fibrosis—however, they may pass the gene on to their children.
The cystic fibrosis transmembrane conductance regulator (CFTR) is a protein that regulates the movement of chloride (a component of salt) and water within cells. In cystic fibrosis, the CFTR protein is defective, which causes chloride to be trapped inside cells and water to be unable to hydrate the outer surfaces of cells. As a result, thick mucus builds up within the lungs and other organs.
A genetic disease results from a change in the DNA sequence of one or more genes (called a mutation). Some genetic diseases, such as cystic fibrosis, are caused by a mutation in a single gene. Others are caused by mutations in multiple genes or by a combination of gene mutations and environmental factors.
Your lungs normally carry oxygen into your bloodstream (when you inhale) and remove the waste gas carbon dioxide (when you exhale). Respiratory failure occurs when this gas exchange function becomes impaired. As a result, the cells in your body experience a lack of oxygen, a buildup of carbon dioxide, or some combination.
A sweat test is considered the “gold standard” for diagnosing cystic fibrosis. During this test, the amount of chloride (a component of salt) is measured from sweat collected from a small area of a child’s arm or leg. Children with cystic fibrosis have high levels of chloride in their sweat.
Cystic Fibrosis Foundation. About cystic fibrosis.
Cystic Fibrosis Foundation. Basics of the CFTR protein.
National Human Genome Research Institute. Genetic disorders. Updated May 18, 2018.
Cystic Fibrosis Foundation. Sweat test.
American Lung Foundation. Learn about cystic fibrosis. Updated March 4, 2020.
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