Everything to know about cystic fibrosis and what causes it

USA Today

10-02-2025

Breathing disorders are common in the U.S. with conditions like COPD affecting some 7% of the population and asthma affecting another 10%. Digestive conditions like GERD, acid reflux, Celiac disease and IBS negatively impact countless millions more.
The genetic disorder cystic fibrosis is unique because it can cause both breathing and digestive problems. Some 40,000 people in the U.S. currently have it, "though this is likely an underestimate as many patients may have mild forms of the condition and remain undiagnosed," says Dr. Ashwin Basavaraj, system chief of pulmonary medicine at NYC Health + Hospitals.
Here's what cystic fibrosis is, what causes it and how it's usually treated once it has been diagnosed.
What is cystic fibrosis (CF) disease?
Cystic fibrosis (CF) is a progressive genetic disease that adversely affects a person's lungs, pancreas and other vital organs, says Dr. Michael Boyle, president and CEO of the Cystic Fibrosis Foundation in Bethesda, Maryland. The disease impacts the lungs by clogging airways with sticky, thick mucus, which traps bacteria and other germs and sometimes leads to inflammation, respiratory infections and even respiratory failure.
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The buildup of mucus in the pancreas can also prevent the release of digestive enzymes that help the body absorb food, "leading to digestive abnormalities, malnutrition and stunted growth," says Basavaraj.
Other common symptoms of CF include coughing attacks (often with phlegm), shortness of breath, greasy and bulky stools, rectal prolapse and constipation. "People with CF are also more susceptible to sinus and respiratory infections and often require persistent use of antibiotics, leading to concerns over antibiotic resistance," adds Boyle.
CF can also affect the liver, sometimes causing liver disease, as well as impact the reproductive system, sometimes "causing infertility in men," says Basavaraj.
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What causes cystic fibrosis? Is cystic fibrosis genetic?
Cystic fibrosis is caused by mutations in a gene known as the cystic fibrosis transmembrane conductance regulator (CFTR), says Basavaraj. He explains that these mutations eventually cause a protein imbalance and water and salt in the body's cells to surface, "resulting in mucus becoming thick and sticky, and difficulty clearing airways and other organs."
In other words, people with CF are born with the disease, inheriting a copy of this gene from each parent, says Boyle.
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How is cystic fibrosis treated?
While there is no cure for CF, there are multiple treatment options. Basavaraj says such options include bronchodilators to help open airways; mucus-thinning medications to help clear up the sticky substance; high-frequency chest wall oscillation (HFCWO) devices to help clear mucus from the lungs; and pancreatic enzymes to help with digestion and nutrient absorption.
Moreover, "there are currently five FDA-approved CFTR modulator oral therapies on the market that each address the underlying cause of cystic fibrosis," adds Boyle. These were developed to be effective against specific mutations and more modulator therapies are in development.
Despite the many advantages these therapies provide, "approximately 10% of individuals cannot benefit from modulators due to their genetic mutations or ability to tolerate the treatment," says Boyle. Because of this, he says, "many people living with CF are still waiting for their breakthrough, which is why we are urgently pursuing efforts to ensure there are treatments available to them."