Definition

Cystic Fibrosis Overview

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What is cystic fibrosis?

Cystic fibrosis (CF) is an inherited disease of the glands that make mucus and sweat. People with CF get a defective gene from both parents. People who have one defective gene from one parent are called carriers. They don't have the disease.

CF is a long-term (chronic) disease that gets worse over time. It is a life-limiting condition. In recent decades, new medicines and improved treatment of respiratory infections and other problems have extended the life expectancy of people with CF.

CF affects a cell protein called cystic fibrosis transmembrane conductance regulator (CFTR). CFTR controls the flow of water and certain salts in and out of the body's cells. As the movement of salt and water in and out of cells is changed, the mucus that many cells normally make gets thicker. This thicker mucus can affect many organs and body systems including:

  • Respiratory. This includes sinuses and lungs.

  • Digestive. This includes pancreas, liver, gallbladder, and intestines.

  • Reproductive. Both men and women may have reproductive problems.

  • Sweat glands. CF makes sweat very salty. When people with CF sweat, they lose large amounts of salt. This upsets their body’s mineral balance and leads to other health problems.

About 40,000 people in the U.S. have the disease. More than half of those with CF in the U.S. are age 18 or older. In the U.S., CF affects both males and females from all racial and ethnic groups. But it is more common in white people whose families are from northern Europe. It is less common among African Americans, Hispanic Americans, Asian Americans, and American Indians.

About 1 in 30 people in the U.S. is a carrier of the cystic fibrosis gene. They don't have symptoms. Often they don't know that they are carriers.

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Online Medical Reviewer: Chris Southard RN

Online Medical Reviewer: Deborah Pedersen MD

Online Medical Reviewer: Jessica Gotwals RN BSN MPH

Date Last Reviewed: 09/01/2025

© 2000-2026 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.

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