The cystic fibrosis transmembrane conductance regulator (CFTR) is a complex protein that helps maintain fluid balance in several organs. Mutations in the CFTR protein can lead to symptoms of cystic fibrosis (CF).

The CFTR is a type of complex protein molecule. Proteins are molecules made up of amino acids. Each cell in the body contains proteins.

Proteins play several important roles. They help build and repair body cells, control many bodily functions, and help transport nutrients around the body.

The CFTR protein helps balance water and salt in many of the organs.

CF is a genetic condition in which mucus builds up in the lungs and digestive system. People with CF have changes to their CFTR protein that affect how it works. This can affect the body in several ways.

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The CFTR protein functions as a channel across the membrane of certain body cells. The membrane is the barrier that surrounds every cell, protecting and organizing them.

It helps maintain the balance of water and salt on many surfaces in the body, such as:

The CFTR protein helps regulate how the body absorbs and produces salts and fluids in these areas as part of cells that produce:

  • mucus
  • sweat
  • saliva
  • tears
  • digestive enzymes

People have a gene that tells their bodies how to make the CFTR protein. If a person has CF, they have mutations to this gene.

Their bodies then make faulty or do not produce enough CFTR proteins. This affects the movement of salt and water in and out of their cells. This leads to thicker and stickier mucus, which can produce symptoms that affect many of the organs.

Cystic fibrosis most often affects the lungs. The CFTR proteins affect how water and chloride move in and out of cells in the lungs, leading to:

  • chloride becoming trapped inside the cells
  • water no longer moving out of the cells

Chloride is part of salt. Less water outside the cells causes mucus in the airways to dehydrate and thicken, leading to mucus sticking in the airways. This causes:

  • breathing problems and difficulty
  • frequent airway infections due to germs in the mucus no longer leaving the airway

Learn more about cystic fibrosis mucus.

The pancreas is a small organ that helps break down parts of food during digestion using fluids called enzymes.

These enzymes flow from the pancreas in small tubes. In people with CF, the CFTR protein causes mucus in these tubes to thicken, blocking the tubes.

This causes enzymes to build up in their pancreas instead of reaching their digestive system. This can lead to several complications, such as pancreatic insufficiency, which is where the small intestine cannot properly digest food.

It may lead to malnutrition.

The CFTR can affect various other organs and systems in people with CF.

Immune system

Thicker mucus in the lungs may build up and further trap bacteria. This may lead to more inflammation and make it harder for the immune system to fight infections.

Bones

CF may cause issues with digestion due to the effect of CFTR on the pancreas. This may include malnutrition, which can lead to the body not getting the necessary vitamins and minerals.

Malnutrition may also lead to a lack of vitamin D and calcium, which are essential for healthy bones. People with CF may have brittle or weak bones, which can lead to fractures.

Liver, bile ducts, and gallbladder

People with CF may have sticky or thicker bile in the bile system. This can cause irritation and inflammation in the bile ducts. This irritation may lead to:

Sweat glands

The effect of CFTR on the movement of sweat and water in the body may cause very salty sweat or salty skin.

Reproductive system

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

Most females with CF are fertile and can become pregnant, but some may take longer to conceive. They may also have:

  • thicker mucus in the cervix
  • ovulation issues due to malnutrition from CF
  • menstrual irregularities

Males with CF typically experience infertility due to other effects of CF.

Several treatments for CF can help manage symptoms or complications.

CFTR modulators are medications that improve how the CFTR protein works. They also help multiple organs in people with CF, as well as:

  • lung function
  • preventing lung problems or other complications

Healthcare professionals use genetic testing to check for mutations to the CFTR gene. Genetic testing can determine whether someone has CF or is a carrier for the CFTR gene mutation.

The tests can use a sample from a person’s blood, saliva, or cells rubbed from inside their cheek.

Learn more about cystic fibrosis testing.

The CFTR is a protein that regulates the composition of mucus and affects the movement of fluids within the cells of the body.

People with CF have CFTR proteins that do not work correctly. This can lead to thicker mucus around the body. They may then experience several symptoms that affect their lungs, digestive system, and other organs.

Certain medications for CF can help manage symptoms and prevent complications associated with CFTR.