A defect in the CFTR gene causes cystic fibrosis (CF). This gene makes a protein that controls the movement of salt and water in and out of your body's cells. In people who have cystic fibrosis, the gene makes a protein that doesn't work right. This causes thick, sticky mucus and very salty sweat.
Research suggests that the CFTR protein also affects the body in other ways. This may help explain other symptoms and complications of cystic fibrosis.
More than a thousand known defects can affect the CFTR gene. What type of defect you or your child has may influence how severe the cystic fibrosis is. Other genes also may play a role in how severe the disease is.
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