“Changes to the CFTR gene — called variants or mutations — cause cystic fibrosis. CFTR makes a protein that works as an ion channel on the surface of a cell. Ion channels are like gates in a cell’s membrane that allow certain molecules to pass through.

CFTR usually makes a gate for chloride ions, a type of mineral with a negative electrical charge. Chloride moves out of the cell, taking water with it, which thins out mucus and makes it more slippery. In people with CF, gene mutations in CFTR prevent this from happening, so the mucus stays sticky and thick.

There are different categories (classes I to VI) of gene mutation in CFTR that depend on the effect they have. Some produce no proteins at all, some produce only small amounts of proteins, and some produce proteins that don’t work properly.

Are you born with cystic fibrosis?

Yes, cystic fibrosis is a genetic condition that you’re born with. People who have CF inherit two mutated CFTR genes, one from each biological parent (it’s inherited in an autosomal recessive manner). “

Cleveland Clinic (Cystic Fibrosis: Causes, Symptoms & Treatment)