Cause of cystic fibrosis
Cystic fibrosis is a genetic condition. It's caused by a faulty gene that affects the movement of salt and water in and out of cells.
This, along with recurrent infections, can result in a build-up of thick, sticky mucus in the body's tubes and passageways – particularly the lungs and digestive system.
A person with cystic fibrosis is born with the condition. It's not possible to "catch" cystic fibrosis from someone else who has it.
How cystic fibrosis is inherited
To be born with cystic fibrosis, a child has to inherit a copy of the faulty gene from both of their parents.
This can happen if the parents are "carriers" of the faulty gene, which means they don't have cystic fibrosis themselves.
It's estimated around 1 in every 25 people in the UK are carriers of cystic fibrosis.
If both parents are carriers, there's a:
- 1 in 4 chance their child won't inherit any faulty genes and won't have cystic fibrosis or be able to pass it on
- 1 in 2 chance their child will inherit a faulty gene from one parent and be a carrier
- 1 in 4 chance their child will inherit the faulty gene from both parents and have cystic fibrosis
If one parent has cystic fibrosis and the other is a carrier, there's a:
- 1 in 2 chance their child will be a carrier
- 1 in 2 chance their child will have cystic fibrosis