Cystic Fibrosis Home > Causes of Cystic Fibrosis
The primary cause of cystic fibrosis is a defect in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The condition occurs when a child receives an abnormal CFTR gene from each parent. A child who inherits one abnormal gene and one normal gene will not develop cystic fibrosis.
The cause of cystic fibrosis (CF) is a defect in a gene called the cystic fibrosis transmembrane conductance regulator (CFTR) gene. This gene makes a protein that controls the movement of salt and water in and out of the cells in your body. In people with cystic fibrosis, the gene does not work effectively. This causes the thick, sticky mucus and very salty sweat that are the main features of cystic fibrosis.
Each of us inherits two CFTR genes, one from each parent. Children who inherit an abnormal CFTR gene from each parent will have cystic fibrosis. Children who inherit an abnormal CFTR gene from one parent and a normal CFTR gene from the other parent will not have cystic fibrosis. However, they will be cystic fibrosis carriers.
Cystic fibrosis carriers:
- Usually have no symptoms of cystic fibrosis
- Live normal lives
- Can pass the abnormal CFTR gene on to their children.
When two cystic fibrosis carriers have a baby, the baby has a:
- One in four chance of inheriting two abnormal CFTR genes and having cystic fibrosis.
- One in four chance of inheriting two normal CFTR genes and not having cystic fibrosis or being a carrier.
- Two in four chance of inheriting one normal CFTR gene and one abnormal CFTR gene. The baby will not have cystic fibrosis, but will be a cystic fibrosis carrier like its parents.