Is There a "Cystic Fibrosis Gene?"
The cause of
cystic fibrosis (CF) is a defect in the cystic fibrosis transmembrane conductance regulator (CFTR) gene.
This gene for cystic fibrosis makes a protein that controls the movement of salt and water in and out of your cells. In people with cystic fibrosis, the gene does not work effectively. As a result, cells that line the passageways of the lungs,
pancreas, and other organs produce abnormally thick, sticky mucus. This mucus obstructs the airways and glands, which causes the characteristic signs and symptoms of cystic fibrosis.
Other factors may influence the course of cystic fibrosis. For example, changes in genes other than CFTR might help explain why some people with the disease are more severely affected than others. However, most of these genetic changes have not been identified.
How Is the Gene for Cystic Fibrosis Inherited?
Cystic fibrosis is inherited in an autosomal recessive pattern, which means that two copies of the cystic fibrosis gene in each cell are altered. In most cases, the parents of an individual with an autosomal recessive disorder are carriers of one copy of the altered gene, but do not show signs and symptoms of the disorder.
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 carrier like its parents.
