What Causes Cystic Fibrosis?
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 CF, 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 CF.
More than a thousand known defects can affect the
CFTR gene. What type of defect you or your child has may influence how severe
CF is. Other genes also may play a role in how severe the disease is.
How Is Cystic Fibrosis Inherited?
Every person inherits two CFTR genesone from
each parent. Children who inherit a faulty CFTR gene from each parent will have
CF.
Children who inherit a faulty CFTR gene from one
parent and a normal CFTR gene from the other parent will be "CF carriers." CF
carriers usually have no symptoms of CF and live normal lives. However,
carriers can pass the faulty CFTR gene on to their children.
The following image shows how two parents who are
both CF carriers can pass the faulty CFTR gene to their children.
Example of an Inheritance
Pattern for Cystic Fibrosis
The image shows how CFTR genes are
inherited. A person inherits two copies of the CFTR geneone from each
parent. If each parent has a normal CFTR gene and a faulty CFTR gene, each
child has a 25 percent chance of inheriting two normal genes; a 50 percent
chance of inheriting one normal gene and one faulty gene; and a 25 percent
chance of inheriting two faulty genes.
|