What causes cystic fibrosis and how common is it?
Cystic fibrosis is a genetic disorder. If you have cystic fibrosis, a particular pair of genes (on chromosome 7) do not work properly. This pair of genes help to control the way the cells handle sodium and chloride ions ('salt'). There are many different abnormalities (mutations) of the 'cystic fibrosis gene', but, basically, they all stop the cell from handling sodium and chloride properly.
As a result, cells in affected organs have a fault in the way sodium and chloride travel in and out of the cells. Basically, too much sodium travels into the cells. Water follows the sodium which leaves too little water outside the cells. This causes the mucus or watery secretions outside the cells to be too thick (for example, in the airways of the lungs).
About 1 in 2500 babies in the UK are born with cystic fibrosis. Cystic fibrosis is an autosomal recessive disorder. This means that in order to develop cystic fibrosis you need to inherit two cystic fibrosis genes, one from your mother and one from your father. If you inherit only one cystic fibrosis gene, you are called a carrier.
About 1 in 25 people in the UK of caucasian decent (white european) are carriers of the cystic fibrosis gene. It is much less common in Afro-Caribbean and Asian people. Carriers do not have the disease as they have one normal gene which can control the salt transport in their cells. But carriers can pass the cystic fibrosis gene on to their children.
When two people who carry the cystic fibrosis gene have a child, there is a:
- 1 in 4 chance that the child will have cystic fibrosis (by inheriting the cystic fibrosis gene from both parents).
- 2 in 4 chance that the child will not have cystic fibrosis, but will be a carrier (by inheriting a cystic fibrosis gene from one parent but the normal gene form the other parent).
- 1 in 4 chance that the child will not have cystic fibrosis, and will not be a carrier (by inheriting the normal gene from both parents).
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- Cystic fibrosis
- What are the symptoms of cystic fibrosis?
- Other symptoms and complications of cystic fibrosis
- How is cystic fibrosis diagnosed?
- What is the treatment for cystic fibrosis?
- Treatments for cystic fibrosis continued
- Other problems linked to Cystic Fibrosis
- What is the outlook for cystic fibrosis?
