Cystic Fibrosis

Page 1 2 3

What is Cystic Fibrosis?

This animation brought to you by Blausen Medical Communications.
Contact Andrew Walbank.

Cystic Fibrosis is a recessive genetic disorder that affects the mucus lining of the lungs, which leads to breathing problems and other health problems. The lungs are composed of air passages, starting from the trachea (or windpipe) which divides into a left and right main bronchus, which keep dividing until they become bronchioles, and finally terminating into alveoli. The alveoli are small folded membranes shaped like a cluster of grapes. They are the interface between the air and blood stream and that is where gas exchange takes place.

Cystic fibrosis is a genetic disorder of exocrine gland secretion - it leads to thickened secretions within the airways within the lungs - which can subsequently become infected. Thus the affected individual suffers from chronic infection within the lung leading to bronchiectasis. The lungs are not the only glands affected, however - numerous other organs which have exocrine glands (e.g. gut, pancreas, skin, vas deferens) are affected.

Who gets Cystic Fibrosis?

This condition is the most conmon genetic lethal disorders in Caucasian people. One in every 25 babies born in Australia will carry the cystic fibrosis gene. The number of Caucasian infants affected with cystic fibrosis ranges from 1:1600 to 1:2500. Each year 70 babies are born in Australia with cystic fibrosis. As a result, new studies into better screening programs are currently being developed.

Predisposing Factors

Cystic fibrosis is an autosomal recessive condition - that means that a person needs two defective genes (one from each parent) to develop the condition. The gene that has been thought to cause cystic fibrosis is called cystic fibrosis transmembrane conductance regulator or CFTR. This gene has been located on chromosome 7.

Click here to view a diagram showing Cystic Fibrosis inheritance pattern

Progression

The severity and extent of the disease varys greatly amongst cystic fibrosis patients. In general, the condition results in defective chloride ion transport across the epithelial cells and increased viscosity of bodily secretions, specifically secretions from the respiratory tract (i.e. lungs, throat) and pancreas. As a result, the patient is predisposed to pancreatic insufficiency and recurrent chest infections.

This condition may also lead to bowel problems such as malaborption, bowel obstructions and constipation. Due to the abnormal transport of chloride ions, this abnormality can be detected in sweat. This abnormality lead to a diagnostic test for cystic fibrosis, named the sweat test.

Page 1 2 3