Introduction
Cystic fibrosis (CF) is a lung disease that is inherited. It seems much more common in white North Americans (1 in 2,500 births) than in black North Americans (1 in 15,300 births). Asian North Americans have the lowest rate of cystic fibrosis (1 in 32,000).
The abnormality is located on chromosome 7 where two cystic fibrosis transmembrane regulator (CFTR) genes (thanks to www.massgenomics.org for this image) have been found to be mutated. Due to these relatively small genetic changes of a few amino acids on chromosome 7 all of the mucous producing glands in the body produce a mucous plug that closes off various glandular ducts in a multitude of organ systems.
The summation of these effects (mainly in the lungs, the pancreas and the liver) is that the life expectancy is significantly shortened to the point where in white people CF is the most common life shortening disease. Here are some of the organ systems affected:
Organ changes in Cystic fibrosis
| Organ system: | Description of changes: |
| lung tissue | bronchial tree lining produces tenacious mucous plugging up airways and causing chronic bronchitis |
| pancreas | 1. digestive juices cannot reach gut leading to pancreatitis, digestive problems and malabsorption of food2. 10% of CF patients develop insulin dependent diabetes mellitus |
| 98% infertility in males | obstructive testicular problems and high proportion of congenital vas deferens maldevelopment |
| decreased fertility rate in women | due to highly viscous cervical secretions and breathing problems (low blood oxygen) |
| liver tissue | small gall fluid ducts clog up from abnormal tenacious gall fluid leading to liver cirrhosis |
| protruding veins in the lower esophagus that lead to vomiting of blood | esophageal varices form as a result of “portal hypertension” from liver cirrhosis |
| pulmonary hypertension | increase of vascular resistance in the lung increases blood pressure in the pulmonary vessels and in the right heart . Can cause coughing up of blood, called hemoptysis |
| salt depletion | an abnormally high excretion of chloride through the skin leads to electrolyte imbalances with an overall loss of salt |
| nasal polyps | CF patients have a high risk of developing recurrent nasal polyps, which lead to nasal obstruction, nasal infections and chronic recurrent sinus problems |
| gall stones | abnormal secretions and dysbalance of soluble gall fluid components leads to gall stones (see gallbladder disease link) and surgery |
Cystic Fibrosis
References:
1. Noble: Textbook of Primary Care Medicine, 3rd ed., Copyright © 2001 Mosby, Inc.
2. National Asthma Education and Prevention Program. Expert Panel Report II. National Heart, Lung and Blood Institute, 1997.
3. Rakel: Conn’s Current Therapy 2002, 54th ed., Copyright © 2002 W. B. Saunders Company
4. Murray & Nadel: Textbook of Respiratory Medicine, 3rd ed., Copyright © 2000 W. B. Saunders Company
5. Behrman: Nelson Textbook of Pediatrics, 16th ed., Copyright © 2000 W. B. Saunders Company
6. Merck Manual: Cystic Fibrosis (thanks to www.merckmanuals.com for this link)
7. Goldman: Cecil Textbook of Medicine, 21st ed., Copyright © 2000 W. B. Saunders Company
8. Ferri: Ferri’s Clinical Advisor: Instant Diagnosis and Treatment, 2004 ed., Copyright © 2004 Mosby, Inc.
9. Rakel: Conn’s Current Therapy 2004, 56th ed., Copyright © 2004 Elsevier
