Understanding Cystic Fibrosis

Causes of Cystic Fibrosis (CF)

CF is caused by hundreds of different gene mutations. The most common mutation is delta F508, usually written as ΔF508.⁹

Channels within the cell membrane allow for the influx or exit of ions such as sodium (NA^±), potassium (k^±), chloride CI”), and calcium (Ca²^±). CI” channels perform several functions, including the transport of chloride ions out of the epithelial cells to the mucus layer. This causes the movement of positively charged sodium ions in the same direction, resulting in the movement of water to the outside by osmosis, making mucus more fluid.

Cystic fibrosis transmembrane regulator (CFTR) regulates the chloride channels found in epithelial cells of all exocrine tissues, such as the sweat glands, and in epithelial cells lining organs in the respiratory and gastrointestinal (GI) tracts.

Source: Adapted from Harrison's Internal Medicine. 16th ed. Chapter 241¹

The result of these mutations is less water reaching the mucus layer. Because of this, thick, sticky mucus secretions clog the intestines and ducts in the digestive organs and build up in the bronchi and lungs, providing a harbor for pathogens.^1,5,7

References:
1. Boucher RC. Cystic Fibrosis. In: Kasper DL, Braunwald E, Fauci AS, Hauser SL, Longo DL, Jameson JL et al., editors. Harrison's Internal Medicine. 16th ed. New York: McGraw-Hill; 2005. p. 1-9.
5. Mason P. Cystic fibrosis-the disease. Hospital Pharmacist 2005;12:201-7.
7. Knowles MR, Durie PR. What is cystic fibrosis? N Engl J Med 2002 August 8;347(6):439-42.
9. Farrell PM, Kosorok MR, Rock MJ, et al. Early diagnosis of cystic fibrosis through neonatal screening prevents severe malnutrition and improves long-term growth. PEDIATRICS 2001;107:1-13.