Cystic fibrosis is primarily characterized by recurrent lung infections and digestive and pancreatic dysfunction. The Cystic Fibrosis Foundation reports that approximately 30,000 Americans have the disease. According to an article in the February 2008 issue of "PLoS Computational Biology," more than 90 percent of people with cystic fibrosis carry mutated genes that encode for a protein called the cystic fibrosis transmembrane conductance regulator. The amino acid affected by this mutation, phenylalanine, is deleted from the protein, and no other amino acid is inserted in its place.
Mutation
A mutation is any change in the sequence of DNA. In the case of the cystic fibrosis transmembrane conductance regulator, also called CFTR, a mutation in the DNA sequence causes a deletion of the amino acid phenylalanine from position number 508. The article in "PLoS Computational Biology" reports that the deletion of phenylalanine from the CFTR protein causes it to not be folded correctly and increases its rate of degradation.
Prevalence
The genetic mutation that causes cystic fibrosis is inherited from a person's mother and father. Cystic fibrosis develops only when genes from both parents are defective; clinical symptoms are not found in people who have only one mutated CFTR gene. The Merck Manuals Online Medical Library reports that approximately 3 percent of Caucasians carry one defective CFTR gene, and the prevalence of the mutated gene is lower in other ethnic groups. This source notes that the incidence of cystic fibrosis in whites is approximately 1 in 13,300 births; in blacks, it is 1 in every 15,300 births; and in Asian-Americans, it is 1 in every 32,000 births.
CFTR Function
The protein CFTR is found in the cell membranes of the digestive system, pancreas, lungs and reproductive organs. It functions to transport salt and water into and out of cells. When its function is compromised, excess mucus builds up, causing the symptoms of cystic fibrosis. Although the disease affects multiple organs, the most prominent symptom of cystic fibrosis is impaired lung function resulting from decreased mucus clearance from the lungs.
Treatments
As of 2011, treatments for cystic fibrosis focus on the symptoms; they cannot correct the function of the CFTR protein. But the Cystic Fibrosis Foundation reports that drugs such as VX-770, VX-809 and ataluren, which aim to correct the function of the defective CFTR, are being investigated for their effectiveness in treating cystic fibrosis.
References
- Cystic Fibrosis Foundation: Overview
- The Merck Manuals Online Medical Library: Cystic Fibrosis
- "PLoS Computational Biology"; Diminished Self-Chaperoning Activity of the "F508 Mutant of CFTR Results in Protein Misfolding; Adrian W. R. Serohijos et al.; February 2008
- Cystic Fibrosis Foundation: Drug Development Pipeline
