Cystic fibrosis (CF) is an inherited autosomal recessive disorder, characterized by chronic obstructive lung disease, pancreatic exocrine insufficiency, and elevated sweat chloride concentration.
- Due to variability in presentation, the most common pitfalls are failure to diagnose and initiate therapies in a timely manner.
- Diagnosis may be delayed in patients with mild or atypical symptoms.
- Most common lethal inherited disease in the Caucasian population
- Carrier frequency of mutations in the CF transmembrane conductance regulator (CFTR) gene:
- 1:29 in Caucasians
- 1:49 in Hispanics
- 1:53 in Native Americans
- 1:62 in African Americans
- 1:90 in Asians
- 1:3,300 in Caucasians
- 1:9,500 in Hispanics
- 1:11,200 in Native Americans
- 1:15,300 in African Americans
- 1:32,100 in Asians
- Located on the long arm of chromosome 7
- Most common mutation results in deletion of phenylalanine at position 508 in the CFTR glycoprotein.
- The Δ508 mutation occurs in ~70% of CF patients.
- >1,700 mutations have been reported in the CFTR gene.
- Presence of gene modifiers may cause incomplete phenotypic presentations.
Prepregnancy carrier detection
- Membrane glycoprotein, which functions as a cyclic AMP–activated chloride channel at the apical surface of epithelial cells
- An abnormality in CFTR results in defective chloride conductance.
- May have other roles in the regulation of membrane channels and the pH of intracellular organelles; may affect cell apical sodium channel regulation
- CFTR abnormalities may act as binding sites for Pseudomonas aeruginosa, promoting proinflammatory responses in the lung.
- In the respiratory system
- Increased mucus viscosity
- Early bacterial colonization despite a robust neutrophilic inflammatory response
- Mucous plugging and atelectasis
- Bronchiectasis and emphysema develop.
- Abnormal nasal sinus development
- In the gastrointestinal (GI) tract
- Progressive pancreatic damage leads to exocrine pancreatic insufficiency.
- Endocrine pancreatic dysfunction
- Focal biliary cirrhosis of the liver
- Hypoplasia of the gallbladder and impaired bile flow
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