Cystic Fibrosis

Basics

Defect of the cystic fibrosis transmembrane conductance regulator (CFTR)
CFTR functions as an ATP-regulated chloride channel that regulates the activity of chloride and sodium channels on the cell surface:
- Abnormal electrolyte transport in exocrine glands and secretory epithelia
- Decreased exocrine pancreatic function with malabsorption
- Thickened mucus, recurrent pulmonary infections, and progressive obstructive damage to the lungs
- Recurrent sinus disease
Occurs in 1:3,600 live births in White population, 1:29,000 in African American population; 1:6,500 in Hispanic population
30% of cases diagnosed by newborn screening
75% cases diagnosed in the first 2 yr of life
∼30,000 children and young adults in the U.S. have CF
Median life expectancy in the U.S. in early 40’s
40% of CF patients are >18 yr
10 million Americans are unknown, asymptomatic carriers of the defective gene
16% of lung transplants in the U.S. due to CF

Genetics
Recessively inherited genetic disease, involving the CFTR gene on the long arm of chromosome 7:

Common organisms in patients with pneumonia; often multiple drug resistance:

Staphylococcus aureus:
- MSSA/MRSA
Pseudomonas aeruginosa:
- Prevalence increases with age; >70% of adults are chronically infected
Haemophilus influenzae
Stenotrophomonas maltophilia
Burkholderia cepacia:
- Prevalence 3%
- Associated with rapid clinical deterioration
Achromobacter xylosoxidans
Mycobacteria (nontuberculous):
- Mycobacterium avium complex, Mycobacterium abscessus
Aspergillus

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