Cystic Fibrosis

Basics

Description

  • 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
    • Cystic fibrosis-related diabetes
  • Occurs in 1:3200 live births in White Americans, 1:10,000 in Hispanic Americans; 1:10,500 in Native Americans; 1:15,000 in Black Americans; 1:30,000 in Asian Americans
  • Affects 40,000 children and adults in US
  • Affects at least 105,000 people in 90 countries
  • >50% of cases in US diagnosed by newborn screening
  • >75% cases diagnosed in the 1st 2 yr of life
  • Median predicted life expectancy: 51.3 yr
  • >50% of CF patients in North America are >18 yr
  • Approximately 1 in 30 Americans are carriers of the defective gene
  • 17% of lung transplants in the US due to cystic fibrosis (CF)
  • CFTR-related metabolic syndrome/cystic fibrosis screen-positive inconclusive diagnosis (CRMS/CFSPID)

Risk Factors

Genetics

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

  • Different mutations; variable phenotypes
  • Classic disease: Homozygous Phe508del mutation
  • Most common lethal genetic disease in the US

Etiology

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

  • Staphylococcus aureus:
    • MSSA/MRSA
  • Pseudomonas aeruginosa:
    • Prevalence increases with age; >60% of adults are chronically infected
  • Haemophilus influenzae
  • Stenotrophomonas maltophilia
  • Burkholderia cepacian complex:
    • Prevalence 1.4%
    • Associated with rapid clinical deterioration
  • Achromobacter xylosoxidans
  • Mycobacteria (nontuberculous):
    • Mycobacterium avium complex, Mycobacterium abscessus
  • Aspergillus: allergic bronchopulmonary aspergillosis (ABPA)

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