Cystic Fibrosis

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General Information About Cystic Fibrosis


Although cystic fibrosis is a multisystem disease involving the skin, pancreas, intestines, liver, and male genitourinary tract, much of the morbidity and mortality result from progressive airway involvement.  Pulmonary disease in cystic fibrosis is caused by mutations of the cystic fibrosis transmembrane conductance regulator (CFTR), a chloride channel expressed on the surface of airway epithelial cells and serous cells of submucosal glands.  More than 1,500 mutations are known to cause disease, categorized into five classes based on the manner in which gene expression and CFTR function has been impaired.

The CFTR is functionally linked to other apical chloride channels and the epithelial sodium channel (ENaC). Aberrant expression or function of the CFTR in the airway leads not only to reduced chloride conductance but dysregulation of epithelial sodium channel activity.  Failure of chloride secretion and  sodium hyperabsorption results in dehydration of the airway surface.  The dessicated secretions and thickened mucus obstruct the airways and impair mucociliary clearance, thus rendering the lung susceptible to bacterial infection, most commonly, Pseudomonas aeruginosa and Staphylococcus aureus.  Infection induces an intense inflammatory response that leads to the destruction and dilation of the smaller lower airways (bronchiectasis) and eventually respiratory failure, thus shortening the life of the patient.

All fifty states have newborn screening for cystic fibrosis, though the screening approaches used by individual states vary.  The only reliable diagnostic test is the quantitative pilocarpine iontophoresis test, also known as the sweat test, performed according to Clinical and Laboratory Standards Institute (CLSI) guidelines and preferably at a Cystic Fibrosis Foundation-accredited care center.  Genetic testing for mutant CFTR alleles should also be performed to confirm the diagnosis.

Treatment for cystic fibrosis lung disease is evolving, incorporating newer therapies that have been developed over the last two decades, including nebulized antibiotics, anti-inflammatory agents, inhaled mucolytic agents, and alternative airway clearance techniques.  More recently, novel therapeutics have emerged that restore airway surface liquid or correct effects of specific CFTR mutation classes, which are currently being tested.  If successful, the course of cystic fibrosis lung disease could be forever changed.

The ATS and its Public Advisory Roundtable are committed to the concept that research will lead to cures.  These advances will depend on education, advocacy and research partnerships to be formed among patients, parents, clinicians and scientists.  Increased research funding will allow us to better understand the pathophysiology of cystic fibrosis lung disease, especially early in life, and advance treatments for the many patients and families we serve.

Source:  Thomas Ferkol, MD,  Secretary-Treasurer, American Thoracic Society

Four Facts About Cystic Fibrosis

  1. Cystic fibrosis (CF) is an inherited chronic disease that leads to life-threatening lung infections and digestive problems. It is a rare disease, affecting about 30,000 children and adults in the United State, and there is no cure.
  2. More than 10 million Americans are unknowing, symptomless carriers of the defective CF gene.  All babies born in the United States are screened for CF at birth as part of Newborn Screening (NBS). A “positive” or “abnormal” NBS result indicates that a child might have cystic fibrosis and should receive diagnostic testing. The most accurate way to tell if a child has CF is the sweat test, a diagnostic test that measures how much salt is in a baby’s sweat.
  3. Although severity of the disease varies from person to person, most people with CF:
    • Do some form of airway clearance at least once and sometimes up to four or more times a day.
    • Take aerosolized medicines—liquid medicines that are made into a mist or aerosol and then inhaled through a nebulizer.
    • Take pancreatic enzyme supplement capsules with every meal and most snacks (even babies who are breastfeeding may need to take enzymes).
    • Take multi-vitamins
  4. Median predicted survival is in the late 30’s and rising.

(Source:  www.cff.org)