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CF Etiology: Loss of CFTR protein activity leads to cystic fibrosis

Loss of CFTR protein activity is the underlying cause of cystic fibrosis (CF). Individual CFTR mutations can lead to decreased quantity or function (and sometimes both) of CFTR proteins at the epithelial cell surface. These defects in CFTR proteins limit ion transport through the apical cell membrane.1,2

Defective ion transport in the lungs, pancreas, gastrointestinal (GI) system, sinuses, skin, and reproductive system leads to the symptoms of CF. The resulting imbalance of fluid and electrolytes causes thick, sticky mucus (in lungs, sinuses) or viscous secretions (in pancreas, GI tract, reproductive tract) to accumulate, which interferes with the proper function of these organs. Defective chloride ion transport in the sweat gland leads to high salt concentration in sweat, but does not impact the morphology of the gland.1-5

The underlying cause of CF is loss of CFTR activity due to defective CFTR protein

Underlying cause of CF

Understand the importance of CFTR protein defects’ effect on total CFTR activity.

  1. Zielenski J. Genotype and phenotype in cystic fibrosis. Respiration. 2000;67(2):117‐133.
  2. Orenstein DM, Spahr JE, Weiner DJ. Cystic Fibrosis: A Guide for Patient and Family. 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2012.
  3. Ramsey B, Richardson MA. Impact of sinusitis in cystic fibrosis. J Allergy Clin Immunol. 1992;90(3 Pt 2):547-552.
  4. Moskowitz SM, Chmiel JF, Sternen DL, et al. Clinical practice and genetic counseling for cystic fibrosis and CFTR-related disorders. Genet Med. 2008;10(12):851-868.
  5. Welsh MJ, Ramsey BW, Accurso F, Cutting GR. Cystic fibrosis: membrane transport disorders. In: Valle D, Beaudet A, Vogelstein B, et al, eds. The Online Metabolic & Molecular Bases of Inherited Disease. The McGraw‐Hill Companies Inc; 2004:part 21, chap 201.