CFTR Cl- channel function in native human colon correlates with the genotype and phenotype in cystic fibrosis

Gastroenterology. 2004 Oct;127(4):1085-95. doi: 10.1053/j.gastro.2004.07.006.


Background & aims: Cystic fibrosis (CF) is caused by over 1000 mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene and presents with a widely variable phenotype. Genotype-phenotype studies identified CFTR mutations that were associated with pancreatic sufficiency (PS). Residual Cl- channel function was shown for selected PS mutations in heterologous cells. However, the functional consequences of most CFTR mutations in native epithelia are not well established.

Methods: To elucidate the relationships between epithelial CFTR function, CFTR genotype, and patient phenotype, we measured cyclic adenosine monophosphate (cAMP)-mediated Cl- secretion in rectal biopsy specimens from 45 CF patients who had at least 1 non-DeltaF508 mutation carrying a wide spectrum of CFTR mutations. We compared CFTR genotypes and clinical manifestations of CF patients who expressed residual CFTR-mediated Cl- secretion with patients in whom Cl- secretion was absent.

Results: Residual anion secretion was detected in 40% of CF patients, and was associated with later disease onset (P < 0.0001), higher frequency of PS (P < 0.0001), and less severe lung disease (P < 0.05). Clinical outcomes correlated with the magnitude of residual CFTR activity, which was in the range of approximately 12%-54% of controls.

Conclusions: Specific CFTR mutations confer residual CFTR function to rectal epithelia, which is related closely to a mild disease phenotype. Quantification of rectal CFTR-mediated Cl- secretion may be a sensitive test to predict the prognosis of CF disease and identify CF patients who would benefit from therapeutic strategies that would increase residual CFTR activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Child
  • Child, Preschool
  • Chlorides / metabolism
  • Colon / metabolism*
  • Cyclic AMP / physiology
  • Cystic Fibrosis / genetics
  • Cystic Fibrosis / metabolism*
  • Cystic Fibrosis Transmembrane Conductance Regulator / genetics
  • Cystic Fibrosis Transmembrane Conductance Regulator / physiology*
  • Genotype
  • Humans
  • Infant
  • Infant, Newborn
  • Middle Aged
  • Mutation
  • Phenotype


  • CFTR protein, human
  • Chlorides
  • Cystic Fibrosis Transmembrane Conductance Regulator
  • Cyclic AMP