Which of the following statements about cystic fibrosis (CF) is not true –

Cystic fibrosis is an autosomal recessive disorder of ion transport in epithelial cells that affect fluid secretion in exocrine glands and the epithelial lining of the respiratory, gastrointestinal and reproductive tracts. Cystic fibrosis occurs due to mutation in the CFTR gene. CFTR was initially recognized as chloride conductance channel but it is now recognized that CFTR can regulate multiple ion channels and cellular processes. These include : Chloride channels Potassium channels Gap junction channels Bicarbonate ions