Cystic Fibrosis
Cystic Fibrosis DEFINITION, ETIOLOGY, PATHOGENESIS Cystic fibrosis (CF) is a genetic disorder causing abnormal secretion of the exocrine glands, mainly affecting the respiratory and gastrointestinal (GI) systems. It is caused by mutations of the CFTR gene encoding CFTR (cystic fibrosis transmembrane conductance regulator; a cellular membrane protein that acts on chloride ion channels in epithelial cells). Synthesis of the defective protein affects the transmembrane transport of sodium and chloride, resulting in lumen dehydration and reduction in water content of exocrine secretions and mucus. High concentrations of sodium chloride inactivate the enzymes and proteins involved in local response to infection.Abnormalities of the respiratory system include increased mucus secretion and retention with secondary chronic infections (DNA released from dead neutrophils increases the mucus viscosity) leading to mucus plugging, segmental atelectasis, bronchiectasis, and cysts (subpleu...