Cystic fibrosis

Question

This gene codes for a transmembrane protein that regulates ion channels in epithelial tissue. Provide an explanation for how this deletion could result in cystic fibrosis.​

Answer 1

Cystic fibrosis (CF) is a genetic disorder with the hallmark symptom of buildup of thick sticky mucus in the lungs. CF is caused by a mutations in the CFTR protein (encoded by the CFTR gene), which is an transmembrane ion channel protein that primarily conducts chloride (Cl-) ions across epithelial cell membranes to the extracellular (outside the cell) space. Normally the CFTR channel allows for a balance of Chloride ions, and consequently water, across epithelial cell membranes, keeping mucous in areas like the nasal passages and lungs watery and pliable.

If the CFTR gene is deleted, there would be a loss of CFTR and a buildup of chloride ions inside the cell. Water, following its osmotic gradient (where salt or solute concentration is highest), would buildup inside the cell and leave the epithelial cell surface and mucus, leading to buildup of thick, sticky mucus and cause cystic fibrosis.