Question

CFTR is present in many other types of epithelial cells, including in the lung and in the pancreas. Cholera does not typically affect these tissues, since infection occurs in the gut, and cholera toxin does not move into the bloodstream. However, some people have a mutation in CFTR that decreases its activity, and thus reduces the release of chloride ions from the cytosol of epithelial cells into the lumen of these organs. Which of the following are the most likely consequences of such CFTR mutations? (select two answers)

no change in fluid secretion from the tissues where CFTR is expressed

decreased fluid secretion from the tissues where CFTR is expressed

increased fluid secretion from the tissues where CFTR is expressed

no change in susceptibility to cholera infection

decreased susceptibility to cholera infection

increased susceptibility to cholera infection

Answer 1

Ans : Option 2 and 5

Decreased fluid secretion from the tissues where CFTR is expressed.

Decreased susceptibility to cholera infection.

Reason :

The CFTR (Cystic Fibrosis Transmembrane Regulator) gene produces the CFTR protein, which regulates the chloride ion (Cl^-) content of epithelial cells that line the nasal cavity, lungs, and stomach. These cells secrete fluids such as sweat, mucus, and tears, which normally are thin and watery. A mutation in CFTR decreases its activity and chloride ions (Cl^-) cannot leave the cell properly through the CFTR protein. Therefore water is retained in the cell due to osmosis and these fluids will become thicker than they should be. This will lead to Cystic Fibrosis, a condition in which obstruct the intestine and block breathing in the lungs.

Cholera kills by causing a severe and unrelenting loss of fluid. Most of the disease victims die from dehydration. Since mutation in CFTR protein results in retaining water and fluid in the cells due to osmosis it gives protection against cholera and have decreased susceptibility to cholera infection.