Assertion (A): Cystic fibrosis is an autosomal recessive genetic disorder. Reason (R): It is characterised by defective electrolyte transport in several epithelia.

Directions: In the following question there are two statements, Assertion (A) and Reason (R), consider both the statements independently and mark your answers as under:
1. If A and R both are correct and R is correct explanation of A.
2. If A and R both are correct and R is not correct explanation of A.
3. If A is correct and R is incorrect.
4. If A is incorrect and R is correct.
5. If A and R both are incorrect.

Both statements are true, but R is not correct explanation of A. Cystic fibrosis (Mucoviscidosis) is an autosomal recessive genetic disorder that affects most critically the lungs and also the pancreas, liver, and intestine. It is caused by a point mutation in the gene cystic fibrosis transmembrane conductance regulator. Cystic fibrosis is characterised by abnormal transport of chloride and sodium across the epithelium in all exocrine tissues, leading to thick viscous secretions in the lungs, pancreas, liver, intestine, and reproductive tract and to an increased salt content in sweat gland secretions.