Which genetic disorder is caused by a mutation in the CFTR gene?

Cystic fibrosis is directly caused by a mutation in the CFTR gene, which plays a crucial role in regulating the movement of salt and water in and out of the cells. This gene encodes a protein called cystic fibrosis transmembrane conductance regulator, important for maintaining the balance of sweat, digestive juices, and mucus.

When mutations occur in the CFTR gene, it can lead to the production of a faulty protein that results in thick, sticky mucus buildup in various organs, primarily affecting the lungs and the digestive system. This can cause severe respiratory issues, difficulty in digestion, and increased risk of infections, which are hallmark symptoms of cystic fibrosis.

The other options represent different genetic disorders that arise from mutations in different genes, unrelated to the CFTR gene. For example, sickle cell anemia is caused by a mutation in the HBB gene, Duchenne muscular dystrophy is linked to mutations in the DMD gene, and hemophilia results from mutations in genes that affect blood clotting factors. Each of these disorders has distinct genetic causes and associated symptoms, further underscoring why cystic fibrosis is uniquely connected to the CFTR gene.