When a change in DNA results in an error in a protein sequence, partially or completely non-functional proteins are created and, in certain cases, a medical condition can result. This is commonly referred to as a harmful mutation. Mutations in the CF transmembrane conductance regulator (CFTR) gene, which encodes a protein expressed in the apical (top) membrane of exocrine epithelial cells, have been found to cause Cystic Fibrosis, a hereditary disorder that affects exocrine glands and is an example of harmful mutation. It causes the production of abnormally thick mucus, resulting in blockage and (often) respiratory infection affecting many of the body’s organs. Some symptoms of this disorder include coughing up thick mucus, commonly acquiring
