6. Example - Gene therapy for cystic fibrosis
The first gene therapy trial for cystic fibrosis began in 2002. This is a life-limiting disease in which thick mucus builds up in the lungs and intestines. The life expectancy of someone born in 2014 with cystic fibrosis is 40 years. Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR ) gene cause the CFTR protein to function incorrectly. The CFTR protein is involved in the transport of ions, such as sodium and potassium, across epithelial cells. These cells form membranes for various linings of the body, including mucus membranes such as those in the lungs and intestines. When this goes wrong, cystic fibrosis develops.
Several gene therapy trials have been completed in which viral vectors or liposomes carrying functional copies of the CFTR gene have been delivered to the airways via nasal inhalation, but with limited success. Although benefits were observed in some patients, the effects were short lived. It is likely that delivery to the lungs is challenging.