It will work something like this. When you have an illness, your doctor will determine whether the problem is caused by a mutated gene that is giving out faulty instructions for the production of a needed protein. If so, new DNA will be inserted into some of your cells. This new DNA will correct the gene's instruction for making the protein. If the treatment is successful, the repaired gene in these cells will go to work, giving out the proper instructions so that the protein is produced.
Cystic fibrosis is one disease that researchers are trying to cure through gene therapy.
In Chapter 4, we explained that with CF the lungs become clogged, making it hard to breathe. The problem is caused when a gene gives faulty instructions for producing the protein that helps make the mucus lining of the lungs. Doctors are trying to move corrected copies of this gene into the lung cells of CF patients, using a virus . We usually think of a virus as causing illness. However, the kind of virus used in this experiment is harmless.