A cell undergoing cell division.
Gene therapy involves isolating a gene and putting it into new cells so that it may function in a way that does not harm the patient. Genetic information is carried in DNA strands which are found in the nucleus of a cell. By cell division, DNA is replicated and is distributed to its offspring cells. This is the naturally occurring method in which scientists use to proliferate desired genes into patients.
Identifying the Normal & Affected Gene
Once the abnormal gene has been identified, copies of the normal gene must be isolated and cloned. Unfortunately, identifying the affected gene is not a simple task; it requires hundreds of experiments, luck, and extensive resort to recombinant DNA technology. The process of cloning involves combining the desired gene with DNA sequences that are easily able to be copied in small organisms such as yeasts and bacteria.
Techniques of Insertion into Human Cells
Now the full DNA, both gene and the rest of the added sequence, is inserted into the small organism which is copied as the cells undergo cell division. Scientists are left with numerous, usually millions or billions of copies of the desired gene, as they clear away the remaining cell components. These copies are once again combined with DNA that is suitable for insertion into human cells which can be administered in several ways: using harmless viruses, physically injecting it, treating the DNA chemically so that cells may take it up, treating the cells so that they are induced in the DNA, or by fusing the cells with membranes that contain the DNA. In any case, mutations are the cause of heredity changes.