Gene therapy is used treat and sometimes it can even cure genetic diseases. This kind of therapy works so that a new gene is inserted into an adenovirus vector, then that vector introduces the modified DNA into the human cell. If the treatment works and the gene is not rejected than it will start to produce a functional protein. Basically the defected genes are either replaced or supplemented by the normal gene.

There are two types of gene therapies, one of them is somatic gene therapy and the other one uses germ cells. In case of somatic cells, the change made in is not transmitted to the next generation and in the other case the purpose of the change in the cells is made with the aim to transfer it to their next generation.

Gene therapy can be implemented in two ways, either outside of the body, ex vivo, or inside of the body, in vivo. In the first case the cells are removed from the patient’s blood or bone marrow and are grown in the lab. Afterwards these cells are exposed to a virus that is carrying the wanted gene, once the virus has entered the cells the gene will become part of the DNA of the cells. The cells are not inserted into the patient’s body straight after the DNA modification, but they are let grown in the laboratory and then injected into the vein of the patient. When in vivo method is used cells are not removed from the patient, vectors are used to insert the wanted gene into the body.

The usage of gene therapy is rather limited. The main reasons why gene therapy is not used widely to fight different diseases are the following. First of all, the vectors that are used to insert genes into the body are usually various viruses, but although they are effective can bring further problems like toxicity, immune responses and targeting issues. Secondly, scientists still have only limited knowledge of the real functions of most of the genes. And lastly, the extremely high costs of gene therapy.