Somatic cell gene therapy involves obtaining blood cells from a person with a genetic disease and then introducing a normal gene into the defective cell. This type of gene therapy does not prevent the disease from occurring in the next generation because it does not affect the sperm and egg cells. Somatic cell gene therapy only effects the other body cells. Somatic cell gene therapy has to be done several times over the coarse of the patient's life because the effects do not last very long.
It is the germline therapy takes place in the reproductive cells. It involves the genetic modification of germ cells that will pass the change on to the next generation. This type of gene therapy only has to be done one time to be permanent.