Gene therapy is a technique for introducing the genetic material of a gene in a patient that lacks that gene because of a mutation.Vectors, the way you insert the "normal" gene in the patient's cell is by vectors. There are different types of viruses use as vector for gene therapy in human including Retrovirus, Adinovirus, Lentiviruses, Poxviruses and Herpes Viruses.Both Healthy and Cancerous cells can be a target. Ex of targeting Healthy cells. One way is by replacing a missing or altered gene with a "normal" one. Ex of targeting Cancer Cells. Scientists can target cancer cells with genes that can be used to destroy the cells. In this technique, cancer cells are introduced to what is called "suicide genes".Gene therapy in germ line cells has the potential to affect not only the individual, but also their children as well. Any genetic changes in the reproductive cells or changes made to the embryo before the stage of differentiation, would affect all future offspring of that person. This makes an vital distinction, affecting major ethcial issues. Germ line therapy (such as sperm cells, ova, and their stem cell precursors.