Is it possible for an adult to grow healthier with gene therapy?

Gene therapy: The problem with gene therapy is that the agent used to insert or remove a dysfunctionaal gene can alter dna in a way that could result in causing cancer. So far the most specific way to alter genes that has been deveolped is a zinc finger endonuclease (sangamo pharm.). They are studying ways to correct multiple types of abnormal genes that cause human diseases.