Gene therapy works in animals but has had limited success in human patients. It may also have unforeseen consequences and has included some human deaths in research studies that have used human patients.
However, there have been cases where human patients have been successfully treated using gene therapy techniques.
Some people have diseases caused by faulty genes. The aim of gene therapy is to replace the faulty genes with normal fully functioning genes.
The video below gives an explanation of the cause and effects of the genetic disorder cystic fibrosis and how it can be treated using gene therapy.