Gene therapy is a way of treating or preventing disease by altering the genetic instructions within an individual’s cells. Genes are responsible for virtually every aspect of cell life: they hold the code for proteins that enable cells to grow, function, and divide. When a gene is defective, it can give rise to proteins that are unable to do their job. When a gene is missing, or is overactive, important bodily functions may be impaired. The goal of gene therapy is to correct such problems by fixing them at the source.
Gene therapy can involve replacing abnormal or absent genes with healthy ones that enable cells to produce useful proteins. It also can involve changing the way genes are regulated, so that under- or overactive genes operate properly. Finally, gene therapy can be used to express entirely foreign genes in cells that alter their function and/or survival.