Gene therapy is the insertion of genes into an individual's cells and tissues to treat a disease, such as a hereditary disease in which a deleterious mutant allele is replaced with a functional one. Although the technology is still in its infancy, it has been used with some success. Antisense therapy is not strictly a form of gene therapy, but is a genetically-mediated therapy and is often considered together with other methods.

Background

On September 14, 1990 at the U.S. National Institutes of Health, W. French Anderson M.D. and his colleagues R. Michael Blaese, M.D., C. Bouzaid, M.D., and Kenneth Culver, M.D., performed the first approved gene therapy procedure on four-year old Ashanthi DeSilva. Born with a rare genetic disease called severe combined immunodeficiency (SCID), she lacked a healthy immune system, and was vulnerable to every passing germ or infection. Children with this illness usually develop overwhelming infections and rarely survive to adulthood; a common childhood illness like chickenpox is life-threatening. Ashanthi led a cloistered existence — avoiding contact with people outside her family, remaining in the sterile environment of her home, and battling frequent illnesses with massive amounts of antibiotics.

In Ashanthi's gene therapy procedure, doctors removed white blood cells from the child's body, let the cells grow in the laboratory, inserted the missing gene into the cells, and then infused the genetically modified blood cells back into the patient's bloodstream. Laboratory tests have shown that the therapy strengthened Ashanthi's immune system by 40%; she no longer has recurrent colds, she has been allowed to attend school, and she was immunized against whooping cough. This procedure was not a cure; the white blood cells treated genetically only work for a few months, after which the process must be repeated (VII, Thompson 1 1993). As of early 2007, she was still in good health, and she was attending college. However, there is no consensus on what portion of her improvement should be attributed to gene therapy versus other treatments. Some would state that the case is of great importance despite its indefinite results, if only because it demonstrated that gene therapy could be practically attempted without adverse consequences.

The road to the first approved gene therapy procedure was rocky and fraught with controversy. The biology of human gene therapy is very complex, and there are many techniques that still need to be developed and diseases that need to be understood more fully before gene therapy can be used appropriately. The public policy debate surrounding the possible use of genetically engineered material in human subjects has been equally complex. Major participants in the debate have come from the fields of biology, government, law, medicine, philosophy, politics, and religion, each bringing different views to the discussion.