Human gene therapy: Insertion of normal DNA directly into cells to correct a genetic defect. The treatment of disease by replacing, altering, or supplementing a gene that is absent or abnormal and whose absence or abnormality is responsible for a disease.
In studies of gene therapy for cancer, for example, researchers are trying to bolster the body's natural capacity to combat cancer and make the tumor more sensitive to other kinds of therapy. Gene therapy, still in its early stages, holds great promise for the treatment of many diseases.
The first gene therapy was done successfully in humans in 1990 by W. French Anderson, R. Michael Blaese and Kenneth W. Culver who infused genetically engineered blood cells to repair an immune deficiency disorder: adenosine deaminase (ADA) deficiency.
In late October of 1999 the U.S. moved to require the disclosure of the results of gene therapy. The move by the Recombinant DNA Advisory Committee came 6 weeks after the death of an 18-year-old Arizona man, Jesse Gelsinger, who was apparently the first person to die as a result of gene therapy. Researchers at the University of Pennsylvania, where Mr. Gelsinger received gene therapy, were prompt to report his death and talked of it publicly. Although there was no evidence that any other patients had died as a result of receiving gene therapy, the committee (which reports to the director of the National Institutes of Health) was concerned that some scientists and companies had not always been so forthcoming with information about side effects experienced by gene therapy patients.