Gene Therapy

Gene Therapy

Gene Therapy is the insertion of a gene or genes into cells in order to provide a new set of instructions to those cells. Gene insertion can be used to correct an inherited genetic defect which is causing disease, to counter or correct the effects of a genetic mutation, or even to program a cell for an entirely new function or property. Genes are composed of molecules of deoxyribonucleic acid, or DNA (see Nucleic Acids), and are usually located in the nucleus of cells. The instructions that direct the development of an organism are encoded within the genes. Some diseases such as cystic fibrosis are caused by an inherited genetic defect. Other diseases are caused by a miscoding of a gene so that the instructions it contains are disrupted or changed. Genetic miscoding occurs when the DNA in a cell is being duplicated during cell growth and division (somatic mutation) and is common when a cell becomes cancerous. Clinical use of gene therapy began on September 14, 1990, at the National Institute of Health in Bethesda, Maryland, when a four-year-old girl received gene therapy treatment for adenosine deaminase (ADA) deficiency, an ordinarily fatal inherited disease of the immune system. Because of this genetic defect she was susceptible to recurrent life-threatening infections. Gene therapy for this patient involved using a genetically modified virus to carry a normal ADA gene into her immune cells. The inserted ADA gene then programmed the cells to produce the missing ADA enzyme, which led to normal immune function in those cells. This treatment temporarily helped her to develop resistance to infection. Gene