Ever since they first learned the chemical nature of heredity, a few medical scientists have shared a dazzling vision: someday, faulty genes would be replaced to treat and cure disease. Today that dream is becoming reality. It is called "gene therapy".Gene therapy became possible in concept in 1953 when Drs. James D. Watson and Francis F. C. Crick, then at Cambridge University, discovered the double helix structure of DNA and showed that its chemistry served as the alphabet and the language of heredity. In the early 1940''s, scientists at the Rockefeller Institute had demonstrated that DNA was the substance of the genes.On Sept. 14, 1990,W. French Anderson, M.D., and his colleagues at the National Institutes of Health, crossed a symbolic threshold with a 4-year-old girl -Ashanthi DeSilva , becoming the first group to begin a clinical trial in the new frontier of medical treatment: human gene therapy.To reverse disease caused by genetic damage, researchers isolate normal DNA and package it into a vector, a molecular delivery truck usually made from a disabled virus. Doctors then infect a target cell —usually from a tissue affected by the illness, such as liver or lung cells— with the vector. The vector unloads its DNA cargo, which then begins producing the missing protein and restores the cell to normal. Gene therapy works from the inside, and should keep working indefinitely. It holds the potential to provide patient-friendly treatment for a variety of diseases.About 4,000 diseases have been traced to genetic disorders. Gene therapy is likely to be most successful with diseases caused by single gene defects.
Developmental and metabolic disorders: Cystic fibrosis, retinoblastoma
Neurological disorders: Parkinson''s, Huntington''s chorea, Alzheimers
Infectious disease: AIDS, Malaria, other viral infections (including human papilloma virus)
Immune-mediated diseases and immunodeficiency: Severe Combined Immunodeficiency Disease, Rheumatoid Arthritis, Type 1 Diabetes and Multiplesclerosis
Acquired disorders: Heart disease, Cancer (including brain cancer)