NCERT · Class 12 · Biology · Biotechnology and its ApplicationsWhat is gene therapy and name the first clinical case where it was successfully applied?

Gene therapy is a corrective molecular technique in which functional genes are inserted into a patient's cells to replace mutated or defective genes responsible for a genetic disorder. The first successful clinical gene therapy was performed in 1990 on a four-year-old girl suffering from adenosine deaminase (ADA) deficiency, an immunodeficiency disorder caused by the deletion of the gene coding for the ADA enzyme.