First clinical application of gene rapy was used in 1992 over a four year old girl for

First clinical application of gene therapy was used in 1992 over a four-year-old girl for a genetic defect that left her with ADA (Adenosine deaminase deficiency), a severe immune system deficiency. The defective gene of the patient's blood cells was replaced by the functional variant. Her immune system was partially restored by the therapy. Production of the missing enzyme was temporarily stimulated, but the new cells with functional genes were not generated. She led a normal life only with the regular injections performed every two months. The effects were successful but temporary.