<prompt> The first gene therapy somatic enzyme was successfully done inSCIDPhenylketonuriaThalassemiaCystic fibrosis  <response>: Deficiency of adenosine deaminase, a condition that affects lymphocytes paicularly, was the first disease to be treated by gene therapy. Deficiency of adenosine deaminase accounts for 15 of all cases of severe combined immunodeficiency SCIDIn 1990, Dr. William French Anderson introduced a new copy the gene, carried on a retroviral vector, into a 4-year-old girl suffering from severe combined immunodeficiency Bubble boy disease.Ref: Harper 30th edition pg: 699 