(a) Name the deficiency for which first clinical gene therapy was given. (b) Mention the cause of and one cure for this deficiency.

(a) ADA or adenosine deaminase deficiency is the deficiency for which the first clinical gene therapy was given (b) It is caused due to deletion of the gene for adenosine deaminase. Cure: Bone marrow transplantation in some children or by enzyme replacement therapy.