Why is the introduction of genetically engineered lymphocytes into a ADA deficiency patient not a permanent cure ? Suggest a possible permanent cure.

Explanation

Introduction of genetically engineered lymphocytes into a ADA deficiency patient is not a permanent cure because these cells are not immortal and the patient requires periodic infusion of such genetically engineered lymphocytes. A possible permanent cure can be isolating the gene producing Adenosine Deaminase (ADA) from bone marrow cells and introducing it into cells at early embryonic stages.