In gene therapy of Adenosine Deaminase (ADA) deficiency, the patient requires periodic infusion of genetically engineered lymphocytes because:
- Retroviral vector is introduced into these lymphocytes.
- Gene isolated from marrow cells producing ADA is introduced into cells at embryonic stages
- Lymphocytes from patient's blood are grown in culture, outside the body
- Genetically engineered lymphocytes are not immortal cells.
Answer
(4) Genetically engineered lymphocytes are not immortal cells.
Solution
As per NCERT, in gene therapy of ADA deficiency, lymphocytes from the patient's blood are grown in culture, a functional ADA cDNA is introduced into them using a retroviral vector, and the cells are returned to the patient.
These genetically engineered lymphocytes are not immortal, they die after some time.
The patient requires periodic infusion of such lymphocytes.
(A permanent cure is possible only if the ADA gene is introduced into cells at early embryonic stages.)
Answer: (4)