Assertion : ADA deficiency cannot be cured permanently by gene therapy.
Reason : The lymphocytes from the blood of patient are grown in culture outside the body.
Answer (d) Assertion is false but reason is true.
(d) : As a first step towards gene therapy, lymphocytes, a kind of white blood cells, are extracted from the bone marrow of the patient and are grown in a culture outside the body. A functional ADA cDNA (using a retroviral vector) is then introduced into these lymphocytes, which are reinjected to the patient’s bone marrow. But as these cells do not always remain alive, the patient requires periodic infusion of such genetically engineered lymphocytes. However, if the isolated gene from bone marrow cells producing ADA is introduced into cells at early embryonic stages, it can be permanent cure.
