MODEL PAPER 3 — BIOLOGY STD 12 Science — Question

A person suffering from ADA deficiency can be cured by various methods which are discusses below:
i. Bone Marrow Transplantation: This procedure requires a suitable donor. An identical twin is supposed to be the best donor as the chances of tissue rejection are very high in bone marrow transplantation.
ii. Enzyme Replacement Therapy: Enzyme replacement therapy is based on administering the missing enzyme to the patient by injection.
iii. Gene Therapy: Gene therapy involves taking out the lymphocytes from the patient's blood. Then are lymphocytes are genetically engineered to add the missing gene. Recombinant lymphocytes are grown in a suitable medium and then administered to the patient. This too is not a permanent cure because lymphocytes have a certain lifespan. The patient needs to be administered lymphocytes after frequent intervals. However, the gene isolated from marrow cells producing ADA is introduced into cells at the early embryonic stage could be a permanent cure for this disease.