The first clinical gene therapy was given in 1990 to a 4-year old girl with ____________.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Adenosine deaminase deficiency
Option (1) Adenosine aminase deficiency — Incorrect. There is no such deficiency; the enzyme is adenosine deaminase.
Option (2) Cytosine deaminase deficiency — Incorrect. Cytosine deaminase is an enzyme found in microbes, not in human cells. The first gene therapy was not for this enzyme.
Option (3) Adenosine deaminase deficiency — Correct. In ADA deficiency the gene for adenosine deaminase is deleted, and the child’s immune system fails. In gene therapy, lymphocytes from the patient’s blood are grown outside the body, a working ADA cDNA is put into them using a retroviral vector, and they are returned to the patient. Since these cells do not live for ever, the patient needs such infusions from time to time.
Option (4) Adenosine protease deficiency — Incorrect. There is no such enzyme. A protease breaks down proteins, not adenosine.
Note: A similar question was also asked in CUET (UG) 2025 on 23-05-2025 (Slot 2), and in CUET (UG) 2023 on 11-06-2023 (Slot 3) and on 05-06-2023 (Slot 3).
NCERT Extract:
Gene Therapy – …
