The first clinical gene therapy was given to a 4-year old girl with:

The correct answer is Option (2) → Adenosine deaminase deficiency (ADA)

Option (1) Insulin deficiency — Incorrect. A lack of insulin causes diabetes. It is treated with insulin injections, and human insulin is now made by recombinant DNA technology in bacteria. That is making a medicine, not gene therapy, and it was not the first gene therapy case.

Option (2) Adenosine deaminase deficiency (ADA) — 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 (3) Chicken Pox — Incorrect. Chicken pox is an infection caused by a virus. Gene therapy corrects a faulty gene, and chicken pox is not caused by any gene defect.

Option (4) Polio — Incorrect. Polio is also a viral disease. It is prevented by vaccination, not treated by putting a gene into the patient’s cells.

Note: A similar question was also asked in CUET (UG) 2025 on 27-05-2025 (Slot 2), and in CUET (UG) 2023 on 11-06-2023 (Slot 3) and on 05-06-2023 (Slot 3).

NCERT Extract:
Gene Therapy – …