The first clinical gene therapy was given for the treatment of:

The correct answer is Option (3) → Adenosine deaminase deficiency

Option (3) Adenosine deaminase deficiency — Correct. Adenosine deaminase (ADA) deficiency was the first disease treated by clinical gene therapy, in 1990. Cancer, HIV (human immunodeficiency virus) infection and haemophilia were not that first case.

Note: A similar question was also asked in CUET (UG) 2025 on 27-05-2025 (Slot 2) and on 23-05-2025 (Slot 2), and in CUET (UG) 2023 on 05-06-2023 (Slot 3).

NCERT Extract:
Gene Therapy – “… The first clinical gene therapy was given in 1990 to a 4-year old girl with adenosine deaminase (ADA) deficiency. This enzyme is crucial for the immune system to function. The disorder is caused due to the deletion of the gene for adenosine deaminase. In some children ADA deficiency can be cured by bone marrow transplantation; in others it can be treated by enzyme replacement therapy, in which functional ADA is given to the patient by injection.”