Question

First clinical gene therapy was done for deficiency of:

• A. Glucocerebrosidase
• B. Acid maltase
• C. Adenosine deaminase
• D. Carbonic anhydrase

Hint:

First gene therapy (1990) targeted ADA deficiency in SCID patients.

Answer 1

The Correct Option is C

Step 1: Understanding gene therapy concept.
Gene therapy is a medical technique where defective genes responsible for disease are replaced or corrected using functional gene copies. It is mainly used for treating genetic disorders at molecular level.

Step 2: Historical development.
The first successful human gene therapy experiment was performed in 1990. It marked a major milestone in medical biotechnology and opened new treatment possibilities.

Step 3: Disease involved in first gene therapy.
The first clinical case involved Severe Combined Immunodeficiency (SCID) caused by deficiency of the enzyme adenosine deaminase (ADA). This enzyme is crucial for immune cell development.

Step 4: Role of ADA enzyme.
ADA breaks down toxic metabolites in lymphocytes. Its deficiency leads to accumulation of toxic compounds, severely weakening the immune system and making patients highly susceptible to infections.

Step 5: Gene therapy method used.
In this treatment, functional ADA genes were inserted into the patient’s T-lymphocytes using viral vectors. These modified cells were then reinfused into the patient.

Step 6: Evaluating options.
Other enzymes like glucocerebrosidase and acid maltase are linked to metabolic disorders but were not part of the first gene therapy trial. Carbonic anhydrase is unrelated.

Step 7: Final conclusion.
Thus, ADA deficiency was the first successful clinical application of gene therapy.