The first clinical gene therapy was given for treating :

Options

A. Rheumatoid arthritis
B. Adenosine deaminase defeciency
C. Diabetes mellitus
D. Chicken pox

Answer

### Step-by-Step Solution:

1. **Understanding Gene Therapy**: Gene therapy involves the introduction, removal, or alteration of genetic material within a person's cells to treat or prevent disease.

2. **Identifying the First Clinical Gene Therapy**: The question asks for the first clinical application of gene therapy. It is important to recognize the historical context and the first successful case.

3. **Reviewing Options**: The options provided are rheumatoid arthritis, adenosine deaminase deficiency, diabetes mellitus, and chicken pox. We need to identify which of these conditions was treated first with gene therapy.

4. **Historical Context**: The first successful clinical gene therapy was conducted in 1990 at the National Institutes of Health (NIH). This therapy was administered to a 4-year-old girl.

5. **Condition Treated**: The specific condition treated was adenosine deaminase (ADA) deficiency. This genetic disorder leads to severe combined immunodeficiency (SCID), where the body lacks functional T and B lymphocytes, resulting in a weakened immune system.

6. **Mechanism of Treatment**: In this case, scientists extracted bone marrow cells from the patient, introduced a functional ADA gene using retroviruses, and then reintroduced these modified cells back into the patient's body.

7. **Conclusion**: Therefore, the first clinical gene therapy was indeed for treating adenosine deaminase deficiency.

### Final Answer:
The first clinical gene therapy was given for treating **adenosine deaminase deficiency**.

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