Which of the following could be a permanent cure for treatment of severe combined immunodeficiency (SCID)?

Options

A. Bone marrow transplantion
B. Enzyme replacement therapy
C. Both (1) and (2)
D. Gene therapy

Answer

**Step-by-Step Solution:**

1. **Understanding SCID**: Severe Combined Immunodeficiency (SCID) is a genetic disorder characterized by the lack of functional B and T lymphocytes, which are crucial for a healthy immune response. This condition arises from various genetic mutations.

2. **Identifying the Cause**: One of the key causes of SCID is the mutation in the gene that codes for the enzyme adenosine deaminase (ADA). This enzyme is essential for the breakdown of purines. Without functional ADA, toxic metabolites accumulate, which inhibits the proliferation and growth of lymphocytes.

3. **Treatment Options**: The question presents several treatment options:
- **Bone Marrow Transplantation**: This involves transplanting healthy bone marrow cells that can produce functional ADA.
- **Enzyme Replacement Therapy**: This therapy provides the patient with functional ADA through injections.
- **Gene Therapy**: This involves introducing a corrected version of the ADA gene into the patient's cells, ideally at early embryonic stages.

4. **Evaluating Permanent Cure**: While bone marrow transplantation and enzyme replacement therapy can treat SCID, they are not considered permanent solutions. Bone marrow transplants can be rejected, and enzyme replacement therapy requires ongoing treatment.

5. **Identifying the Permanent Solution**: Gene therapy offers a permanent cure by correcting the underlying genetic defect. By introducing a functional ADA gene into the patient's cells, particularly at early embryonic stages, the body can produce its own ADA, thus addressing the root cause of SCID.

6. **Conclusion**: Therefore, the most effective and permanent cure for SCID is gene therapy.

**Final Answer**: Gene therapy.

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