Which technique would you expect to be completely curative in SCID ?

Options

A. Gene therapy in adult stage.
B. Gene therapy in embroynic stage.
C. Bone marrow transplantation.
D. Enzyme replacement therapy.

Answer

### Step-by-Step Solution:

1. **Understanding SCID**: Severe Combined Immunodeficiency (SCID) is a genetic disorder characterized by the absence or dysfunction of T and B lymphocytes, leading to a severely compromised immune system.

2. **Cause of SCID**: One of the common causes of SCID is the deficiency of the enzyme adenosine deaminase (ADA). The gene responsible for producing this enzyme is either faulty or absent in SCID patients.

3. **Current Treatment Options**:
- **Bone Marrow Transplantation**: This method involves transplanting healthy bone marrow from a compatible donor to the patient. While it can provide some immune function, it is not a permanent solution.
- **Enzyme Replacement Therapy**: This involves administering the ADA enzyme to the patient. Similar to bone marrow transplantation, it can alleviate symptoms temporarily but does not cure the underlying genetic defect.

4. **Permanent Solution**: The only technique that offers a complete and permanent cure for SCID is **gene therapy**. This involves introducing a correct copy of the ADA gene into the patient's cells.

5. **Timing of Gene Therapy**: For gene therapy to be most effective, it should be administered at an early embryonic stage. This allows the corrected gene to be integrated into the patient's cells from the beginning of development, providing a lasting solution.

6. **Conclusion**: Among the treatment options, gene therapy administered at the embryonic stage is the most effective and curative approach for SCID.

### Final Answer:
The technique that would be expected to be completely curative in SCID is **gene therapy in the embryonic stage**.

---