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

Options

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

Answer

To determine which technique would be completely curative for Severe Combined Immunodeficiency (SCID), we need to analyze the options provided and understand the nature of SCID.

### Step-by-Step Solution:

1. **Understanding SCID**:
- SCID is a genetic disorder characterized by the absence or dysfunction of both B and T lymphocytes, which are crucial for the immune response. This condition arises due to mutations in genes that are essential for the development and function of these immune cells.

2. **Identify the Cause**:
- One of the common causes of SCID is the mutation of the gene that codes for the enzyme adenosine deaminase (ADA). This enzyme is necessary for breaking down purines, and its deficiency leads to toxic accumulation, inhibiting lymphocyte proliferation.

3. **Evaluate Treatment Options**:
- **Gene Therapy in Adult Stage**: This involves introducing a functional copy of the mutated gene into the adult's cells. However, since SCID is a genetic disorder, treating it at this stage may not provide a permanent solution.
- **Gene Therapy in Embryonic Stage**: This technique involves correcting the genetic defect before the immune system develops. By introducing a functional ADA gene at this early stage, it can lead to the development of a fully functional immune system, providing a permanent cure.
- **Bone Marrow Transplantation**: This method can provide a temporary solution by introducing healthy stem cells that can produce functional immune cells, but it is not a guaranteed permanent cure.
- **Enzyme Replacement Therapy**: This involves administering the functional ADA enzyme to the patient. While it can alleviate symptoms, it does not address the underlying genetic defect, thus not providing a permanent cure.

4. **Conclusion**:
- The most effective and potentially curative treatment for SCID is **gene therapy in the embryonic stage**. This approach allows for the correction of the genetic defect before the immune system is fully developed, leading to a permanent resolution of the disorder.

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