The first somatic cell gene therapy was targeted against the disease :

Options

A. SCID
B. Cystic fibrosis
C. Cancer
D. Phenylketonuria

Answer

### Step-by-Step Solution:

1. **Understanding Gene Therapy**:
- Gene therapy is a collection of methods aimed at correcting gene defects. It involves the insertion of normal genes into an individual's cells to replace or compensate for defective genes.

2. **Identifying the First Clinical Gene Therapy**:
- The first clinical application of gene therapy occurred in 1990. It was a significant milestone in the field of biotechnology.

3. **Case Study of the First Patient**:
- The first patient to receive gene therapy was a four-year-old girl diagnosed with a condition known as adenosine deaminase (ADA) deficiency.

4. **Understanding ADA Deficiency**:
- ADA deficiency is crucial for the immune system. The absence of this enzyme inhibits the proliferation of lymphocytes, which are essential for a functioning immune response.

5. **Consequences of ADA Deficiency**:
- Without adequate ADA, the proliferation of lymphocytes is inhibited, leading to a lack of T-cells. This condition makes individuals highly susceptible to viral and bacterial infections.

6. **Name of the Disease**:
- The condition resulting from ADA deficiency is known as Severe Combined Immunodeficiency (SCID).

7. **Conclusion**:
- Therefore, the first somatic cell gene therapy was targeted against Severe Combined Immunodeficiency (SCID).

### Final Answer:
The first somatic cell gene therapy was targeted against the disease known as Severe Combined Immunodeficiency (SCID).

---