Which enzyme is deficient in SCID disease ?

Options

A. Phosphofructokinase
B. Phosphodiesterase
C. Alcohol dehydrogenase
D. Adenosine deaminase

Answer

**Step-by-Step Solution:**

1. **Understanding SCID**: SCID stands for Severe Combined Immunodeficiency. It is a genetic disorder characterized by a significant deficiency in the immune system, making individuals highly susceptible to infections.

2. **Identifying the Enzyme**: The enzyme that is deficient in SCID is known as Adenosine Deaminase (ADA).

3. **Role of Adenosine Deaminase**: Adenosine deaminase is crucial for the proliferation of T-lymphocytes, which are essential components of the immune system. These cells help the body fight off infections.

4. **Consequences of Deficiency**: In individuals with SCID, the absence of adenosine deaminase leads to a failure in the proliferation of T-lymphocytes. As a result, there is a significant reduction in the number of T-cells, which compromises the immune response.

5. **Increased Vulnerability**: Due to the lack of functional T-lymphocytes, individuals with SCID are more vulnerable to infections from viruses and bacteria, leading to severe health complications.

6. **Conclusion**: Therefore, the enzyme that is deficient in SCID disease is Adenosine Deaminase (ADA).

**Final Answer**: The enzyme deficient in SCID disease is Adenosine Deaminase (ADA).

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