Which of the following is not an autoimmune disorder?

Options

A. Myasthenia gravis
B. Rheumatoid arthritis
C. Hashimoto's disease
D. Down's syndrome

Answer

To determine which of the following is not an autoimmune disorder, we will analyze each option provided:

1. **Myasthenia Gravis**:
- Myasthenia Gravis is an autoimmune disorder where the immune system produces antibodies that interfere with the communication between nerves and muscles. This leads to muscle weakness and fatigue.

2. **Rheumatoid Arthritis**:
- Rheumatoid Arthritis is also an autoimmune disorder. In this condition, the immune system attacks the joints, leading to inflammation, pain, and potential joint damage.

3. **Hashimoto's Disease**:
- Hashimoto's Disease is another autoimmune disorder. It involves the immune system attacking the thyroid gland, leading to hypothyroidism due to the destruction of thyroid tissue.

4. **Down Syndrome**:
- Down Syndrome is not an autoimmune disorder. It is a genetic condition caused by the presence of an extra 21st chromosome (trisomy 21). This condition is related to chromosomal abnormalities rather than the immune system attacking the body’s own cells.

Based on this analysis, the answer to the question "Which of the following is not an autoimmune disorder?" is **Down Syndrome**.

### Summary of the Solution:
- Myasthenia Gravis: Autoimmune disorder (affects nerve-muscle communication).
- Rheumatoid Arthritis: Autoimmune disorder (affects joints).
- Hashimoto's Disease: Autoimmune disorder (affects thyroid gland).
- Down Syndrome: **Not an autoimmune disorder** (chromosomal disorder).

### Correct Answer: Down Syndrome

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