In human beings, 45 chromosomes / single X/XO abnormality causes

Options

A. Down 's syndrome
B. Klinefelter's syndrome
C. Turner's syndrome
D. Edward's sundrome

Answer

**Step-by-Step Solution:**

1. **Understanding Chromosomal Abnormalities**: In humans, the normal chromosomal count is 46, which includes 44 autosomes and 2 sex chromosomes (XX for females and XY for males). An abnormality in this count can lead to various syndromes.

2. **Identifying the Given Condition**: The question states a condition with 45 chromosomes and a single X/XO abnormality. This indicates that there is a missing sex chromosome, which is characteristic of certain syndromes.

3. **Analyzing the Options**:
- **Down Syndrome**: Typically caused by an extra chromosome 21 (47 chromosomes total), not related to the X chromosome count.
- **Klinefelter Syndrome**: Usually involves males with an extra X chromosome (XXY), resulting in 47 chromosomes, not applicable here.
- **Turner Syndrome**: Characterized by females with only one X chromosome (45 chromosomes total, 44 autosomes + 1 X), which fits the description of the condition given.
- **Edward Syndrome**: Caused by an extra chromosome 18 (47 chromosomes total), not related to the X chromosome count.

4. **Conclusion**: Since Turner syndrome is the only condition that matches the description of having 45 chromosomes with a single X chromosome, the answer is C) Turner syndrome.

**Final Answer**: C) Turner syndrome

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