In human being ,45 chromosomes (44+ XO) cause:

Options

A. Down's syndrome
B. klinefelter's syndrome
C. Turner's syndrome
D. Edward's syndrome

Explanation

**Step-by-Step Solution:**

1. **Understanding Chromosome Count**: In humans, the normal chromosome count is 46 (23 pairs). The notation 44 + XO indicates that there are 44 autosomes and one X chromosome, meaning there is a missing sex chromosome (Y chromosome).

2. **Identifying the Condition**: The condition characterized by 45 chromosomes (44 + XO) is associated with Turner syndrome. In Turner syndrome, a female is born with a single X chromosome instead of the usual two sex chromosomes (XX).

3. **Differentiating Other Syndromes**:
- **Down Syndrome**: This is caused by trisomy of chromosome 21, resulting in 47 chromosomes (46 + 1).
- **Klinefelter Syndrome**: This condition is characterized by the presence of an extra X chromosome in males (XXY), resulting in 47 chromosomes.
- **Edwards Syndrome**: This is caused by trisomy of chromosome 18, leading to 47 chromosomes.

4. **Conclusion**: Since the question specifies 45 chromosomes (44 + XO), the correct answer is Turner syndrome, which is characterized by the presence of a single X chromosome in females.

**Final Answer**: Turner syndrome is caused by 45 chromosomes (44 + XO).

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