A monosomic (2N-1) abnormality in human is

Options

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

Answer

**Step-by-Step Solution:**

1. **Understanding Monosomy**: Monosomy refers to the condition where an individual has one less chromosome than the normal diploid number. In humans, the normal diploid number is 46 (2N = 46), so a monosomic condition would be represented as 2N - 1, which equals 45 chromosomes.

2. **Identifying Monosomic Conditions**: Among the chromosomal abnormalities in humans, we need to identify which condition corresponds to a monosomic state (2N - 1).

3. **Analyzing the Given Options**:
- **Klinefelter Syndrome**: This condition is characterized by an extra X chromosome (47 chromosomes total, 2N + 1). Therefore, it does not represent a monosomic condition.
- **Turner Syndrome**: This condition occurs when there is a missing X chromosome (45 chromosomes total, 2N - 1). This is indeed a monosomic condition.
- **Edwards Syndrome**: This is a trisomy of the 18th chromosome (47 chromosomes total, 2N + 1), so it does not represent a monosomic condition.
- **Down Syndrome**: This is a trisomy of the 21st chromosome (47 chromosomes total, 2N + 1), so it also does not represent a monosomic condition.

4. **Conclusion**: The only condition that fits the description of a monosomic abnormality (2N - 1) in humans is Turner Syndrome.

**Final Answer**: The monosomic (2N - 1) abnormality in humans is Turner Syndrome.

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