Barr body is absent in female of

Options

A. Klinefelter's syndrome
B. Turner's syndrome
C. normal female
D. Down syndrome is female

Answer

To solve the question "Barr body is absent in female of," we need to analyze the provided options regarding the presence or absence of Barr bodies in different genetic conditions.

### Step-by-Step Solution:

1. **Understanding Barr Bodies**:
- Barr bodies are inactivated X chromosomes found in females. Typically, females have two X chromosomes (XX), and one of these X chromosomes is randomly inactivated in each cell, forming a Barr body.

2. **Analyzing the Options**:
- **Option 1: Klinefelter Syndrome (XXY)**:
- This condition occurs in males who have an extra X chromosome. In Klinefelter Syndrome, there is one Barr body present because there are two X chromosomes (one active and one inactive).
- **Conclusion**: Barr body is present.

- **Option 2: Turner Syndrome (X0)**:
- Turner Syndrome occurs in females who have only one X chromosome (X0). Since there is no second X chromosome, there is no Barr body formed.
- **Conclusion**: Barr body is absent.

- **Option 3: Normal Female (XX)**:
- Normal females have two X chromosomes, and thus, one of the X chromosomes is inactivated, resulting in one Barr body.
- **Conclusion**: Barr body is present.

- **Option 4: Down Syndrome (Trisomy 21)**:
- Down Syndrome is a chromosomal disorder involving an extra chromosome 21. Females with Down Syndrome still have two X chromosomes, resulting in one Barr body.
- **Conclusion**: Barr body is present.

3. **Final Answer**:
- Based on the analysis, the only condition where Barr body is absent is **Turner Syndrome (Option 2)**.

### Summary:
The correct answer is **Turner Syndrome** where Barr bodies are absent due to the presence of only one X chromosome.