Mark the odd one w.r.t syndrome which occurs due to failure of segregation of homologous pair of chromosomes during cell division cycle.

Options

A. Klinefelter's syndrome
B. Down's syndrome
C. Turner's syndrome
D. Thalassemia

Answer

To solve the question of identifying the odd one out with respect to syndromes caused by the failure of segregation of homologous chromosomes during cell division, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks us to identify which syndrome is not caused by the failure of segregation of homologous chromosomes during cell division.

2. **Analyze Each Option**:
- **Klinefelter Syndrome**: This syndrome is caused by the presence of an extra X chromosome in males (47, XXY). It results from nondisjunction during meiosis, leading to abnormal segregation of sex chromosomes.
- **Down Syndrome**: This genetic disorder is caused by Trisomy 21, where there is an extra copy of chromosome 21. This is also a result of nondisjunction during meiosis.
- **Turner Syndrome**: This condition occurs when there is a missing X chromosome in females (45, X). It results from the failure of proper segregation of sex chromosomes.
- **Thalassemia**: This is an inherited blood disorder that is caused by mutations in the hemoglobin genes and is not directly related to the failure of chromosome segregation during meiosis.

3. **Identify the Odd One Out**:
- Klinefelter, Down, and Turner syndromes are all caused by nondisjunction and improper segregation of chromosomes. In contrast, thalassemia is caused by genetic mutations and does not involve the failure of chromosome segregation.

4. **Conclusion**: The odd one out is **Thalassemia** (Option D), as it does not result from the failure of segregation of homologous chromosomes during cell division.

### Final Answer:
**Thalassemia** is the odd one out.

---