Which of the following is not a Mendelian disorder?

Options

A. Haemophilia
B. Cystic fibrosis
C. Turner's syndrome
D. Thalessemia

Answer

To determine which of the following is not a Mendelian disorder, we will analyze each option provided in the question:

### Step-by-Step Solution:

1. **Understand Mendelian Disorders**:
- Mendelian disorders are genetic conditions that are caused by mutations in a single gene and follow Mendel's laws of inheritance. They are typically categorized into autosomal dominant, autosomal recessive, or X-linked inheritance patterns.

2. **Evaluate Each Option**:
- **Option 1: Hemophilia**:
- Hemophilia is an X-linked recessive disorder caused by mutations in genes responsible for blood clotting. It is a Mendelian disorder.

- **Option 2: Cystic Fibrosis**:
- Cystic Fibrosis is an autosomal recessive disorder caused by mutations in the CFTR gene. It is also a Mendelian disorder.

- **Option 3: Turner's Syndrome**:
- Turner's Syndrome is a chromosomal condition that affects females, characterized by the absence of one of the X chromosomes (monosomy). It is not caused by a mutation in a single gene but rather by a chromosomal abnormality. Therefore, it is not a Mendelian disorder.

- **Option 4: Thalassemia**:
- Thalassemia is an autosomal recessive disorder caused by mutations in the genes that produce hemoglobin. It is classified as a Mendelian disorder.

3. **Conclusion**:
- After evaluating all the options, we find that Turner's Syndrome (Option 3) is not a Mendelian disorder, while Hemophilia, Cystic Fibrosis, and Thalassemia are.

### Final Answer:
- **Turner's Syndrome is not a Mendelian disorder.**