Which of the following abnormalities is due to autosomal dominant mutation ?

Options

A. Colour blindness
B. Thalassemia
C. Myotonic dystrophy
D. Haemophilia

Answer

To determine which of the listed abnormalities is due to an autosomal dominant mutation, we can analyze each option step by step.

### Step 1: Understand Autosomal Dominant Inheritance
Autosomal dominant inheritance means that only one copy of the mutated gene (from either parent) is sufficient to cause the disorder. This type of inheritance typically results in the disorder being expressed in every generation.

### Step 2: Evaluate Each Option
1. **Color Blindness**:
- Color blindness, or color vision deficiency, is primarily linked to mutations on the X chromosome. It is more common in males and does not follow autosomal dominant inheritance.
- **Conclusion**: Not autosomal dominant.

2. **Thalassemia**:
- Thalassemia is an inherited blood disorder characterized by reduced hemoglobin production. It is primarily inherited in an autosomal recessive manner, meaning two copies of the mutated gene are needed to express the disorder.
- **Conclusion**: Not autosomal dominant.

3. **Myotonic Dystrophy**:
- Myotonic dystrophy is a type of muscular dystrophy that is indeed caused by an autosomal dominant mutation. Individuals with this disorder typically have one affected parent, and the disorder can manifest in successive generations.
- **Conclusion**: This is an autosomal dominant disorder.

4. **Hemophilia**:
- Hemophilia is a genetic disorder that affects blood clotting and is primarily linked to mutations on the X chromosome, making it an X-linked recessive disorder.
- **Conclusion**: Not autosomal dominant.

### Step 3: Identify the Correct Answer
Based on the analysis, the only condition that is due to an autosomal dominant mutation is **Myotonic Dystrophy**.

### Final Answer
The abnormality due to an autosomal dominant mutation is **Myotonic Dystrophy**.

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