Which of the following is the example of pleiotropic gene , -

Options

A. haemophilia
B. thalassemia
C. sickle-cell anaemia
D. colour blindness

Explanation

To determine which of the following is an example of a pleiotropic gene, we need to understand what pleiotropy is and analyze the options provided.

### Step-by-Step Solution:

1. **Define Pleiotropy**:
- Pleiotropy occurs when a single gene influences multiple phenotypic traits. This means that one gene can have several effects on different characteristics of an organism.

2. **Analyze the Options**:
- **Option 1: Hemophilia**:
- Hemophilia is an X-linked recessive disorder that primarily affects blood clotting due to a deficiency in clotting factors. It does not control multiple traits, so it is not an example of pleiotropy.
- **Option 2: Thalassemia**:
- Thalassemia is a genetic disorder affecting hemoglobin production. While it has several health effects (like anemia and organ enlargement), it is primarily related to the production of hemoglobin and does not control multiple distinct traits. Thus, it is not a pleiotropic gene.
- **Option 3: Sickle Cell Anemia**:
- Sickle cell anemia is an autosomal recessive disorder caused by a mutation in the beta-globin gene. This mutation leads to the production of abnormal hemoglobin, which causes red blood cells to become sickle-shaped. This shape change results in various effects, including anemia, pain crises, organ damage, and increased risk of infections. Since this gene affects multiple traits and health conditions, it is a classic example of pleiotropy.
- **Option 4: Colorblindness**:
- Colorblindness is also an X-linked recessive disorder that affects the perception of colors. Similar to hemophilia, it does not influence multiple traits, so it is not an example of pleiotropy.

3. **Conclusion**:
- Based on the analysis, the correct answer is **Option 3: Sickle Cell Anemia**, as it is a clear example of a pleiotropic gene affecting multiple traits and health conditions.

### Final Answer:
The example of a pleiotropic gene is **Sickle Cell Anemia** (Option 3).