Sickle cell anaemia is an example of

Options

A. Epistasis
B. Codominance
C. Pleiotropy
D. Incomplete dominance

Answer

### Step-by-Step Solution:

1. **Identify the Condition**: Sickle cell anemia is a genetic disorder that affects the shape of red blood cells.

2. **Understand the Inheritance**: It is an inherited disorder, meaning it is passed down from parents to offspring through genes.

3. **Recognize the Affected Cells**: The primary cells affected in sickle cell anemia are red blood cells (RBCs). In this condition, the RBCs take on a sickle or crescent shape instead of the normal disc shape.

4. **Determine the Cause**: The abnormal shape of the RBCs in sickle cell anemia is caused by a mutation in the gene that encodes for hemoglobin, the protein in red blood cells that carries oxygen.

5. **Identify the Type of Genetic Phenomenon**: Sickle cell anemia is an example of pleiotropy. Pleiotropy occurs when a single gene influences multiple phenotypic traits. In the case of sickle cell anemia, the mutation affects not only the shape of the red blood cells but also leads to various complications such as pain, anemia, and increased risk of infections.

6. **Distinguish from Other Genetic Concepts**: Other options like epistasis, co-dominance, and incomplete dominance do not accurately describe sickle cell anemia:
- **Epistasis** involves one gene suppressing the effect of another gene.
- **Co-dominance** refers to both alleles in a heterozygote being fully expressed.
- **Incomplete dominance** results in a blending of traits, producing a new phenotype.

7. **Conclusion**: Therefore, sickle cell anemia is best classified as an example of pleiotropy.