Sickle cell anemia is an example of

Options

A. (a) Point mutation
B. (b) Frameshift mutation
C. (c) X-linked recessive inheritance
D. (d) Both (A) and (C)

Answer

### Step-by-Step Solution:

1. **Understanding Sickle Cell Anemia**:
- Sickle cell anemia is a genetic disorder characterized by the abnormal shape of red blood cells (RBCs). In normal conditions, RBCs are biconcave, but in sickle cell anemia, they take on a sickle shape.

2. **Genetic Basis**:
- This disorder is caused by a mutation in the beta-globin gene, which is located on chromosome 11. The mutation is a point mutation where a single nucleotide change occurs, leading to the substitution of glutamic acid with valine in the hemoglobin protein.

3. **Inheritance Pattern**:
- Sickle cell anemia follows an autosomal recessive inheritance pattern. This means that for an individual to express the disease, they must inherit two copies of the mutated gene (one from each parent). If they inherit only one mutated gene, they are carriers (heterozygous) but do not show symptoms.

4. **Pedigree Analysis**:
- In a pedigree chart, if both parents are carriers (heterozygous), there is a 25% chance that their offspring will inherit the disease (homozygous recessive), a 50% chance they will be carriers (heterozygous), and a 25% chance they will be unaffected (homozygous dominant).

5. **Conclusion**:
- Given the options provided, sickle cell anemia is best described as an example of a **point mutation** due to the specific change in one nucleotide that leads to the disorder.

### Final Answer:
- **Sickle cell anemia is an example of a point mutation.**