A person with sickle cell anaemia is

Options

A. more prone to malaria
B. more prone to typhoid
C. less prone to malaria
D. less prone to typhoid

Explanation

### Step-by-Step Solution:

1. **Understanding Sickle Cell Anemia**:
- Sickle cell anemia is a genetic disorder that affects the shape of red blood cells (RBCs). In this condition, the RBCs become rigid and shaped like a sickle or crescent, rather than being round and flexible.

2. **Genetic Mutation**:
- The condition is caused by a mutation in the hemoglobin gene. Specifically, at the 6th position of the beta-globin chain of hemoglobin, the amino acid glutamic acid is replaced by valine due to a single nucleotide substitution in the DNA sequence.

3. **Effects of the Shape Change**:
- The sickle-shaped cells can block blood flow in small blood vessels, leading to pain and potential organ damage. They also have a shorter lifespan than normal RBCs, which can lead to anemia.

4. **Geographical Association**:
- Sickle cell anemia is particularly prevalent in regions where malaria is common, such as parts of Africa. This is because individuals with sickle cell trait (carriers of one sickle cell allele) have some protection against malaria.

5. **Health Implications**:
- While individuals with sickle cell anemia can suffer from various health complications, including pain crises and increased risk of infections, they also have a survival advantage in malaria-endemic regions.