A harmful condition which is also potential saviour form a mosquito borne infectious disease

Options

A. Thalassemia
B. Sicke cell anaemia
C. Leukemia
D. Pernicious anamia

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for a harmful condition that also provides some form of protection against a mosquito-borne infectious disease.

2. **Identifying the Condition**: One well-known condition that fits this description is sickle cell anemia. It is a genetic disorder characterized by the production of abnormal hemoglobin, leading to the deformation of red blood cells into a sickle shape.

3. **Genetic Basis of Sickle Cell Anemia**: Sickle cell anemia is caused by a mutation in the HBB gene, which encodes the beta chain of hemoglobin. This mutation involves the substitution of adenine (A) with thymine (T) at the 17th nucleotide position of the HBB gene.

4. **Impact of the Mutation**: This genetic change alters the codon from GAG (which codes for glutamic acid) to GTG (which codes for valine). The resulting abnormal hemoglobin is referred to as HBS, which leads to the sickling of red blood cells.

5. **Heterozygous Advantage**: Individuals who are heterozygous for the sickle cell trait (carrying one normal allele HBB and one mutated allele HBS) exhibit increased resistance to malaria, a mosquito-borne infectious disease. This provides a survival advantage in regions where malaria is prevalent.

6. **Conclusion**: Therefore, the harmful condition that also serves as a potential savior against malaria is sickle cell anemia.

**Final Answer**: Sickle cell anemia.

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