## **Core Concept**
A missense mutation is a type of point mutation where a single nucleotide change results in a codon that codes for a different amino acid. This change can lead to the synthesis of a protein with an altered function or structure. Missense mutations are significant in understanding various genetic disorders.

## **Why the Correct Answer is Right**
The correct answer, , is a classic example of a missense mutation. This mutation leads to the substitution of glutamic acid with valine at position 6 of the hemoglobin subunit beta (HBB) gene, resulting in sickle hemoglobin (HbS). This change causes red blood cells to assume a sickle shape under certain conditions, leading to sickle cell disease. The mutation affects the hemoglobin's function, causing it to polymerize under low oxygen conditions, which is the primary pathophysiological mechanism behind sickle cell disease.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option does not represent a well-known missense mutation related to a significant genetic disorder in the same way that does.
- **Option B:** While this option might seem plausible, it does not directly correspond to a commonly cited example of a missense mutation like .
- **Option C:** This option is not a recognized example of a missense mutation in the context provided.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that sickle cell disease, caused by the mutation, is an autosomal recessive disorder. This means that individuals must inherit two copies of the mutated gene (one from each parent) to express the disease. Carriers, who have one normal and one mutated gene, typically have a protective advantage against malaria.

## **Correct Answer:** . Sickle cell anemia mutation (Glu6Val)