Most common mutation in hereditary spherocytosis
**Core Concept**
Hereditary spherocytosis is a genetic disorder characterized by the production of red blood cells that are sphere-shaped rather than the normal biconcave disk shape. This condition is often related to mutations in genes that encode for proteins involved in the cytoskeleton of red blood cells. The most common mutations affect the **ankyrin**, **spectrin**, **band 3**, and **protein 4.2** genes.
**Why the Correct Answer is Right**
The correct answer is related to mutations in the **ankyrin** gene, which is the most common cause of hereditary spherocytosis. Ankyrin is a protein that plays a crucial role in maintaining the structure of red blood cells by anchoring spectrin to the membrane. Mutations in the ankyrin gene lead to a deficiency or dysfunction of the ankyrin protein, resulting in the loss of membrane stability and the formation of spherocytes.
**Why Each Wrong Option is Incorrect**
**Option A:** This choice is incorrect because, although mutations in the spectrin gene can cause hereditary spherocytosis, they are not the most common mutation.
**Option B:** This option is incorrect as band 3 mutations can also lead to hereditary spherocytosis but are less common than ankyrin mutations.
**Option D:** This choice is incorrect because protein 4.2 mutations are another cause but not the most frequent one.
**Clinical Pearl / High-Yield Fact**
Hereditary spherocytosis is characterized by anemia, jaundice, and splenomegaly. The diagnosis can be confirmed by peripheral blood smear showing spherocytes and a positive osmotic fragility test.
**Correct Answer:** D. Ankyrin gene mutation