Involved in Hereditary spherocytosis-a) Spectrinb) Ankyrinc) Pyrind) Band 4.2e) Actin
**Core Concept**
Hereditary spherocytosis (HS) is a genetic disorder characterized by the production of abnormal red blood cells (RBCs) that are sphere-shaped rather than the normal biconcave disk shape. This abnormal shape leads to premature destruction of RBCs in the spleen, resulting in anemia.
**Why the Correct Answer is Right**
The correct answer is related to the cytoskeletal proteins that provide mechanical stability and shape to RBCs. Spectrin is a key protein that forms a network of filaments under the RBC membrane, maintaining its shape and flexibility. Mutations in the genes encoding spectrin or other associated proteins can lead to the production of abnormal RBCs with a reduced surface area-to-volume ratio, resulting in the characteristic spherocytic shape.
**Why Each Wrong Option is Incorrect**
* **Option A:** Spectrin is involved in maintaining the shape and integrity of RBCs, and mutations in the spectrin gene can lead to HS. This option is correct, so it will not be discussed further.
* **Option B:** Ankyrin is another protein that interacts with spectrin and is involved in anchoring the RBC membrane to the spectrin network. While ankyrin mutations can cause HS, it is not the primary protein involved.
* **Option C:** Pyrin is a protein involved in the regulation of inflammation and is associated with familial Mediterranean fever. It is not related to HS.
* **Option D:** Band 4.2 is a protein that interacts with spectrin and is involved in maintaining the RBC membrane. However, it is not the primary protein involved in HS.
* **Option E:** Actin is a protein involved in muscle contraction and is not directly related to the maintenance of RBC shape or HS.
**Clinical Pearl / High-Yield Fact**
Hereditary spherocytosis can be inherited in an autosomal dominant or autosomal recessive pattern and is characterized by a family history of anemia, jaundice, and splenomegaly.
**Correct Answer: A. Spectrin**