SPTB

SPTB (Spectrin Beta, Erythrocytic) is a protein that in humans is encoded by the SPTB gene. This protein is a major constituent of the cytoskeleton, which provides structure and stability to cells. Mutations in the SPTB gene can lead to a variety of blood disorders, including hereditary spherocytosis and hereditary elliptocytosis.

Function

The SPTB protein is a component of the spectrin molecule, which forms a network on the inner surface of the cell membrane. This network helps to maintain the shape and flexibility of red blood cells, which need to deform in order to pass through small blood vessels. The SPTB protein also interacts with other proteins to stabilize and organize the cell membrane and to link the membrane to the rest of the cell.

Clinical significance

Mutations in the SPTB gene can cause hereditary spherocytosis and hereditary elliptocytosis. These conditions are characterized by abnormal shapes of red blood cells, which can lead to anemia, jaundice, and an enlarged spleen.

Hereditary spherocytosis is caused by mutations that result in a shortage of SPTB protein. Without enough of this protein, the spectrin network is unstable and the red blood cells are spherical rather than their normal doughnut-like shape. These spherical cells are more fragile than normal and are broken down prematurely in the spleen, leading to anemia.

Hereditary elliptocytosis is caused by mutations that alter the structure of the SPTB protein. These changes disrupt the spectrin network and lead to red blood cells that are elliptical rather than doughnut-shaped. These elliptical cells are less flexible than normal and can get stuck in small blood vessels, leading to anemia.

See also

• Spectrin
• Hereditary spherocytosis
• Hereditary elliptocytosis
• Anemia
• Jaundice
• Spleen

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