Clinical Considerations
- Hereditary spherocytosis is a disease in which defective spectrin weakens the red blood cell membrane skeleton.
- Defective spectrin in hereditary spherocytosis has decreased ability to bind band 4.1 protein.
- Weak spectrin-band 4.1 binding makes red blood cells fragile and misshapen.
- Spherocytes are spherical, fragile red blood cells.
- The spleen removes damaged or abnormal red blood cells from circulation.
- Destruction of spherocytes in the spleen leads to anemia.
- Anemia means reduced oxygen-carrying capacity of the blood, usually because of too few functional red blood cells or too little hemoglobin.
- Acceleration and deceleration forces are rapid speed changes that can stretch or shear brain tissue.
- High-speed car accidents and shaken-baby syndrome can create sudden acceleration and deceleration forces on the brain.
- Axons are long nerve cell processes that carry signals away from the nerve cell body.
- Shearing damage means tearing or stretching injury caused by forces moving tissue layers in different directions.
- Sudden acceleration and deceleration can shear axons.
- White matter contains many nerve fibers, while gray matter contains many nerve cell bodies and synapses.
- Axonal shearing is especially likely near the interface between white matter and gray matter.
- Diffuse axonal injury is widespread axon injury caused by stretching or shearing forces.
- Diffuse axonal injury can cause persistent coma.
- Coma is a prolonged state of unconsciousness.
- Only a minority of affected individuals regain consciousness after severe persistent coma from diffuse axonal injury.
- Spectrin cleavage means spectrin is cut apart.
- Irreparable spectrin cleavage damages the neuronal cytoskeleton.
- The neuronal cytoskeleton supports nerve cell structure, including axons.
- Destruction of the neuronal cytoskeleton causes loss of plasma membrane integrity.
- Loss of plasma membrane integrity can lead to cell death.
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