Spherocytosis

Spherocytosis is an auto-hemolytic anemia characterized by the production of red blood cells that are sphere-shaped, rather than donut-shaped. It is caused by a molecular defect in one of the proteins of the red blood cell cytoskeleton (usually ankyrin, sometimes spectrin). Because the cell skeleton has a defect, the blood cell contracts to its smallest and least flexible configuration, a sphere, rather than the more flexible donut-shape, which also has a larger surface area to which oxygen can attach.

These misshapen but healthy red blood cells are mistaken by the spleen for old or damaged red blood cells and are thus constantly being broken down, causing a cycle whereby the body destroys its own blood supply (hemolysis). This usually results in symptoms of fatigue, pallor, and splenomegaly for patients with the disorder, in serious cases necessitating blood transfusions. Furthermore, the detrius of the broken-down blood cells builds up in the gallbladder, often causing gallstones or "sludge" to develop.

The standard treatment for spherocytosis is splenectomy, the surgical removal of the spleen. While this does not change the shape of the blood cells, it does remove the more obvious physical symptoms of the disorder, as the blood cells are no longer constantly broken down. Though it offers near-immediate relief from symptoms, splenectomy is often not performed until the patient is in late childhood, so as not to hinder the patient's ability to fight off childhood infections. In recent years, the surgery is often performed laprascopically, which has a shorter recovery time and a much smaller scar. Following splenectomy, it is highly recommended that a patient receive a pneumovax vaccine every five years, along with a yearly flu shot, to combat the patient's new lower tolerance for infections. Some patients are also given supplemental antibiotics such as penicillin until early adulthood.

The sphere-shaped red blood cells are known as spherocytes, and have a high osmotic fragility--when placed into water, they are likely to burst. They are most commonly found in immunologically-mediated hemolytic anemias and in hereditary spherocytosis, but the former would have a positive direct Coombs antibody test and the latter would not.

Sphercytosis is an autosomal dominant trait, most commonly (though not exclusively) found in Japanese and Northern European families, although an estimated 25% of cases are due to spontaneous mutations. A patient has a 50% chance of passing the disorder onto his/her children, presuming that his/her partner does not have the mutation too. Several different genetic markers have been documented to produce the disorder in varying degrees of severity.