What is Hereditary Spherocytosis?

Hereditary spherocytosis is a genetically inherited blood disorder that results in the formation of abnormally shaped red blood cells. An individual with this disorder has spherical red blood cells instead of the normal disc-shaped cells. Symptoms include anemia, fatigue, jaundice, pale skin and splenomegaly, in which the spleen becomes dangerously enlarged. The greatest risk for people with hereditary spherocytosis is low red blood cell count, which can be life-threatening if severe enough.

The underlying cause of inherited spherocytosis is a defect in one or more genes' coding for proteins called spectrin and ankyrin. These proteins are components of red blood cell membranes. Defects in the proteins cause cell membranes to become fragile and the cells themselves to have an abnormal shape. As a result, these cells are at risk of premature destruction in the spleen, because this organ is responsible for destroying damaged red blood cells and typically destroys cells that are abnormally shaped.

People affected by hereditary spherocytosis can differ widely in terms of the severity of their symptoms. In some people, the condition is asymptomatic, and others have mild anemia that becomes worse during illness of stress. For some, the condition results in episodes of severe hemolytic anemia, in which red blood cells are destroyed faster than they can be replaced. The risk of such episodes occurring during stress or illness is much higher, because bone marrow generation of red blood cells slows down or stops at such times.

Treatment for hereditary spherocytosis depends on the severity of the disease. Possible treatments include monitoring of red blood cell levels with transfusions in emergency situations and splenectomy, in which the spleen is removed. Removal of the spleen cures most cases of inherited spherocytosis, because without the spleen, red blood cell destruction cannot occur at an abnormally high rate.

While splenectomy is curative in most cases, people who have this surgery are at increased risk of certain types of infection. This is because in addition to its role in red blood cell destruction, the spleen is also an immune organ that is important in antibody-mediated removal of bacteria from the bloodstream. An individual who has undergone splenectomy is at risk of fatal sepsis, a condition that can develop when certain types of bacteria infect the blood, urine, lungs or skin.

An alternative surgery called a partial splenectomy might be performed in people with hereditary spherocytosis. By removing only part of the spleen, the rate of red blood cell destruction is reduced, and the immunologic function of the organ is retained. In people with very severe disease, this option is not always suitable, because the rate of cell destruction might be too high even after partial spleen removal.