This disorder is caused by a defective gene. The defect results in an abnormal red cell membrane so that the affected cells have a smaller surface area for their volume than normal red blood cells. The cells are less resistant to stresses and rupture easily. The anemia varies in its severity. In severe cases the disorder may be detected in early childhood, or in mild cases it may go unnoticed until later in adult life. This disorder is most common in people of northern European descent but has been found in all races. Jaundice and pallor (pale coloring) may be noted in infants, and the spleen is enlarged in most cases. After the spleen is removed, the life span of the red blood cell returns to normal. A family history of spherocytosis increases the risk for this disorder.
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