Spherocytosis, in most cases, is an inherited disease that changes the shape of and decreases the life of red blood cells. This destruction of the red blood cells leads to anemia.

The shape of a normal red blood cell resembles a disk. Normal red blood cells are flexible and easily change shape to move smoothly through the small blood vessels between organs of the body.

A person with spherocytosis has red blood cells that are very round and have difficulty changing this shape. The lack of ability to change shapes makes moving through the small blood vessels difficult. Therefore, the red blood cells stay in the spleen longer than normal. This lengthy stay in the spleen damages the cell membranes. Eventually, the spleen will destroy these abnormal red blood cells.