Ankyrin deficiency (Hereditary Spherocytosis)
Ankyrin deficiency, also known as hereditary spherocytosis, a genetic disorder of the red blood cell membrane clinically characterized by anemia, jaundice (yellowing) and splenomegaly (enlargement of the spleen), due to deficiency of ankyrin, a protein in the membrane of the red cell. In HS the red cells are smaller, rounder, and more fragile than normal. The red cells have a spherical rather than the biconcave-disk shape of the normal red cell. These rotund red cells (spherocytes) are osmotically fragile and less flexible than normal red cells and tend to get trapped in narrow blood passages, particularly in the spleen, and there they break up (hemolyze) leading to hemolytic anemia. The clogging of the spleen with red cells almost invariably causes splenomegaly.