What is Hereditary Spherocytosis?

Hereditary Spherocytosis (HS) is a congenital disorder of the red cells in the blood. Its incidence is highest in families of Northern European ancestry. The degree of severity ranges from very mild and asymptomatic to severe and life-threatening. Other names for HS are: Congenital Spherocytic Anemia, Congenital Hemolytic Jaundice, Hereditary Microspherocytic Hemolytic Anemia, and Minkowski-Chauffard Syndrome.

2) What does the term "spherocytosis" mean?

The term "spherocytosis" refers to the shape of the red cells in HS. It means that the red cells are spherical. This spherical shape is abnormal. Normal red cells look like biconcave discs, kind of donut-shaped, but with a pallor in the center instead of a hole. This shape enables red cells to circulate throughout the body, even through the tiniest little blood vessels (capillaries), and deliver the much-needed oxygen to all the tissues and organs.

3) What are red blood cells?

Red blood cells (a.k.a. red cells, erythrocytes, and (less commonly) red corpuscles) are the most numerous cells in the blood. A healthy adult has about 4 to 6 million red cells per mm³ of blood. Red cells contain the protein hemoglobin, which gives blood its red color. Hemoglobin plays a vital part in the cycle of oxygen transportation to the tissues and the removal of carbon dioxide.

4) What are the main characteristics of Hereditary Spherocytosis?

The main characteristics of HS are a) smaller, spherical red cells lacking the area of pallor in the middle, b) an overactive, enlarged spleen, and c) overactive bone marrow.

5) So... what causes all the trouble in Hereditary Spherocytosis?

In HS, the abnormally shaped red cells cannot endure the various strains and pressures of circulation, and rupture easily. What is more, because they have this abnormal spherical shape, the spleen tags them as old or defective, traps them, and destroys them. Essentially, in HS, the body attacks and destroys its own blood supply. Therefore, HS is a type of hemolytic anemia, or, to be more precise, auto-hemolytic anemia. As a result of the increased hemolysis (breakdown of red cells), bilirubin (a waste product of hemolysis) rises to dangerously high levels. Also, the bone marrow works overtime to make up for the loss of so many red cells, and as a result, a lot of immature red cells (called "reticulocytes") are released into the circulation.

6) What are the symptoms of Hereditary Spherocytosis?

When symptomatic, HS manifests itself with signs characteristic of anemia: fatigue, fever, loss of concentration, jaundice, irritability, weakness, shortness of breath. The abnormally high levels of bilirubin have been connected to a high incidence of gallstones.

7) How is Hereditary Spherocytosis diagnosed?

Laboratory tests that can diagnose HS include physical examination (to detect splenomegaly), a complete blood count (to check for anemia), a peripheral smear (to look for spherocytes), a reticulocyte count (reticulocytes are elevated in HS), a bilirubin test (bilirubin is elevated in HS), as well as a special test to assess the fragility of the red cells (osmotic fragility test).

8) How is Hereditary Spherocytosis treated?

When indicated, surgical removal of the spleen (splenectomy) can correct the anemia; however, the genetic defect that produces the abnormal (spherical) red cells will not be affected. In mild to moderate cases, folic acid or iron supplementation are indicated, although long-term iron supplementation can cause problems of its own. Gene therapy is still at a very early stage and there is no immediate prospect of human clinical trials.