Sickle cell disease (SCD) is an inherited disorder of hemoglobin, which gives red blood cells their color and carries oxygen to the tissues.

In SCD, the abnormal hemoglobin (Hgb SS) makes the red cells rigid and distorted from the usual round shape into sickle shapes. These stiff, crescent-shaped sickled red blood cells can plug up small blood vessels and decrease blood flow to various parts of the body. This leads to anemia, organ damage and painful episodes, sometimes called a “crisis.”