Sickle cell anemia is an inherited blood disorder that causes chronic anemia, periodic episodes of pain, and other complications. In sickle cell anemia, the red blood cells become rigid and shaped like crescents, or sickles, rather than being flexible and round. This change in shape prevents red blood cells from getting into small blood vessels. As a result, the tissues do not get enough oxygen. Lack of oxygen can cause pain and damage in the arms, legs, and organs (e.g., spleen, kidney, brain).
Sickle cell anemia gets its name from the change of shape (sickling) that happens in the red blood cells. The sickling is caused by an abnormal type of hemoglobin (an iron-protein compound in red blood cells that transports oxygen) known as hemoglobin S.
This disorder is common in the African-descended population of the United States and Canada. It affects millions of people around the world, mainly those whose ancestors come from sub-Saharan Africa, Spanish-speaking regions (South America, Cuba, Central America), Saudi Arabia, India, and Mediterranean countries (Turkey, Greece, and Italy).