Sickle Cell Disease
(Sickle Cell Anemia)

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Sickle cell anemia facts

  • Sickle cell anemia is an inherited disorder of the hemoglobin in blood.
  • Sickle cell anemia requires the inheritance of two sickle cell genes.
  • Sickle cell trait, which is the inheritance of one sickle gene, almost never causes problems.
  • Virtually all of the major symptoms of sickle cell anemia are the direct result of the abnormally shaped sickled red blood cells blocking the flow of blood.
  • The current treatment of sickle cell anemia is directed primarily toward managing the individual features of the illness as they occur.

What is sickle cell anemia?

Sickle cell anemia (sickle cell disease) is a disorder of the blood caused by an inherited abnormal hemoglobin (the oxygen-carrying protein within the red blood cells). The abnormal hemoglobin causes distorted (sickled) red blood cells. The sickled red blood cells are fragile and prone to rupture. When the number of red blood cells decreases from rupture (hemolysis), anemia is the result. This condition is referred to as sickle cell anemia. The irregular sickled cells can also block blood vessels causing tissue and organ damage and pain.

Sickle cell anemia is one of the most common inherited blood anemias. The disease primarily affects Africans and African Americans. It is estimated that in the United States, some 90,000 to 100,000 Americans are afflicted with sickle cell anemia. Overall, current estimates are that one in 500 U.S. African American births is affected with sickle cell anemia.

How is sickle cell anemia inherited?

Sickle cell anemia is inherited as an autosomal (meaning that the gene is not linked to a sex chromosome) recessive condition. This means that the gene can be passed on from a parent carrying it to male and female children. In order for sickle cell anemia to occur, a sickle cell gene must be inherited from both the mother and the father, so that the child has two sickle cell genes.

The inheritance of just one sickle gene is called sickle cell trait or the "carrier" state. Sickle cell trait does not cause sickle cell anemia. Persons with sickle cell trait usually do not have many symptoms of disease and have hospitalization rates and life expectancies identical to unaffected people. When two carriers of sickle cell trait mate, their offspring have a one in four chance of having sickle cell anemia. (In some parts of Africa, one in five persons is a carrier for sickle cell trait.)

Picture of Sickle Cell Red Blood Cell
Picture of Sickle Cell Red Blood Cell
Medically Reviewed by a Doctor on 3/4/2014

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Sickle Trait and Sickle Cell Disease

People can dream, but their road to success can be derailed in the most unusual ways, perhaps none as strange as that which affected Ryan Clark of the Pittsburgh Steelers. When his team plays in Denver, the Mile High City, so named because it sits at an altitude of 5,280 feet, Clark is sidelined. This is because of an incident in 2007 in which Clark ended up critically ill requiring emergency surgery because of his genetics; he suffers from sickle trait, a condition that affects the shape and function of red blood cells.