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Sickle cell anemia
Definition:
Sickle cell anemia is an inherited disease in which the red blood cells, normally disc-shaped, become crescent shaped. As a result, they function abnormally and cause small blood clots. These clots give rise to recurrent painful episodes called "sickle cell pain crises." Alternative Names:
Anemia - sickle cell; Hemoglobin SS disease (Hb SS); Sickle cell disease Text Continues Below
Causes, incidence, and risk factors:
Sickle cell anemia is caused by an abnormal type of hemoglobin called hemoglobin S. Hemoglobin is a protein inside red blood cells that carries oxygen. Hemoglobin S, however, reduces the amount of oxygen inside the cells, distoring their shape. The fragile, sickle-shaped cells deliver less oxygen to the body's tissues, and can break into pieces that disrupt blood flow. Sickle cell anemia is inherited as an autosomal recessive trait , which means it occurs in someone who has inherited hemoglobin S from both parents. Sickle cell disease is much more common in certain ethnic groups, affecting approximately one out of every 500 African Americans. Someone who inherits hemoglobin S from one parent and normal hemoglobin (A) from the other parent will have sickle cell trait. Someone who inherits hemoglobin S from one parent and another type of abnormal hemoglobin from the other parent will have another form of sickle cell disease, such as thalassemia. Although sickle cell disease is present at birth, symptoms usually don't occur until after 4 months of age. Sickle cell anemia may become life threatening . Blocked blood vessels and damaged organs can cause acute painful episodes, or "crises." There are several types of crises: - Hemolytic crisis occurs when damaged red blood cells break down
- Splenic sequestration crisis is when the spleen enlarges and traps the blood cells
- Aplastic crisis results when an infection causes the bone marrow to stop producing red blood cells
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