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What is sickle cell anemia?

Sickle cell anemia is an inherited disease of red blood cells. Normally red blood cells contain a protein called hemoglobin A, which carries oxygen to all the organs in the body. With sickle cell anemia, however, the body makes a different kind of protein, called hemoglobin S.

The problem is that when a red blood cell with hemoglobin S releases oxygen, the cell changes from the usual doughnut shape to a sickle or S shape, and becomes stiff rather than soft and flexible like normal red blood cells. This "sickled cell," which resembles a crescent moon, can't continue to glide through the small blood vessels as usual. Instead, it gets stuck in the tiny blood vessels, blocking the flow of blood and causing pain.

The spleen, an organ on the left side of the abdomen across from the liver, is responsible for filtering the blood for infections and other abnormalities. Normal red blood cells can change shape and squeeze through this filter, but sickled cells get stuck and cannot recirculate through the body, so that the number of circulating blood cells goes down. Meanwhile, the bone marrow, where red blood cells are made, pitches in by making more cells. It can't keep up with the destruction, though, so the total number of red blood cells drops to a low level and the body becomes anemic. ("Anemic" is the medical word for having a low number of red blood cells.)

What is sickle cell anemia?

Sickle cell anemia is an inherited disease of red blood cells. Normally red blood cells contain a protein called hemoglobin A, which carries oxygen to all the organs in the body. With sickle cell anemia, however, the body makes a different kind of protein, called hemoglobin S.

The problem is that when a red blood cell with hemoglobin S releases oxygen, the cell changes from the usual doughnut shape to a sickle or S shape, and becomes stiff rather than soft and flexible like normal red blood cells. This "sickled cell," which resembles a crescent moon, can't continue to glide through the small blood vessels as usual. Instead, it gets stuck in the tiny blood vessels, blocking the flow of blood and causing pain.

The spleen, an organ on the left side of the abdomen across from the liver, is responsible for filtering the blood for infections and other abnormalities. Normal red blood cells can change shape and squeeze through this filter, but sickled cells get stuck and cannot recirculate through the body, so that the number of circulating blood cells goes down. Meanwhile, the bone marrow, where red blood cells are made, pitches in by making more cells. It can't keep up with the destruction, though, so the total number of red blood cells drops to a low level and the body becomes anemic. ("Anemic"