Anemia, sickle cell
A genetic blood disease due to the presence of an abnormal form of hemoglobin, namely hemoglobin S. Hemoglobin is the molecule in red blood cells that transports oxygen from the lungs to the farthest reaches of the body. Sickle cell anemia affects millions of people throughout the world. It is particularly common among people whose ancestors came from sub-Saharan Africa; Spanish-speaking regions (South America, Cuba, Central America); Saudi Arabia; India; and Mediterranean countries, such as Turkey, Greece, and Italy. In the USA, sickle cell disease occurs in about 1 in every 500 African-American births and 1 in every 1,000-1,400 Hispanic-American births. Sickle cell anemia is caused by an error in a gene that makes the beta globin chain of hemoglobin. The resultant abnormal hemoglobin (sickle hemoglobin) deforms the red blood cells when they are under low oxygen conditions. Children who inherit 2 copies of the sickle gene, one from each parent, have sickle cell anemia. Children who inherit the sickle gene from only one parent do not have the disease, but will carry the sickle cell trait. Individuals with sickle cell trait generally have no symptoms. About 2 million Americans (or 1 in 12 African-Americans) carry the sickle gene. The sickle mutation occurred thousands of years ago. The sickle gene became common in malarious areas because it affords a selective advantage against malaria. In the U.S., Canada, and many other countries where malaria is rare today, the sickle gene can no longer use its anti-malarial advantage. Instead, the sickle gene may be a serious threat to the carrier's children, who may inherit two abnormal sickle hemoglobin genes and have sickle cell anemia. In sickle cell anemia, the hemoglobin molecules tend to aggregate after unloading oxygen. They form long, rod-like structures that force the red cells to assume a sickle shape. Unlike normal red cells, which are usually smooth and deformable, the sickle red cells cannot squeeze through small blood vessels. The sickle cells block little vessels depriving the organs of blood and oxygen. This leads to the periodic episodes of pain and damages the vital organs. Whereas normal red blood cells last about 120 days in the bloodstream, sickle red cells die after only about 10 to 20 days. Because they cannot be replaced fast enough, the blood is chronically short of red blood cells causing anemia — sickle cell anemia.

Medical dictionary. 2011.

Look at other dictionaries:

  • sickle cell — n 1) an abnormal red blood cell of crescent shape 2) a condition characterized by sickle cells: SICKLE CELL ANEMIA, SICKLE CELL TRAIT * * * see drepanocyte * * * an erythrocyte shaped like a sickle or crescent owing to the presence of …   Medical dictionary

  • Sickle cell anemia — A genetic blood disease due to the presence of an abnormal form of hemoglobin, namely hemoglobin S. Hemoglobin is the molecule in red blood cells that transports oxygen from the lungs to the farthest areas of the body. Sickle cell anemia affects… …   Medical dictionary

  • Sickle cell disease — A genetic blood disease due to the presence of an abnormal form of hemoglobin, namely hemoglobin S. Hemoglobin is the molecule in red blood cells that transports oxygen from the lungs to the farthest reaches of the body. Sickle cell disease, also …   Medical dictionary

  • sickle-cell anaemia — noun a congenital form of anemia occurring mostly in blacks; characterized by abnormal blood cells having a crescent shape • Syn: ↑sickle cell anemia, ↑sickle cell disease, ↑crescent cell anemia, ↑crescent cell anaemia, ↑drepanocytic anemia,… …   Useful english dictionary

  • sickle-cell disease — noun a congenital form of anemia occurring mostly in blacks; characterized by abnormal blood cells having a crescent shape • Syn: ↑sickle cell anemia, ↑sickle cell anaemia, ↑crescent cell anemia, ↑crescent cell anaemia, ↑drepanocytic anemia,… …   Useful english dictionary

  • sickle cell anemia disease — ☆ sickle cell anemia disease n. an inherited chronic anemia found chiefly among blacks, characterized by an abnormal red blood cell (sickle cell) containing a defective form of hemoglobin that causes the cell to become sickle shaped when deprived …   Universalium

  • sickle cell anemia disease — ☆ sickle cell anemia disease n. an inherited chronic anemia found chiefly among blacks, characterized by an abnormal red blood cell (sickle cell) containing a defective form of hemoglobin that causes the cell to become sickle shaped when deprived …   English World dictionary

  • sickle-cell disease — n SICKLE CELL ANEMIA * * * a hereditary blood disease that mainly affects people of African ancestry but also occurs in the Mediterranean region and reaches high frequencies in parts of Saudi Arabia and India. It occurs when the sickle cell gene… …   Medical dictionary

  • sickle-cell anemia — n a chronic anemia that occurs in individuals (as those of African or Mediterranean descent) who are homozygous for the gene controlling hemoglobin S and that is characterized by destruction of red blood cells and by episodic blocking of blood… …   Medical dictionary

  • sickle-cell anemia — sickle cell anemia. См. серповидноклеточная анемия. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

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