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 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.

* * *

a hereditary hemolytic anemia, seen primarily in West Africa and in people of West African descent, and less often in the Mediterranean basin and a few other areas. It is an autosomal recessive disorder in which mutation of the HBB gene (locus: 11p15.5), which encodes the β-globin chain, results in hemoglobin S, which has decreased solubility in the deoxygenated state and results in abnormal sickle-shaped erythrocytes (sickle cells). Homozygous individuals have 85 to 95 percent sickle cells and have the full-blown syndrome with accelerated hemolysis, increased blood viscosity and vaso-occlusion, arthralgias, acute attacks of abdominal pain, ulcerations of the lower extremities, and periodic attacks of any of the conditions called sickle cell crises. The heterozygous condition is called sickle cell trait and is usually asymptomatic. See also sickle cell disease, under disease. Called also sicklemia.

Medical dictionary. 2011.

Look at other dictionaries:

  • 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.

  • sickle cell anemia — Pathol. a chronic hereditary blood disease, occurring primarily among Africans or persons of African descent, in which abnormal hemoglobin causes red blood cells to become sickle shaped and nonfunctional, characterized by enlarged spleen, chronic …   Universalium

  • sickle cell anemia — An inherited disease in which the red blood cells have an abnormal crescent shape, block small blood vessels, and do not last as long as normal red blood cells. Sickle cell anemia is caused by a mutation (change) in one of the genes for… …   English dictionary of cancer terms

  • sickle cell anemia — sickle cell a nemia noun uncount a blood disease that mainly affects black people …   Usage of the words and phrases in modern English

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

  • sickle-cell anemia — noun Date: 1922 a chronic inherited anemia that occurs primarily in individuals of African, Mediterranean, or southwest Asian ancestry who are homozygous for the gene controlling hemoglobin S and that is characterized especially by episodic… …   New Collegiate Dictionary

  • sickle-cell anemia — noun A disease characterized by sickle shaped red blood cells. Syn: sickle cell disease …   Wiktionary

  • sickle cell anemia — Synonyms and related words: Christmas disease, Hand Schuller Christian disease, Hartnup disease, Letterer Siwe syndrome, Werdnig Hoffmann disease, achromatic vision, acute leukemia, albinism, anemia, angiohemophilia, aplastic anemia, chronic… …   Moby Thesaurus

  • sickle cell anemia — sick′le cell ane′mia n. pat a chronic hereditary blood disease, primarily affecting indigenous Africans and their descendants, in which an accumulation of oxygen deficient sickle cells results in anemia, blood clotting, and joint pain Also called …   From formal English to slang

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”