sickle cell disease


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Related to sickle cell disease: sickle cell trait, Sickle cell crisis

sickle cell disease

or

sickle cell anemia,

inherited disorder of the blood in which the oxygen-carrying hemoglobinhemoglobin
, respiratory protein found in the red blood cells (erythrocytes) of all vertebrates and some invertebrates. A hemoglobin molecule is composed of a protein group, known as globin, and four heme groups, each associated with an iron atom.
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 pigment in erythrocytes (red blood cells) is abnormal. This "hemoglobin-S" crystallizes in small capillaries, where the concentration of oxygen in the blood is low (but sufficient for normal hemoglobin), causing the red blood cells to assume distorted, sicklelike shapes. Linus PaulingPauling, Linus Carl
, 1901–94, American chemist, b. Portland, Oreg. He was one of the few recipients of two Nobel Prizes, winning the chemistry award in 1954 and the peace prize in 1962.
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 discovered the chemical abnormality of the hemoglobin molecule that causes the erythrocyte sickling in 1949.

The sickled red blood cells tend to clog small blood vessels, depriving the tissues they serve of blood and oxygen. Painful "crises" result, with symptoms depending on the site affected (e.g., joint and abdominal pain or kidney damage). Strokes or seizures can occur if the brain is affected. Lung infections resulting from the patient's disinclination to take painful deep breaths are a frequent complication. In addition, the sickled erythrocytes are fragile and subject to rupture and destruction, leading to hemolytic anemia (reduction of oxygen-carrying hemoglobin caused by premature destruction of red blood cells) and such symptoms as fatigue, jaundice, and headaches.

Treatment

There is no cure for the disease, but advancements in treatment have improved median survival to 42 years for men and 48 years for women. Cerebral hemorrhage or shock is the usual cause of mortality in children. Recent studies have indicated that regular blood transfusions can prevent strokes in children. Anemia is treated with folic acid. Sickle cell crises may be treated with intravenous hydration, pain medication, antibiotics, oxygen, and transfusions. Hydroxyurea, formerly used as a cancer treatment, has been helpful to many adults with the disease, lessening the frequency and severity of crises. New drugs for reducing the severity of crises are being tested as well. One acts as a lubricant, allowing sickled cells to flow more easily through tiny vessels. The other helps to prevent tissue deprived of blood from dying during a crisis.

Incidence

The disease occurs mainly in persons of sub-Saharan African, especially W African, origin, but it also occurs in persons of Mediterranean, Middle Eastern, and Indian origin. The mutation may at one time have had an advantageous effect; those who have the sickle cell trait have a higher survival rate in malaria-infested zones.

Under normal circumstances the disease occurs only in those patients who inherit the gene for the abnormal hemoglobin from both parents. This so-called homozygous form of the disease occurs in 1 in 400 African Americans. About 8% of African Americans have sickle cell trait; that is, they are heterozygotes, usually symptomless carriers who have inherited a normal hemoglobin gene from one parent and hemoglobin-S from the other. There are also intermediate forms of the disease that result when a gene for hemoglobin-S is inherited from one parent and a gene for any of several other abnormal kinds of hemoglobin is inherited from the other. Genetic screening (see genetic testinggenetic testing,
medical screening for genetic disorders, by examining either a person's DNA directly or a person's biochemistry or chromosomes for indirect evidence. Testing may be done to identify a genetic disorder a person has, whether the disorder is already evident or not,
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) is recommended for prospective parents at risk of passing on the disease. If both parents are carriers (i.e., have sickle cell trait), then each child has a one in four chance of having sickle cell disease.

References in periodicals archive ?
These results support further clinical investigation of this agent as a potentially disease-modifying therapy for sickle cell disease.
We have identified unsuspected silent infarctions occurring during acute anemic events in 18% of children with sickle cell disease and 7% of controls," he said, adding that children with acute anemia may need closer observation.
We have had a sharp fall in the cases of newborn with sickle cell disease and that is an encouraging sign but there are still far too many patients living with the condition.
These standards are another step in providing consistent care across the country for people with sickle cell disease and bringing this under recognised condition from the margins to the mainstream.
Sickle Cell disease affects mainly people of African/black, Mediterranean and Asian origin.
The pediatric brain in sickle cell disease has been widely studied in the past 20 years, and it is known that up to 30% of these children have neurocognitive abnormalities.
We expected to see iatrogenic transmission (1,8) because the children in this study all had sickle cell disease and more than half had had blood transfusions, and many had had multiple transfusions.
Sickle cell disease causes red blood cells, which are normally disc-shape, to become sickle-shape (crescent-shape).
It is thought there are 6,000 adults and children with sickle cell disease in Britain.
Refuerzo of Wayne State University, Detroit, reviewed the records of 30 pregnant women with sickle cell disease who were treated at that institution between 1997 and 2001.
of West Palm Beach donated $1,000 to the Sickle Cell Disease Association of Palm Beach County.
Lanetta Jordan, President of the FSCDR, "The notion of making a comedy about a life-threatening disease like Sickle Cell Disease is a mockery of humanity.

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