sickle-cell anaemia

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Related to sickle-cell disease: cystic fibrosis, Sickle cell crisis

sickle-cell anaemia (SCA)

a human abnormality in which defective HAEMOGLOBIN molecules (Hbs) cause the red blood cells to have a twisted ‘sickle’ shape resulting in major circulatory problems and eventually death. The condition is controlled by a single autosomal gene on chromosome 11, with two alleles, S and s . The mutant haemoglobin has one amino acid alteration in its beta chain, number six having changed from GLUTAMIC ACID to VALINE possibly as a result of SUBSTITUTION MUTATION. Sickle-cell anaemics have an s/s genotype, while heterozygotes (S/s) have a condition called sickle-cell ‘trait’ with a tendency for their blood to sickle at low oxygen tension. Although SELECTION operates strongly against individuals with SCA the mutant allele has remained at fairly high frequency in some populations (e.g. in Central Africa), probably because the heterozygotes are at an advantage relative to the normal (S/s) types in terms of resistance to the MALARIA PARASITE, producing a GENETIC POLYMORPHISM. In North America, however, SCA is a transient polymorphism amongst blacks of African descent since the malarial selection pressure has been removed and its frequency in the population is expected to fall, although the success of modern medical treatment in reducing mortality has the effect of preserving the gene in the population.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
References in periodicals archive ?
Biree Andemariam, director of the New England Sickle Cell Institute at the University of Connecticut Health Center, has talked to her adult patients about CRISPR's potential for treating sickle-cell disease. "Patients are very intrigued by it.
"For 90 percent of people with sickle-cell disease who live in this world, this will still be something far too expensive for them to have access to," he says.
That's what scientist Tim Townes did when he "created" designer mice to study sickle-cell disease. Deliberately inflicting disease or injury on an otherwise healthy animal violates the animal's rights, says McArdle.
In people with sickle-cell disease, deformed red blood cells can't transport oxygen efficiently.
Using mice with sickle-cell disease, Brittain and her colleagues are planning to test compounds that inhibit alpha-4-beta-1 integrin to see whether they can avert vessel blockage.
Sickle-cell disease is an inherited disorder of red blood cells.
Leboulch and his team took bone marrow from mice with sickle-cell disease and added the modified gene to it.
This anemia leaves the body oxygen starved and causes the pain and fatigue of sickle-cell disease, says molecular geneticist Thomas M.
Sickle-cell disease is a genetic disorder that affects about 72,000 people in the United States, most of them African Americans.
In people with sickle-cell disease, however, hemoglobin doesn't hold onto oxygen well.
People with sickle-cell disease are also at high risk of other complications, especially stroke.
Thus doctors can now prescribe hydroxyurea for their patients even though the compound has yet to pass FDA muster specifically as a treatment for sickle-cell disease.