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.
References in periodicals archive ?
That's what scientist Tim Townes did when he "created" designer mice to study sickle-cell disease.
A team of government and university researchers identified nine women and three men who had this lung complication of sickle-cell disease.
People with sickle-cell disease make elongated versions of hemoglobin, the protein in red blood cells that totes oxygen.
In people with sickle-cell disease, deformed red blood cells can't transport oxygen efficiently.
In the study's earlier years, the first 12 children with sickle-cell disease received a bone marrow transplant plus busulfan and cyclophosphamide, two drugs known to facilitate transplants.
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.
Sickle-cell disease is a genetic disorder that affects about 72,000 people in the United States, most of them African Americans.
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.