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 ?
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.
This anemia leaves the body oxygen starved and causes the pain and fatigue of sickle-cell disease, says molecular geneticist Thomas M.
People with sickle-cell disease are also at high risk of other complications, especially stroke.
Acute chest syndrome--characterized by chest pain, fever, high blood pressure in the lungs, and a chest X ray showing clogged or collapsed lungs--is the most life-threatening complication of sickle-cell disease.
In just the third published case of nitric oxide use to treat sickle-cell disease, Paulette Mehta of the University of Florida College of Medicine in Gainesville and her colleagues reported similar success in the November 1999 CRITICAL CARE MEDICINE.
There are many possible explanations for nitric oxide's apparent benefits to people with sickle-cell disease.
The oxygen affinity of hemoglobin from three people without sickle-cell disease was unaffected.
He's starting a multicenter trial to test whether inhaled nitric oxide can reduce pain or illness in sickle-cell disease.
In mice with a disorder resembling sickle-cell disease, breathing nitric oxide seems to increase the survival of animals stressed by low oxygen, Head reported in the September 1999 ANESTHESIOLOGY.