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Base-pair substitution that causes sickle cell anemia. The gene defect is a single nucleotide mutation of the β-globin gene, which results in glutamate being substituted by valine at position 6 of the β-globin chain. [62] Hemoglobin S with this mutation is referred to as HbS, as opposed to the normal adult HbA.
In the most common variant of sickle-cell disease, the 20th nucleotide of the gene for the beta chain of hemoglobin is altered from the codon GAG to GTG. Thus, the 6th amino acid glutamic acid is substituted by valine—notated as an "E6V" mutation—and the protein is sufficiently altered to cause the sickle-cell disease. [12]
A single point mutation in this polypeptide chain, which is 147 amino acids long, results in the disease known as Sickle Cell Anemia. [18] Sickle-cell anemia is an autosomal recessive disorder that affects 1 in 500 African Americans, and is one of the most common blood disorders in the United States. [17]
Sickle cell disease is a blood disorder wherein there is a single amino acid substitution in the hemoglobin protein of the red blood cells, which causes these cells to assume a sickle shape, especially when under low oxygen tension.
He found that the prevalence of sickle-cell trait (heterozygous condition) among people inhabiting coastal areas was higher than 20%. [8] At the time the highest record was 8% among African-Americans.) [ 10 ] He was posed with the question as to why such a deadly disease (in homozygous condition ) would be more prevalent in a localised area in ...
When combined with Hemoglobin S (β^6Glu → Val) it causes a severe form of Sickle cell disease known as Hemoglobin S/O-Arab. Detection of Hb O-Arab can be carried out with a blood test, identifying the carries of hemoglobinopathies, so as to inform patients their chances of producing an affected child and ensure appropriate guidance is given.
The Duffy antigen gene was the fourth gene associated with the resistance after the genes responsible for sickle cell anaemia, thalassemia and glucose-6-phosphate dehydrogenase. [ citation needed ] In 1950, the Duffy antigen was discovered in a multiply-transfused hemophiliac named Richard Duffy, whose serum contained the first example of anti ...
In 1998, Olekowski et al. [5] identified a new mismatch specific endonuclease. The enzyme was purified from celery and was given the name CEL I. CEL I was shown to cut DNA with high specificity on both strands at the 3′ side of base-substitution mismatches, and can therefore be used in enzyme mutation detection methods to identify mutations and polymorphisms.