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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. [5]
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.
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]
HbC can combine with other abnormal hemoglobins and cause serious hemoglobinopathies. Individuals with sickle cell–hemoglobin C (HbSC), have inherited the gene for sickle cell disease (HbS) from one parent and the gene for hemoglobin C disease (HbC) from the other parent. Since HbC does not polymerize as readily as HbS, there is less sickling ...
In 1956, Ingram, John A. Hunt, and Antony O. W. Stretton determined that the change in the haemoglobin molecule in sickle cell disease and trait was the substitution of the glutamic acid in position 6 of the β-chain of the normal protein by valine.
Sickle hemoglobin (HbS) is the most common variant of hemoglobin and arises due to an amino acid substitution in the beta-globin subunit at the sixth residue from glutamic acid to valine. There are different forms of sickle cell disease. HB SS which is the most common and severe form of sickle cell.
This can lead to changes in protein structure or function, which can cause potentially lead to changes in phenotype, sometimes pathogenic. A well known example in humans is sickle cell anemia, due to a mutation in beta globin where at position 6 glutamic acid (negatively charged) is exchanged with valine (not charged).