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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.
Hemoglobin S/ beta thalassemia: common in African and Mediterranean populations, it is clinically similar to sickle-cell anemia. [ 91 ] Delta-beta thalassemia is a rare form of thalassemia in which there is a reduced production of both the delta and beta globins.
Prior to surgery in people with sickle cell anemia (HbSS) who already have a hemoglobin above 85g/L, or who require a prolonged operation with general anesthetic, or who need high-risk surgery [3] [4] [6] [7] To optimise hemoglobin S levels, for example to prevent a stroke occurring in a child.
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 ...
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.
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.
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. [7]
Sickle cell disorders, which are the most prevalent form of hemoglobinopathy. Sickle hemoglobin (HbS) is prone to polymerize when deoxygenated, precipitating within the red blood cell. This damages the RBC membrane resulting in its premature destruction and consequent anemia.