The Genetic Disorder Which is Called Sickle Cell Anemia

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Sickle cell anemia is a genetic disease, yet infants affected by the disease usually exhibit signs after four months of age. The symptoms vary in nature and intensity and are usually related to anemia and pain. The anemia leads to extreme weakness and reduced working capacity, along with breathlessness, dizziness, headache, pale complexion and low temperature of extremities (Steinberg, 2008). Another major problem associated with SCA is excruciating pain, arising suddenly. and known as a sickle cell crisis (Dunlop Bennett, 2006). Small blood vessels in the circulatory system become clogged by clumping together of sickle-shaped RBCs. This occlusion obstructs the blood flow in capillaries and is painful. The regions affected are bones including joints, lungs, spleen, and abdomen. Pain, in the lungs, leads to severe chest crisis. Further symptoms of SCA arise due to complications arising as a result of these basic conditions. An understanding of the Genetics of SCA requires a basic understanding of the overall structure of the hemoglobin molecule and its genetics. Hemoglobin is a 146 amino acid long protein with a molecular weight of 15,867 Daltons. It is located inside the RBCs and is the major oxygen carrier molecule in blood. It is a tetrameric protein made of four protein subunits: two alpha globins and two beta globins, each of which carries an iron-containing molecule called heme, which is imperative for oxygen transport function of hemoglobin (Perutz, 1960). Each hemoglobin molecules binds to four molecules of oxygen (HbO4), which imparts the bright red color to the blood. Of the subunits of hemoglobin, the beta globins are encoded by HBB gene, thus mutations in HBB results in altered structures of beta globins.