DOI: 10.36347/sjams.2015.v03i06.017

Pages: 2244-2252

This paper reviews Sickle cell anaemia.Sickle cell anaemia is a homozygous form of HbS(HbSS).This result from single point replacement of glutamine by valine at position 6 of β- globin chain.This reduces solubilty of the red cells which in turn leads to polymerisation and vaso-occlussion in the vasculature. The β - globin gene is found on the short arm of chromosome 11. The association of two mutant β -globin subunits forms haemoglobin S (HbS). Under low - oxygen conditions, the absence of a polar amino acid at position of six of the β - globin chain promotes the non - covalent polymerization of haemoglobin, which distorts red blood cells into a sickle shape and decreases their elasticity. In sickle cell disease, low oxygen tension promotes red blood cell sickling and repeated episodes of sickling damage the cell membrane and decreases the cell's elasticity. These cells fail to return to normal shape when normal oxygen tension is restored. As a consequence, these rigid blood cells are unable to deform as they pass through narrow capillaries, leading to vessel occlusion and Ischaemia. The actual anaemia of the illness is caused by haemolysis, the destruction of the red cells inside the spleen.Those suffering from this illness are present with chronic anaemia which those with normal adult haemoglobin genotype will not survive because of the misshape of the cells leading to destruction of the cells at the spleen.