Sickle cell anaemia is a genetic disorder that causes the normally round RBCs (erythrocytes) to mutate into a sickle like shape. This abnormality has far reaching repercussions as the RBCs now carry a far less amount of oxygen than required as the oxygen carrying capacity of the cells is reduced drastically.
This causes mental retardation and premature deaths due to lack of oxygen. However, in a recent study conducted at the Stanford University, it was proven beyond doubt that sickle cell anaemia does not lead to premature deaths. This comes as a major sigh of relief for African-Americans as the gene causing this condition is most prominent amongst them.
This disease is caused by the formation of an abnormal haemoglobin, haemoglobin-S. It differs from normal haemoglobin in the aspect that instead of CTC triple codon, it has CAC triple codon and so it transcripts Valine instead of Glutamic acid. For this to happen, both the haemoglobin genes must be of haemoglobin-S type.
The affect of this is that RBCs formed are sickle shaped as a result of which, the cells cannot pass through narrow capillaries and have a tendency to clot and degenerate rapidly. This results in low blood circulation, also known as anaemia. This later leads to jaundice and a damaged spleen and brain.
RELEVANCE OF THIS GENE
This gene is found in vast portions of the human population, mainly in people from the African continent. This is so because; a combination of the haemoglobin-S and the normal haemoglobin gene renders the person immune to malaria. This is so because now the RBCs become oval like in shape and so the malaria parasite cannot penetrate the membrane and it dies.
Earlier it was thought that people with this gene were at a higher risk of premature deaths however in a recently conducted study on Africans serving the U.S army, by the Stanford University the results came out a firm negative. This clearly dismissed the notion of premature deaths being linked to this gene once and for all and instead tied them to the poor living conditions in Africa. This comes as a major relief to the millions of Africans that have migrated across the Atlantic to the U.S.