Sickle Cell Disease Analysis

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Sickle cell disease has the ability to affect millions of people globally, but is most prevalent in countries that are malaria rife (, 2015). Despite the disease having the capacity to destroy lives, it also has the ability to act as a form of defence against the effects of malaria. The disease is directly caused by a single point mutation on the gene sequence that codes for beta-globin (Midence and Elander, 1994). This is brought about by the substitution of an Adenine base for a Tyrosine base, thus coding for the mutated form of the beta-globin gene, which will result in the formation of sickle cells (Hb S) (Serjeant and Serjeant, 2001). This mutation only affects adult hemoglobin, as foetal hemoglobin contains gamma-globin instead…show more content…
The severity and type of symptoms experienced by the sufferer can help to explain why some people with the disease are killed in childhood, and why the disease can be so mild in others. Symptoms most commonly associated with the disease are anaemia, acute chest syndrome, strokes, renal failure and an increased defencelessness to infections caused by bacteria (Ashley-Koch, Yang and Olney, 2000). These symptoms occur sporadically due to the fact that red blood cells in the body may behave, as they should, in a healthy person most of the time. (Tidy, 2015). However, when too many red blood cells become sickled the symptoms will be manifested in the patient or the patient will suffer sickle cell crisis (Tidy, 2015). It has been noted that the major cause of death in children with sickle cell disease is most commonly due to bacterial infection or strokes (Ashley-Koch, Yang and Olney, 2000). If a child with sickle cell disease is exposed to other diseases, they are unlikely to survive and thus some paediatric patents with sickle cell disease do not make it to…show more content…
Gamma-globin has a higher affinity for oxygen than the beta-globin that we have as adults. Gamma-globin helps us gain oxygen supplies from the mother, and is also unaffected by sickle cell mutations. Regardless of whether the child is carrying two copies of the sickle cell disease gene, it will not show any signs of the disease until the gamma-globin gene is switched off and the beta-globin gene is switched on, which happens just after birth (Murayama and Nalbandian, 1973). On average, 0.5% of the hemoglobin in adults is foetal hemoglobin, however, some people have an elevated level of foetal hemoglobin, up to 8%(Dover et al., 1992). Due to the fact that sickle cell disease only affects beta-globin, the presence of a greater percentage of gamma-globin will dramatically reduce the effects of sickle cell disease on a person. From experiments conducted, it has been seen that there could be a level above which the presence of foetal hemoglobin in a person expressing sickle cell disease will reduce the seriousness of the disease (Powars et al., 1984). This variation in the levels of foetal hemoglobin in adults explains why some people have a mild case of sickle cell disease compared to those without. Foetal hemoglobin plays an essential role in determining how severe the disease is as at birth. As soon as the gamma-globin gene is switched off and the beta-globin gene is turned on; the clock starts ticking on
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