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Sickle Cell Anaemia

Sickle Cell Anaemia. The sickle cell trait protects you from malaria!

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Sickle Cell Anaemia

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  1. Sickle Cell Anaemia The sickle cell trait protects you from malaria! The sickle cell anaemia is thought to provide a biological advantage against malaria. The highest rate of HbS occurs in high endemic regions of malaria in Africa (Sub-Sahara). The frequency of mutation in this region has remained at 20% over 1000 years. It is likely that through natural selection the HbS gene spread as it reduces the risk of fatal malarial anaemia and cerebral malaria. Heterozygous individuals do not suffer all the adverse effects of the sickle cell anaemia and still mortality from malaria is reduced. • Treatment • 1. Pain control • Rest, rehydration, analgesia • Pethidine, morphine, diamorphine • 2. Blood transfusion • Advantage: increase the number of normal red blood cell • Disadvantage: alloimmunization, transmission of infection agents, iron overload • 3. Hydroxyurea • Reduce painful episodes and acute chest syndrome, hospitalization, transfusion, mortality rate • Advantage: increase hemoglobin F level • Disadvantage: long term use, biological difference, induction of tumor (carginogenicity), children effectiveness • 4. Bone marrow transplantation • Advantage: curative, • Disadvantage: suitable donor and neurological complications • 5. Prevention • Proper neutrinos( vitamin, mineral) • Good sleep • Less stress • Diagnosis • CBC (Complete Blood Count) • Low number of red blood cells • Low hemoglobin values in blood • Low hematocrit (Fraction of the blood composed of red blood cells) • Hemoglobin Electrophoresis • Reveal the presence of HbS • HbA (normal RBCs) has a percentage lower than 95% • Sickle Cell Test (Sickledex) • Reveal the presence of HbS • Usually used for confirmation • Clinical Picture and Blood Film • Reveal red blood cells in Sickled-shaped • (refer to Picture 1) • Solubility Test • HbS is precipitated and forms a • cloudy solution when blood contains • a significant amount of HbS which is • dissolved in a deoxygenating agent How the sickle cell trait protects you from malaria Etiology and Epidemiology Sickle cell anaemia is a disease with a genomic point mutation of the haemoglobin beta gene (HBB) on chromosome 11 at position 15.4, which alters haemoglobin so that upon deoxygenation the haemoglobin molecule undergoes a structural change forming the sickle cell. Sickle cell anaemia affects predominantly African American persons and is located simultaneously with their migration. In western and central Africa up to 25% of the population have this disease. Though overall approximately 8% of the African population are affected. Is also be found in Portugal, Spain, Italy, Greece, Turkey, Lebanon, Israel, Saudi Arabia, Kuwait and Yemen. Generally misshapen sickle cells are poor hosts for P.falciparum. Parasite can in fact grow well in oxygenated normal RBCs and in cells that contain mutated Hb. However, the antimalarial effect occurs when the RBCs become sickle. It is likely that sickle cells interrupt parasite metabolism and low oxygen tension retards the parasite replication. The presence of parasite also causes cells to sickle faster (approx. 20-fold) thus increasing the likelihood of sickle cell destruction in the spleen. The parasite maturation is also retarded since sickle cells are more unstable than the healthy cells. HbS can help to limit the rate and development of malaria infection. Individuals who are heterozygous for sickle-cell allele (HbAS) are protected against most severe outcomes of disease such as severe malarial anaemia, high-density parasitaemia and mortality. HbAS seems to have the most protective advantage against malaria mortality early in life, reducing the parasite loads especially in children between 2-16 months. Homozygotes for sickle allele also have some protection against malaria but suffer from sickle cell disease complications and premature death. A model of infected sickle red blood cell Author’s Name/s Goes Here, Author’s Name/s Goes Here, Author’s Name/s Goes Here Address/es Goes Here, Address/es Goes Here, Address/es Goes Here Pathogenesis of Sickle hemoglobin 1 INTRO + TABLE Pathogenesis of Sickle hemoglobin 2 • Sickle cell research • Application of genetics lies at the cutting edge of sickle cell related research - this is what may generate new treatments for this disease.Examples of current research projects about sickle cell anaemia: • Monash University and the University of Sydney: • Reactivating the foetal globin gene that is usually silenced after birth • Production of ‘healthy’ haemoglobin in persons with mutations with adult haemoglobin gene • The main goal is to identify regulatory proteins involved in control of the switch between the foetal and adult globin gene Harvard • Medical School and the Massachusetts Institute of Technology: • ‘Correction’ of defective human globin gene by the addition of anti-sickling human beta-haemoglobin gene • Increase in number of functional RBCs • Studies include safety of gene vectors, safer methods of partial bone marrow replacement Conclusion

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