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However, people with normal hemoglobin are prone to infections and in this category infant mortality is high. The sickle cell trait is advantageous if the causative agent is Plasmodium falciparum. The natural selection process has selected sickle cell trait as a protective measure against malaria that is highly prevalent in Africa, but when an individual inherits two mutated copies of the gene, the individual suffers from the SCD. Sickle cell trait is advantageous to people in malaria-prone areas as it provides a survival tactic to the affected. The former results in disease, while the latter, protects against malaria. In SCD, the person has two abnormal copies of a gene while sickle cell trait has one mutated allele. The presence of sickle cell genes results in two conditions: sickle cell disease or sickle cell trait. Researchers indicate that occurrence of the disease decreases early mortality rate (2-16 years) especially in areas where malaria is endemic. Tanzania follows with 11,877, Uganda with 10,877, Angola with 9,017, Cameroon with 7,172, Zambia 6,039, and Ghana, guinea, Niger recording less than 6,000 sickle cell births per year. Studies indicate that the number in Nigeria and Congo is likely to increase to approximately 14000, respectively by the year 2050. The Democratic Republic of Congo comes seconds with a 39,743 sickle cell births per year. The rate accounts for almost 2% of all newborns annually. Nigeria records the highest disease incidence in the world with approximately 91,011 children born with the defect. West African countries report the highest prevalence of about 25% of the population. The disease is more dominant 10-40%, in equatorial countries of Africa and less 1-2%, in North Africa and less than 1% in South Africa. The occurrence of the disease is high in Africa due to the predominance of malaria. In the European countries, migration of the tropical and subtropical people increased the number of deaths due to SCD from 113,000 to 176,000 by 2013. The disease is predominant in tropical regions of sub-Sahara Africa where malaria is endemic. In pregnant women the symptoms are more pronounced, resulting in spontaneous abortion and intrauterine growth retardation.
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Silent strokes cause severe brain damage. A silent stroke also occurs predominantly in younger patients, whereas 10-15% of SCD children suffer from an asymptomatic stroke. Progressive narrowing of blood vessels may lead to symptomatic stroke due to insufficient brain oxygen supply.In children, cerebral infarction occurs and cerebral hemorrhage in adults. Sickle cell anemia results in loss of spleen function, leading to increased risk of severe bacterial infections. Other symptoms of the disease include frequent infections, stunted or delayed growth, and vision problems. In babies, the hand-foot syndrome may develop when the blood vessels are blocked.
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Fatigue follows due to less circulating oxygen in the blood capillaries. Anemia results when the condition leaves the body with lasting fewer amounts of red blood cells. The pain results from the blocked capillaries. The intensity of the pain varies among different people from a few episodes to more in a year. People with sickle cell anemia suffer from periods of pain called crises. These distorted RBC's are unable to carry enough oxygen to attend to the needs of the body, degrade quickly and also block capillaries, leading to improper distribution of blood to various organs and tissues of the body. Whereas a single allele (Heterozygous Hgbs) is capable of producing more than 50% of the hemoglobin, inheritance of both alleles, (homozygous Hgbs) distorts the shape of RBC from flat disk-shaped cells to sickle-shaped cells. Countries With The Highest Number Of Sickle Cell Births Per Year Pathophysiology In the case of sickle cell, a mutation in a single nucleotide of the hemoglobin-Beta genes occurs resulting in the substitution of Glumatic acid by Valine at position-6. The genes inherited from the parents determines the type of hemoglobin the person makes in red blood cells (RBC). The genes responsible for sickle cell disease are located on chromosome 11. Sickle cell anemia is a disease caused by the genetic inheritance of mutated alleles responsible for the condition.