CAUSES of Sickle Cell Anemia
Sickle Cell Anemia is caused by one main factor. Sickle Cell Anemia is a genetic disease. This means that this disease is not contagious, and can only be passed down from parent to offspring. People who have this disease are born with it. The disease is carried on the HBB gene, the gene that codes for hemoglobin. Hemoglobin is a protein that is filled with iron, and it is what gives red blood cells the red coloration. The function of hemoglobin is to carry oxygen throughout the blood stream and body. Sickle Cell Anemia occurs when there is a mutation on this gene. The mutated variant of this gene, HbS, is what causes this disease. Since this disease is an Autosomal Recessive Disease, it can only be passed down from parent to offspring when both parents possess at least one HbS gene. If only one parent has the HbS gene, their child can become a carrier of the disease. These children have the mutated gene, but they do not usually show symptoms of the disease.
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The image above shows a pedigree of this disease. A person with no red indicates an unaffected person, the red dot indicates a carrier, and the full red person indicates an affected person with SCA. As you can see, when both parents are carriers of the trait, 1 in 4 of the children are fully affected by SCA. 1 in 2 are carriers, and 1 in 4 are unaffected by the disease.
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|Brian Oh|Biology 2|Final Project|5/30/2013|