Pathology – Sickle Cell Anemia
Sickle Cell Anemia is a genetic disorder characterized by abnormal red blood cells that have a sickle shape. This is an autosomal recessive condition that leads to the development of Hgb S. Hemoglobin S is the result of a genetic mutation that involves the substitution of glutamine with valine in the gene responsible for coding the beta-globin chain of hemoglobin. Approximately 8% of individuals of African descent possess the Hob S gene. Pathology The examination of the blood sample reveals the presence of crescent-shaped red blood cells, Howell-Jolly bodies, and an increased number of immature red blood cells. Pathophysiology refers to the study of the functional changes that occur in the body as a result of a disease or injury. Hemoglobin S undergoes polymerization in low-oxygen conditions, which can be triggered by factors such as infection, physical activity, or dehydration. resulting in the deformation of red blood cell morphology and increased vulnerability to hemolysis Symptoms and Signs Chronic hemolytic anemia, a condition characterized by the breakdown of red blood cells, can result in jaundice and leg ulcers. It can also cause vaso-occlusive crises, which are episodes of severe pain in the back or limbs due to blockage of small blood vessels by sickled cells. The repeated infarction of the spleen can lead to auto-splenectomy. Additionally, aplastic crises, often triggered by Parvovirus BIS infection, may occur. Individuals with this condition are more susceptible to infections caused by encapsulated organisms such as Salmonella. On imaging, a "Crew cut" appearance can be observed on skull x-rays due to expansion of the bone marrow. Therapy Supportive measures such as blood transfusions, administration of fluids, pain management, and oxygen therapy are recommended during episodes of hemolytic and vaso-occlusive crises. In severe cases of vaso-occlusive crises, plasma exchange may be considered, particularly for conditions like stroke or acute chest syndrome. Additionally, hydroxyurea can be prescribed to patients who experience recurrent crises as it helps increase levels of Hgb F. Allogeneic hematopoietic stem cell transplantation for a life-threatening condition. Individuals diagnosed with Hgb C illness, which is caused by a distinct mutation in the B-chain of hemoglobin, and those who have sickle cell trait, meaning they carry one copy of the Hgb S gene, typically experience less severe forms of sickle cell anemia. The presence of the Hgb S gene confers immunity against Plasmodium falciparum malaria.
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