Sickle cell anemia

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Sickle cell anemia, associated with the abnormal hemoglobin HbS gene, is common in Africa, India, and among African Americans but rare in the Caucasian and Asian populations. In the sickle cell trait, this occurs sin about 9% of African Americans, one abnormal gene is present. A single point mutation occurs in the hemoglobin  molecule, causing the normal glutamic acid at position 6 of the beta china to be replaced with valine, resulting in HbS. The amino acid substitution is on the surface, resulting in a tendency for the hemoglobin molecule to crystallize with anoxia. However, heterozygous individuals have no symptoms, and oxygen transport by fetal (HbF) and adult hemoglobin (HbA) is normal .Sickle cell trait offers protection again malaria, and this selective advantage is thought to have favored the persistence of the HbS gene, especially in regions where malaria is common . Sickle cell disease represents the homozygous condition (S/S) and occurs in about 0.2 % of African Americans. The onset of sickle cell anemia occurs in infancy as HbS replaces HbF; death often occurs early in adult life. Patients with sickle cell anemia have >80% HbS in their blood with a decrease or an absence of normal HbA. Whatever the cause of anemia, the pathophysiological effect in the same –hypoxia. Symptoms include pallor of the lips and skin, weakness, fatigue, lethargy, dizziness, and fainting .If the anemia is severe, myocardial hypoxia can lead to angina pain. It has no available cure. However treatment for the symptoms and complications of the disease. Bone marrow transplants may offer a cure in small no of cases.

Source:

1.T ext book of physiology Medical physiology Lippincott Williams and Wilkins

Filed Under: Hematology

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