Answer to Question #88076 in Zoology for Batool
Hemoglobinopathies represent a group of hereditary diseases caused by the presence of defective globins in the erythrocytes. Hemoglobin structures reduce the oxygen capacity of the blood, disrupt oxygen transport, increase the number of red blood cells and make it difficult for them to pass through the microvessels. All the features lead to hemolytic anemia and local tissue ischemia. For example, sickle cell anemia is a hereditary hemoglobinopathy associated with the impairment of the structure of the hemoglobin protein associated with the formation of a specific crystalline structure of hemoglobin. The hemoglobin form is referred to hemoglobin S. The red blood cells that carry hemoglobin S instead of the normal hemoglobin A have a characteristic sickle shape whereas the disease is called sickle cell anemia. The condition is associated with a mutation in the HBB gene, resulting in the synthesis of abnormal hemoglobin S, which contains glutamic acid in the sixth position of the β-chain instead of valine. Under hypoxic conditions, hemoglobin S polymerizes and forms long cords that make red blood cells sickle-shaped.