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Hemoglobinopathies and Thalassemia: Learning Objectives

Medical Importance

Knowledge of mutant hemoglobins and how their pathophysiologic mechanisms result in clinical disease is useful in the diagnosis and treatment of these genetic diseases. Of more than 700 known mutant hemoglobins only a few are associated with serious medical problems. The most important of these is Hb S which in homozygous and some heterozygous combinations results in sickle cell disease. Other less common but medically important abnormal hemoglobins includes those that cause methemoglobinemia, Heinz body anemias, and erythrocytosis.


  1. Identify the different chromosomes responsible for alpha-globin and beta-globin synthesis and to list the three types of hemoglobin found in normal adult blood.

  2. Describe the precipitating factors and pathophysiologic process by which hemoglobin S causes sickling, as well as the symptoms and signs of the consequences of sickling.

  3. List the rationale for the following sickle cell disease therapies: penicillin, folic acid, and hydroxyurea.

  4. Describe the basic genetic differences between alpha-thalassemia and beta-thalassemia.

  5. Describe the genetic, hematologic, and clinical differences between alpha-thalassemia trait, hemoglobin H disease, and hydrops fetalis.

  6. Describe the hematologic findings and pathophysiological changes that are associated with beta-thalassemia major.

  7. List the mechanisms and consequences of iron overload and infections associated with beta-thalassemia major.