Hematologic Conditions: Common Hemoglobinopathies.

Hemoglobinopathies are genetic disorders that lead to abnormal structure of the hemoglobin molecule. Genetic mutation results in major changes in the hemoglobin structure, with dysfunctions related to changes in shape, oxygen-carrying capacity, or ability to clump together, causing obstruction of the vascular system. Sickle cell disease and beta thalassemia major are two common hemoglobinopathies worldwide. However, they occur infrequently in the United States, with approximately 101,000 individuals affected. Sickle cell disease phenotypically is exhibited in patients with two hemoglobin S genes but the disease broadly includes many other hemoglobin abnormalities. Complications vary according to genotype and include acute pain crisis, vasoocclusive events, and acute chest syndrome. Blood transfusions are a mainstay of therapy. The two main categories of thalassemias are beta thalassemias and alpha thalassemias. Symptoms range from severe to none. The severity depends on how many genes are affected. Patients with the most severe form of beta thalassemia (ie, two affected genes) are categorized as having thalassemia major or transfusion-dependent disease. The primary treatment for beta thalassemia major currently is transfusions, although stem cell transplantation is a potentially curative option.