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The thalassemias are a group of inherited hematologic disorders caused by defects in the synthesis of one or more of the hemoglobin chains. Alpha thalassemia is caused by reduced or absent synthesis of alpha globin chains, and beta thalassemia is caused by reduced or absent synthesis of beta globin chains. Imbalances of globin chains cause hemolysis and impair erythropoiesis. Silent carriers of alpha thalassemia and persons with alpha or beta thalassemia trait are asymptomatic and require no treatment. Alpha thalassemia intermedia, or hemoglobin H disease, causes hemolytic anemia. Alpha thalassemia major with hemoglobin Bart's usually results in fatal hydrops fetalis. Beta thalassemia major causes hemolytic anemia, poor growth, and skeletal abnormalities during infancy. Affected children will require regular lifelong blood transfusions. Beta thalassemia intermedia is less severe than beta thalassemia major and may require episodic blood transfusions. Transfusion-dependent patients will develop iron overload and require chelation therapy to remove the excess iron. Bone marrow transplants can be curative for some children with beta thalassemia major. Persons with thalassemia should be referred for preconception genetic counseling, and persons with alpha thalassemia trait should consider chorionic villus sampling to diagnose infants with hemoglobin Bart's, which increases the risk of toxemia and postpartum bleeding. Persons with the thalassemia trait have a normal life expectancy. Persons with beta thalassemia major often die from cardiac complications of iron overload by 30 years of age. (Am Fam Physician. 2009;80(4):339-344, 371. Copyright © 2009 American Academy of Family Physicians.)
The thalassemias (named from the Greek word for sea, thalassa1) are a group of inherited autosomal recessive hematologic disorders2 that cause hemolytic anemia because of the decreased or absent synthesis of a globin chain. Imbalances of globin chains cause hemolysis and impair erythropoiesis. Family physicians need to know how to diagnose thalassemias, how to distinguish them from other causes of a microcytic anemia, and the treatment options for severe forms of thalassemia.
Epidemiology
Approximately 5 percent of the world's population has a globin variant, but only 1.7 percent has alpha or beta thalassemia trait.2 Thalassemia affects men and women equally and occurs in approximately 4.4 of every 10,000 live births. Alpha thalassemia occurs most often in persons of African and Southeast Asian descent, and beta thalassemia is most common in persons...