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Clinical manifestations and diagnosis of the thalassemias

Edward J Benz, Jr, MD
Section Editor
Stanley L Schrier, MD
Deputy Editor
Jennifer S Tirnauer, MD


The thalassemias are a group of disorders in which the normal ratio of alpha globin to beta globin production is disrupted due to a disease-causing variant in one or more of the globin genes. This abnormal alpha- to beta-chain ratio causes the unpaired chains to precipitate and causes destruction of red blood cell precursors in the bone marrow (ineffective erythropoiesis) and circulation (hemolysis). As a result, affected individuals have variable degrees of anemia and extramedullary hematopoiesis, which in turn can cause bone changes, impaired growth, and iron overload.

This topic review discusses the clinical manifestations and diagnosis of alpha and beta thalassemia, the two most common forms. Thalassemias involving delta, gamma, epsilon, and zeta chains are rare and usually not associated with significant disease outside of the neonatal period.

The pathogenesis and treatment of alpha and beta thalassemia, including the role of hematopoietic cell transplantation (HCT), monitoring of iron stores, and iron chelation, are discussed in detail separately.

Genetics – (see "Introduction to hemoglobin mutations" and "Molecular genetics of the thalassemic syndromes")

Pathogenesis – (see "Pathophysiology of alpha thalassemia" and "Pathophysiology of beta thalassemia")

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Literature review current through: Nov 2017. | This topic last updated: Nov 22, 2017.
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