Thalassemia is a blood disorder passed down through families (inherited) in which the body makes an abnormal form of hemoglobin, the protein in red blood cells that carries oxygen. The disorder results in excessive destruction of red blood cells, which leads to anemia.
- Hemolytic anemia
- Sickle cell disease
Overview, Causes, & Risk Factors
Hemoglobin is made of two proteins: Alpha globin and beta globin. Thalassemia occurs when there is a defect in a gene that helps control production of one of these proteins.
There are two main types of thalassemia:
- Alpha thalassemia occurs when a gene or genes related to the alpha globin protein are missing or changed (mutated).
- Beta thalassemia occurs when similar gene defects affect production of the beta globin protein.
Alpha thalassemias occur most commonly in persons from southeast Asia, the Middle East, China, and in those of African descent.
Beta thalassemias occur in persons of Mediterranean origin, and to a lesser extent, Chinese, other Asians, and African Americans.
There are many forms of thalassemia. Each type has many different subtypes. Both alpha and beta thalassemia include the following two forms:
- Thalassemia major
- Thalassemia minor
You must inherit the defective gene from both parents to develop thalassemia major.
Thalassemia minor occurs if you receive the defective gene from only one parent. Persons with this form of the disorder are carriers of the disease and usually do not have symptoms.
Beta thalassemia major is also called Cooley’s anemia.
Risk factors for thalassemia include:
- Asian, Chinese, Mediterranean, or African American ethnicity
- Family history of the disorder
Pictures & Images
Thalassemia major is an inherited form of hemolytic anemia, characterized by red blood cell (hemoglobin) production abnormalities. This is the most severe form of anemia, and the oxygen depletion in the body becomes apparent within the first 6 months of life. If left untreated, death usually results within a few years. Note the small, pale (hypochromic), abnormally-shaped red blood cells associated with thalassemia major. The darker cells likely represent normal RBCs from a blood transfusion.Thalassemia minor
Thalassemia minor is an inherited form of hemolytic anemia that is less severe than thalassemia major. This blood smear from an individual with thalassemia shows small (microcytic), pale (hypochromic), variously-shaped (poikilocytosis) red blood cells. These small red blood cells (RBCs) are able to carry less oxygen than normal RBCs.
Review Date : 1/31/2010
Reviewed By : Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; and Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital; and David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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