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Thalassemias

(Mediterranean Anemia; Thalassemia Major and Minor)

(See also Overview of Anemia.)

Thalassemias are a group of inherited disorders resulting from an imbalance in the production of one of the four chains of amino acids that make up hemoglobin (the oxygen-carrying protein found in red blood cells).

  • Symptoms depend on the type of thalassemia.

  • Some people have jaundice and abdominal fullness or discomfort.

  • Diagnosis usually requires special hemoglobin tests.

  • Mild thalassemia may not require treatment, but severe thalassemia may require bone marrow transplantation.

Hemoglobin is made up of two pairs of globin chains. Normally, adults have one pair of alpha chains and one pair of beta chains. Sometimes one or more of these chains is abnormal. Thalassemias are categorized according to the amino acid chain affected. The two main types are

  • Alpha-thalassemia (the alpha globin chain is affected)

  • Beta-thalassemia (the beta globin chain is affected)

Alpha-thalassemia is most common in blacks (25% carry at least one copy of the defective gene), and beta-thalassemia is most common in people of Mediterranean and Southeast Asian ancestry.

Thalassemias are also categorized according to how many copies of the defective gene people have:

  • Thalassemia minor: One copy of the defective gene

  • Thalassemia major: Two copies of the defective gene

Symptoms of Thalassemia

All thalassemias have similar symptoms, but they vary in severity.

In alpha-thalassemia minor and beta-thalassemia minor, people have mild anemia with no symptoms.

In alpha-thalassemia major, people have moderate or severe symptoms of anemia, including fatigue, shortness of breath, paleness, and an enlarged spleen, which leads to a feeling of fullness and abdominal discomfort.

In beta-thalassemia major (sometimes called Cooley anemia), people have severe symptoms of anemia, such as fatigue, weakness, and shortness of breath, and they may also have jaundice, causing yellowing of the skin and whites of the eyes, skin ulcers, and gallstones. People may also have an enlarged spleen. Overactive bone marrow may cause some bones, especially those in the head and face, to thicken and enlarge. The long bones in the arms and legs may weaken and fracture easily.

Children who have beta-thalassemia major may grow more slowly and reach puberty later than they normally would. Because iron absorption may be increased and frequent blood transfusions (providing even more iron) are needed, excessive iron may accumulate and be deposited in the heart muscle, eventually causing iron overload disease and heart failure and early death.

Diagnosis of Thalassemia

  • Blood tests

  • Hemoglobin electrophoresis

  • Prenatal testing

Blood tests are done for diagnosis of thalassemia. Doctors measure blood counts and examine a sample of blood under a microscope. Characteristic abnormalities of the red blood cells can be seen.

Hemoglobin electrophoresis, another blood test, is also done. In electrophoresis, an electrical current is used to separate the different types of hemoglobin and thus detect abnormal hemoglobin. Testing a drop of blood by electrophoresis is helpful but may be inconclusive, especially for alpha-thalassemia. Therefore, the diagnosis is usually based on special hemoglobin tests and determination of hereditary patterns.

Genetic testing can be done to detect thalassemias before birth.

Treatment of Thalassemia

  • Sometimes blood transfusions, removal of the spleen, or iron chelation therapy

  • Stem cell transplantation

Most people who have a mild thalassemia do not need treatment.

People who have more severe thalassemia may need to have surgery to remove the spleen (splenectomy), blood transfusions, or iron chelation therapy. In chelation therapy, excess iron is removed from the blood. Iron chelators may be given by mouth using deferasirox or deferiprone or by an infusion of deferoxamine, which can be given under the skin (subcutaneous) or into a vein (intravenous).

Some people who have a severe form of thalassemia may need stem cell transplantation.

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