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Thalassemias

Thalassemias are inherited blood disorders. They cause the body to make fewer healthy red blood cells and less hemoglobin than normal.

Causes

Normal hemoglobin has four protein chains—two alpha globin and two beta globin. The two major types of thalassemia, alpha and beta, are named after defects in these protein chains.

Four genes are needed to make enough alpha globin protein chains. Alpha thalassemia trait occurs when one or two of the four genes are missing. If more than two genes are missing, the result is moderate to severe anemia.

The most severe form of alpha thalassemia is known as alpha thalassemia major or hydrops fetalis. Babies with this disorder usually die before or shortly after birth.

Two genes (one from each parent) are needed to make enough beta globin protein chains. Beta thalassemia occurs when one or both genes are altered. The severity of beta thalassemia depends on how badly one or both genes are affected. If both genes are affected, the result is moderate to severe anemia. The severe form of beta thalassemia also is known as thalassemia major or Cooley's anemia.

Symptoms

Signs and symptoms of thalassemias are due to lack of oxygen in the bloodstream. This occurs because the body doesn't make enough healthy red blood cells and hemoglobin. The severity of symptoms depends on the severity of the disorder.

No Symptoms

Alpha thalassemia silent carriers generally have no signs or symptoms of the disorder. This is because the lack of alpha globin protein is so small that hemoglobin works normally.

Mild Anemia

People who have alpha or beta thalassemia trait can have mild anemia. However, many people with this type of thalassemia have no signs or symptoms. Mild anemia can make you feel tired. It's often mistaken for iron-deficiency anemia.

Mild to Moderate Anemia and Other Signs and Symptoms

People with beta thalassemia intermedia have mild to moderate anemia. They also may have other health problems, such as:

  • Slowed growth and delayed puberty. Anemia can slow down a child's growth and development.
  • Bone problems. Thalassemia may make bone marrow (the spongy material inside bones that makes blood cells) expand. This causes wider bones than normal. Bones also may be brittle and break easily.
  • An enlarged spleen. The spleen is an organ that helps your body fight infection and remove unwanted material. When a person has a thalassemia, the spleen has to work very hard. As a result, the spleen becomes larger than normal. This makes anemia worse. If the spleen becomes too large, it must be removed.
Severe Anemia and Other Signs and Symptoms

People with hemoglobin H disease or beta thalassemia major (also called Cooley's anemia) have severe thalassemia. Signs and symptoms occur within the first 2 years of life. They may include severe anemia and other serious health problems, such as:

  • Pale and listless appearance
  • Poor appetite
  • Dark urine
  • Slowed growth and delayed puberty
  • Jaundice (a yellowish color of the skin or whites of the eyes)
  • Enlarged spleen, liver, and heart
  • Bone problems (especially bones in the face)

Diagnosis

Doctors diagnose thalassemias using blood tests, including a complete blood count (CBC) and special hemoglobin tests.

  • A CBC provides information about the amount of hemoglobin and the different kinds of blood cells, such as red blood cells, in a sample of blood. People who have thalassemias have fewer healthy red blood cells and less hemoglobin in their blood than normal. People who have alpha or beta thalassemia trait may have smaller than normal red blood cells.
  • Hemoglobin tests measure the types of hemoglobin in a blood sample. People who have thalassemias have problems with the alpha or beta globin protein chains of hemoglobin.

Treatment

Doctors use three standard treatments for moderate and severe forms of thalassemia. These include blood transfusions, iron chelation therapy, and folic acid supplements. Other treatments have been developed or are being tested, but they're used much less often.

Blood Transfusions

Transfusions of red blood cells are the main treatment for people who have moderate or severe thalassemias. A blood transfusion, given through a needle in a vein, gives you healthy red blood cells with normal hemoglobin. Red blood cells live for only about 120 days. So, you may need repeated transfusions to maintain a supply of healthy red blood cells.

If you have hemoglobin H disease or beta thalassemia intermedia, you may need blood transfusions on occasion. For example, you may need this treatment when you have an infection or other illness, or when your anemia is severe enough to cause tiredness.

If you have beta thalassemia major, or Cooley's anemia, you need regular blood transfusions (often every 2 to 4 weeks). These will help you maintain normal hemoglobin levels and red blood cell numbers. Blood transfusions allow you to feel better, enjoy normal activities, and live into adulthood.

Blood transfusions are lifesaving, but they're expensive and carry a risk of transmitting infections and viruses (for example, hepatitis). However, this risk is very low in the United States because of careful blood screening.

Iron Chelation Therapy

Because the hemoglobin in red blood cells is an iron-rich protein, regular blood transfusions can lead to a buildup of iron in the blood. This condition is called iron overload. It damages the liver, heart, and other parts of the body.

To prevent this damage, iron chelation therapy is needed to remove excess iron from the body. Two medicines are used for iron chelation therapy.

  • Deferoxamine is a liquid medicine that's given slowly under the skin, usually with a small portable pump used overnight. This therapy takes time and can be mildly painful. Side effects include loss of vision and hearing.
  • Deferasirox is a pill taken once a day. Side effects include headache, nausea (feeling sick to the stomach), vomiting, diarrhea, joint pain, and fatigue (tiredness).
Folic Acid Supplements

Folic acid is a B vitamin that helps build healthy red blood cells. You may need to take folic acid supplements in addition to blood transfusions and/or iron chelation therapy.

 

Source

National Heart, Lung, and Blood Institute, USA.