Thalassemia

Definition

Thalassemias are inherited disorders characterized by abnormal production of hemoglobin. They result in low hemoglobin production, and excessive destruction of red blood cells.

Alternative Names

Causes, incidence, and risk factors

Hemoglobin contains two chains, alpha and beta globin. Genetic abnormalities, which cause an imbalance in the production of either chain, may be inherited.

Beta thalassemias are caused by a mutation in the beta globin chain. The mutated genes must be inherited from both parents to acquire the major form of this disease. If one mutated gene is inherited, the person will be a carrier of the disease, but will not have symptoms. This is the minor form of the disease.

In the major form, children are normal at birth, but develop anemia during the first year of life. Growth failure, bone deformities, and enlarged liver and spleen are some of the problems that can occur. Blood transfusions may modify some of the signs of the disease, but iron overload from the transfusions may cause damage to the heart, liver, and endocrine systems.

The mild form of beta thalassemia produces small red blood cells, with no symptoms. Risk factors include a family history of thalassemia and an ethnic background that has shown susceptibility to the disease.

Beta thalassemias occur in people of Mediterranean origin, and to a lesser extent, Chinese, other Asians, and blacks.

Alpha thalassemias occur most commonly in people from southeast Asia and China, and are caused by deletion of a gene or genes from the alpha globin chain. The most severe form of alpha thalassemia causes stillbirth (death of a fetus before delivery).

Symptoms

• Fatigue
• Shortness of breath
• Jaundice
• Bone deformities in the face

Signs and tests

• Enlarged spleen
• Peripheral blood smear shows small, abnormally-shaped red blood cells
• Complete blood count shows anemia
• Hemoglobin electrophoresis shows abnormal hemoglobin

• RBC indices (size, hemoglobin content)
• Osmotic fragility

Treatment

People with severe thalassemia receive regular blood transfusions and folate supplements. People who receive the blood transfusions should avoid iron supplements and oxidative drugs such as sulfonamides, because iron levels in their bodies can become toxic.

Patients who receive significant numbers of blood transfusions require treatment to remove iron from the body (chelation therapy). Bone marrow transplant is being investigated as a treatment, and is most successful in children.

Expectations (prognosis)

In severe thalassemia, death from heart failure can occur between the ages of 20 and 30. Hypertransfusion programs (frequent transfusions) with chelation therapy improve outcome. Successful bone marrow transplant is curative. Less severe forms of thalassemia usually do not shorten life span.

Complications

Untreated, thalassemia major leads to heart failure and liver problems, as well as susceptibility to infection.

Iron overload as a side effect of treatment can cause damage to the heart, liver, and endocrine systems. This complication is managed by daily injections of an iron chelating agent, which binds to iron and causes it to be released from the body in the urine.

Calling your health care provider

Call for an appointment with your health care provider if symptoms develop that are suggestive of thalassemia.

Call your health care provider if symptoms develop after treatment.

Prevention

• Genetic counseling in families with known thalassemia
• Prenatal screening