Clinical thalassemia (major and minor) are hereditary disorders characterized by defective production of hemoglobin , which leads to decreased production and increased destruction of red blood cells.

Alternative Names

Thalassemia major; Thalassemia; Mediterranean anemia; Cooley's anemia; Thalassemia intermedia

Causes, incidence, and risk factors

An imbalance in the alpha and beta globin chains necessary for the production of hemoglobin is caused by the inheritance of a defective gene. There are two types of thalassemia, alpha thalassemia and beta thalassemia. Genes must be inherited from both parents to acquire the disease. If one gene is inherited, the person will be a carrier of the disease, but will not have symptoms. Alpha thalassemias occur most commonly in people from southeast Asia and China, and are caused by deletion of a gene or genes from the globin chain. The most severe form of alpha thalassemia causes a stillborn fetus. Beta thalassemia occurs in people of Mediterranean origin, and to a lesser extent, Chinese, other Asians, and blacks. It is caused by a mutation in the beta globin chain. Affected 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 disease manifestation, but iron overload from the transfusions can cause damage to the heart, liver, and endocrine systems. A milder form of the disease, thalassemia minor, produces small red blood cells, with no symptoms. Risk factors include a family history of thalassemia and an ethnic background susceptible to the disease. The incidence varies widely throughout the world.

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

This disease may also alter the results of the following tests:

RBC indices

(size, hemoglobin content)

Osmotic fragility

Treatment

With severe thalassemia, regular blood transfusions and

folate supplementation are given. People who receive the blood transfusions should avoid iron supplements and oxidative drugs such as sulfonamides, because iron levels can become toxic. Patients who receive significant numbers of blood transfusions require therapy to remove iron from the body, called 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 or 20 and 30. Hypertransfusion programs with chelation therapy improve outcome, and successful bone marrow transplantation is curative. Less severe forms of thalassemia usually do not impact on life span.

Complications

Untreated, thalassemia major leads to heart failure as well as liver dysfunction, and 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 iron to it and causes it to be excreted 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