Thalassemia Facts

November 22, 2024

This page was reviewed under our medical and editorial policy by YunZu (Michele) Wang, M.D., assistant professor, Department of Pediatrics, City of Hope^® Cancer Center Duarte

Thalassemia is a rare genetic blood disorder passed from parent to child. It affects fewer than 2% of people worldwide. Some people with mild thalassemia have no symptoms and don’t need treatment. Others may experience problems with how the body grows or have symptoms such as fatigue. How severe the condition is depends on the number of genetic mutations someone inherits.

What Is Thalassemia?

Thalassemia is the result of genetic mutations that cause the body to produce less hemoglobin than normal. Hemoglobin is a protein that plays a key role in transporting oxygen throughout the body via the red blood cells. When people inherit thalassemia, their body makes less hemoglobin, which makes it harder for them to produce healthy red blood cells and deliver oxygen to the rest of the body.

Thalassemia vs. Anemia

While thalassemia often causes anemia, the two terms refer to different conditions.

Thalassemia is the term used to describe the genetic disorder that changes how the hemoglobin protein is produced inside the body. Anemia, meanwhile, is a health condition in which a person does not have enough hemoglobin or red blood cells. People can have thalassemia but not develop anemia symptoms. Anemia can also be caused by other conditions and affects many people who don’t have thalassemia.

What Causes Thalassemia?

Thalassemia is caused by genetic mutations affecting one or both of the two protein chains that make up hemoglobin. These chains are called the alpha globin protein and the beta globin protein.

There are two main types of thalassemia:

Alpha thalassemia occurs when the mutations affect the alpha globin protein. A person inherits two alpha globin protein genes from each parent, for a total of four. To inherit alpha thalassemia, at least one of the person’s parents must have at least one genetic mutation that changes how the body produces alpha globin protein. A person with one alpha globin protein gene mutation has alpha thalassemia minima and has no symptoms. If someone develops alpha thalassemia because he or she inherits two alpha globin protein gene mutations, this is called alpha thalassemia trait and may not cause any symptoms. If the person inherits three alpha protein globin mutations, this is called alpha thalassemia intermedia or Hemoglobin H, and usually causes more symptoms. If all four alpha globin protein genes inherited are mutated, it’s referred to as alpha thalassemia major and can cause significant problems in the fetus.

Beta thalassemia occurs when the mutations affect the beta globin protein. To inherit beta thalassemia, at least one of the person’s parents must have at least one genetic mutation that changes how the body produces beta globin protein. If someone develops beta thalassemia because he or she inherits a gene mutation from one parent, this is called thalassemia minor. If the person inherited the condition from both parents, it’s referred to as thalassemia major, which usually causes more symptoms.

Risk Factors

The main risk factor for developing thalassemia is having at least one parent who also has the condition. However, people from certain geographic areas and races are more likely to have thalassemia, including those who are:

• From the Mediterranean
• From China or Southeast Asia
• From Africa or of African-American ancestry
• From the Middle East

Thalassemia Diagnosis

If the care team suspects that a patient may have thalassemia, they will perform a physical exam and ask questions about the patient’s family history. The doctor may evaluate whether the patient has an enlarged spleen, which could be a sign of this condition.

Thalassemia Tests

Blood testing can help the care team definitively diagnose thalassemia. Some tests that may be used during the diagnosis process include:

• A complete blood count to test for anemia
• Examination of a sample of red blood cells for abnormalities
• A hemoglobin electrophoresis test, which can diagnose beta thalassemia
• A genetic test to look for changes that suggest alpha thalassemia