Topic Overview

What is thalassemia?

Thalassemia (say "thal-uh-SEE-mee-uh") is an inherited blood disorder that causes your body to make less hemoglobin or abnormal hemoglobin.. Hemoglobin helps red blood cells spread oxygen through your body. Low levels of hemoglobin may cause anemia, an illness that makes you feel weak and tired. Severe anemia can damage organs and lead to death.

What are the types of thalassemia?

There are two main types: alpha and beta. Beta thalassemia is the most common.

Beta thalassemia

You need both alpha- and beta-globin to make hemoglobin. Beta thalassemia occurs when one or both of the two genes that make beta-globin don't work or only partly work as they should.

• If you have one damaged gene, you may have mild anemia and probably won't need treatment. This is called beta thalassemia minor or beta thalassemia trait. It happens when you get a normal gene from one parent and a thalassemia gene from the other.
• When both genes are damaged, it means you got a thalassemia gene from each parent. You may have moderate or severe anemia.
  • If you have moderate anemia (beta thalassemia intermedia), you may need blood transfusions.
  • People with severe anemia (called beta thalassemia major or Cooley's anemia) need blood transfusions throughout life. Symptoms of anemia usually begin within a few months after birth.

Alpha thalassemia

This type occurs when one or more of the four alpha-globin genes that make hemoglobin are missing or damaged.

• If one gene is missing or damaged: Your red blood cells might be smaller than normal. You will have no symptoms and you will not need treatment. But you are a silent carrier. This means you don't have the disease but can pass the defective gene to your child.
• If two genes are missing or damaged: You will have very mild anemia that will typically not need treatment. This is called alpha thalassemia minor or alpha thalassemia trait.
• If three genes are missing: You will have mild to moderately severe anemia. This is sometimes called hemoglobin H disease. If it is severe, you may need blood transfusions.
• If all four genes are missing: This is called alpha thalassemia major or hydrops fetalis. The fetus will be stillborn, or the child will die soon after birth.

What causes thalassemia?

A defect in one or more genes causes thalassemia.

If you, either parent, or any of your siblings have thalassemia or carry a gene for thalassemia and you're thinking about having a child, you may want to talk to a genetic counselor before you get pregnant. A genetic counselor can tell you how likely it is that your child will have the disease and how severe it might be.