Thalassemia | Causes & Risk Factors


What causes thalassemia?

You get thalassemia when you inherit a missing or damaged gene from one or both parents. There are two forms of inherited thalassemia:

  • Thalassemia minor occurs when you inherit the problem from only one parent. If you have thalassemia minor, you will not have any symptoms even though you have a damaged or missing gene. This is known as being a “silent carrier” of thalassemia. If your partner also has thalassemia, you can pass it to your children.
  • Thalassemia major develops when you inherit the problem from both parents. If both of your parents are carriers, you have a 25% risk of having the kind of thalassemia that will cause symptoms. If your parents are both carriers, you have a 50% risk of becoming a carrier yourself.

There are two types of thalassemia: alpha thalassemia and beta thalassemia. These are named for alpha-globin and beta-globin, the proteins that make up normal hemoglobin. The type of thalassemia you have depends on what kind of genes you inherit from your parents. If you inherit more than one damaged gene, your thalassemia may be more severe.

Who is at risk for thalassemia?

Thalassemia can affect both men and women. Certain ethnic groups are at greater risk.

  • Alpha thalassemia most often affects people who are of Southeast Asian, Indian, Chinese or Filipino descent.
  • Beta thalassemia most often affects people who are of Mediterranean (Greek, Italian and Middle Eastern), Asian or African descent.

Written by editorial staff

Reviewed/Updated: 02/11
Created: 11/09