Thalassemia Types

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 genetic disorder affecting how the body produces hemoglobin. The two main types of the condition are called alpha thalassemia and beta thalassemia. The type of thalassemia someone has depends on whether they inherit genetic mutations that affect the alpha globin protein chain or the beta globin protein chain. 

There are also subtypes of alpha and beta thalassemia. These describe how severe the condition is based on how many genetic mutations a person inherits.

Alpha Thalassemia

Alpha thalassemia develops if the person inherits a genetic mutation that affects one of the four alpha globin protein chains. These four chains form part of the mechanism that helps the body produce hemoglobin. There are several subtypes of alpha thalassemia.

Alpha Thalassemia Minima

If the patient inherits only one gene defect, he or she will have alpha thalassemia minima. People with alpha thalassemia minima do not experience any thalassemia symptoms and do not require treatment. These people are called alpha thalassemia carriers.

Alpha Thalassemia Minor

If the patient inherits two gene defects, this is called alpha thalassemia minor. The patient may experience mild symptoms, such as fatigue, and require some treatment.

Hemoglobin H Disease

Hemoglobin H disease develops if the patient inherits three genetic mutations or defects. It can cause more severe symptoms and require regular thalassemia treatment.

Hydrops Fetalis

Hydrops fetalis, also called hemoglobin Bart’s (HB) hydrops fetalis or alpha thalassemia major, develops when someone inherits four gene defects. It usually results in stillbirth, but those who survive usually require lifelong treatment.

Beta Thalassemia

Beta thalassemia develops if the patient inherits a genetic mutation that affects one or both of the beta globin protein chains helping the body produce hemoglobin. There are several subtypes of beta thalassemia, listed below.

Beta Thalassemia Minor

If the patient inherits a gene defect in only one part of the beta globin chain, he or she will have beta thalassemia minor, which can cause minor symptoms that may not require treatment. This person is referred to as a beta thalassemia carrier.

Beta Thalassemia Intermedia

If the patient inherits gene defects in both parts of the beta globin chain and experiences moderate symptoms that require some treatment, this is called beta thalassemia intermedia.

Beta Thalassemia Major (Cooley’s Anemia)

If the patient inherits gene defects in both parts of the beta globin chain and experience more severe symptoms requiring treatment, this is called beta thalassemia major or, sometimes, Cooley’s anemia.