People whose hemoglobin does not produce enough beta protein have beta thalassemia. It is found in people of Mediterranean descent, such as Italians and Greeks, and is also found in the Arabian Peninsula, Iran, Africa, Southeast Asia and southern China.

There are three types of beta thalassemia that also range from mild to severe in their effect on the body.

Thalassemia Minor or Thalassemia Trait. In this condition, the lack of beta protein is not great enough to cause problems in the normal functioning of the hemoglobin. A person with this condition simply carries the genetic trait for thalassemia and will usually experience no health problems other than a possible mild anemia. As in mild alpha thalassemia, physicians often mistake the small red blood cells of the person with beta thalassemia minor as a sign of iron-deficiency anemia and incorrectly prescribe iron supplements.

Thalassemia Intermedia. In this condition the lack of beta protein in the hemoglobin is great enough to cause a moderately severe anemia and significant health problems, including bone deformities and enlargement of the spleen. However, there is a wide range in the clinical severity of this condition, and the borderline between thalassemia intermedia and the most severe form, thalassemia major, can be confusing. The deciding factor seems to be the amount of blood transfusions required by the patient. The more dependent the patient is on blood transfusions, the more likely he or she is to be classified as thalassemia major. Generally speaking, patients with thalassemia intermedia need blood transfusions to improve their quality of life, but not in order to survive.

Thalassemia Major or Cooley's Anemia. This is the most severe form of beta thalassemia in which the complete lack of beta protein in the hemoglobin causes a life-threatening anemia that requires regular blood transfusions and extensive ongoing medical care. These extensive, lifelong blood transfusions lead to iron-overload which must be treated with chelation therapy to prevent early death from organ failure.


Other Forms of Thalassemia

In addition to the alpha and beta thalassemias, there are other related disorders that occur when the gene for alpha or beta thalassemia combines with an abnormal or mutant gene.

E Beta Thalassemia. Hemoglobin E is one of the most common abnormal hemoglobins. It is usually found in people of Southeast Asian ancestry, such as Cambodians, Vietnamese and Thai. When combined with beta thalassemia, hemoglobin E produces E beta thalassemia, a moderately severe anemia which is similar in symptoms to beta thalassemia intermedia.

Sickle Beta Thalassemia. This condition is caused by a combination of beta thalassemia and hemoglobin S, the abnormal hemoglobin found in people with sickle cell disease. It is commonly found in people of Mediterranean ancestry, such as Italians, Greeks and Turks. The condition varies according to the amount of normal beta globin produced by the beta gene. When no beta globin is produced by the beta gene, the condition is almost identical with sickle cell disease. The more beta globin produced by the beta gene, the less severe the condition.
 

Alpha Thalassemia - Beta Thalassemia - Variant Hemoglobin