Beta-Thalassemia

Thalassemia variant alleles are common in patients from Africa, parts of the Asian continent and Mediterranean countries.

Beta-thalassemias are caused by mutations on one of the 2 beta globin genes:

National Heart, Lung, and Blood Institute; National Institutes of Health; U.S. Department of Health and Human Services. Thalassemias. With permission.

The mutations can cause either reduced expression (β⁺) or absence of expression (β⁰), which will influence the severity of the disease.

Beta-thalassemia minor (trait) patients (β/β⁰ or β/β⁺) are usually asymptomatic and may have mild anemia in addition to marked microcytosis.
Beta-thalassemia intermedia patients (β⁺/β⁺) will usually have moderate microcytic anemia and may require transfusion later in life.
Beta-thalassemia major patients (β⁰/β⁰ or β⁰/β⁺) will have severe life-long transfusion-dependent anemia. Unless they are very young, refugee patients with this condition will usually have already been diagnosed in their country of origin. Both major and intermedia patients should be referred to a Hematologist. The management of these conditions is outside the scope of these guidelines.

If a patient has any of the beta-thalassemia alleles mentioned above and is planning a pregnancy, his/her partner should also be tested. Based on the parents’ alleles, if there is any risk of beta-thalassemia major or intermedia in the fetus, they should be referred to Medical Genetics for pre-conception counselling.