Alpha-Thalassemia

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

Alpha-thalassemias are caused by gene deletions (sometimes mutations) on one of the 4 alpha globin genes:

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

Silent carriers (1 missing gene) are asymptomatic and usually have normal red blood cells, although some patients can have a slight microcytosis.
Alpha-thalassemia trait patients (2 missing genes) will have mild anemia with hypochromia and microcytosis.
Hemoglobin H disease patients (3 missing genes) should be referred to a Hematologist. The clinical severity is variable. Most patients are not transfusion-dependent but might require episodic transfusions (during pregnancy for example). They should take folic acid supplements (1-2mg daily) and avoid iron supplements unless they are clearly iron deficient.

If a patient has any of the alpha-thalassemia alleles mentioned above and is planning a pregnancy, his/her partner should also be tested. Based on the parents’ alleles, if there any risk of hemoglobin H disease or hydrops fetalis (4 missing genes) in the fetus, they should be referred to Medical Genetics for pre-conception counselling.