Depending upon which gene is defective, persons may develop either alpha-thalassemia or beta-thalassemia.
A person develops alpha-thalassemia if they inherit at least one defective alpha hemoglobin gene from either parent. According to the National Heart Lung and Blood Institute, persons of “Southeast Asian, Indian, Chinese or Filipino origin or ancestry” are more prone to develop alpha-thalassemia.
The alpha hemoglobin chain consists of four genes (two obtained from each parent) so it is possible to inherit four defective alpha genes in all. The more defective alpha hemoglobin genes which you inherit, the more severe the form of the disease.
• Alpha-thalassemia silent carrier (one defective gene): Disease carrier. No symptoms;
• Alpha-thalassemia minor or alpha-thalassemia trait (two defective genes): Very mild symptoms;
• Hemoglobin H disease (three defective genes): Moderate to severe symptoms; and
• Alpha-thalassemia major or hydrops fetalis (four defective genes): Generally fatal and causes death shortly after birth.
Beta-thalassemia occurs when at least one of the two inherited beta hemoglobin genes are defective. This form of thalassemia occurs most often in persons of “Mediterranean (Greek, Italian, and Middle Eastern), Asian, or African origin or ancestry.” (NHLBI).
The severity of this form of thalassemia depends upon whether one or two defective genes have been inherited.
• Beta-thalassemia minor or beta-thalassemia trait (one defective gene): Mild symptoms; and
• Beta-thalassemia major (also known as Cooley’s anemia): Symptoms present by age two.
Since the disorder is inherited, there is no cure for thalassemia. However, a number of treatments are available depending on the form and severity of the disorder including: blood transfusions, supplements (iron and folic acid) and iron chelation therapy (Deferoxamine, Deferasirox).
In some instances, persons may be treated by a transplant of the blood and bone marrow stem cells. The percentage of people who receive transplants is relatively small since it is difficult to find suitable donors.