Overview of Beta-Thalassemia

Beta-thalassemias are a group of hereditary blood disorders characterized by anomalies in the synthesis of the beta chains of hemoglobin resulting in variable phenotypes ranging from severe anemia to clinically asymptomatic individuals. Three main forms have been described: thalassemia major, thalassemia intermedia, and thalassemia minor. Individuals with thalassemia major usually present within the first 2 years of life with severe anemia, requiring regular red blood cell (RBC) transfusions. Patients with thalassemia intermedia present later in life with moderate anemia and do not require regular transfusions. Thalassemia minor is clinically asymptomatic, but some subjects may have moderate anemia. Beta-thalassemias are caused by point mutations or, more rarely, deletions in the beta-globin gene on chromosome 11, leading to reduced (beta+) or absent (beta0) synthesis of the beta chains of hemoglobin (Hb). Transmission is autosomal recessive; however, dominant mutations have also been reported. Diagnosis of thalassemia is based on hematologic and molecular genetic testing. Laboratory tests that are conventionally performed to diagnose the β-thalassemia and HbE are classified into two groups, based on the purposes, including the screening tests and confirmatory tests.