Table 3.2.

Common genotypes and basic classification of beta thalassemia

Common genotypes	Name	Phenotype
β/β	Normal	None
β/β0	Beta thalassemia trait	Thalassemia minor: asymptomatic, mild microcytic hypochromic anemia
β/β+
β+/β+	Beta thalassemia intermedia	Variable severity
β+/β0		Mild to moderate anemia
βE/β+		Possible extramedullary hematopoiesis
βE/β0		Iron overload
β0/β0	Beta thalassemia major (Cooley’s Anemia)	Severe anemia
		Transfusion dependence
		Extramedullary hematopoiesis
		Iron overload

Abbreviations: β⁰ a β-thalassemia mutation that eliminates globin transcription or translation, β⁺ a β-thalassemia mutation that decreases globin transcription or translation, β^E the β-globin mutation that results in Hb E