Beta Thalassemia

Type	Genotype	Description
Normal	β2/β2
β-thalassemia trait	-/β2	HbA2 >4%. Slightly anemic, low MCV and MCH. Clinically asymptomatic.
β-thalassemia intermedia	-/βo or β+/β+	High HbF, variable. Anemic (symptoms usually develop when hemoglobin level is below 7.0 g/dL), very low MCV and MCH, splenomegaly, variable bone changes, variable transfusion dependency
β-thalassemia major	-o/-o	HbF >90% (un-transfused). Severe hemolytic anemia, very low MCV and MCH. Hepatosplenomegaly, chronic transfusion dependency.

Variant	Chromosome 11	Signs and Symptoms
Beta thalassemia trait	One gene defect	Asymptomatic
Beta thalassemia intermedia	Two genes defective (mild to moderate decrease in beta globin synthesis)	Variable degrees of severity of symptoms of thalassemia major
Beta thalassemia major	Two genes defective (severe decrease in beta globin synthesis)	Abdominal swelling, growth retardation, irritability, jaundice, pallor, skeletal abnormalities, splenomegaly; requires lifelong blood transfusions

Beta Thalassemia Signs

Presentation varies with severity. Thalassemia minor rarely has physical abnormalities with hemoglobin ≥9 g/dL.
In severe forms, findings vary depending on disease control.
In severe, untreated cases, there may be:
- Hepatosplenomegaly
- Bony deformities (frontal bossing, prominent facial bones)
- Marked pallor
- Slight to moderate jaundice
Exercise intolerance, cardiac flow murmur, or heart failure can occur secondary to severe anemia. These features are absent in well-treated patients.
Growth restriction is common even with well-controlled chelation therapy.
Iron overload can cause endocrinopathy with diabetes, thyroid, adrenal, and pituitary disorders.