There are two beta globin genes and beta thalassemia results when mutations (not deletions) occur in one or both beta globin genes. The more gene mutations, the more severe the anemia. Infants usually present during the first year of life and are asymptomatic at birth.
| Beta Thalassemia Minor/Trait | Beta Thalassemia Major |
Mutation in one of the two beta chain genes
| Both genes are deleted and there is limited to no beta globin production
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Asymptomatic mild microcytic hypochromic anemia
| Presents around one year of age with severe anemia, jaundice, splenomegaly, growth restriction, and bone malformations. This is a hemolytic anemia. Can lead to death if not treated with chronic blood transfusions.
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| Peripheral smear findings: target cells and basophilic stippling | Peripheral smear findings: NRBCs, microcytic hypochromic anemia, target cells
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| Increased amount of Hb A2 and normal Hb F | Hb F is often 95-100%
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| Other laboratory findings:
Signs of hemolysis:
- Increased lactate dehydrogenase (LDH) and indirect bilirubin. Both are released as RBCs breakdown.
- Decreased haptoglobin. Haptoglobin is used up as it binds the released hemoglobin from the lysed RBCs.
- Negative Coombs test. A positive Coombs test would indicate an immune system related hemolysis. Thalassemia is not an immune phenomenon.
Signs of iron overload:
- Increased serum iron. Iron is increased due to the ineffective erythropoiesis and as a result of life-long transfusions.
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