Thalassemia is caused by a disorder of globin production. It is characterised by microcytic anaemia with a relatively normal iron study.
α-thalassemia is more common among Africans (Trans: α-/α-) and Asians (cis: αα/—).
β-thalassemia is more common among Mediterraneans (Italians and Greeks)
Types of thalassemia
| Type | Description |
|---|---|
| α-thalassemia | Caused by the deletion of alpha globin genes. 4 genes code for alpha-globin. The severity of the disease worsens the more alpha genes are deleted. Subtypes include: αα/αα (normal); αα/α- (silent carrier); α-/α- or αα/— α (thalassemia trait – minor symptoms); —/— (Hemoglobin Barts – stillbirth) |
| β-thalassemia | Caused by a point mutation at a splice site or promoter sequence of the beta globin gene. 2 genes code for beta globin. A β gene may be fully functional (β), low function (β), or non-functional (β0). Includes β-thalassemia minor (one normal and one mutated gene), and β-thalassemia major (Cooley’s anemia – two mutated genes) |
- Pathophysiology
- Inadequate production of structurally normal globin → increased haemolysis, slow erythropoiesis, decreased haemoglobin → anaemia
- Signs and symptoms
- Symptoms of anaemia
- Hepatosplenomegaly
- Bony abnormalities
- Fractures
- Heart failure
- Differentials
- Iron deficiency anaemia
- Sickle cell disease
- Investigations
- Complete Blood Count
- Low Hb (may be normal)
- Low MCH out of proportion to the anemia (Mentzer index < 13)
- Normal iron studies
- Hemoglobin electrophoresis for diagnosis
- Genetic testing
- Complete Blood Count
- Treatment
- Transfusion for a highly symptomatic patient or Hb < 7 g/dL
- Keep Hb > 9 g/dL
- Iron chelation therapy (deferoxamine and deferasirox) for repeated transfusions
- Splenectomy in case of hypersplenism
- A bone marrow transplant may be curative
- Transfusion for a highly symptomatic patient or Hb < 7 g/dL
- Long-term complications
- Gallstones
- Infections
- Ulcers
- Hypersplenism
- Thrombosis
- Cardiac complications from haemachromatosis