Curriculum · Hematology
Pathophysiology and genetics of thalassaemia
What it is
Thalassemia is a defect in the production of the alpha or the beta chains of hemoglobin. The result is an imbalance in globin chain synthesis, and it is that imbalance, rather than the defect in one chain by itself, which harms the red cell line.
The imbalance leads to two things at once:
- Ineffective erythropoiesis, meaning red cells die in the bone marrow
- Hemolysis
Causes and risk
Alpha thalassemia comes from a mutation in the alpha gene on chromosome 16 that results in failure to produce alpha globin chains.
Beta thalassemia comes from a mutation in the beta gene on chromosome 11 that results in failure to produce beta globin chains. The alpha globin chains then accumulate in the red cells, and it is this accumulation that produces the hemolysis and the ineffective erythropoiesis of the beta form.