Thalassemia is the most common hemoglobinopathy and can be divided in to alpha thalassemia (highly prevalent in Southern China, Malaysia, and Thailand; milder forms in individuals of West coast African origin) and beta thalassemia (Mediterranean: Italy, Greece, less frequent in African individuals).
It is a heterogeneous disease characterized by a deficient synthesis of one or more of the polypeptide chains of hemoglobin.

Morphological findings in the blood smear are depending on type and heterozygous / homozygous:
* Thalassemia minor (heterozygous): No or mild anemia, microcytosis and hypochromia.
* Thalassemia major (homozygous): intense hemolytic anemia; striking and characteristic anisocytosis, target cells, schistocytes, basophilic stippling, polychromatophilia, Pappenheimer, Howell-Jolly bodies and normoblasts can be seen.