What is the most severe form of thalassemia called?

1. Thalassemia is an inherited condition in which maturation of the red cells does not proceed normally. 2. It occurs typically in people from the Middle East, the Mediterranean, Africa and Southeast Asia. 3. Its most severe form is called Cooley's anemia. 4. Hemoglobin S disease points to sickle cell disease, a different inherited hemoglobin disorder. 5. Polycythemia vera is an excess of immature erythrocytes, the opposite direction of abnormality. 6. Pernicious anemia is an absorption disorder of vitamin B12 and is unrelated to globin maturation. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 18 "The Cardiovascular System: Blood", section 18.3 Erythrocytes_