The Congenital Dyserythropoietic Anemias (CDAs) consist of a group of rare hereditary disorders of erythropoiesis, characterized by ineffective erythropoiesis and distinct morphologic abnormalities of the majority of erythroblasts in the bone marrow. The three classical types of CDAs have been defined on the basis of bone marrow morphology. This working classification is still used in clinical practice. The subcategorizing are CDA type I, CDA type II and CDA type III. There are, however, families that fall within the general definition of the CDAs, but do not conform to any of the three classical types. CDA type IV, CDA variants: CDA with prominent erythroblastosis after splenectomy, CDA with intra erythrocytic inclusions, CDA with thrombocytopenia and, finally, the very rare form of CDA without dysplasia.
