Chapter 446 Congenital Dyserythropoietic Anemias
The congenital dyserythropoietic anemias (CDA) are a heterogeneous class of genetic disorders characterized by unique morphologic abnormalities in marrow erythroblasts: multinuclearity, abnormal nuclear fragments, and intrachromatin bridges between cells, associated with ineffective erythropoiesis. Three major types of CDA (types I, II, and III) are defined (see 
Table 446-1 on the Nelson Textbook of Pediatrics website at www.expertconsult.com), although additional subgroups and variants have also been identified. These rare disorders are characterized by variable degrees of anemia, increased marrow erythroid activity (ineffective erythropoiesis), and secondary hemochromatosis.
