Variants of congenital dyserythropoietic anaemia: an update.

During the past decade a large number of variant congenital dyserythropoietic anaemias (CDA) have been described. The morphological, genetical, clinical and serological features of the classical types (I, II and III) are not well delineated, so, there are no exact borders between classical and variant forms. In the present review attention will be given to variant serological features, variant globin chain synthesis, variant genetical and morphological features and variant clinical presentations. Finally, it is emphasized that the existence of transitional forms between dysplastic and hypoplastic affections of bone marrow function points to the stem cell origin of these disorders.