Clinical and Ultrastructural Aspects of Congenital Dyserythropoietic Anaemia Type I

S ummary . A case of congenital dyserythropoietic anaemia (CDA) type I is described This is characterized by erythroblastic multinuclearity and ineffective erythropoiesis. By contrast to ‘HEMPAS’ or CDA type II, the acidified‐serum test is negative. The morphological features of the bone marrow have been studied by electron microscopy. These include loss of nuclear envelope, uneven condensation of nuclear chromatin with spongy appearance, chromatin bridges connecting nuclei of divided cells and also cytoplasmic connection between cells by bundles of microtubules. The persistence of microtubules in the cytoplasm and presence of cytoplasmic organelles within the nuclear area are other unusual features. The significance of these findings is discussed in relation to speculation concerning the pathogenesis of the disease.