Congenital dyserythropoiesis characterized by marked macrocytosis, vitamin B12- and folate-independent megaloblastic change and absence of the defining features of congenital dyserythropoietic anaemia types I or III.

Four patients with congenital dyserythropoiesis characterized by marked macrocytosis, little or no anaemia, and vitamin B12- and folate-independent megaloblastic erythropoiesis are reported. Their erythroblasts also showed various dysplastic changes but not those diagnostic for congenital dyserythropoietic anaemia (CDA) types I or III. The haematological features of the four patients, who included two siblings, resemble those of a previously reported patient and together these patients form a recognizable subgroup within those cases of CDA not belonging to CDA types I-III. In two of the cases studied, and possibly a third, the inheritance was as an autosomal recessive character.