ANEMIA, CONGENITAL DYSERYTHROPOIETIC, TYPE IVb

Congenital dyserythropoietic anemia type IVb (CDAN4B) is an autosomal recessive hematologic disorder characterized by neonatal jaundice, hyperbilirubinemia, and severe congenital hemolytic anemia requiring transfusion. Bone marrow examination shows erythroid hyperplasia and evidence of ineffective erythropoiesis consistent with dyserythropoiesis. Peripheral blood smear shows variable red cell abnormalities, including polychromasia, nucleated red cells, anisopoikilocytosis, and fragmented red cells. Spherocytes may be absent, suggesting nonspherocytic anemia (see, e.g. CNSHA1, 300908), but patients do not have enzymatic defects, and spherocytes are occasionally seen. Fetal and embryonic hemoglobin are increased and persistent; the presence of additional variants in globin genes may affect the severity of the phenotype. The disorder sometimes presents as hydrops fetalis (Viprakasit et al., 2014; Magor et al., 2015). For a discussion of genetic heterogeneity of congenital dyserythropoietic anemia, see CDAN1A (224120). [from OMIM]