Congenital dyserythropoietic anemia (CDA) is a rare heterogeneous hereditary disorder characterized by ineffective erythropoiesis and morphological abnormalities of erythrocytes and bone marrow erythroblasts.Currently, six types of CDA with different genetic mutations have been identified, with CDAII being the most prevalent. CDA II is an autosomal recessive disorder with the causative gene on the SEC23B gene at 20q11.2. To date, 110 mutations in the SEC23B gene have been reported in CDA II. This paper reports a case of congenital dyserythropoietic anemia type II caused by a new SEC23B mutation and accompanied by a large segmental deletion at the SEC23B gene locus. In addition, we reviewed the diagnostic and therapeutic advances in CADII.