Congenital dyserythropoietic anemia, type II with SEC23B exon 12 c.1385 A → G mutation, and pseudo-Gaucher cells in two siblings.

OBJECTIVE AND IMPORTANCE: Congenital dyserythropoietic anemia (CDA) represents a genotypically and phenotypically heterogeneous group of disorders. CDA type II, the most frequent variant, was recently shown to be caused by mutations in the gene encoding the secretory COPII component SEC23B. We report two siblings hailing from Punjab in northern India with classical CDA type II where this mutation was demonstrated.

CLINICAL PRESENTATION: A 7-year-old girl presented with transfusion-dependent anemia, splenomegaly, and progressive growth failure since 1 year of age. Her 5-year-old brother was similarly afflicted, but there was no other family history. Extensive prior work-up for hemolytic anemia, storage and metabolic disorders, and infectious diseases was negative. Hemoglobin was 71 g/l with normal leukocyte, platelet, and corrected reticulocyte counts. Bone marrow examination revealed marked normoblastic erythroid hyperplasia with dyserythropoiesis (36%) and the presence of bi- and multinucleated erythroblasts with equal-sized nuclei. Many pseudo-Gaucher cells were also seen. Iron stores were increased although ring sideroblasts were absent. Hereditary erythrocyte multinuclearity with positive acidified serum (HEMPAS) test revealed lysis of the red cells in four out of five control sera.

TECHNIQUE: Genomic DNA sequencing of the SEC23B exon 12 revealed homozygosity for c.1385 A → G; Y462C mutations in both siblings.

CONCLUSION: CDA has traditionally been a difficult diagnosis to establish, since it requires exclusion of other causes of dyserythropoiesis and the performance of complex tests including HEMPAS and electron microscopy for confirmation. The availability of molecular genetic testing for SEC23B promises to streamline and hasten the diagnostic process for this rare and intriguing disease.