LAUSR

Dear Editor, Hereditary sideroblastic anemia (SA) is characterized by anemia with ringed sideroblasts in the bone marrow (BM) [1]. Phenotypic expression is highly variable, and the most common hereditary SA is X-linked sideroblastic anemia (XLSA, OMIM #300751) caused by mutation of the erythroid-specific δ-aminolevulinate synthase gene, ALAS2 [2-4]. We present a case of a 12-month-old boy with severe congenital anemia who was finally diagnosed as having XLSA after simultaneous BM study and molecular genetic analysis by massively parallel sequencing (MPS). The boy was referred from an outpatient pediatric clinic because of severe anemia and progressive pallor. He was a full-term baby, and no one in his family had been diagnosed as having anemia. The pallor was considered pathological, and his weight gain of 7.9 kg was insufficient, leaving him below the third percentile for his age. He was transfused packed red blood cells (RBCs) to correct his Hb level of 59 g/L; however, his pallor persisted, and Hb level recovered only temporarily. He was subsequently referred to the Department of Pediatrics at Kangbuk Samsung Hospital. The initial complete blood count, as determined at our institute, was as follows: Hb, 70 g/L; hematocrit, 27.5%; mean corpuscular volume, 63.2 fL; mean corpuscular hemoglobin, 15.9 pg; mean corpuscular hemoglobin concentration, 25.1 g/dL; red cell distribution width, 31.3%; white blood cells, 7.0×10/L; and platelets, 417×10/L. A peripheral blood smear revealed a dimorphic red cell population due to transfusion (Fig. 1A). His iron profile suggested plentiful body iron stores, as indicated by the following parameter values: elevated serum iron, 49.8 μmol/L (laboratory reference range, 11.6–43.3); normal ferritin, 267.1 pmol/L (36.0–898.8); and total iron-binding capacity, 52.4 μmol/L (42.2–68.0). Hemolytic anemia was excluded by negative direct and indirect Coombs’ tests, and he had normal lactate dehydrogenase (324 IU/L [0–250]) and haptoglobin (4.76 μmol/L [3.00–20.00]) levels. BM aspirate smear revealed an estimated myeloid:erythroid ratio of 1.6:1 and showed small erythroblasts with abnormal condensation of nuclear chromatin and ragged cytoplasm (Fig. 1B,