What is the most likely underlying disorder?

B. Peripheral slide reveals many target (codocytes)-shaped microcytic hypochromic red

blood cells (RBC). There is no evidence of sickled RBCs. Elevated ferritin level rules out iron defi-ciency as a cause of the anemia. Hemoglobin E trait (heterozygous) cases usually present with nor-mal hemoglobin, but exhibit mild microcytosis and hypochromia, and hemoglobin electrophoresis would reveal a smaller amount of HbE (30%), normal level of HbF, and HbA of 70%. Patients with hemoglobin E disease (homozygous) exhibit mild degree of anemia with microcytosis, hypochromia, and target cells. Hemoglobin electrophoresis reveals much higher HbE levels (90%). Cases of HbE/beta-thalassemia exhibit moderate to severe microcytosis with hypochromia and the presence of target cells. Hemoglobin electrophoresis shows elevated HbF levels ( 40%), with the remaining being HbE (60%). The etiology of the increased levels of HbF in HbE/beta0-thalassemia appears to relate to survival advantage of erythroid progenitors committed to HbF synthesis in the highly stim-ulated bone marrow environment. Blood transfusions have been shown to decrease HbF levels rela-tive to HbE by decreasing erythropoietin levels and bone marrow stimulation (Blood. 1 999;94(9 ):3199, Hematol Oneal Clin North Am. 20 10;24(6): 1 055, Hematology Am Soc Hematol Educ Program. 2007; Hemoglobin E Syndromes:79).