Ts1Cje mice display erythroid abnormalities. (A) Flow cytometric analysis of Ter119 and CD71 cell-surface markers allows identification of different erythroblast populations. Regions I and II, proerythroblasts and early basophilic; regions III and IV, late basophilic and chromatophilic erythroblasts. (B) Erythrocyte maturation was perturbed in the Ts1Cje 3-week-old BM and spleen with an increase in the proportion of early erythroblasts and a concomitant decrease in the proportion of late erythroblasts n = 3 mice of each genotype for BM and n = 4 of each genotype for spleen. (C) Further stratifying the Ter119⁺ population into Ery.A, Ery.B, and Ery.C populations demonstrates a significant increase in the proportion of Ery.A and Ery.B cells and a concomitant decrease in the proportion of Ery.C cells in both the Ts1Cje BM and spleen. n = 3 mice of each genotype for BM and n = 4 of each genotype for spleen. (D) The overall proportion of Ter119⁺ cells in the Ts1Cje BM is decreased, whereas it is increased in the spleen. n = 3 mice of each genotype for BM and n = 4 of each genotype for spleen. *P < .05; **P < .01; ***P < .001. Error bars represent SEM.