Ablation of miR-144/451 alleviates β-thalassemia in mice. β-thalassemic (Hbb^th3/+) and miR-144/451^−/− (miR^−/−) mice were intercrossed and analyzed. (A-D) Erythroid indices (y-axis) of 8-week-old mice according to the genotype (x-axis). n = 12 mice for each genotype. (E) RBC survival. RBCs in 8-week-old mice were biotinylated at time 0. Loss of biotin-labeled RBCs over time was quantified via streptavidin labeling and flow cytometry. Differences between Hbb^th3/+miR^+/+ and Hbb^th3/+miR^−/− mice were significant at all time points at which measurements were made between days 2 and 34 (Benjamini-Hochberg false discovery rate–adjusted P value = .002-.02). (F) Representative images of blood smears (Giemsa stain) from mice with the indicated genotypes. Images were obtained using an Eclipse Ni microscope and a 40× objective lens; bars represent 5 μm. (G) Representative images of spleens from mice with the indicated genotypes. Bar represents 1 cm. (H) Summary of spleen weights. n = 7 mice for each genotype. All bar charts show data as mean values ± standard deviation (SD); ∗∗∗∗P <.0001; ∗∗∗P <.001; ∗∗P <.01.