Hematological analysis of SLFN14^K208N/+mice. (A) Flow cytometry–based counting of platelets and erythrocytes. (Ai) Flow cytometry forward scatter (FSC) and side scatter (SSC) plots showing size overlap of erythrocyte (red oval) and platelet (green oval) populations. (Aii) Gating method shown for double stain using CD41 (R2) and Ter119 (R3). Representative plots of n = 18 mice per genotype. (B) Platelet (PLT) (i) and erythrocyte (RBC) (ii) count and platelet (iii) and erythrocyte (iv) size from flow cytometry–based counting. Data are mean ± standard error of the mean (SEM); n = 18 mice per genotype. (C) Immature platelet fraction in SLFN14^K208N/+ mice. CD41⁺ platelets were gated, and the immature platelet population was assessed by SYTO13 staining. Data are mean ± SEM; n = 13 to 20 mice per genotype. (D) Whole blood smears from wild-type and SLFN14^K208N/+ mice. Blood smears were stained with H&E histological stain to view blood cell size and morphology. Poikilocytes (irregularly shaped cells; arrowheads) and microcytes (arrows) are shown. Representative images of n = 6 or 7 mice per genotype. Scale bar, 10 µm. (E) SLFN14^K208N/+ mice are anemic. Hemoglobin levels were measured by an automated hematology analyzer in SLFN14^K208N/+ mice and wild-type controls. Data are mean ± SEM; n = 23 to 26 mice per genotype. *P < .05, ***P < .001, ****P < .0001.