In contrast, haploinsufficient Cux1+/fl;Vav-iCre+ (referred to as Cux1+/−) mice displayed mild macrocytic anemia without significant abnormalities in absolute leukocyte numbers (Supplementary Fig. 3k–m), although myelodysplastic features were evident in blood and bone marrow cytospins (Supplementary Fig. 3f–j). Here, CUX1 is linked to macrocytic anemia.