ASXL2 and leukemia: Given that ASXL2 mutations occur as heterozygous mutations in leukemia patients14, 15, we also investigated the effects of heterozygous loss of Asxl2. Competitive transplantation of Mx1-cre Asxl2fl/WT mice versus Mx1-cre Asxl2fl/fl and Mx1-cre control mice revealed that deletion of even a single copy of Asxl2 was associated with substantial decrements in HSPC self-renewal (Fig. 2e,f).