Three Asx homologs have been identified in mammals: ASXL1, ASXL2, and ASXL3. Among them, ASXL1 mutations are often found in a wide range of myeloid malignancies (Carbuccia et al., 2009) and Bohring-Opitz syndrome (Hoischen et al., 2011). Here, ASXL1 is linked to Bohring-Opitz syndrome.