Wang and colleagues (2014) developed a constitutive Asxl1 murine knockout line by disrupting the translation start site of Asxl1. A small fraction of the homozygous knockout mice survived for a maximum of 18-42 days, and some of these developed MDS with anemia, thrombocytopenia and neutropenia. The gene discussed is ASXL1; the disease is anemia (phenotype).