ASXL1 and chronic myelomonocytic leukemia: Heterozygous ASXL1 mutations that occur in earlier exons have been documented in primary chronic myelomonocytic leukemia samples (Abdel-Wahab et al., 2011), suggesting that this subset have true loss of one allele, and thus that haploinsufficiency also can contribute to the onset of hematologic malignancy.