Mutations in the Additional Sex Combs-Like 1 (ASXL1) epigenetic regulator have been found to occur at high frequency in patients with myeloid malignancies (48% of CML, 20% of MDS, 10% of MPN, and 20% of AML) [85,93,94,95,96,97,98,99,100,101,102]. The gene discussed is ASXL1; the disease is myeloproliferative disorder.