EZH2 and myelodysplastic syndrome: In contrast, EZH2 inactivating deletion, frameshift, nonsense and missense mutations have been identified in myelodysplastic syndromes (MDS), myeloproliferative neoplasms (MPN), MDS-MPN overlap disorders and T-cell acute lymphocytic leukemia [54–56], implicating that EZH2 loss-of-function is associated with development of malignancy and EZH2 may function as a tumor suppressor.