The lysine methyltransferase called enhancer of zeste homolog 2 (EZH2) is a component of the polycomb repressive complex 2 (PRC2), and it plays a complex, multifaceted role in gene expression for stem cell differentiation; mutations in EZH2 are seen in 4% of patients with AML [137]. The gene discussed is EZH2; the disease is acute myeloid leukemia.