This histone mark is established by Enhancer of zeste homolog 2 (EZH2), the histone methyltransferase of the Polycomb Repressive Complex 2 (PRC2), and has been detected in genes involved in cell differentiation, synaptic function, neurodegeneration, and epilepsy, as well as in maintaining the distinct characteristics and functions of various cell types within an organism or tissue, such as NEUROG2, OLIG2, and HOXA1-5 [30,31]. The gene discussed is EZH2; the disease is epilepsy.