EZH2 and obesity due to melanocortin 4 receptor deficiency: All identified genetic factors have been proven to account for only a small proportion of phenotypic changes in obesity.[6] Epigenetic regulation is characterized by stable changes occurring through biochemical modifications in the DNA bases and structure of the chromosome, but not in the DNA sequence.[7,8] Enhancer of zeste homolog 2 (EZH2) is a key epigenetic modulator in the family of polycomb group genes (PcGs) that includes critical epigenetic regulators that repress gene transcription.