LSD1, MLL1, EED, and G9a impact the hematopoietic system.123 Genetic mutations in H3K4 methyltransferases are linked to syndromes involving bone and facial deformities, intellectual impairment, and often reduced body size and microcephaly.123 Furthermore, it has been determined that mutations in other histone methylation regulators, such as EZH1 and NSD1, can be a causative factor for overgrowth syndrome. The gene discussed is KMT2A; the disease is microcephaly.