A similar genotype–phenotype network association has been identified for Kleefstra syndrome, which is caused by loss-of-function mutations of EHMT1, encoding euchromatic histone methyltransferase 1 (EHMT1), a transcriptional repressor via mono- and dimethylation of histone 3 lysine 9 (H3K9me1/2). The gene discussed is EHMT1; the disease is Kleefstra syndrome.