Kleefstra Syndrome (KS, OMIM#610253) is a rare syndromic form of intellectual disability (ID) associated with autistic features (Kleefstra et al. 2005, 2012; Koemans et al. 2017; Vermeulen et al. 2017), caused by haploinsufficiency of the EHMT1 gene. The gene discussed is EHMT1; the disease is Kleefstra syndrome.