Mutations in other histone methylation modifier genes similarly cause phenotypically distinct neurodevelopmental syndromes, with these overlapping features, which are also reported in Wiedemann-Steiner syndrome (MIM: 605130, KMT2A), Kleefstra syndrome 2 (MIM: 617768, KMT2C), Kabuki syndrome 1 (MIM: 147920, KMT2D), Kleefstra syndrome 1 (MIM: 610253, EHMT1) and SETD1A-related disease (Ng et al., 2010; Jones et al., 2012; Kleefstra et al., 2012; Singh et al., 2016). Here, KMT2D is linked to Kleefstra syndrome 2.