Pathogenic variants in KMT2 genes are associated with epigenetic neurodevelopmental disorders including Wiedemann-Steiner syndrome (MIM:605130; KMT2A), childhood dystonia 28 (DYT-KMT2B, MIM:617284; KMT2B), Kleefstra syndrome type 2 (MIM:617768; KMT2C), Kabuki syndrome type 1 (MIM:147920; KMT2D) and O’Donnell-Luria-Rodan syndrome (MIM:618512, KMT2E) that have overlapping but distinct phenotypes and distinct episignatures (2,5,15–22). This evidence concerns the gene KMT2B and Wiedemann-Steiner syndrome.