EHMT1 and Coffin-Siris syndrome 1: Wiedemann-Steiner syndrome (WDSTS, OMIM #605130), Kleefstra syndrome type 1 (KLEFS1, OMIM #610253) and Coffin-Siris syndrome type 1 (CSS1, OMIM #135900) are ultra-rare genetic conditions associated with mutations in epigenetic regulating genes [1].