The biological relevance of these proteins is highlighted by the clinical consequences of their haploinsufficiency, as KMT2A and TCF20 are the causative genes of Wiedemann-Steiner syndrome (WDSTS, OMIM #605130) and of a syndromic neurodevelopmental disorder (OMIM #618430), respectively [108,109]. The gene discussed is TCF20; the disease is Wiedemann-Steiner syndrome.