Rett syndrome is, like Rubinstein-Taybi, a disorder of the epigenetic machinery, and interconnection with RSTS has been highlighted by the findings of reduced CBP-bound protein CREB and phospho-CREB levels in MECP2 mutant iPSCs and amelioration of the neuronal morphological alterations by pharmacological activation of CREB signaling [31]. This evidence concerns the gene CREBBP and atypical Rett syndrome.