CREBBP and Rubinstein-Taybi syndrome due to CREBBP mutations: More recently, Negri et al. and Di Fede et al. have reported 10 cases with an initial clinical diagnosis of RSTS and CREBBP/EP300 mutations negative carrying causal variants in three genes encoding members of epigenetic machinery but with other chromatin-modifying enzymatic mechanisms: ASXL1 (two patients), KMT2A (seven patients) and KMT2D (one patient) [160,161].