DNMT3B and Rett syndrome: Here, we focused on the latest findings linking ncRNAs into the molecular and neural phenotypical defects of human disorders with deficiencies in (i) epigenetic modifiers, like MeCP2 (methyl-CpG-binding-protein-2) for the Rett syndrome (RTT) and DNMT3B (DNA-methyltrasferase-3B) for the Immumodeficiency, Centromeric instability, Facial anomalies (ICF) syndrome (Type1) or (ii) in the establishment of DNA methylation signature, as for the imprinting disorders (Figure 1).