MECP2 and atypical Rett syndrome: The second mechanism involves the acquisition of methyl-binding domain proteins [methyl-CpG-binding domain protein 1 (MBD1-4), methyl CpG binding protein 2 (Rett syndrome) (MeCP2) and Kaiso] and the recruitment of additional factors with repressive properties, such as histone deacetylases (17,18).