Rett syndrome (RTT) is a rare non-heritable human genetic disorder caused by mutations in the MECP2 gene (methyl-CpG-binding protein 2), located on the X chromosome which mainly occurs de novo in parental gametes. RTT occurs almost exclusively in females while males are more severely affected and rarely survive infancy. The syndrome can be divided in four stages. The first symptoms occur between six and eighteen months of age with indicators such as muscle hypotonia, microcephaly and growth arrest. This is followed by the rapid regression stage with characteristics similar to autism and also include other features: hand stereotypies, respiratory abnormalities, loss of hand skills, speech and social interactions, mental retardation and seizures. The subsequent stage leads to scoliosis and anxiety development while Parkinson-like diseases can be noticed in the last stage. Amelioration of the social component of the autistic-like behavior occurs before the early teenage years and affected women live up to sixty years of age. Mutated MeCP2 protein cannot bind to methylated DNA and the transcription of target gene is enabled. Due to the recent discovery that only two domains of the MeCP2 protein, methyl-binding domain (MBD) and transcriptional repressor domain (TRD), are adequate for normal functioning of the MeCP2 protein and repression of Rett syndrome, it is obvious that the MeCP2 protein works as a bridge between methylated DNA and repressor complex. Interestingly, both lack and excess of the MeCP2 protein in the brain lead to the same outcome. In recent times, gene therapy is used to provide a healthy copy of a mutated gene to a patient’s body, but the main problem is optimal dosage of a gene in the target tissue. Thus, much more work is needed to find an effective way of healing this complex syndrome.