Rett Syndrome

Abstract Rett syndrome is a neurological disease of early postnatal brain growth found almost exclusively in girls and is the third most common cause, after Down syndrome and Fragile X syndrome, of severe mental retardation. Typically, girls with Rett syndrome show developmental regression including loss of communication and motor skills, stereotypic hand movements and a deceleration of head growth. The defective gene, methyl CpG binding protein 2 (Rett syndrome) (MECP2) is normally involved in the transcription silencing of genes (turning genes ‘off ’). In Rett syndrome, the MECP2 protein does not work properly in approximately half of the patient's cells due to X inactivation. This is thought to lead to inappropriate communication between MECP2‐positive and MECP2‐negative cells in the brain, and the Rett syndrome phenotype.