Neurobiology of Rett syndrome.

Girls with Rett syndrome display signs of neuronal dysfunction including mental retardation, seizures, stereotyped movements, and abnormal breathing and autonomic control. Decelerating head growth during infancy might reflect a disorder in production or pruning of neuronal synapses or both. Recent immunocytochemical studies in rodent brain investigating development of MeCP2, the transcription factor mutated in Rett syndrome, suggest that expression is delayed until the time of synapse formation. These findings are consistent with other evidence that Rett syndrome disrupts genetic programs that establish and refine synaptic connections.