[Rett syndrome: the state of research, and future perspectives].

Rett syndrome (RTT) is a neurodevelopmental disorder characterized by normal early psychomotor development followed by the loss of psychomotor and acquired purposeful hand skills and the onset of stereotyped movement of the hands and gait disturbance. The causative gene was discovered, and the disease was found to be caused by a mutation of methyl-CpG-binding protein 2. However, in many ways this clinically peculiar condition remains a mystery. I review the current status of clinical and basic research on RTT including data on the neurophysiology of the disease, neurotransmitter involvement, neuroimaging and neuropathology findings, molecular biology, animal models, regenerative medicine including ES cells and iPS cells, and other interventions and therapeutic trials.