Background: Rett syndrome was first described 40 years ago as a profoundly disabling condition in girls.
Method: Over the last 20 years' national surveys, neuropathological and neurophysiological research have steadily improved understanding of its character and natural history.
Results: In the last two years identification of the causative mutations in the gene methyl CpG binding protein 2 (Xq28) has led to a sudden expansion in knowledge about the underlying developmental disorder, with important implications for clinical practice and new opportunities to develop more effective intervention.
Conclusions: It is now clear that the disorder occurs in males and females and that there is a wide range in severity.