Cerebral metabolites of noradrenaline, dopamine and serotonin, y-aminobutyric acid, and 23 amino acids were present in normal concentrations in the CSF of 5 girls with Rett syndrome studied in the Depts of Pharmacology and Therapeutics, and Dept of Paediatrics, University of British Columbia, Vancouver, Canada. The authors doubt that any biochemical abnormalities have been clearly established as characteristic of the syndrome. 
COMMENT. A previous report of low CSF levels of monoamine metabolites in patients with Rett syndrome  is not supported by the present study. Hyperammonemia reported originally by Rett is another suggested biochemical basis for the syndrome unconfirmed in subsequent reports. The lack of uniformity of these findings suggests that Rett syndrome is a nonspecific entity with more than one etiology.