Significant reductions in CSF metabolites of norepinephrine, dopamine, and serotonin are reported in 32 female patients with suspected Rett syndrome from the Baylor College of Medicine, Houston, Texas. CSF biopterin, an essential cofactor that may limit the synthesis of biogenic amines, was elevated in patients compared with controls. Diet, drugs, and nutritional status, that may affect monoamine metabolites, were thought to be unlikely explanations for these biochemical changes. 
COMMENT. Abnormal biochemical findings reported in Rett syndrome, including hyperammonemia, have not been substantiated. If specific and unexplained by anticonvulsant drugs or diet, this report is the first to suggest a metabolic disorder underlying the stereotypic hand movements and other neurologic signs of Rett syndrome. Abnormal CSF biogenic amines are also reported in Parkinson's disease, Huntington's chorea, and Lesch-Nyhan syndrome.