The lipid membrane composition of cerebral tissue from five patients, age 12-30 years, and from 14 age-matched controls was studied at the Department of Psychiatry and Neurochemistry and Pediatrics, University of Goteborg, Goteborg, Sweden. A selective loss of myelin-associated lipids and an enrichment of gangliosides was demonstrated in the temporal white matter. The ganglioside pattern showed an increase of astroglial cell-associated gangliosides and reduced proportions of gangliosides GDla and GTlb. The fatty acid compositions of ethanolamine phosphoglyceride, choline phosphoglyceride, and galactosylceramide were normal. 
COMMENT: There is as yet no specific biochemical marker for Rett syndrome. These changes in lipid membranes are thought to be secondary, confirming the neuropathologic finding of slight demyelination in Rett syndrome. PET studies performed on six patients with Rett syndrome at the Division of Child Neurology, National Center Hospital for Mental Disorders, Kodaira, Tokyo, Japan showed that cerebral blood flow and oxygen metabolism were abnormal and the cerebral metabolic rate of oxygen and oxygen extraction fraction were low. Impaired oxidated metabolism in Rett syndrome is suggested by this study. 
A significant increase in B-endorphin in the cerebrospinal fluid, an elevation of the CSF/Plasma B-endorphin ratio and a decrease in CSF Cortisol are reported in a study of 15 girls with Rett syndrome at the Unite de Neuropediatrie, Centre Gui de Chauliac, Montpellier, France. The plasma Cortisol and B-endorphin levels were similar in the patient and control groups . The authors comment that the inconsistent nature of the CSF endorphin increase exclude its use as a biologic marker of Rett syndrome.