Reduced cerebrospinal fluid B-endorphin levels in Rett syndrome.

Cerebrospinal fluid (CSF) levels of B-endorphin (B-EP), B-lipotropin (B-LPH) and ACTH were measured in nine girls with Rett syndrome with features of autistic behavior (3.7-12.1 years of age) and in ten children with chronic leukemia (control group). The peptides were measured by radioimmunoassay, either directly in the sample (ACTH) or after Sephadex G-75 column chromatography, in order to eliminate interfering substances (B-LPH and B-EP). The CSF B-EP patient levels (20.8 +/- 13.1 fmol/ml, means +/- SD) were significantly lower than in age-matched controls (69.1 +/- 32.6, P less than 0.01), whereas the B-LPH and ACTH levels were in the control range. No correlations were found between the clinical findings and CSF neuropeptide concentrations. These data demonstrate a decrease in central opiate activity in girls with Rett syndrome.