Cerebrospinal Fluid β-Endorphin and Cortisol Study in Rett Syndrome:

An evaluation of cerebrospinal fluid and plasma β-endorphin and cortisol levels was performed in 15 girls affected with classic Rett syndrome. There were no differences between the patient group and the control group in plasma cortisol and β-endorphin levels. But in Rett syndrome, a significant increase in β-endorphin was noted in the cerebrospinal fluid, with an elevation of the cerebrospinal fluid/plasma β-endorphin ratio and a decrease in cerebrospinal fluid cortisol. A substantial overlap between patients and control group diminishes the diagnostic value of cerebrospinal fluid β-endorphin assay in girls suspected of having Rett syndrome. (J Child Neurol 1991;6:257-262).