We report on the first positron emission tomographic study of dopamine receptor binding in Rett syndrome. The patient is a 25 year old Austrian woman diagnosed at age 2 and followed since then by Rett. A computed axial tomogram (CT scan) showed cortical atrophy, and enlarged ventricles but normal structure of the caudate/putamen. Following the CT scan 20 mCi of 11 C N-methyl spiperone, a butyrophenone with a high affinity for dopamine D2 receptors was administered intravenously. The patient was found to have dopamine D2 receptor binding activity in the low normal range. The caudate/cerebellar activity ratio was below the mean regression line (p = 0.10) that relates the CA/CB ratio as a function of age. Levels of cerebrospinal fluid neurotransmitter metabolites were normal.
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