[Neuroimaging and neurochemical studies of Rett syndrome]

We review here the current status of neuroimaging and neurochemical research on Rett syndrome (RTT), with reference to neurophysiological, neuropathological, and immuno-histochemical changes previously described. Abnormalities have been reported in the intermediates of the biogenic amine neurotransmitters/receptor systems, and of beta-phenylethylamine (PEA), an endogenous amine synthesized by the decarboxylation of phenylalanine in dopaminergic neurons of the nigrostratal system. We also discuss the roles of other neurotransmitters including beta-endrophin, substance P and neurotrophic factors including nerve growth factors. Recently, mutations in the gene encoding methyl-CpG binding protein 2 (MeCP2), mapped to Xq28, have been identified in patients with RTT. Multiple abnormalities in various neurotransmitter/receptor systems may accounts for the pervasive defects in RTT.