MECP2 and Rett syndrome: Recent research shows that MeCP2 protein deficiency in Rett disease does not only affect neurons, but also glial cells, especially astrocytes (increase in extracellular glutamate concentration is seen due to decreased expression of excitatory amino acid transporter 1 (EAAT1) and increased expression of glutamine synthetase, as well as increased expression of glial acid fibrillar protein [GFAP] and S100 protein) and oligodentrocytes (thinner myelin due to reduced expression of genes associated with myelin production) [167].