MECP2 and Rett syndrome: A severe impairment of the OXPHOS apparatus, in particular a deficit of the MRC complex II and ATP synthase activities, has been shown in the brain of MeCP2-308 heterozygous female mouse models of RTT [16,19,185] and in cortical astrocytes [186], resulting in strong shortage of mitochondrial ATP production and a decrease in brain ATP levels; consistently, a large increase in ROS production by the defective complex II has been found [19].