MECP2 and Rett syndrome: Mutations in the MECP2 gene/or its altered expression cause an extensive variety of human diseases ranging from neurodevelopmental disorders to neurodegenerative diseases: RTT, ASD, FASD, X-linked mental retardation, severe neonatal encephalopathy, MDS, Angelman syndrome, PPM-X syndrome, Huntington disease, early onset schizophrenia, and Hirschsprung’s disease [16,109,115].