MECP2 and encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy: Related epilepsy syndromes can include but are not limited to Ohtahara syndrome, West syndrome, Lennox–Gaustaut syndrome, Dravet syndrome (not SCN1A-related), classic Rett syndrome (not MECP2-related), and atypical Rett syndrome (not CDKL5-related).