The phenotype of patients with a STXBP1 pathogenic variant ranges [25] from the generic early onset epilepsy encephalopathy, to Ohathara syndrome [36,37], EME [38], West syndrome [39,40], Dravet syndrome [41], but also includes intellectual disability (ID) in the absence of epilepsy [42,43,44], classic MECP2-negative RTT and atypical RTT [45]. The gene discussed is MECP2; the disease is early-infantile DEE.