In conclusion, our findings uncover that most of Dravet syndrome phenotypic manifestations are not attributable to an interaction between Nav1.1 haploinsufficiency and development of brain circuits, but, conversely, strictly to the reduction of Nav1.1 function, as they also appear in an already established mature network. The gene discussed is SCN1A; the disease is encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy.