SCN1A and encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy: Initial insights into the neurobiological function of Nav1.1 came from studies of a mouse model of Dravet Syndrome, where the loss of one copy of Scn1a impaired the excitability of hippocampal inhibitory interneurons but not excitatory neurons (Yu et al., 2006).