SCN2A and Seizure: Contrary to the previous proposal that loss-of-function Scn2a mutations may reduce excitability of Nav1.2 expressing inhibitory neurons and thereby lead to epileptic seizures33, we show here that the epileptic phenotypes in mice with Scn2a deficiency depend on Nav1.2 deficiency in excitatory neurons, suggesting critical contributions of impaired functions of excitatory neurons to the pathophysiology of epileptic seizures associated with SCN2A mutations.