SCN1A and epilepsy: According to this hypothesis, the severity of epileptic phenotypes of Nav1.1 mutations is dependent on the extent of Nav1.1 functional damage due to mutations, as, for instance, the spectrum of severity of Nav1.1-associated forms of epilepsy results from an increasing severity of loss of function mutations in Nav1.1 channels and increasing impairment of action potential firing of the GABAergic inhibitory neurons [88].