SCN2A and familial hemiplegic migraine: This review comprehensively analyzes the molecular mechanisms and pathophysiological significance of voltage-gated sodium channels, with particular emphasis on elucidating the molecular-action mechanisms of the distinct subtypes of these channels, including Nav1.1, Nav1.2, and Nav1.6, across various neurological disorders such as familial hemiplegic migraine, epilepsy, autism spectrum disorder, and retinal dysfunction.