SCN1A and cerebellar ataxia: SCN1A haploinsufficiency producing Nav1.1 dysfunction mainly affects GABAergic neurons, which according to the affected site, cortex, cerebellum, basal ganglia, or hypothalamus, are the cause of epileptic seizure, ataxia, crouching gait, thermal dysregulation, and sleep disturbances [96, 98, 101, 102].