SCN8A and Cognitive impairment: Online Mendelian Inheritance in Man (OMIM) terms them as developmental and epileptic encephalopathy 13, benign familial infantile seizures 5 or cognitive impairment with or without cerebellar ataxia.<h4>Methods</h4>In this study, we describe clinical and genetic results on eight individuals from six families with <i>SCN8A</i> pathogenic variants identified via exome sequencing.<h4>Results</h4>Clinical findings ranged from normal development with well-controlled epilepsy to significant developmental delay with treatment-resistant epilepsy.