SCN2A and developmental and epileptic encephalopathy: Among 24 patients with identified genetic etiologies, there were 13 with DEE, 6 patients had seizures with neurodevelopmental regressive symptoms, 2 patients with muscle disease (1 patient with muscle dystrophy carrying DMD gene and 1 patient with congenital muscle dystrophy with seizures), 1 with autism with SCN2A mutation, 1 with spinocerebellar ataxia, and 1 patient with Marfan syndrome.