SCN1A and encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy: Dravet Syndrome (DS) is one of the most prevalent and severe developmental epileptic encephalopathies, characterized by frequent seizures and a high risk of sudden unexpected death in epilepsy.1 The seizures are often unresponsive to anti-epileptic drugs,2 and accompanied by cognitive impairment, developmental delay, and motor dysfunction.3,4 In 80% of the cases, DS is caused by a de novo variant in SCN1A, which encodes the voltage-gated sodium channel NaV1.1 α-subunit.3 However, patients with the same variant show substantial variability in phenotype and treatment response.