SCN2A and developmental and epileptic encephalopathy: Expression and functional characterization of the Na<sub>V</sub>1.2 A1659V variant was performed in HEK293 cells by western blotting, confocal microscopy, and patch clamp electrophysiology.<h4>Results</h4>The same de novo pathogenic <i>SCN2A</i> variant was detected in 3 patients with DEE characterized by early onset, severe ID, and seizures unresponsive to SCB.