Because of this preferential expression of NaV1.2 during the vulnerable developmental period when most autism spectrum disorder–associated (ASD-associated) mutations exert their influence (4), NaV1.2 is well positioned to exert a potent effect on AP initiation and conduction, thereby influencing neuronal excitability and activity-dependent development in the maturing brain. The gene discussed is SCN2A; the disease is autism spectrum disorder.