SCN2A encodes the neuronal sodium channel Nav1.2, a voltage-gated ion channel that mediates sodium ion permeability across excitable membranes 1. The channel forms a sodium-selective pore that opens and closes in response to membrane voltage changes, allowing Na+ ions to flow according to their electrochemical gradient 2. SCN2A is highly expressed in developing neurons and plays critical roles in neuronal excitability and action potential generation 2. SCN2A dysfunction causes a spectrum of neurodevelopmental disorders, with SCN2A haploinsufficiency being a leading monogenic cause of autism spectrum disorder, intellectual disability, and infantile seizures 3. Disease pathophysiology depends on mutation type: gain-of-function missense mutations typically cause early-infantile onset seizures responsive to sodium channel blockers, while loss-of-function truncating mutations cause later-onset epilepsies or non-seizure phenotypes with poor drug responsiveness 4. Beyond epilepsy, SCN2A variants are associated with episodic ataxia and developmental and epileptic encephalopathies 5. Recent evidence indicates microglial over-pruning of synapses contributes to autism-associated SCN2A deficiency 6. Emerging therapeutic approaches include CRISPR activation to upregulate the functional gene copy, which rescues electrophysiological deficits, synaptic transmission, and seizure susceptibility in preclinical models 3. Phenotype-genotype correlation enables precision medicine approaches guiding therapeutic selection 7.