SCN2A mRNA

Class

antisense oligonucleotide (elsunersen), developed with Ionis, designed to selectively decrease expression of gain-of-function SCN2A transcripts

Pathway

reduces expression of the mutant, gain-of-function SCN2A sodium channel gene product, directly addressing the genetic driver of SCN2A-DEE seizures

SCN2A is the gene encoding Nav1.2, a voltage-gated sodium channel subunit that governs the initiation and propagation of electrical signals in neurons, particularly in the developing brain. Certain mutations in SCN2A produce a gain-of-function channel that opens too readily or stays open too long, driving excessive neuronal firing and severe, early-onset seizure disorders classified as developmental and epileptic encephalopathies. Because the disease arises from too much channel activity rather than too little, the therapeutic logic is to reduce the amount of the disease-associated transcript being translated into protein, rather than to block the channel pharmacologically after it is made. Antisense oligonucleotides are short synthetic nucleic acid strands designed to bind a specific messenger RNA sequence and trigger its degradation or otherwise reduce its translation, lowering the quantity of protein produced from that gene. Applying this approach to SCN2A aims to bring total sodium channel dosage back toward a functional range, dampening hyperexcitability at its genetic source rather than only managing downstream seizure activity. This mechanism is relevant broadly to genetically defined epilepsies where a single gene's altered dosage or altered channel behavior is the primary driver, and it reflects a wider strategy of using nucleic acid therapeutics to correct disease at the transcript level.