Voltage-Gated Sodium Channels in Epilepsy and Neurological Disorders

Voltage-gated sodium channels are transmembrane proteins that underlie the rapid depolarisation phase of neuronal action potentials. Aberrant function or expression of specific channel subtypes—particularly NaV1.1, NaV1.2 and NaV1.6—has been implicated in a spectrum of epilepsies and other neurodevelopmental disorders. Mutations may alter channel gating, trafficking or splice-isoform proportions, giving rise to either gain-of-function effects, which heighten excitability and provoke early-onset seizures, or loss-of-function effects, which can impair network synchrony and manifest as later-onset epilepsy, intellectual disability or autism spectrum features. Genetic and biophysical studies in patients and animal models have delineated genotype–phenotype correlations, revealing that even identical variants may produce variable clinical severity depending on cellular context, co-expression of auxiliary subunits and developmental stage. Advances in molecular profiling, electrophysiology and computational modelling are converging to inform precision therapies, including tailored pharmacological modulation and splice-switching strategies. This body of work underscores the global relevance of sodium channelopathies and paves the way for mechanism-driven interventions in refractory epilepsy and associated comorbidities.

Research from Nature Portfolio

Dynamic action potential clamp studies of recurrent SCN2A variants have demonstrated that gain-of-function mutations consistently underlie early-infantile epilepsies, whereas loss-of-function mutations associate with later-onset seizures and intellectual disability. The approach outperforms traditional voltage clamp in predicting the impact of channel variants on neuronal firing, although it does not fully account for clinical severity among gain-of-function alleles. Foundations laid by mouse models of Nav1.2 haploinsufficiency reveal that deletion of one SCN2A allele in excitatory neurons leads to absence-like seizures sensitive to ethosuximide, whereas inhibitory neuron-specific deletion is without effect, highlighting cell-type specificity in channelopathy pathogenesis. Complementary work on febrile seizures shows that NaV1.2 and NaV1.6 contribute differentially to temperature-driven hyperexcitability: upregulation of NaV1.2 promotes somatic currents at febrile temperatures, lowering seizure threshold, while loss of NaV1.6 exacerbates susceptibility, providing a mechanistic basis for clinically observed febrile convulsions.

Voltage-Gated Sodium Channels in Epilepsy and Neurological Disorders publication trend

The graph below shows the total number of articles in voltage-gated sodium channels in epilepsy and neurological disorders across all publications each year (not limited to Nature Index journals).

Technical terms

Voltage-gated sodium channel (VGSC): A membrane protein that opens in response to depolarisation, allowing sodium influx and initiating the action potential.

NaV1.2, NaV1.6: Specific α-subunit isoforms of VGSCs encoded by SCN2A and SCN8A genes, with distinct expression patterns and roles in action potential initiation and propagation.

Action potential clamp (AP clamp): An electrophysiological technique that imposes a recorded action potential waveform on a cell to assess the contribution of ion currents to spike shape and timing.

Gain-of-function mutation: A genetic change that enhances channel activity, such as increased persistent current or hyperpolarised activation, leading to neuronal hyperexcitability.

Loss-of-function mutation: A variant that reduces or abolishes channel activity, often by impairing gating or surface expression, which can disrupt network synchrony.

Haploinsufficiency: A condition in which loss of one gene copy (heterozygous deletion) results in insufficient protein product to sustain normal function.

Axon initial segment (AIS): The proximal region of the axon where action potentials are typically initiated, enriched in specific VGSC subtypes.

References

1. Predicting functional effects of ion channel variants using new phenotypic machine learning methods. PLOS Computational Biology (2023).
2. Nav1.2 haplodeficiency in excitatory neurons causes absence-like seizures in mice. Communications Biology (2018).
3. Differential roles of NaV1.2 and NaV1.6 in regulating neuronal excitability at febrile temperature and distinct contributions to febrile seizures. Scientific Reports (2018).
4. Functional correlates of clinical phenotype and severity in recurrent SCN2A variants. Communications Biology (2022).
5. Developmental dynamics of voltage-gated sodium channel isoform expression in the human and mouse brain. Genome Medicine (2021).
6. Voltage Gated Sodium Channel Genes in Epilepsy: Mutations, Functional Studies, and Treatment Dimensions. Frontiers in Neurology (2021).