SCN8A Gene - Nav1.6
<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">SCN8A — Sodium Voltage-Gated Channel Alpha Subunit 8</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>SCN8A</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Sodium Voltage-Gated Channel Alpha Subunit 8</td>
</tr>
<tr>
<td class="label">Chromosome</td>
<td>12q13.13</td>
</tr>
<tr>
<td class="label">NCBI Gene</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/6334" target="_blank">6334</a></td>
</tr>
<tr>
<td class="label">Ensembl</td>
<td><a href="https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000175550" target="_blank">ENSG00000175550</a></td>
</tr>
<tr>
<td class="label">OMIM</td>
<td><a href="https://omim.org/entry/600402" target="_blank">600402</a></td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/Q9UQD0" target="_blank">Q9UQD0</a></td>
</tr>
<tr>
<td class="label">Diseases</td>
<td>Epilepsy, Cognitive Impairment, Movement Disorders, Alzheimer's Disease</td>
</tr>
<tr>
<td class="label">Expression</td>
<td>Brain, Cerebellum, Hippocampus, Cortex</td>
</tr>
<tr>
<th class="infobox-subheader" colspan="2">Key Mutations</th>
</tr>
<tr>
<td colspan="2" style="font-size:0.85em">N1768D, R1872H, R1617Q</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/ataxia" style="color:#ef9a9a">Ataxia</a>, <a href="/wiki/migraine" style="color:#ef9a9a">Migraine</a>, <a href="/wiki/ms" style="color:#ef9a9a">Ms</a>, <a href="/wiki/parkinson" style="color:#ef9a9a">PARKINSON</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">32 edges</a></td>
</tr>
</table>
SCN8A — Sodium Voltage-Gated Channel Alpha Subunit 8
Introduction
Scn8A Gene Nav1.6 is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Overview
Mermaid diagram (expand to render)
SCN8A (Sodium Voltage-Gated Channel Alpha Subunit 8) is a gene located on chromosome 12q13.13 that encodes the Nav1.6 voltage-gated sodium channel, a critical ion channel protein expressed predominantly in the central nervous system["@luo2020"]. The gene is catalogued as NCBI Gene ID [6334](https://www.ncbi.nlm.nih.gov/gene/6334) and OMIM [600402](https://omim.org/entry/600402).
Nav1.6 is one of the primary sodium channels responsible for action potential initiation and propagation in [neurons](/entities/neurons). It is particularly abundant in the axon initial segment (AIS) and nodes of Ranvier, where it plays a essential role in neuronal excitability["@hu2019"].
Function
The SCN8A gene encodes the alpha subunit of the voltage-gated sodium channel Nav1.6. This protein forms the pore of the channel and contains the voltage sensor that detects changes in membrane potential.
Channel Structure
The Nav1.6 channel consists of a large alpha subunit (∼260 kDa) that forms the functional ion channel, associated with auxiliary beta subunits that modulate channel trafficking and function[@catterall2020]. The alpha subunit contains four homologous domains (I-IV), each with six transmembrane segments (S1-S6). The S4 segments serve as voltage sensors, while the S5-S6 segments form the pore.
Brain Expression
SCN8A exhibits high expression in multiple brain regions:
- Cerebellum: High expression in Purkinje cells and granule cells
- [Hippocampus](/brain-regions/hippocampus): Prominent in CA1 pyramidal neurons
- [Cortex](/brain-regions/cortex): Expressed in layer 2/3 pyramidal neurons
- Brainstem: Motor neurons and sensory neurons
- Thalamus: Relay neurons
Expression data is available from the [Allen Human Brain Atlas](https://human.brain-map.org/microarray/search/show?search_term=SCN8A).
Physiological Role
Nav1.6 channels are critical for:
Action Potential Initiation: Located at the axon initial segment, Nav1.6 is the primary channel responsible for threshold determination
High-Frequency Firing: Nav1.6 supports rapid firing rates essential for information processing
Saltatory Conduction: Channels at nodes of Ranvier enable fast action potential propagation
Resurgent Current: Nav1.6 generates resurgent currents that promote rapid firing
Disease Associations
SCN8A mutations are linked to several neurological conditions:
Epilepsy
De novo missense mutations in SCN8A are a well-established cause of early-onset epileptic encephalopathy[@veeramah2012]. These mutations typically result in gain-of-function, leading to increased neuronal excitability. Affected individuals present with infantile spasms, focal seizures, and refractory epilepsy.
Cognitive Impairment
SCN8A mutations are associated with intellectual disability, developmental delay, and autism spectrum disorders[@larsen2015]. The severity correlates with mutation type and location.
Movement Disorders
Mutations can cause ataxia, dystonia, and tremor due to dysfunction in cerebellar and basal ganglia circuits[@wagnon2017].
Alzheimer's Disease
Recent research suggests SCN8A may play a role in Alzheimer's disease pathogenesis. Sodium channel dysfunction contributes to [amyloid-beta](/proteins/amyloid-beta) toxicity and [tau](/proteins/tau)-induced neuronal injury[@zhang2023].
Key Mutations
| Mutation | Effect | Associated Phenotype |
|----------|--------|----------------------|
| N1768D | Gain-of-function | Severe early-onset epilepsy |
| R1872H | Gain-of-function | Epilepsy, developmental delay |
| R1617Q | Loss-of-function | Ataxia, movement disorder |
Therapeutic Implications
Channel Blockers
Several sodium channel blockers have been investigated for SCN8A-related disorders:
- Phenytoin: Used empirically, though not specific for Nav1.6
- Mexiletine: Open-label studies show reduction in seizure frequency
- Carbamazepine: Variable response depending on mutation
Emerging Therapies
- ASO Therapy: Antisense oligonucleotides targeting mutant SCN8A are in preclinical development
- Gene Therapy: CRISPR-based approaches to correct pathogenic mutations
Interacting Proteins
SCN8A interacts with several proteins:
- Navβ1 (SCN1B): Auxiliary subunit that modulates channel kinetics
- Navβ2 (SCN2B): Regulates channel trafficking to the membrane
- Ankyrin-G: Anchors channels at the axon initial segment
- Calmodulin: Calcium-dependent regulation of channel function
See Also
- [Sodium Channels](/mechanisms/sodium-channels)
- [Voltage-Gated Ion Channels](/mechanisms/voltage-gated-ion-channels)
- [Epilepsy Mechanisms](/diseases/epilepsy)
- [Action Potential](/mechanisms/action-potential)
Background
The study of Scn8A Gene Nav1.6 has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
External Links
- [NCBI Gene*: [https://www.ncbi.nlm.nih.gov/gene/6334](https://www.ncbi.nlm.nih.gov/gene/6334)](/institutions/nih)
- [Ensembl*: [https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000175550](https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000175550)](/genes/ar)
- [OMIM*: [https://omim.org/entry/600402](https://omim.org/entry/600402)](/entities/htt)
- [UniProt*: [https://www.u](/entities/htt)niprot.org/uniprot/Q9UQD0](https://www.uniprot.org/uniprot/Q9UQD0)
- Allen Human Brain Atlas: [SCN8A expression](https://human.brain-map.org/microarray/search/show?search_term=SCN8A)
References
[Luo et al., Nav1.6 in neuronal excitability (2020) (2020)](https://pubmed.ncbi.nlm.nih.gov/32855378/)
[Hu et al., Axon initial segment sodium channels (2019) (2019)](https://pubmed.ncbi.nlm.nih.gov/31154987/)
[Unknown, Catterall WA, Sodium channel structure (2020) (2020)](https://pubmed.ncbi.nlm.nih.gov/32057025/)
[Veeramah et al., SCN8A mutations in epileptic encephalopathy (2012) (2012)](https://pubmed.ncbi.nlm.nih.gov/22842151/)
[Larsen et al., SCN8A and neurodevelopmental disorders (2015) (2015)](https://pubmed.ncbi.nlm.nih.gov/26637798/)
[Wagnon et al., SCN8A movement disorders (2017) (2017)](https://pubmed.ncbi.nlm.nih.gov/28327375/)
[Zhang et al., SCN8A in Alzheimer's disease (2023) (2023)](https://pubmed.ncbi.nlm.nih.gov/37648745/)Pathway Diagram
The following diagram shows the key molecular relationships involving SCN8A Gene - Nav1.6 discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)