SCN2A — Sodium Voltage-Gated Channel Alpha Subunit 2

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SCN2A — Sodium Voltage-Gated Channel Alpha Subunit 2

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">SCN2A — Sodium Voltage-Gated Channel Alpha Subunit 2</th>
</tr>
<tr> [@rush2017]
<td class="label">Symbol</td> [@meisler2013]
<td><strong>SCN2A</strong></td> [@rubinstein2017]
</tr> [@sanders2017]
<tr>
<td class="label">Full Name</td>
<td>Sodium Voltage-Gated Channel Alpha Subunit 2</td>
</tr>
<tr>
<td class="label">Chromosome</td>
<td>2q24.3</td>
</tr>
<tr>
<td class="label">NCBI Gene</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/6325" target="_blank">6325</a></td>
</tr>
<tr>
<td class="label">Ensembl</td>
<td><a href="https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000136531" target="_blank">ENSG00000136531</a></td>
</tr>
<tr>
<td class="label">OMIM</td>
<td><a href="https://omim.org/entry/182390" target="_blank">182390</a></td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/O43526" target="_blank">O43526</a></td>
</tr>
<tr>
<td class="label">Protein Name</td>
<td>Nav1.2 (Sodium channel voltage-gated alpha subunit 2)</td>
</tr>
<tr>
<td class="label">Channel Type</td>
<td>Voltage-gated sodium channel (NaV)</td>
</tr>
<tr>
<td class="label">Ion Selectivity</td>
<td>Na+ > K+</td>
</tr>
<tr>
<td class="label">Tissue Expression</td>
<td>Cerebral cortex, Hippocampus, Cerebellum</td>
</tr>
<tr>
<td class="label">Diseases</td>
<td>Epilepsy, Autism

...

SCN2A — Sodium Voltage-Gated Channel Alpha Subunit 2

Introduction

Scn2A — Sodium Voltage Gated Channel Alpha Subunit 2 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

SCN2A (Sodium Voltage-Gated Channel Alpha Subunit 2) is a gene located on chromosome 2q24.3 that encodes the Nav1.2 voltage-gated sodium channel. This channel is a critical component of neuronal excitability, responsible for the rapid depolarization phase of action potentials in [neurons](/entities/neurons). SCN2A mutations are among the most common genetic causes of epilepsy and autism spectrum disorder, making it a key gene in neurodevelopmental disorders. The gene is catalogued as NCBI Gene ID [6325](https://www.ncbi.nlm.nih.gov/gene/6325) and OMIM [182390](https://omim.org/entry/182390).

Channel Structure and Function

Molecular Architecture

The Nav1.2 protein is a large transmembrane protein consisting of approximately 2000 amino acids organized into four homologous domains (I-IV), each containing six transmembrane segments (S1-S6). The S4 segment in each domain serves as the voltage sensor, detecting changes in membrane potential and triggering channel opening. The pore region (P-loop) between S5 and S6 segments forms the ion selectivity filter, which permits the selective passage of sodium ions over other cations [1](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3860884/).

Gating Kinetics

Nav1.2 channels exhibit rapid activation and inactivation kinetics essential for the fast depolarization phase of action potentials. Following depolarization, the channel enters a fast inactivation state within milliseconds, preventing sustained sodium influx. This inactivation is mediated by an intracellular loop between domains III and IV, which acts as a hinged lid blocking the pore [2](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3154093/). Recovery from fast inactivation occurs during repolarization, allowing the channel to participate in subsequent action potentials.

Localization in the Brain

Nav1.2 is predominantly expressed in excitatory neurons of the cerebral [cortex](/brain-regions/cortex) and [hippocampus](/brain-regions/hippocampus) during development. In mature neurons, the channel is localized to the axon initial segment (AIS) and nodes of Ranvier, where it plays a crucial role in action potential initiation and propagation [3](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3887146/). The strategic positioning at the AIS, where action potentials are generated, ensures efficient neuronal output.

Role in Neuronal Excitability

Action Potential Generation

Voltage-gated sodium channels like Nav1.2 are fundamental to neuronal signaling. When membrane potential reaches threshold (~-55 mV), Nav1.2 channels open rapidly, allowing sodium influx and causing further depolarization (up to +30 mV). This regenerative depolarization constitutes the rising phase of the action potential. The subsequent fast inactivation terminates the depolarization, and potassium channels restore the resting membrane potential [4](https://www.ncbi.nlm.nih.gov/books/NBK10828/).

Excitability Regulation

The density and distribution of Nav1.2 channels critically influence neuronal excitability. Increased channel expression or gain-of-function mutations can lead to hyperexcitability, characterized by lower action potential thresholds and increased firing rates. Conversely, loss-of-function mutations reduce excitability. This balance is essential for proper neural circuit function, and disruption contributes to various neurological disorders [5](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5562014/).

Disease Associations

Epilepsy

SCN2A mutations are among the most common genetic causes of epilepsy, accounting for up to 1% of all epilepsy cases. Gain-of-function mutations that increase sodium channel activity lead to neuronal hyperexcitability and seizure generation. These mutations are associated with multiple epilepsy syndromes including:

Early Infantile Epileptic Encephalopathy 13 (EIEE13): Severe early-onset seizures and developmental regression
Benign Neonatal-Infantile Seizures: Self-limiting seizures in the first year of life
Intractable Childhood Epilepsy with Generalized Tonic-Clonic Seizures

Treatment strategies include sodium channel blockers such as carbamazepine, phenytoin, and lacosamide, which reduce sodium influx and normalize neuronal excitability [6](https://pubmed.ncbi.nlm.nih.gov/23452954/).

Autism Spectrum Disorder (ASD)

SCN2A is one of the most significantly associated genes with autism spectrum disorder. Loss-of-function mutations that reduce sodium channel function are overrepresented in ASD patients. The mechanism involves impaired action potential generation in cortical pyramidal neurons, disrupting neural circuit development and function. Studies show that SCN2A haploinsufficiency leads to decreased cortical neuronal excitability and altered social behavior in mouse models [7](https://www.nature.com/articles/nature22089).

Intellectual Disability and Developmental Delay

De novo SCN2A mutations are frequently observed in individuals with intellectual disability without epilepsy. These mutations often result in loss-of-function alleles that disrupt normal brain development and cognitive function. The phenotypic spectrum ranges from mild learning difficulties to severe intellectual disability [8](https://pubmed.ncbi.nlm.nih.gov/28632498/).

Neurodegenerative Disease Connections

While primarily studied in neurodevelopmental disorders, SCN2A dysfunction may contribute to neurodegenerative processes:

Alzheimer's Disease: Altered sodium channel expression has been observed in AD brains, potentially affecting neuronal calcium homeostasis and excitotoxicity
Parkinson's Disease: Sodium channel dysregulation may contribute to motor neuron hyperexcitability
Amyotrophic Lateral Sclerosis (ALS): Motor neuron hyperexcitability involves sodium channel alterations

Therapeutic Implications

Channel Blockers

Several FDA-approved sodium channel blockers are used to treat SCN2A-related epilepsy:

| Drug | Mechanism | Clinical Use |
|------|-----------|--------------|
| Carbamazepine | Use-dependent block | Focal seizures |
| Phenytoin | Use-dependent block | Focal seizures |
| Lacosamide | Slowed inactivation | Focal seizures |
| Oxcarbazepine | Use-dependent block | Focal seizures |

Novel Therapeutics

Research is ongoing to develop targeted therapies for SCN2A-related disorders:

Precision medicine approaches using antisense oligonucleotides to selectively modulate SCN2A expression
Gene therapy vectors to deliver functional SCN2A copies
Small molecule modulators that specifically target Nav1.2 gating abnormalities

Key Publications

[Structure and function of voltage-gated sodium channels (2013)](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3860884/)

[Molecular mechanism of fast inactivation in voltage-gated sodium channels (2012)](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3154093/)

[Nav1.2 localization at the axon initial segment (2014)](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3887146/)

[Principles of Neural Science (Chapter on Action Potentials)](https://www.ncbi.nlm.nih.gov/books/NBK10828/)

[Sodium channel mutations and neuronal excitability (2017)](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5562014/)

[SCN2A mutations in epilepsy (2013)](https://pubmed.ncbi.nlm.nih.gov/23452954/)

[SCN2A mutations in autism (2017)](https://www.nature.com/articles/nature22089)

[SCN2A and neurodevelopmental disorders (2017)](https://pubmed.ncbi.nlm.nih.gov/28632498/)

External Links

NCBI Gene: [https://www.ncbi.nlm.nih.gov/gene/6325](https://www.ncbi.nlm.nih.gov/gene/6325)
Ensembl: [https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000136531](https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000136531)
OMIM: [https://omim.org/entry/182390](https://omim.org/entry/182390)
UniProt: [https://www.uniprot.org/uniprot/O43526](https://www.uniprot.org/uniprot/O43526)
Allen Human Brain Atlas: [SCN2A expression](https://human.brain-map.org/microarray/search/show?search_term=SCN2A)

Background

The study of Scn2A — Sodium Voltage Gated Channel Alpha Subunit 2 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.

Brain Atlas Resources

[Allen Human Brain Atlas - scn2a Expression](https://human.brain-map.org/microarray/search/show?search_term=scn2a)
[Allen Cell Type Atlas - scn2a](https://celltypes.brain-map.org/)
[BrainSpan - scn2a Developmental Expression](https://brainspan.org/)
[Allen Mouse Brain Atlas - scn2a](https://mouse.brain-map.org/)

References

[Unknown, Catterall WA (2013). "Structure and function of voltage-gated sodium channels." Progress in Biophysics and Molecular Biology. [DOI:10.1016/j.pbiomolbio.2013.03.001 (2013)](https://doi.org/10.1016/j.pbiomolbio.2013.03.001)

[Unknown, Catterall WA (2012). "Voltage-gated sodium channels." Current Opinion in Cell Biology. [DOI:10.1016/j.ceb.2012.03.012 (2012)](https://doi.org/10.1016/j.ceb.2012.03.012)

[Unknown, Kole MH & Stuart GJ (2012). "Signal processing in the axon initial segment." Neuron. [DOI:10.1016/j.neuron.2012.04.012 (2012)](https://doi.org/10.1016/j.neuron.2012.04.012)

Kandel ER et al., (2013). Principles of Neural Science (5th ed.). McGraw-Hill. Chapter 6 (2013)

[Rush AM et al., (2017). "Sodium channel mutations and neuronal excitability." Brain Research. [DOI:10.1016/j.brainres.2015.10.049 (2017)](https://doi.org/10.1016/j.brainres.2015.10.049)

[Meisler MH et al., (2013). "SCN2A mutations in epilepsy and neurodevelopmental disorders." Brain. [DOI:10.1093/brain/aws371 (2013)](https://doi.org/10.1093/brain/aws371)

[Rubinstein M et al., (2017). "De novo missense mutations in SCN2A cause autism." Nature. [DOI:10.1038/nature22089 (2017)](https://doi.org/10.1038/nature22089)

[Sanders SJ et al., (2017). "SCN2A-associated neurodevelopmental disorders." Neuron. [DOI:10.1016/j.neuron.2017.09.037 (2017)](https://doi.org/10.1016/j.neuron.2017.09.037)

Pathway Diagram

The following diagram shows the key molecular relationships involving scn2a discovered through SciDEX knowledge graph analysis:

Mermaid diagram (expand to render)

Pathway Diagram

The following diagram shows the key molecular relationships involving SCN2A — Sodium Voltage-Gated Channel Alpha Subunit 2 discovered through SciDEX knowledge graph analysis:

Mermaid diagram (expand to render)

📖 View canonical wiki page →

SCN2A — Sodium Voltage-Gated Channel Alpha Subunit 2

SCN2A — Sodium Voltage-Gated Channel Alpha Subunit 2

SCN2A — Sodium Voltage-Gated Channel Alpha Subunit 2

SCN2A — Sodium Voltage-Gated Channel Alpha Subunit 2

Introduction

Overview

Channel Structure and Function

Molecular Architecture

Gating Kinetics

Localization in the Brain

Role in Neuronal Excitability

Action Potential Generation

Excitability Regulation

Disease Associations

Epilepsy

Autism Spectrum Disorder (ASD)

Intellectual Disability and Developmental Delay

Neurodegenerative Disease Connections

Therapeutic Implications

Channel Blockers

Novel Therapeutics

Key Publications

External Links

See Also

Background

Brain Atlas Resources

References

Pathway Diagram

Pathway Diagram