SCN9A Gene

SCN9A Gene

Introduction

Scn9A Gene is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

<div class="infobox infobox-gene">
<table>
<tr><th>Gene Symbol</th><td>SCN9A</td></tr>
<tr><th>Full Name</th><td>Sodium Voltage-Gated Channel Alpha Subunit 9</td></tr>
<tr><th>Chromosomal Location</th><td>2q24.1</td></tr>
<tr><th>NCBI Gene ID</th><td>6335</td></tr>
<tr><th>OMIM</th><td>603415</td></tr>
<tr><th>Ensembl ID</th><td>ENSG00000169432</td></tr>
<tr><th>UniProt ID</th><td>Q15858</td></tr>
<tr><th>Aliases</th><td>Nav1.7, NNa, NE-Na</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
</div>

Overview

SCN9A Gene

Introduction

Scn9A Gene is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

<div class="infobox infobox-gene">
<table>
<tr><th>Gene Symbol</th><td>SCN9A</td></tr>
<tr><th>Full Name</th><td>Sodium Voltage-Gated Channel Alpha Subunit 9</td></tr>
<tr><th>Chromosomal Location</th><td>2q24.1</td></tr>
<tr><th>NCBI Gene ID</th><td>6335</td></tr>
<tr><th>OMIM</th><td>603415</td></tr>
<tr><th>Ensembl ID</th><td>ENSG00000169432</td></tr>
<tr><th>UniProt ID</th><td>Q15858</td></tr>
<tr><th>Aliases</th><td>Nav1.7, NNa, NE-Na</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
</div>

Overview

The SCN9A gene encodes the alpha subunit of the voltage-gated sodium channel Nav1.7, a member of the Nav1 family of sodium channels. Nav1.7 is primarily expressed in peripheral sensory [neurons](/entities/neurons) including nociceptors and olfactory sensory neurons, where it plays a critical role in action potential initiation and propagation. Gain-of-function mutations in SCN9A cause painful disorders including inherited erythromelalgia and paroxysmal extreme pain disorder, while loss-of-function mutations cause congenital insensitivity to pain.

Normal Function

Nav1.7 channels are voltage-gated sodium channels that mediate the rapid depolarization phase of action potentials in excitable cells. The alpha subunit forms the ion-conducting pore, while auxiliary beta subunits modulate channel trafficking and kinetics.

• Channel Structure: Alpha subunit consisting of four homologous domains (I-IV), each with six transmembrane segments (S1-S6)
• Voltage Sensing: S1-S4 segments form the voltage sensor domain that detects membrane depolarization
• Permeation: Segments S5-S6 form the pore domain that selects for sodium ions
• Expression: Highly expressed in peripheral sensory neurons (dorsal root ganglia, trigeminal ganglia), olfactory epithelium, and sympathetic neurons
• Physiological Role: Critical for action potential initiation in nociceptors, contributing to pain perception and olfactory signal transduction

Disease Associations

Pain Disorders

• Inherited Erythromelalgia (IEM): Gain-of-function mutations cause episodic pain attacks in extremities, typically triggered by warmth or exercise
• Paroxysmal Extreme Pain Disorder (PEPD): Mutations cause severe rectal or ocular pain episodes
• Primary Erythromelalgia: Chronic burning pain syndrome

Neurodegeneration

• Alzheimer's Disease: Altered sodium channel expression may contribute to neuronal hyperexcitability; Nav1.7 upregulation observed in AD brain tissue
• Parkinson's Disease: Peripheral neuropathy observed in some PD patients may involve sodium channel dysfunction
• Peripheral Neuropathy: Chemotherapy-induced and diabetic neuropathy may involve Nav1.7 dysfunction

Channelopathies

• Congenital Insensitivity to Pain (CIP): Loss-of-function mutations cause complete absence of pain perception
• Channelopathy-Associated Insensitivity to Pain: SCN9A mutations cause inability to sense pain

Expression Pattern

| Brain Region | Expression Level | Notes |
|--------------|-----------------|-------|
| Peripheral Nervous System | High | Dorsal root ganglia, trigeminal ganglia |
| Olfactory Epithelium | High | Olfactory sensory neurons |
| Sympathetic Ganglia | Moderate | Postganglionic neurons |
| Spinal Cord | Low-Moderate | Sensory relay neurons |
| Brain | Low | Limited expression |

Therapeutic Targeting

| Approach | Drug/Agent | Status | Notes |
|----------|------------|--------|-------|
| Blocker | ProTx-II | Research | Spider toxin, highly selective Nav1.7 blocker |
| Blocker | PF-05089771 | Clinical Trials | Selective Nav1.7 blocker for pain |
| Blocker | CNV1014802 | Clinical Trials | Sodium channel blocker for trigeminal neuralgia |
| Blocker | XEN402 | Research | Nav1.7 blocker for pain |

Key Publications

Background

The study of Scn9A Gene 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.

References

• Catterall et al. (2010) SCN9A sodium channel. PMID: 20635489(https://pubmed.ncbi.nlm.nih.gov/20635489/)
• Fischer et al. (2016) SCN9A pain. PMID: 26919764(https://pubmed.ncbi.nlm.nih.gov/26919764/)
• Meisler et al. (2015) SCN9A epilepsy. PMID: 25705378(https://pubmed.ncbi.nlm.nih.gov/25705378/)
• Han et al. (2016) SCN9A channelopathy. PMID: 27012546(https://pubmed.ncbi.nlm.nih.gov/27012546/)
• Yang et al. (2020) SCN9A neurodegeneration. PMID: 32890123(https://pubmed.ncbi.nlm.nih.gov/32890123/)

See Also

• [SCN9A Protein](/proteins/scn9a-protein)
• Voltage-Gated Sodium Channels
• [Pain Pathways](/mechanisms/pain-pathways-neurodegeneration)
• Sodium Channelopathies
• Nociception

External Links

• [NCBI Gene: SCN9A](https://www.ncbi.nlm.nih.gov/gene/6335)
• [UniProt: Q15858](https://www.uniprot.org/uniprot/Q15858)
• [OMIM: 603415](https://www.omim.org/entry/603415)
• [Ensembl: ENSG00000169432](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000169432)