SCN3A

protein-coding

sodium voltage-gated channel alpha subunit 3, the group of Sodium voltage-gated channel alpha subunits

Gene summary

Voltage-gated sodium channels are transmembrane glycoprotein complexes composed of a large alpha subunit with 24 transmembrane domains and one or more regulatory beta subunits. They are responsible for the generation and propagation of action potentials in neurons and muscle. This gene encodes one member of the sodium channel alpha subunit gene family, and is found in a cluster of five alpha subunit genes on chromosome 2. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jul 2008]

MANE transcript

NM_006922.4

Inheritance

AD

ClinVar variants

P:48U:1210B:603

Top phenotype

Epilepsy, familial focal, with variable foci 4; Developmental and epileptic encephalopathy 62

gnomAD constraint

pLI —, LoF o/e 0.1

Max pathogenic AF

—

Genomic locus

chr2:165,087,526-165,204,050

External References & Databases

Transcript & Mutation Effects

hg38 • Region Span ~116.5 kb
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GenCC Phenotypes & Disease Associations

Curated gene-disease validity assertions and inheritance patterns

developmental and epileptic encephalopathy, 62STRONG

Inheritance Pattern: AD

Disease ID:MONDO:0033371

Submitter: Labcorp Genetics (formerly Invitae)

epilepsy, familial focal, with variable foci 4STRONG

Inheritance Pattern: AD

Disease ID:MONDO:0054776

Submitter: Labcorp Genetics (formerly Invitae)

undetermined early-onset epileptic encephalopathySUPPORTIVE

Inheritance Pattern: AD

Disease ID:MONDO:0018614

Submitter: Orphanet

genetic developmental and epileptic encephalopathyDEFINITIVE

Inheritance Pattern: AD

Disease ID:MONDO:0100062

Submitter: ClinGen

SCN3A was first reported in relation to autosomal dominant developmental and epileptic encephalopathy in 2017 (Lamar et al., PMID: 28235671). Per criteria outlined by the ClinGen Lumping and Splitting Working Group, we found no difference in molecular mechanism (gain-of-function) AND/OR inheritance pattern (autosomal dominant) AND/OR phenotypic variability (with or without malformations of cortical development) but also there is a report of loss-of-function associated variant as well. Therefore, the following disease entities have been lumped into one disease entity, developmental and epileptic encephalopathy (OMIM: 617938). 16 variants (variant types of missense, in-frame indel, and frameshift) that have been reported in 29 probands in 7 publications (PMIDs: 28235671, 27848944, 29466837, 29740860, 31618753, 31677917, 32515017) are included in this curation. More evidence is available in the literature, but the maximum score for genetic evidence (12 pts.) has been reached. The mechanism of pathogenicity is reported to be gain-of-function. This gene-disease association is also supported by Voltage-Clamp Electrophysiology study (PMIDs: 32515017, 29466837). Authors generated disease-associated Nav1.3 variants and expressed these variants in a heterologous mammalian cell line(HEK-293T) for characterization via whole-cell voltage clamp recording. As a result, prominent gain of channel function with an increase in the slowly-inactivating current component and/or a left/hyperpolarizing shift in the voltage dependence of channel activation was shown in the cell expressed variant alleles. In summary, SCN3A is definitively associated with autosomal dominant developmental and epileptic encephalopathy. This has been repeatedly demonstrated in both the research and clinical diagnostic settings, and has been upheld over time.

genetic developmental and epileptic encephalopathyDEFINITIVE

Inheritance Pattern: AD

Disease ID:MONDO:0100062

Submitter: Illumina

epilepsy, familial focal, with variable foci 4STRONG

Inheritance Pattern: AD

Disease ID:MONDO:0054776

Submitter: G2P

genetic developmental and epileptic encephalopathySTRONG

Inheritance Pattern: AD

Disease ID:MONDO:0100062

Submitter: PanelApp Australia

Clinical Genomic Database (CGD)

Epilepsy, familial focal, with variable foci 4; Developmental and epileptic encephalopathy 62AD

Manifestation: Neurologic

Intervention: General

Rationale: Genetic knowledge may be beneficial related to issues such as selection of optimal supportive care, informed medical decision-making, prognostic considerations, and avoidance of unnecessary testing

Comments: As with other conditions involving seizures, optimal seizure control is beneficial, and awareness of genetic causes may help with medication selection

Refs: 24157691; 29466837Source: CGD (NHGRI)

ClinVar Associated Diseases & Phenotypes

Reported disease conditions connected to SCN3A variants in ClinVar

26 Conditions Cataloged
not providedTotal: 2009
Inborn genetic diseasesTotal: 184
not specifiedTotal: 101
Developmental and epileptic encephalopathy, 62Total: 98
SCN3A-related disorderTotal: 73
Epilepsy, familial focal, with variable foci 4Total: 72
Developmental and epileptic encephalopathyTotal: 5
SeizureTotal: 5

ClinVar Variants & Pathogenicity by Type

Statistics based on transcript NM_006922.4. Only rare variants are included.

We include only reliable ClinVar variants with their consequences to MANE Select, MANE Plus Clinical transcripts, or transcripts with TSL equal to 1. Click a count to filter the variants table below.

Slight differences between displayed counts and ClinVar may occur due to a different transcript/consequence chosen by our variant effect predictor, or because we classify Benign/Likely benign as Likely benign and Pathogenic/Likely pathogenic as Likely pathogenic.

EffectPLPVUSLBBSum
synonymous
13
clinvar
489
clinvar
13
clinvar
515
missense
3
clinvar
30
clinvar
1123
clinvar
97
clinvar
4
clinvar
1257
nonsense
1
clinvar
2
clinvar
29
clinvar
32
start loss
0
frameshift
1
clinvar
6
clinvar
34
clinvar
41
splice donor/acceptor (+/-2bp)
5
clinvar
11
clinvar
16
Total5431210586171861

Highest pathogenic variant AF is 0.000021889802

Loading ClinVar variants...

Transcript Catalog

Annotated transcript isoforms across RefSeq and Ensembl databases

Showing 4 of 29 transcripts
Transcript IDSourceProtein IDCoding ExonsMANE Status
NM_006922.4RefSeqNP_008853.326MANE Select
ENST00000283254.12EnsemblENSP00000283254.726MANE Select
NM_001081676.2RefSeqNP_001075145.126Standard
NM_001081677.2RefSeqNP_001075146.126Standard

Gene Ontology (GO) Annotations & Pathways

Biological processes, molecular functions, cellular components and pathways

Pathways ConsensusPathDB

  • Taste transduction - Homo sapiens (human)
  • Developmental Biology
  • Phase 0 - rapid depolarisation
  • Cardiac conduction
  • Muscle contraction

Biological Process

  • sodium ion transport
  • neuronal action potential
  • regulation of ion transmembrane transport
  • sodium ion transmembrane transport
  • membrane depolarization during action potential

Molecular Function

  • voltage-gated ion channel activity
  • voltage-gated sodium channel activity

Cellular Component

  • voltage-gated sodium channel complex
  • cytoplasm
  • plasma membrane
  • axon

gnomAD Constraint

Source: gnomAD

Gene type
protein_coding
Transcript type
protein_coding
Transcript
ENST00000283254
Coding exons
26
Length
116546
Individuals with no LoFs
125728
Homozygous LoFs
0
Heterozygous LoFs
20
Defined
125748
p
0.0000795
Z-ScoreObservedExpectedObserved/ExpectedMutation RateTotal Possible
Missense4.626291.05e+30.5990.000055513365
Missense (PolyPhen)299563.360.530747247
Synonymous-1.244013711.080.00002043695
Loss of Function7.63883.10.09630.000004761032

Population LoF Frequency

PopulationCAFp-valueStatus
African0.000250.00018rare
Latino/Admixed American0.000230.00020rare
Ashkenazi Jewish0.0000990.000099rare
East Asian00.0absent
Finnish0.0000930.000092rare
European (Non-Finnish)0.0000530.000053rare
South Asian00.0absent
Other0.000160.00016rare

dbNSFP Gene Annotations

Source: dbNSFP

Function
FUNCTION: Mediates the voltage-dependent sodium ion permeability of excitable membranes. Assuming opened or closed conformations in response to the voltage difference across the membrane, forms a sodium-selective channel through which Na(+) ions may pass in accordance with their electrochemical gradient (PubMed:24157691, PubMed:28235671, PubMed:29466837). May contribute to the regulation of serotonin/5-hydroxytryptamine release by enterochromaffin cells (By similarity). In pancreatic endocrine cells, required for both glucagon and glucose-induced insulin secretion (By similarity). {ECO:0000250|UniProtKB:A2ASI5, ECO:0000269|PubMed:24157691, ECO:0000269|PubMed:28235671, ECO:0000269|PubMed:29466837}.;
Disease
DISEASE: Epilepsy, familial focal, with variable foci 4 (FFEVF4) [MIM:617935]: An autosomal dominant form of epilepsy characterized by focal seizures arising from different cortical regions, including the temporal, frontal, parietal, and occipital lobes. Seizure types commonly include temporal lobe epilepsy, frontal lobe epilepsy, and nocturnal frontal lobe epilepsy. Some patients may have intellectual disability or autism spectrum disorders. Seizure onset usually occurs in the first or second decades, although later onset has been reported, and there is phenotypic variability within families. A subset of patients have structural brain abnormalities. Penetrance of the disorder is incomplete. FFEVF4 is characterized by onset of focal seizures in the first years of life. {ECO:0000269|PubMed:24157691, ECO:0000269|PubMed:28235671}. Note=The disease is caused by mutations affecting the gene represented in this entry.; DISEASE: Epileptic encephalopathy, early infantile, 62 (EIEE62) [MIM:617938]: A form of epileptic encephalopathy, a heterogeneous group of severe childhood onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. EIEE62 is characterized by onset of seizures in the first year of life. {ECO:0000269|PubMed:29466837}. Note=The disease is caused by mutations affecting the gene represented in this entry.;

Recessive Scores

pRec
0.106

Intolerance Scores

LoFtool
0.00586
RVIS EVS
-2.48
RVIS percentile EVS
0.97

Essentials

Essential (CRISPR)
N
Essential (CRISPR2)
N
Essential (gene trap)
N
Indispensability pred.
E
Indispensability score
0.881

Gene Damage Prediction

AllRecessiveDominant
MendelianMediumMediumMedium
Primary ImmunodeficiencyMediumMediumMedium
CancerMediumMediumMedium
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