SCN3A
protein-codingsodium 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
Inheritance
ClinVar variants
Top phenotype
gnomAD constraint
Max pathogenic AF
Genomic locus
External References & Databases
Transcript & Mutation Effects
hg38 • Region Span ~116.5 kbGenCC Phenotypes & Disease Associations
Curated gene-disease validity assertions and inheritance patterns
Inheritance Pattern: AD
Disease ID:MONDO:0033371
Submitter: Labcorp Genetics (formerly Invitae)
Inheritance Pattern: AD
Disease ID:MONDO:0054776
Submitter: Labcorp Genetics (formerly Invitae)
Inheritance Pattern: AD
Disease ID:MONDO:0018614
Submitter: Orphanet
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.
Inheritance Pattern: AD
Disease ID:MONDO:0100062
Submitter: Illumina
Inheritance Pattern: AD
Disease ID:MONDO:0054776
Submitter: G2P
Inheritance Pattern: AD
Disease ID:MONDO:0100062
Submitter: PanelApp Australia
Clinical Genomic Database (CGD)
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
ClinVar Associated Diseases & Phenotypes
Reported disease conditions connected to SCN3A variants in ClinVar
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.
| Effect | PathogenicP | Likely pathogenicLP | VUS | Likely benignLB | BenignB | Sum |
|---|---|---|---|---|---|---|
| synonymous | 13 | 489 | 13 | 515 | ||
| missense | 3 | 30 | 1123 | 97 | 4 | 1257 |
| nonsense | 1 | 2 | 29 | 32 | ||
| start loss | 0 | |||||
| frameshift | 1 | 6 | 34 | 41 | ||
| splice donor/acceptor (+/-2bp) | 5 | 11 | 16 | |||
| Total | 5 | 43 | 1210 | 586 | 17 | 1861 |
Highest pathogenic variant AF is 0.000021889802
Transcript Catalog
Annotated transcript isoforms across RefSeq and Ensembl databases
| Transcript ID | Source | Protein ID | Coding Exons | MANE Status |
|---|---|---|---|---|
| RefSeq | NP_008853.3 | 26 | MANE Select | |
| Ensembl | ENSP00000283254.7 | 26 | MANE Select | |
| RefSeq | NP_001075145.1 | 26 | Standard | |
| RefSeq | NP_001075146.1 | 26 | Standard |
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:
- 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-Score | Observed | Expected | Observed/Expected | Mutation Rate | Total Possible | |
|---|---|---|---|---|---|---|
| Missense | 4.62 | 629 | 1.05e+3 | 0.599 | 0.0000555 | 13365 |
| Missense (PolyPhen) | 299 | 563.36 | 0.53074 | 7247 | ||
| Synonymous | -1.24 | 401 | 371 | 1.08 | 0.0000204 | 3695 |
| Loss of Function | 7.63 | 8 | 83.1 | 0.0963 | 0.00000476 | 1032 |
Population LoF Frequency
| Population | CAF | p-value | Status |
|---|---|---|---|
| African | 0.00025 | 0.00018 | rare |
| Latino/Admixed American | 0.00023 | 0.00020 | rare |
| Ashkenazi Jewish | 0.000099 | 0.000099 | rare |
| East Asian | 0 | 0.0 | absent |
| Finnish | 0.000093 | 0.000092 | rare |
| European (Non-Finnish) | 0.000053 | 0.000053 | rare |
| South Asian | 0 | 0.0 | absent |
| Other | 0.00016 | 0.00016 | rare |
dbNSFP Gene Annotations
Source:
- 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
| All | Recessive | Dominant | |
|---|---|---|---|
| Mendelian | Medium | Medium | Medium |
| Primary Immunodeficiency | Medium | Medium | Medium |
| Cancer | Medium | Medium | Medium |