rs780809852

Variant names:

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 3P and 4B. PM1PP2BS2

The NM_001165963.4(SCN1A):c.5501C>T(p.Ala1834Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000161 in 1,613,778 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. A1834A) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000016 ( 0 hom. )

Consequence

SCN1A
NM_001165963.4 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1U:8

Conservation

PhyloP100: 8.06

Publications

8 publications found

Variant links:

Genes affected

SCN1A (HGNC:10585): (sodium voltage-gated channel alpha subunit 1) Voltage-dependent sodium channels are heteromeric complexes that regulate sodium exchange between intracellular and extracellular spaces and are essential for the generation and propagation of action potentials in muscle cells and neurons. Each sodium channel is composed of a large pore-forming, glycosylated alpha subunit and two smaller beta subunits. This gene encodes a sodium channel alpha subunit, which has four homologous domains, each of which contains six transmembrane regions. Allelic variants of this gene are associated with generalized epilepsy with febrile seizures and epileptic encephalopathy. Alternative splicing results in multiple transcript variants. The RefSeq Project has decided to create four representative RefSeq records. Three of the transcript variants are supported by experimental evidence and the fourth contains alternate 5' untranslated exons, the exact combination of which have not been experimentally confirmed for the full-length transcript. [provided by RefSeq, Oct 2015]

SCN1A links:

SCN1A-AS1 (HGNC:54069): (SCN1A and SCN9A antisense RNA 1)

SCN1A-AS1 links:

LOC102724058 (HGNC:):

LOC102724058 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -1 ACMG points.

PM1

In a hotspot region, there are 10 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 7 uncertain in NM_001165963.4

PP2

Missense variant in the SCN1A gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 848 curated pathogenic missense variants (we use a threshold of 10). The gene has 89 curated benign missense variants. Gene score misZ: 5.2206 (above the threshold of 3.09). Trascript score misZ: 7.6022 (above the threshold of 3.09). GenCC associations: The gene is linked to familial or sporadic hemiplegic migraine, myoclonic-astatic epilepsy, arthrogryposis, Dravet syndrome, malignant migrating partial seizures of infancy, generalized epilepsy with febrile seizures plus, type 2, migraine, familial hemiplegic, 3, developmental and epileptic encephalopathy, 6A, familial hemiplegic migraine, generalized epilepsy with febrile seizures plus, genetic developmental and epileptic encephalopathy, Lennox-Gastaut syndrome.

BS2

High AC in GnomAdExome4 at 24 AD,Unknown gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SCN1A	NM_001165963.4 link	c.5501C>T	p.Ala1834Val	missense_variant	Exon 29 of 29	ENST00000674923.1	NP_001159435.1	P35498-1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	UniProt
SCN1A	ENST00000674923.1 link	c.5501C>T	p.Ala1834Val	missense_variant	Exon 29 of 29		NM_001165963.4	ENSP00000501589.1	P35498-1
SCN1A	ENST00000303395.9 link	c.5501C>T	p.Ala1834Val	missense_variant	Exon 28 of 28	5		ENSP00000303540.4	P35498-1
SCN1A	ENST00000375405.7 link	c.5468C>T	p.Ala1823Val	missense_variant	Exon 26 of 26	5		ENSP00000364554.3	P35498-2
SCN1A	ENST00000409050.2 link	c.5417C>T	p.Ala1806Val	missense_variant	Exon 28 of 28	5		ENSP00000386312.1	P35498-3

Frequencies

GnomAD3 genomes

AF:

0.0000132

AC:

AN:

152024

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.000414

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.00000797

AC:

AN:

250870

AF XY:

0.0000148

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000164

AC:

AN:

1461754

Hom.:

Cov.:

AF XY:

0.0000165

AC XY:

AN XY:

727190

show subpopulations

African (AFR)

AF:

0.0000299

AC:

AN:

33464

American (AMR)

AF:

0.00

AC:

AN:

44710

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26134

East Asian (EAS)

AF:

0.00

AC:

AN:

39696

South Asian (SAS)

AF:

0.0000580

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53414

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.0000153

AC:

AN:

1111924

Other (OTH)

AF:

0.0000166

AC:

AN:

60386

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.488

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000132

AC:

AN:

152024

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74272

show subpopulations

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

41386

American (AMR)

AF:

0.00

AC:

AN:

15246

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3468

East Asian (EAS)

AF:

0.00

AC:

AN:

5162

South Asian (SAS)

AF:

0.000414

AC:

AN:

4830

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10614

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68002

Other (OTH)

AF:

0.00

AC:

AN:

2088

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0.00000000770867), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.400

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.0000936

Hom.:

ExAC

AF:

0.00000824

AC:

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1Uncertain:8

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Uncertain:3

Nov 19, 2023

Revvity Omics, Revvity

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Dec 01, 2017

GeneDx

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

p.Ala1834Val (GCG>GTG): c.5501 C>T in exon 26 of the SCN1A gene (NM_001165963.1) The Ala1834Val missense change has not been published as a mutation, nor has it been reported as a benign polymorphism to our knowledge. It was not observed in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. This variant is a conservative substitution of one uncharged, non-polar amino acid for another at a position that is conserved in placental mammals but is not conserved in more distantly related species. However, it alters a position between the sixth transmembrane domain and the IQ domain and other missense mutations associated with Dravet syndrome (Phe1831Ser, Ala1832Pro, Leu1835Phe) have been reported in this region of the protein. In silico analysis is inconsistent with regard to the effect this variant may have on the protein structure/function. Therefore, based on the currently available information, it is unclear whether Ala1834Val is a disease-causing mutation or a rare benign variant.The variant is found in INFANT-EPI panel(s). -

Mar 01, 2022

CeGaT Center for Human Genetics Tuebingen

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

SCN1A: PP2, PP3 -

Severe myoclonic epilepsy in infancy

Uncertain:2

Mar 26, 2024

Genomic Medicine Center of Excellence, King Faisal Specialist Hospital and Research Centre

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Aug 07, 2018

Genomic Research Center, Shahid Beheshti University of Medical Sciences

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Severe myoclonic epilepsy in infancy;C1858673:Generalized epilepsy with febrile seizures plus, type 2;C5543353:Developmental and epileptic encephalopathy 6B

Pathogenic:1

Lifecell International Pvt. Ltd

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The missense variant NM_001165963.4 (SCN1A):c.5501C>T (p.Ala1834Val) has not been reported previously as a pathogenic variant nor as a benign variant, to our knowledge. The p.Ala1834Val variant is observed in 2/30,616 (0.0065%) alleles from individuals of gnomAD South Asian background in gnomAD. The p.Ala1834Val variant is novel (not in any individuals) in 1kG. There is a small physicochemical difference between alanine and valine, which is not likely to impact secondary protein structure as these residues share similar properties. The gene SCN1A has a low rate of benign missense variation as indicated by a high missense variants Z-Score of 5.22. Missense Variants Z-Score is produced by the Exome Aggregation Consortium (60,706 adult humans) by computing a signed Z score for the deviation of observed counts from the expected number. Positive Z scores indicate increased constraint (intolerance to variation) and therefore that the gene had fewer missense variants than expected. (DOI: 10.1038/nature19057). The Missense Badness and MPC scores for this variant is 0.35 and 1.56 respectively. Missense Badness Score is the normalized fold difference of missense substitutions between observed and expected variants from ExAC dataset. This score is then combined with orthogonal deleteriousness metrics into one score called MPC (for Missense badness, PolyPhen-2, and Constraint) designed to classify whether a missense variants is deleterious.Variants with MPC ≥ 2 have a rate nearly 6 times higher in cases than in controls. While those with intermediate MPC values (1 ≤ MPC < 2) have a more modest excess in cases. The gene SCN1A contains 537 pathogenic missense variants, indicating that missense variants are a common mechanism of disease in this gene. 4 variants within 6 amino acid positions of the variant p.Ala1834Val have been shown to be pathogenic, while none have been shown to be benign. The p.Ala1834Val missense variant is predicted to be damaging by both SIFT and PolyPhen2. The alanine residue at codon 1834 of SCN1A is conserved in all mammalian species. The nucleotide c.5501 in SCN1A is predicted conserved by GERP++ and PhyloP across 100 vertebrates. For these reasons, this variant has been classified as Likely Pathogenic. -

Developmental and epileptic encephalopathy

Uncertain:1

Oct 31, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces alanine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 1834 of the SCN1A protein (p.Ala1834Val). This variant is present in population databases (rs780809852, gnomAD 0.006%). This missense change has been observed in individual(s) with clinical features of SCN1A-related conditions (PMID: 27457812, 36820031; internal data). ClinVar contains an entry for this variant (Variation ID: 206867). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is expected to disrupt SCN1A protein function with a positive predictive value of 95%. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Generalized epilepsy with febrile seizures plus, type 2

Uncertain:1

Aug 07, 2018

Genomic Research Center, Shahid Beheshti University of Medical Sciences

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Developmental and epileptic encephalopathy 6B

Uncertain:1

Jul 17, 2023

Victorian Clinical Genetics Services, Murdoch Childrens Research Institute

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as VUS-3B. Following criteria are met: 0103 - Loss of function and gain of function are known mechanisms of disease in this gene and are associated with SCN1A-related epilepsy (PMID: 28488083). (I) 0107 - This gene is associated with autosomal dominant disease. However, there is emerging evidence of a recessive mode of inheritance (PMID: 34917021, PMID: 34174751). (I) 0200 - Variant is predicted to result in a missense amino acid change from alanine to valine. (I) 0251 - This variant is heterozygous. (I) 0302 - Variant is present in gnomAD (v2, v3) <0.001 for a dominant condition (4 heterozygotes, 0 homozygotes). (SP) 0501 - Missense variant consistently predicted to be damaging by multiple in silico tools or highly conserved with a major amino acid change. (SP) 0604 - Variant is not located in an established domain, motif, hotspot or informative constraint region. (I) 0705 - No comparable missense variants have previous evidence for pathogenicity. (I) 0808 - Previous reports of pathogenicity for this variant are conflicting. This variant has been reported multiple times as a VUS, and once as likely pathogenic (LOVD, ClinVar), and has been observed in a heterozygous individual with moyamoya disease and a partial trisomy 13 (PMID: 36820031). It has also been observed in a single homozygous family with intellectual disability (PMID: 27457812). (I) 0901 - This variant has strong evidence for segregation with disease. This variant has segregated within a single family with three homozygous individuals with intellectual disability, where heterozygous individuals were not reported as affected (PMID: 27457812). (SP) 1007 - No published functional evidence has been identified for this variant. (I) 1208 - Inheritance information for this variant is not currently available in this individual. (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.24

BayesDel_addAF

Uncertain

0.10

BayesDel_noAF

Uncertain

0.090

CADD

Uncertain

(source)

DANN

Uncertain

1.0

DEOGEN2

Uncertain

0.71

.;.;.;D;.;D;.;.;.

Eigen

Uncertain

0.49

Eigen_PC

Uncertain

0.58

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Uncertain

0.86

D;D;D;D;.;.;.;D;D

M_CAP

Pathogenic

0.40

MetaRNN

Uncertain

0.64

D;D;D;D;D;D;D;D;D

MetaSVM

Uncertain

0.65

MutationAssessor

Uncertain

2.2

.;.;.;M;.;M;.;.;.

PhyloP100

8.1

PrimateAI

Uncertain

0.62

PROVEAN

Uncertain

-3.1

.;.;.;D;.;D;.;D;D

REVEL

Uncertain

0.56

Sift

Uncertain

0.0010

.;.;.;D;.;D;.;D;D

Sift4G

Benign

0.24

.;.;.;T;.;T;.;T;T

Polyphen

0.89

.;.;.;.;P;.;P;P;.

Vest4

0.40, 0.48, 0.47, 0.63

MutPred

0.41

.;.;.;Loss of disorder (P = 0.0662);.;Loss of disorder (P = 0.0662);.;.;.;

MVP

0.91

MPC

1.6

ClinPred

0.96

GERP RS

5.8

Varity_R

0.55

gMVP

0.89

Mutation Taster

=0/100

disease causing

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.0

Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over