NM_000334.4:c.1926G>T

Variant names:

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 7P and 1B. PM1PP2PP3_StrongBS1_Supporting

The NM_000334.4(SCN4A):c.1926G>T(p.Trp642Cys) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000397 in 1,613,860 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 13/22 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

Frequency

Genomes: 𝑓 0.00026 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000016 ( 0 hom. )

Consequence

SCN4A
NM_000334.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:4

Conservation

PhyloP100: 7.87

Publications

0 publications found

Variant links:

Genes affected

SCN4A (HGNC:10591): (sodium voltage-gated channel alpha subunit 4) 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. It is expressed in skeletal muscle, and mutations in this gene have been linked to several myotonia and periodic paralysis disorders. [provided by RefSeq, Jul 2008]

SCN4A Gene-Disease associations (from GenCC):

hyperkalemic periodic paralysis
Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae), G2P, Orphanet
paramyotonia congenita of Von Eulenburg
Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Laboratory for Molecular Medicine, Genomics England PanelApp, Labcorp Genetics (formerly Invitae), G2P, Orphanet
SCN4A-related myopathy, autosomal recessive
Inheritance: AR Classification: DEFINITIVE Submitted by: Illumina, ClinGen
hypokalemic periodic paralysis, type 2
Inheritance: AD Classification: STRONG Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae)
potassium-aggravated myotonia
Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
congenital myasthenic syndrome 16
Inheritance: AR Classification: STRONG, LIMITED Submitted by: PanelApp Australia, Ambry Genetics, Genomics England PanelApp, Labcorp Genetics (formerly Invitae)
congenital myopathy
Inheritance: AR Classification: STRONG Submitted by: Genomics England PanelApp
congenital myopathy 22A, classic
Inheritance: AR Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
acetazolamide-responsive myotonia
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
hypokalemic periodic paralysis
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
myotonia fluctuans
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
myotonia permanens
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
postsynaptic congenital myasthenic syndrome
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

SCN4A links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

PM1

In a repeat II (size 272) in uniprot entity SCN4A_HUMAN there are 27 pathogenic changes around while only 3 benign (90%) in NM_000334.4

PP2

Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 97 curated pathogenic missense variants (we use a threshold of 10). The gene has 19 curated benign missense variants. Gene score misZ: 1.5606 (below the threshold of 3.09). Trascript score misZ: 2.2224 (below the threshold of 3.09). GenCC associations: The gene is linked to congenital myasthenic syndrome 16, paramyotonia congenita of Von Eulenburg, hyperkalemic periodic paralysis, hypokalemic periodic paralysis, type 2, congenital myopathy, hypokalemic periodic paralysis, SCN4A-related myopathy, autosomal recessive, congenital myopathy 22A, classic, potassium-aggravated myotonia, postsynaptic congenital myasthenic syndrome, myotonia fluctuans, myotonia permanens, acetazolamide-responsive myotonia.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.983

BS1

Variant frequency is greater than expected in population amr. GnomAd4 allele frequency = 0.000263 (40/152192) while in subpopulation AMR AF = 0.00262 (40/15280). AF 95% confidence interval is 0.00198. There are 0 homozygotes in GnomAd4. There are 31 alleles in the male GnomAd4 subpopulation. Median coverage is 32. This position passed quality control check. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SCN4A	NM_000334.4 link	c.1926G>T	p.Trp642Cys	missense_variant	Exon 12 of 24	ENST00000435607.3	NP_000325.4	P35499

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SCN4A	ENST00000435607.3 link	c.1926G>T	p.Trp642Cys	missense_variant	Exon 12 of 24	1	NM_000334.4	ENSP00000396320.1		P35499
SCN4A	ENST00000581514.1 link	n.*15G>T		downstream_gene_variant		3

Frequencies

GnomAD3 genomes

AF:

0.000263

AC:

AN:

152192

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00262

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000602

AC:

AN:

249176

AF XY:

0.0000518

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.000435

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:

1461668

Hom.:

Cov.:

AF XY:

0.0000151

AC XY:

AN XY:

727116

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.000537

AC:

AN:

44720

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.00

AC:

AN:

86252

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53400

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1111842

Other (OTH)

AF:

0.00

AC:

AN:

60370

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.467

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:

0.000263

AC:

AN:

152192

Hom.:

Cov.:

AF XY:

0.000417

AC XY:

AN XY:

74358

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41448

American (AMR)

AF:

0.00262

AC:

AN:

15280

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5198

South Asian (SAS)

AF:

0.00

AC:

AN:

4832

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10626

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68022

Other (OTH)

AF:

0.00

AC:

AN:

2088

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.492

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:

0.0000401

Hom.:

Bravo

AF:

0.000238

ExAC

AF:

0.00000826

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not provided

Uncertain:2

Jun 11, 2024

GeneDx

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge -

Aug 05, 2021

AiLife Diagnostics, AiLife Diagnostics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Paramyotonia congenita of Von Eulenburg;C0238357:Familial hyperkalemic periodic paralysis;C2750061:Hypokalemic periodic paralysis, type 2;C2931826:Potassium-aggravated myotonia;C3280112:Congenital myasthenic syndrome 16;C5830453:Congenital myopathy 22A, classic;C5830501:Congenital myopathy 22B, severe fetal

Uncertain:1

Jun 17, 2024

Fulgent Genetics, Fulgent Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Familial hyperkalemic periodic paralysis

Uncertain:1

Jan 04, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces tryptophan, which is neutral and slightly polar, with cysteine, which is neutral and slightly polar, at codon 642 of the SCN4A protein (p.Trp642Cys). This variant is present in population databases (rs781412058, gnomAD 0.04%). This variant has not been reported in the literature in individuals affected with SCN4A-related conditions. ClinVar contains an entry for this variant (Variation ID: 575671). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt SCN4A 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. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

1.0

BayesDel_addAF

Pathogenic

0.34

BayesDel_noAF

Pathogenic

0.58

CADD

Pathogenic

(source)

DANN

Uncertain

0.99

DEOGEN2

Pathogenic

0.99

Eigen

Pathogenic

1.0

Eigen_PC

Pathogenic

0.91

FATHMM_MKL

Pathogenic

0.98

LIST_S2

Pathogenic

0.99

M_CAP

Pathogenic

0.75

MetaRNN

Pathogenic

0.98

MetaSVM

Pathogenic

0.98

MutationAssessor

Pathogenic

4.3

PhyloP100

7.9

PrimateAI

Pathogenic

0.82

PROVEAN

Pathogenic

-12

REVEL

Pathogenic

0.94

Sift

Pathogenic

0.0

Sift4G

Uncertain

0.0070

Polyphen

1.0

Vest4

0.90

MutPred

0.93

Loss of helix (P = 0.2022);

MVP

0.96

MPC

1.1

ClinPred

0.97

GERP RS

4.7

Varity_R

0.96

gMVP

0.97

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.010

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