NM_000334.4:c.674G>A

Variant names:

Variant summary

Our verdict is Likely pathogenic. The variant received 7 ACMG points: 7P and 0B. PM1PP2PP3_Strong

The NM_000334.4(SCN4A):c.674G>A(p.Arg225Gln) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000268 in 1,564,876 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 (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R225W) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000020 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000028 ( 0 hom. )

Consequence

SCN4A
NM_000334.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: 7.91

Publications

1 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 7 ACMG points.

PM1

In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 5 uncertain 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, 0.991

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000334.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SCN4A	NM_000334.4	MANE Select	c.674G>A	p.Arg225Gln	missense	Exon 5 of 24	NP_000325.4

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SCN4A	ENST00000435607.3	TSL:1 MANE Select	c.674G>A	p.Arg225Gln	missense	Exon 5 of 24	ENSP00000396320.1

Frequencies

GnomAD3 genomes

AF:

0.0000197

AC:

AN:

151944

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000655

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.000194

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.0000946

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000282

AC:

AN:

177494

AF XY:

0.0000317

show subpopulations

Gnomad AFR exome

AF:

0.000101

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.0000773

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000273

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000276

AC:

AN:

1412814

Hom.:

Cov.:

AF XY:

0.0000244

AC XY:

AN XY:

698116

show subpopulations

African (AFR)

AF:

0.0000617

AC:

AN:

32398

American (AMR)

AF:

0.00

AC:

AN:

37760

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

25320

East Asian (EAS)

AF:

0.0000539

AC:

AN:

37082

South Asian (SAS)

AF:

0.00

AC:

AN:

80120

European-Finnish (FIN)

AF:

0.00

AC:

AN:

50066

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5700

European-Non Finnish (NFE)

AF:

0.0000304

AC:

AN:

1085854

Other (OTH)

AF:

0.0000342

AC:

AN:

58514

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.426

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:

0.0000197

AC:

AN:

152062

Hom.:

Cov.:

AF XY:

0.0000404

AC XY:

AN XY:

74312

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41470

American (AMR)

AF:

0.0000654

AC:

AN:

15292

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.000194

AC:

AN:

5148

South Asian (SAS)

AF:

0.00

AC:

AN:

4816

European-Finnish (FIN)

AF:

0.0000946

AC:

AN:

10572

Middle Eastern (MID)

AF:

0.00

AC:

AN:

292

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

67984

Other (OTH)

AF:

0.00

AC:

AN:

2106

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.542

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.00000378

ExAC

AF:

0.0000170

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Hyperkalemic periodic paralysis

Uncertain:1

Nov 22, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces arginine, which is basic and polar, with glutamine, which is neutral and polar, at codon 225 of the SCN4A protein (p.Arg225Gln). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This missense change has been observed in individual(s) with clinical features of autosomal recessive congenital myopathy or myasthenic syndrome (PMID: 36099689). ClinVar contains an entry for this variant (Variation ID: 477431). 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 SCN4A protein function with a positive predictive value of 80%. This variant disrupts the p.Arg225 amino acid residue in SCN4A. Other variant(s) that disrupt this residue have been observed in individuals with SCN4A-related conditions (PMID: 26700687, 36099689), which suggests that this may be a clinically significant amino acid residue. 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 v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.99

BayesDel_addAF

Pathogenic

0.56

BayesDel_noAF

Pathogenic

0.57

CADD

Pathogenic

(source)

DANN

Pathogenic

1.0

DEOGEN2

Pathogenic

0.99

Eigen

Pathogenic

0.96

Eigen_PC

Pathogenic

0.82

FATHMM_MKL

Pathogenic

0.98

LIST_S2

Pathogenic

1.0

M_CAP

Pathogenic

0.84

MetaRNN

Pathogenic

0.99

MetaSVM

Pathogenic

0.94

MutationAssessor

Pathogenic

4.3

PhyloP100

7.9

PrimateAI

Pathogenic

0.90

PROVEAN

Uncertain

-3.3

REVEL

Pathogenic

0.97

Sift

Pathogenic

0.0

Sift4G

Uncertain

0.0070

Polyphen

1.0

Vest4

0.96

MutPred

0.96

Loss of MoRF binding (P = 0.0202)

MVP

0.97

MPC

0.98

ClinPred

0.97

GERP RS

4.2

Varity_R

0.87

gMVP

0.98

Mutation Taster

=15/85

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

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over