NM_000334.4:c.205G>A

Variant names:

• chr17-63972637-C-T
• rs886053249
• NM_000334.4:c.205G>A

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 3P and 0B. PP2 PP3_Moderate

The NM_000334.4(SCN4A):​c.205G>A​(p.Gly69Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000248 in 1,610,650 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: 𝑓 0.000039 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000023 (0 hom.)
• Consequence: SCN4A NM_000334.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:9
• Conservation: PhyloP100: 7.87
• Publications: 1 publications found

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

ACMG classification

Our verdict: Uncertain_significance. The variant received 3 ACMG points.

• 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, 0.907

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SCN4A	NM_000334.4	c.205G>A	p.Gly69Arg	missense_variant	Exon 1 of 24	ENST00000435607.3	NP_000325.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SCN4A	ENST00000435607.3	c.205G>A	p.Gly69Arg	missense_variant	Exon 1 of 24	1	NM_000334.4	ENSP00000396320.1

Frequencies

GnomAD3 genomes AF: 0.0000395 AC: 6 AN: 152060 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000242

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000386

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000441

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.00 AC: 0 AN: 242904 AF XY: 0.00

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: 0.0000233 AC: 34 AN: 1458472 Hom.: 0 Cov.: 32 AF XY: 0.0000193 AC XY: 14 AN XY: 725224

African (AFR) AF: 0.0000299 AC: 1 AN: 33428

American (AMR) AF: 0.00 AC: 0 AN: 44168

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26076

East Asian (EAS) AF: 0.0000506 AC: 2 AN: 39538

South Asian (SAS) AF: 0.00 AC: 0 AN: 85612

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53158

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 0.0000261 AC: 29 AN: 1110458

Other (OTH) AF: 0.0000332 AC: 2 AN: 60268

GnomAD4 genome AF: 0.0000394 AC: 6 AN: 152178 Hom.: 0 Cov.: 32 AF XY: 0.0000269 AC XY: 2 AN XY: 74394

African (AFR) AF: 0.0000241 AC: 1 AN: 41498

American (AMR) AF: 0.00 AC: 0 AN: 15294

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3468

East Asian (EAS) AF: 0.000387 AC: 2 AN: 5170

South Asian (SAS) AF: 0.00 AC: 0 AN: 4822

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10614

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 294

European-Non Finnish (NFE) AF: 0.0000441 AC: 3 AN: 67998

Other (OTH) AF: 0.00 AC: 0 AN: 2108

Alfa AF: 0.0000334 Hom.: 0

Bravo AF: 0.0000264

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:9

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hyperkalemic periodic paralysis Uncertain:2

Dec 15, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glycine, which is neutral and non-polar, with arginine, which is basic and polar, at codon 69 of the SCN4A protein (p.Gly69Arg). This variant is present in population databases (no rsID available, gnomAD 0.004%). 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: 324553). 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) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on SCN4A protein function. 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.

Jan 12, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease.

not specified Uncertain:1

Oct 26, 2023

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: SCN4A c.205G>A (p.Gly69Arg) results in a non-conservative amino acid change in the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 242904 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.205G>A has been reported in the literature in at least one individual affected with Non-dystrophic Myotonia (Ivanova_2018; no PMID). This report does not provide unequivocal conclusions about association of the variant with Acetazolamide-Responsive Myotonia. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Three submitters have cited clinical-significance assessments for this variant to ClinVar after 2014. All submitters classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance.

Hypokalemic periodic paralysis, type 2 Uncertain:1

Jan 12, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease.

Paramyotonia congenita of Von Eulenburg Uncertain:1

Jan 12, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease.

not provided Uncertain:1

Jun 22, 2023

Clinical Genetics Laboratory, Skane University Hospital Lund

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Paramyotonia congenita of Von Eulenburg;C0238357:Hyperkalemic periodic paralysis;C2750061:Hypokalemic periodic paralysis, type 2;C2931826:Potassium-aggravated myotonia;C3280112:Congenital myasthenic syndrome 16;C3714580:Hypokalemic periodic paralysis, type 1 Uncertain:1

Mar 25, 2022

Fulgent Genetics, Fulgent Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Potassium-aggravated myotonia Uncertain:1

Jan 12, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease.

Congenital myasthenic syndrome 16 Uncertain:1

Jan 12, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease.

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.87
BayesDel_addAF	Pathogenic	0.35	D
BayesDel_noAF	Pathogenic	0.26
CADD	Uncertain	26
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.83	D
Eigen	Uncertain	0.45
Eigen_PC	Uncertain	0.38
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.94	D
M_CAP	Pathogenic	0.73	D
MetaRNN	Pathogenic	0.91	D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Uncertain	2.7	M
PhyloP100		7.9
PrimateAI	Uncertain	0.78	T
PROVEAN	Pathogenic	-6.4	D
REVEL	Pathogenic	0.74
Sift	Uncertain	0.010	D
Sift4G	Benign	0.073	T
Vest4		0.72
ClinPred		0.99	D
GERP RS		4.4
PromoterAI		-0.020	Neutral
Varity_R		0.56
gMVP		0.88
Mutation Taster		=63/37	polymorphism

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

Other links and lift over

dbSNP: rs886053249; hg19: chr17-62049997;