rs80338960

Positions:

• chr17-63943006-T-C

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM1 PM2 PP3_Strong PP5_Very_Strong

The NM_000334.4(SCN4A):​c.4108A>G​(p.Met1370Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,624 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 Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: SCN4A NM_000334.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2 O:1
• Conservation: PhyloP100: 8.02

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]

ACMG classification

Verdict is Pathogenic. Variant got 16 ACMG points.

• PM1: In a repeat IV (size 298) in uniprot entity SCN4A_HUMAN there are 26 pathogenic changes around while only 1 benign (96%) in NM_000334.4
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.989
• PP5: Variant 17-63943006-T-C is Pathogenic according to our data. Variant chr17-63943006-T-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 21157.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr17-63943006-T-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SCN4A	NM_000334.4	c.4108A>G	p.Met1370Val	missense_variant	23/24	ENST00000435607.3	NP_000325.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SCN4A	ENST00000435607.3	c.4108A>G	p.Met1370Val	missense_variant	23/24	1	NM_000334.4	ENSP00000396320.1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251196 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135756

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad SAS 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: 0.00000137 AC: 2 AN: 1461624 Hom.: 0 Cov.: 37 AF XY: 0.00 AC XY: 0 AN XY: 727098

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000504

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 31

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hyperkalemic periodic paralysis Pathogenic:1 Other:1

not provided, no classification provided	literature only	GeneReviews	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jun 17, 2022	For these reasons, this variant has been classified as Pathogenic. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C15"). ClinVar contains an entry for this variant (Variation ID: 21157). This missense change has been observed in individuals with hyperkalemic periodic paralysis, paramyotonia congenita, and/or sodium channel myotonia (PMID: 11757950, 32660787). It has also been observed to segregate with disease in related individuals. This variant is present in population databases (rs80338960, gnomAD 0.006%). This sequence change replaces methionine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 1370 of the SCN4A protein (p.Met1370Val). -

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Athena Diagnostics

May 24, 2019

The best available variant frequency is uninformative because there are too few occurrences in population data. Found in at least one symptomatic patient. Predicted to have a damaging effect on the protein. Moderate co-segregation with disease in affected and unaffected individuals, but from a single family. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.76
BayesDel_addAF	Pathogenic	0.45	D
BayesDel_noAF	Pathogenic	0.58
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.97	D
Eigen	Uncertain	0.68
Eigen_PC	Uncertain	0.59
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Pathogenic	0.82	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	1.2	D
MutationAssessor	Pathogenic	4.7	H
PrimateAI	Uncertain	0.66	T
PROVEAN	Uncertain	-3.9	D
REVEL	Pathogenic	0.95
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0010	D
Polyphen		0.84	P
Vest4		0.93
MutPred		0.91		Gain of catalytic residue at M1370 (P = 0.0544);
MVP		0.94
MPC		0.91
ClinPred		1.0	D
GERP RS		3.9
Varity_R		0.93
gMVP		0.88

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

LitVar

Other links and lift over

dbSNP: rs80338960; hg19: chr17-62020366;