chr17-63968322-G-A

Position:

• chr17-63968322-G-A

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_000334.4(SCN4A):​c.737C>T​(p.Ser246Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000206 in 1,455,676 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 13/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: SCN4A NM_000334.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter P:1 U:1 O:2
• Conservation: PhyloP100: 10.0

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 Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.942

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SCN4A	NM_000334.4	c.737C>T	p.Ser246Leu	missense_variant	6/24	ENST00000435607.3	NP_000325.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SCN4A	ENST00000435607.3	c.737C>T	p.Ser246Leu	missense_variant	6/24	1	NM_000334.4	ENSP00000396320	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000206 AC: 3 AN: 1455676 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 723078

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000271

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Pathogenic:1 Uncertain:1 Other:2

Revision: criteria provided, single submitter

Submissions by phenotype

Familial hyperkalemic periodic paralysis Uncertain:1 Other:1

not provided, no classification provided	literature only	GeneReviews	-	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Aug 10, 2023	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. Experimental studies have shown that this missense change does not substantially affect SCN4A function (PMID: 12766226). 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. ClinVar contains an entry for this variant (Variation ID: 21161). This variant has not been reported in the literature in individuals affected with SCN4A-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces serine, which is neutral and polar, with leucine, which is neutral and non-polar, at codon 246 of the SCN4A protein (p.Ser246Leu). -

Congenital myasthenic syndrome 16 Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

OMIM

Jun 10, 2003

- -

Congenital myasthenic syndrome Other:1

not provided, no classification provided

literature only

GeneReviews

-

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.59	D
BayesDel_noAF	Pathogenic	0.60
CADD	Pathogenic	32
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.98	D
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	D
M_CAP	Pathogenic	0.68	D
MetaRNN	Pathogenic	0.94	D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	4.0	H
MutationTaster	Benign	1.0	D;D
PrimateAI	Pathogenic	0.91	D
PROVEAN	Pathogenic	-4.9	D
REVEL	Pathogenic	0.83
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.94
MutPred		0.30		Loss of ubiquitination at K249 (P = 0.0877);
MVP		0.98
MPC		0.84
ClinPred		1.0	D
GERP RS		5.2
Varity_R		0.91
gMVP		0.97

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

LitVar

Other links and lift over

dbSNP: rs80338951; hg19: chr17-62045682; COSMIC: COSV101438416; COSMIC: COSV101438416;