rs777298727

Variant names:

• chr17-63944714-T-C
• rs777298727
• NM_000334.4:c.3871A>G

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM1 PP3

The NM_000334.4(SCN4A):​c.3871A>G​(p.Ile1291Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000685 in 1,460,074 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: not found (cov: 32)
  • Exomes 𝑓: 0.0000068 (0 hom.)
• Consequence: SCN4A NM_000334.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• 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 Uncertain_significance. Variant got 3 ACMG points.

• PM1: In a helix (size 20) in uniprot entity SCN4A_HUMAN there are 6 pathogenic changes around while only 0 benign (100%) in NM_000334.4
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.794

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SCN4A	NM_000334.4	c.3871A>G	p.Ile1291Val	missense_variant	Exon 21 of 24	ENST00000435607.3	NP_000325.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SCN4A	ENST00000435607.3	c.3871A>G	p.Ile1291Val	missense_variant	Exon 21 of 24	1	NM_000334.4	ENSP00000396320.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.0000365 AC: 9 AN: 246900 Hom.: 0 AF XY: 0.0000299 AC XY: 4 AN XY: 133830

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000264

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

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: 0.00000685 AC: 10 AN: 1460074 Hom.: 0 Cov.: 32 AF XY: 0.00000689 AC XY: 5 AN XY: 726118

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.000225

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.0000302

ExAC AF: 0.0000247 AC: 3

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hyperkalemic periodic paralysis Uncertain:1

Oct 18, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces isoleucine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 1291 of the SCN4A protein (p.Ile1291Val). This variant is present in population databases (rs777298727, gnomAD 0.03%). This missense change has been observed in individual(s) with clinical features of congenital myopathy (internal data). ClinVar contains an entry for this variant (Variation ID: 586514). 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 not expected to disrupt SCN4A protein function with a negative 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. -

not provided Uncertain:1

Oct 23, 2023

Athena Diagnostics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Available data are insufficient to determine the clinical significance of the variant at this time. The frequency of this variant in the general population is higher than would generally be expected for pathogenic variants in this gene. (http://gnomad.broadinstitute.org) The variant is located in a region that is considered important for protein function and/or structure. Computational tools predict that this variant is damaging. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.35
BayesDel_addAF	Benign	-0.018	T
BayesDel_noAF	Uncertain	0.030
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.71	D
Eigen	Uncertain	0.36
Eigen_PC	Uncertain	0.31
FATHMM_MKL	Uncertain	0.84	D
LIST_S2	Benign	0.83	T
M_CAP	Uncertain	0.24	D
MetaRNN	Pathogenic	0.79	D
MetaSVM	Pathogenic	0.95	D
MutationAssessor	Benign	0.69	N
PrimateAI	Pathogenic	0.81	D
PROVEAN	Benign	-0.84	N
REVEL	Uncertain	0.60
Sift	Uncertain	0.026	D
Sift4G	Benign	0.12	T
Polyphen		1.0	D
Vest4		0.75
MutPred		0.71		Gain of helix (P = 0.2059);
MVP		0.89
MPC		0.83
ClinPred		0.39	T
GERP RS		2.5
Varity_R		0.62
gMVP		0.38

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: rs777298727; hg19: chr17-62022074;