NM_000334.4:c.606G>T

Variant names:

• chr17-63971727-C-A
• rs769107760
• NM_000334.4:c.606G>T

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 0P and 2B. BP4_Moderate

The NM_000334.4(SCN4A):​c.606G>T​(p.Met202Ile) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000415 in 1,444,960 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000042 (0 hom.)
• Consequence: SCN4A NM_000334.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.284

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_benign. Variant got -2 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.15395641).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SCN4A	NM_000334.4	c.606G>T	p.Met202Ile	missense_variant	Exon 4 of 24	ENST00000435607.3	NP_000325.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SCN4A	ENST00000435607.3	c.606G>T	p.Met202Ile	missense_variant	Exon 4 of 24	1	NM_000334.4	ENSP00000396320.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000415 AC: 6 AN: 1444960 Hom.: 0 Cov.: 33 AF XY: 0.00000558 AC XY: 4 AN XY: 717190

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: 0.00000543

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ExAC AF: 0.00000828 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Hyperkalemic periodic paralysis Uncertain:1

Feb 21, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces methionine with isoleucine at codon 202 of the SCN4A protein (p.Met202Ile). The methionine residue is moderately conserved and there is a small physicochemical difference between methionine and isoleucine. This variant is present in population databases (rs769107760, ExAC 0.005%) but has not been reported in the literature in individuals with an SCN4A-related disease. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated, but these predictions have not been confirmed by published functional studies. In summary, this variant is a rare missense change that is not predicted to affect protein function. There is no indication that it causes disease, but the available evidence is currently insufficient to prove that conclusively. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.26
BayesDel_addAF	Uncertain	0.044	T
BayesDel_noAF	Benign	-0.18
CADD	Benign	13
DANN	Benign	0.97
DEOGEN2	Uncertain	0.54	D
Eigen	Benign	-1.1
Eigen_PC	Benign	-0.97
FATHMM_MKL	Benign	0.20	N
LIST_S2	Benign	0.53	T
M_CAP	Benign	0.045	D
MetaRNN	Benign	0.15	T
MetaSVM	Uncertain	-0.13	T
MutationAssessor	Benign	-0.15	N
PrimateAI	Benign	0.32	T
PROVEAN	Benign	-0.56	N
REVEL	Uncertain	0.44
Sift	Benign	0.064	T
Sift4G	Benign	0.66	T
Polyphen		0.0010	B
Vest4		0.48
MutPred		0.54		Loss of phosphorylation at T207 (P = 0.2034);
MVP		0.50
MPC		0.28
ClinPred		0.063	T
GERP RS		0.65
Varity_R		0.084
gMVP		0.55

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: rs769107760; hg19: chr17-62049087;