rs864622785

Positions:

• chr17-63964600-A-C

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM2 PP3_Strong PP5_Moderate

The NM_000334.4(SCN4A):​c.1320T>G​(p.Asn440Lys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: SCN4A NM_000334.4 missense
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 0.0670

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]

LOC105371858 (HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.99
• PP5: Variant 17-63964600-A-C is Pathogenic according to our data. Variant chr17-63964600-A-C is described in ClinVar as [Pathogenic]. Clinvar id is 221261.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SCN4A	NM_000334.4	c.1320T>G	p.Asn440Lys	missense_variant	9/24	ENST00000435607.3	NP_000325.4
LOC105371858	XR_001752969.2	n.295A>C		non_coding_transcript_exon_variant	4/5
LOC105371858	XR_001752970.2	n.350A>C		non_coding_transcript_exon_variant	4/5
LOC105371858	XR_934910.3	n.170A>C		non_coding_transcript_exon_variant	3/4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SCN4A	ENST00000435607.3	c.1320T>G	p.Asn440Lys	missense_variant	9/24	1	NM_000334.4	ENSP00000396320.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Familial hyperkalemic periodic paralysis Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

May 24, 2018

This sequence change replaces asparagine with lysine at codon 440 of the SCN4A protein (p.Asn440Lys). The asparagine residue is highly conserved and there is a moderate physicochemical difference between asparagine and lysine. This variant is not present in population databases (ExAC no frequency). This variant has been observed to segregate with paramyotonia congenita in several families (PMID: 22106717, 22914841). ClinVar contains an entry for this variant (Variation ID: 221261). Experimental studies have shown that this missense change alters voltage gating in the sodium channel, consistent with gain of function (PMID: 22914841). For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.20	D
BayesDel_noAF	Uncertain	0.050
CADD	Benign	22
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.99	D
Eigen	Uncertain	0.36
Eigen_PC	Benign	0.15
FATHMM_MKL	Uncertain	0.78	D
LIST_S2	Uncertain	0.97	D
M_CAP	Pathogenic	0.91	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.2	H
PrimateAI	Pathogenic	0.86	D
PROVEAN	Pathogenic	-4.9	D
REVEL	Pathogenic	0.82
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.97
MutPred		0.88		Gain of ubiquitination at N440 (P = 0.0289);
MVP		0.92
MPC		0.97
ClinPred		1.0	D
GERP RS		-1.7
Varity_R		0.96
gMVP		0.99

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.36		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.36		Position offset: -1

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs864622785; hg19: chr17-62041960;