rs1555601897

Positions:

• chr17-63948763-A-G

Variant summary

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

The NM_000334.4(SCN4A):​c.2992T>C​(p.Cys998Arg) variant causes a missense, splice region change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 1/1 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: SCN4A NM_000334.4 missense, splice_region
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 6.02

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 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, 0.985

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SCN4A	NM_000334.4	c.2992T>C	p.Cys998Arg	missense_variant, splice_region_variant	16/24	ENST00000435607.3	NP_000325.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SCN4A	ENST00000435607.3	c.2992T>C	p.Cys998Arg	missense_variant, splice_region_variant	16/24	1	NM_000334.4	ENSP00000396320	P1
SCN4A	ENST00000584310.1	n.315T>C		splice_region_variant, non_coding_transcript_exon_variant	2/3	4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Familial hyperkalemic periodic paralysis Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Mar 06, 2017

In summary, this variant is a novel missense change with uncertain impact on protein function. It has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with an SCN4A-related disease. This sequence change replaces cysteine with arginine at codon 998 of the SCN4A protein (p.Cys998Arg). The cysteine residue is highly conserved and there is a large physicochemical difference between cysteine and arginine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.32	D
BayesDel_noAF	Pathogenic	0.23
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.83	D
Eigen	Uncertain	0.44
Eigen_PC	Uncertain	0.38
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.97	D
M_CAP	Pathogenic	0.66	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Uncertain	0.68	D
MutationAssessor	Pathogenic	3.8	H
MutationTaster	Benign	1.0	D;D
PrimateAI	Pathogenic	0.80	T
PROVEAN	Pathogenic	-11	D
REVEL	Pathogenic	0.81
Sift	Pathogenic	0.0	D
Sift4G	Uncertain	0.010	D
Polyphen		0.83	P
Vest4		0.98
MutPred		0.83		Gain of loop (P = 0.0079);
MVP		0.90
MPC		1.2
ClinPred		1.0	D
GERP RS		4.2
Varity_R		0.99
gMVP		0.89

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs1555601897; hg19: chr17-62026123;