17-63968041-C-T

Variant names:

• chr17-63968041-C-T
• rs147936148
• NM_000334.4:c.1018G>A

Variant summary

Our verdict is Benign. The variant received -8 ACMG points: 1P and 9B. PP2 BP4_Strong BP6 BS1

The NM_000334.4(SCN4A):​c.1018G>A​(p.Ala340Thr) variant causes a missense change. The variant allele was found at a frequency of 0.000104 in 1,613,834 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A340S) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.00014 (0 hom., cov: 32)
  • Exomes 𝑓: 0.00010 (0 hom.)
• Consequence: SCN4A NM_000334.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:5 B:5
• Conservation: PhyloP100: 3.60
• Publications: 5 publications found

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]

SCN4A Gene-Disease associations (from GenCC):

• hyperkalemic periodic paralysis

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), G2P, Genomics England PanelApp, Orphanet
• paramyotonia congenita of Von Eulenburg

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, G2P, Labcorp Genetics (formerly Invitae), Genomics England PanelApp, Laboratory for Molecular Medicine
• SCN4A-related myopathy, autosomal recessive

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Illumina, ClinGen, PanelApp Australia
• hypokalemic periodic paralysis, type 2

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp
• potassium-aggravated myotonia

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
• congenital myasthenic syndrome 16

  Inheritance: AR Classification: STRONG, LIMITED Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae), Ambry Genetics
• congenital myopathy

  Inheritance: AR Classification: STRONG Submitted by: Genomics England PanelApp
• congenital myopathy 22A, classic

  Inheritance: AR Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
• acetazolamide-responsive myotonia

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• hypokalemic periodic paralysis

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• myotonia fluctuans

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• myotonia permanens

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• postsynaptic congenital myasthenic syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Benign. The variant received -8 ACMG points.

• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 97 curated pathogenic missense variants (we use a threshold of 10). The gene has 19 curated benign missense variants. Gene score misZ: 1.5606 (below the threshold of 3.09). Trascript score misZ: 2.2224 (below the threshold of 3.09). GenCC associations: The gene is linked to SCN4A-related myopathy, autosomal recessive, hyperkalemic periodic paralysis, paramyotonia congenita of Von Eulenburg, congenital myasthenic syndrome 16, acetazolamide-responsive myotonia, myotonia permanens, hypokalemic periodic paralysis, type 2, potassium-aggravated myotonia, congenital myopathy 22A, classic, congenital myopathy, myotonia fluctuans, postsynaptic congenital myasthenic syndrome, hypokalemic periodic paralysis.
• BP4: Computational evidence support a benign effect (MetaRNN=0.018307596).
• BP6: Variant 17-63968041-C-T is Benign according to our data. Variant chr17-63968041-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 429845.
• BS1: Variant frequency is greater than expected in population eas. GnomAd4 allele frequency = 0.000138 (21/152198) while in subpopulation EAS AF = 0.00347 (18/5182). AF 95% confidence interval is 0.00224. There are 0 homozygotes in GnomAd4. There are 11 alleles in the male GnomAd4 subpopulation. Median coverage is 32. This position passed quality control check.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000334.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SCN4A	NM_000334.4	MANE Select	c.1018G>A	p.Ala340Thr	missense	Exon 6 of 24	NP_000325.4	P35499

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SCN4A	ENST00000435607.3	TSL:1 MANE Select	c.1018G>A	p.Ala340Thr	missense	Exon 6 of 24	ENSP00000396320.1	P35499

Frequencies

GnomAD3 genomes AF: 0.000138 AC: 21 AN: 152086 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00347

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000294

Gnomad OTH AF: 0.000480

GnomAD2 exomes AF: 0.000193 AC: 48 AN: 248490 AF XY: 0.000163

Gnomad AFR exome AF: 0.0000646

Gnomad AMR exome AF: 0.0000290

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00217

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000623

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.000101 AC: 147 AN: 1461636 Hom.: 0 Cov.: 32 AF XY: 0.000113 AC XY: 82 AN XY: 727094

African (AFR) AF: 0.0000299 AC: 1 AN: 33480

American (AMR) AF: 0.0000224 AC: 1 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26134

East Asian (EAS) AF: 0.00209 AC: 83 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53386

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.0000522 AC: 58 AN: 1111816

Other (OTH) AF: 0.0000663 AC: 4 AN: 60372

GnomAD4 genome AF: 0.000138 AC: 21 AN: 152198 Hom.: 0 Cov.: 32 AF XY: 0.000148 AC XY: 11 AN XY: 74414

African (AFR) AF: 0.00 AC: 0 AN: 41540

American (AMR) AF: 0.00 AC: 0 AN: 15282

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3460

East Asian (EAS) AF: 0.00347 AC: 18 AN: 5182

South Asian (SAS) AF: 0.00 AC: 0 AN: 4822

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10574

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 294

European-Non Finnish (NFE) AF: 0.0000294 AC: 2 AN: 68030

Other (OTH) AF: 0.000475 AC: 1 AN: 2104

Alfa AF: 0.0000866 Hom.: 0

Bravo AF: 0.000151

ExAC AF: 0.000165 AC: 20

Asia WGS AF: 0.000866 AC: 3 AN: 3478

EpiCase AF: 0.000164

EpiControl AF: 0.000178

ClinVar

ClinVar submissions

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
-	-	2	Hyperkalemic periodic paralysis (2)
-	2	-	not provided (2)
-	1	-	Congenital myasthenic syndrome 16 (1)
-	-	1	Hypokalemic periodic paralysis, type 2 (1)
-	1	-	Microcephaly (1)
-	-	1	Paramyotonia congenita of Von Eulenburg (1)
-	1	-	Paramyotonia congenita of Von Eulenburg;C0238357:Hyperkalemic periodic paralysis;C2750061:Hypokalemic periodic paralysis, type 2;C2931826:Potassium-aggravated myotonia;C3280112:Congenital myasthenic syndrome 16;C3714580:Hypokalemic periodic paralysis, type 1 (1)
-	-	1	Potassium-aggravated myotonia (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.086
BayesDel_addAF	Benign	-0.27	T
BayesDel_noAF	Benign	-0.16
CADD	Benign	20
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.67	D
Eigen	Benign	-0.066
Eigen_PC	Benign	-0.00056
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.90	D
M_CAP	Uncertain	0.14	D
MetaRNN	Benign	0.018	T
MetaSVM	Uncertain	0.73	D
MutationAssessor	Benign	1.5	L
PhyloP100		3.6
PrimateAI	Benign	0.47	T
PROVEAN	Benign	-1.1	N
REVEL	Uncertain	0.34
Sift	Benign	0.33	T
Sift4G	Benign	0.33	T
Polyphen		0.30	B
Vest4		0.17
MVP		0.81
MPC		0.37
ClinPred		0.030	T
GERP RS		4.1
Varity_R		0.13
gMVP		0.70
Mutation Taster		=51/49	polymorphism

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

Other links and lift over

dbSNP: rs147936148; hg19: chr17-62045401;