rs199473605

chr3-38560374-C-Gchr3-38560374-C-T

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PM1 PM2 PM5 PP2 PP3_Strong

The NM_001099404.2(SCN5A):c.4018G>C(p.Val1340Leu) variant causes a missense change. The variant allele was found at a frequency of 0.00000274 in 1,461,876 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 (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V1340I) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: SCN5A NM_001099404.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 6.09

Genes affected

SCN5A (HGNC:10593): (sodium voltage-gated channel alpha subunit 5) The protein encoded by this gene is an integral membrane protein and tetrodotoxin-resistant voltage-gated sodium channel subunit. This protein is found primarily in cardiac muscle and is responsible for the initial upstroke of the action potential in an electrocardiogram. Defects in this gene have been associated with long QT syndrome type 3 (LQT3), atrial fibrillation, cardiomyopathy, and Brugada syndrome 1, all autosomal dominant cardiac diseases. Alternative splicing results in several transcript variants encoding different isoforms. [provided by RefSeq, May 2022]

ACMG classification

Verdict is Pathogenic. Variant got 11 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 10 uncertain in NM_001099404.2
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr3-38560374-C-T is described in Lovd as [Pathogenic].
• PP2: Missense variant where missense usually causes diseases, SCN5A
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.951

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SCN5A	NM_001099404.2	c.4018G>C	p.Val1340Leu	missense_variant	23/28	ENST00000413689.6
SCN5A	NM_000335.5	c.4015G>C	p.Val1339Leu	missense_variant	23/28	ENST00000423572.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SCN5A	ENST00000413689.6	c.4018G>C	p.Val1340Leu	missense_variant	23/28	5	NM_001099404.2	P4
SCN5A	ENST00000423572.7	c.4015G>C	p.Val1339Leu	missense_variant	23/28	1	NM_000335.5	A1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1461876 Hom.: 0 Cov.: 32 AF XY: 0.00000550 AC XY: 4 AN XY: 727242

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: 0.00000270

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Cardiovascular phenotype Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jul 22, 2016

The p.V1340L variant (also known as c.4018G>C), located in coding exon 22 of the SCN5A gene, results from a G to C substitution at nucleotide position 4018. The valine at codon 1340 is replaced by leucine, an amino acid with highly similar properties. A similar substitution has been reported in the same codon among individuals with Brugada syndrome; however, it has not been shown to segregate with disease among family members in the literature to date (Garcia-Castro et al. Rev Esp Cardiol. 2010;63(7):856-9, Kapplinger et al. Heart Rhythm. 2010;7(1):33-46, Samani et al. Heart Rhythm. 2009;6(9):1318-26). In vitro functional analysis suggests the protein domain is important for sodium ion channel activity of cardiomyocytes (Samani et al. Heart Rhythm. 2009; 6(9):1318-26). The p.V1340L variant was not reported in population based cohorts in the following databases: Database of Single Nucleotide Polymorphisms (dbSNP), NHLBI Exome Sequencing Project (ESP), and 1000 Genomes Project. In the ESP, this variant was not observed in 6503 samples (13006 alleles) with coverage at this position. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this variant remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.97
CardioboostArm	Pathogenic	0.98
CardioboostCm	Uncertain	0.80
BayesDel_addAF	Pathogenic	0.46	D
BayesDel_noAF	Pathogenic	0.42
Cadd	Pathogenic	28
Dann	Uncertain	1.0
Eigen	Uncertain	0.65
Eigen_PC	Uncertain	0.61
FATHMM_MKL	Uncertain	0.93	D
M_CAP	Pathogenic	0.66	D
MetaRNN	Pathogenic	0.95	D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D;D;D
PrimateAI	Pathogenic	0.86	D
PROVEAN	Uncertain	-2.9	D;D;D;D;D;D;D;D;D
REVEL	Pathogenic	0.92
Sift	Pathogenic	0.0	D;D;D;D;D;D;D;D;D
Sift4G	Uncertain	0.0050	D;D;D;D;D;D;D;D;D
Polyphen		0.99	D;D;.;D;.;D;D;.;.
Vest4		0.89
MutPred		0.82		Loss of catalytic residue at V1340 (P = 0.1674);.;Loss of catalytic residue at V1340 (P = 0.1674);Loss of catalytic residue at V1340 (P = 0.1674);.;Loss of catalytic residue at V1340 (P = 0.1674);.;.;.;
MVP		0.95
MPC		1.4
ClinPred		0.99	D
GERP RS		4.3
Varity_R		0.93
gMVP		0.99

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.12		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: rs199473605; hg19: chr3-38601865;