rs199473100

chr3-38606683-G-A

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5

The NM_001099404.2(SCN5A):c.1126C>T(p.Arg376Cys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,024 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 Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R376H) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: SCN5A NM_001099404.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:3 U:2 O:1
• Conservation: PhyloP100: 2.87

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 12 ACMG points.

• PM1: In a helix (size 11) in uniprot entity SCN5A_HUMAN there are 11 pathogenic changes around while only 0 benign (100%) 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 chr3-38606682-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 67639.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP2: Missense variant where missense usually causes diseases, SCN5A
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.949
• PP5: Variant 3-38606683-G-A is Pathogenic according to our data. Variant chr3-38606683-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 67638.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=2, Pathogenic=1, Uncertain_significance=2, not_provided=1}. Variant chr3-38606683-G-A is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SCN5A	NM_001099404.2	c.1126C>T	p.Arg376Cys	missense_variant	9/28	ENST00000413689.6
SCN5A	NM_000335.5	c.1126C>T	p.Arg376Cys	missense_variant	9/28	ENST00000423572.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SCN5A	ENST00000413689.6	c.1126C>T	p.Arg376Cys	missense_variant	9/28	5	NM_001099404.2	P4
SCN5A	ENST00000423572.7	c.1126C>T	p.Arg376Cys	missense_variant	9/28	1	NM_000335.5	A1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461024 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 726738

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: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:3 Uncertain:2 Other:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Pathogenic:2 Other:1

not provided, no classification provided	literature only	Cardiovascular Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust	-	This variant has been reported in the following publications (PMID:19841300;PMID:20129283). -
Likely pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Feb 20, 2017	The Arg376Cys variant was identified in three members of a family with sick sinus syndrome (Detta et al., 2014). Functional studies showed a significant reduction of the inward sodium current in heterologous cells that were expressing the Arg376Cys allele (Detta et al., 2014).The Arg376Cys variant results in a non-conservative amino acid substitution of a positively charged Arginine with an uncharged, polar Cysteine at a position that is conserved in mammals. This variant resides in the extracellular pore loop region between S5-S6 of DI. In silico analysis predicts Arg376Cys is damaging to the protein structure/function. While this allele has been observed in one out of 1300 control individuals (Kapa et al., 2009; Kapplinger et al., 2012), it was absent from individuals in both the NHLBI Exome Sequencing Project and the Exome Aggregation Consortium database, indicating it is not a common benign variant in these populations. Moreover, a missense pathogenic variant at the same residue (Arg376His) and in nearby residues (Met369Lys, Trp374Gly, Gly386Arg) have been reported in the Human Gene Mutation Database in association with Brugada syndrome (Stenson et al., 2014).Therefore, this variant is a strong candidate for a pathogenic variant, however the possibility that it is a benign variant cannot be excluded. -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Sep 12, 2023	For these reasons, this variant has been classified as Pathogenic. This variant disrupts the p.Arg376 amino acid residue in SCN5A. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 15851228, 16344400, 28341781). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. Experimental studies have shown that this missense change affects SCN5A function (PMID: 24295898). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. ClinVar contains an entry for this variant (Variation ID: 67638). This missense change has been observed in individuals with clinical features of Brugada syndrome and/or SCN5A-related conditions (PMID: 24295898, 34461752; Invitae). It has also been observed to segregate with disease in related individuals. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces arginine, which is basic and polar, with cysteine, which is neutral and slightly polar, at codon 376 of the SCN5A protein (p.Arg376Cys). -

not specified Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Jul 05, 2018

The SCN5A c. 1126C>T; p. Arg376Cys variant (rs199473100) is reported in the literature in 1 family and 3 individuals, of which 2 were affected with sick sinus syndrome-1 (SSS1), and the third may not have yet manifested disease phenotypes (Detta 2014). Functional analyses in vitro demonstrate a significant reduction in sodium channel currents (Detta 2014), similar to analyses of other SCN5A variants associated with SSS1, and consistent with impaired excitability of cardiomyocytes leading to SSS1 (Gui 2010). This variant is reported as either likely pathogenic or of uncertain significance, each by 1 laboratory in ClinVar (Variation ID: 78534), and considered disease causing in HGMD. This variant is absent from most general population databases (1000 Genomes Project and Genome Aggregation Database), with a single individual in the Exome Variant Server, indicating it is not a common polymorphism. Additionally, other variants at this codon (c.1127G>A, p.Arg376His; c.1127G>T, p.Arg376Leu) have been reported in individuals with Brugada syndrome (Rossenbacker 2004) and sudden unexplained death (Christiansen 2016), respectively. The Arg376His variant is reported as pathogenic by 2 laboratories, and likely pathogenic by 1 laboratory in ClinVar (Variation ID: 78535). The Arg376Leu variant is not in ClinVar. The arginine at codon 376 is highly conserved, and computational analyses (SIFT, PolyPhen-2) predict that this variant is deleterious. Based on available information, this variant is considered to be likely pathogenic. -

Brugada syndrome 1 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Mendelics

May 28, 2019

- -

Cardiovascular phenotype Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Mar 20, 2020

The c.1126C>T (p.R376C) alteration is located in exon 9 (coding exon 8) of the SCN5A gene. This alteration results from a C to T substitution at nucleotide position 1126, causing the arginine (R) at amino acid position 376 to be replaced by a cysteine (C). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.85
CardioboostArm	Pathogenic	0.92
CardioboostCm	Benign	0.097
BayesDel_addAF	Pathogenic	0.35	D
BayesDel_noAF	Pathogenic	0.27
Cadd	Pathogenic	30
Dann	Pathogenic	1.0
Eigen	Uncertain	0.58
Eigen_PC	Uncertain	0.55
FATHMM_MKL	Uncertain	0.96	D
M_CAP	Pathogenic	0.84	D
MetaRNN	Pathogenic	0.95	D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D;D;D
PrimateAI	Uncertain	0.69	T
PROVEAN	Pathogenic	-5.0	D;D;D;D;D;D;D;D;D
REVEL	Pathogenic	0.94
Sift	Uncertain	0.0010	D;D;D;D;D;D;D;D;D
Sift4G	Uncertain	0.0030	D;D;D;D;D;D;D;D;D
Polyphen		1.0	D;D;.;D;.;D;D;.;.
Vest4		0.89
MutPred		0.77		Loss of MoRF binding (P = 0.053);Loss of MoRF binding (P = 0.053);Loss of MoRF binding (P = 0.053);Loss of MoRF binding (P = 0.053);Loss of MoRF binding (P = 0.053);Loss of MoRF binding (P = 0.053);Loss of MoRF binding (P = 0.053);Loss of MoRF binding (P = 0.053);Loss of MoRF binding (P = 0.053);
MVP		0.92
MPC		1.3
ClinPred		1.0	D
GERP RS		4.7
Varity_R		0.64
gMVP		0.97

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

Publications

LitVar

Other links and lift over

dbSNP: rs199473100; hg19: chr3-38648174; COSMIC: COSV105205316;