NM_001099404.2:c.2821_2822delTCinsAA

Variant names:

• chr3-38581337-GA-TT
• rs137854605
• NM_001099404.2:c.2821_2822delTCinsAA

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PP3 PP5

The NM_001099404.2(SCN5A):​c.2821_2822delTCinsAA​(p.Ser941Asn) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. It is difficult to determine the true allele frequency of this variant because it is of type MNV, and the frequency of such variant types in population databases may be underestimated and unreliable. 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. S941C) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: SCN5A NM_001099404.2 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2 U:1
• Conservation: PhyloP100: 10.0
• Publications: 12 publications found

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]

SCN5A Gene-Disease associations (from GenCC):

• Brugada syndrome

  Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: ClinGen, Orphanet
• Brugada syndrome 1

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, Laboratory for Molecular Medicine, G2P, Genomics England PanelApp, Labcorp Genetics (formerly Invitae)
• dilated cardiomyopathy

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• dilated cardiomyopathy 1E

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae), Ambry Genetics
• familial long QT syndrome

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• long QT syndrome 3

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae), G2P
• sick sinus syndrome 1

  Inheritance: AD, AR Classification: STRONG, LIMITED Submitted by: Labcorp Genetics (formerly Invitae)
• progressive familial heart block, type 1A

  Inheritance: SD, AD Classification: STRONG, MODERATE Submitted by: Ambry Genetics, Genomics England PanelApp
• atrial standstill

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• familial atrial fibrillation

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• familial isolated dilated cardiomyopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• familial sick sinus syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• paroxysmal familial ventricular fibrillation

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• progressive familial heart block

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• arrhythmogenic right ventricular cardiomyopathy

  Inheritance: AD Classification: LIMITED Submitted by: ClinGen
• catecholaminergic polymorphic ventricular tachycardia

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen
• short QT syndrome

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

ACMG classification

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

• PP3: No computational evidence supports a deleterious effect, but strongly conserved according to phyloP
• PP5: Variant 3-38581337-GA-TT is Pathogenic according to our data. Variant chr3-38581337-GA-TT is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 9384.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SCN5A	NM_001099404.2	c.2821_2822delTCinsAA	p.Ser941Asn	missense_variant		ENST00000413689.6	NP_001092874.1
SCN5A	NM_000335.5	c.2821_2822delTCinsAA	p.Ser941Asn	missense_variant		ENST00000423572.7	NP_000326.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SCN5A	ENST00000413689.6	c.2821_2822delTCinsAA	p.Ser941Asn	missense_variant		5	NM_001099404.2	ENSP00000410257.1
SCN5A	ENST00000423572.7	c.2821_2822delTCinsAA	p.Ser941Asn	missense_variant		1	NM_000335.5	ENSP00000398266.2

Frequencies

GnomAD3 genomes Cov.: 32

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Pathogenic:1

Feb 01, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces serine, which is neutral and polar, with asparagine, which is neutral and polar, at codon 941 of the SCN5A protein (p.Ser941Asn). Information on the frequency of this variant in the gnomAD database is not available, as this variant may be reported differently in the database. This missense change has been observed in individual(s) with clinical features of SCN5A-related conditions (PMID: 10911008). In at least one individual the variant was observed to be de novo. This variant is also known as c.2971_2972delinsAA. ClinVar contains an entry for this variant (Variation ID: 9384). Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Not Available"; PolyPhen-2: "Benign"; Align-GVGD: "Not Available"). Experimental studies have shown that this missense change affects SCN5A function (PMID: 10911008, 17698727, 20339117). In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Long QT syndrome 3 Pathogenic:1

Jul 27, 2000

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Cardiovascular phenotype Uncertain:1

Sep 27, 2017

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.2821_2822delinsAA variant (also known as p.S941N), located in coding exon 16 of the SCN5A gene, results from an in-frame deletion of TC and insertion of AA at nucleotide positions 2821 to 2822. This results in the substitution of the serine residue at codon 941 for an asparagine residue, an amino acid with highly similar properties. This alteration has been reported to be de novo in a child with ventricular fibrillation, torsade de pointes, and prolonged QT intervals (Schwartz PJ et al. N. Engl. J. Med., 2000 Jul;343:262-7; Ruan Y et al. Circulation, 2007 Sep;116:1137-44). Limited sodium channel functional studies by these authors have suggested some effects on sodium current when compared to wild-type. This amino acid position is highly conserved in available vertebrate species. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
PhyloP100		10
Mutation Taster		=0/100	disease causing

Splicing

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

Other links and lift over

dbSNP: rs137854605; hg19: chr3-38622828;