NM_001099404.2:c.611+1G>A

Variant names:

• chr3-38620842-C-T
• rs794728843
• NM_001099404.2:c.611+1G>A

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1_Moderate PM2 PP5_Very_Strong

The NM_001099404.2(SCN5A):​c.611+1G>A variant causes a splice donor, intron change. The variant allele was found at a frequency of 0.00000254 in 1,576,130 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: SCN5A NM_001099404.2 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:8 O:1
• Conservation: PhyloP100: 6.06
• Publications: 4 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: Pathogenic. The variant received 12 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.02131879 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 3-38620842-C-T is Pathogenic according to our data. Variant chr3-38620842-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 201427.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SCN5A	NM_001099404.2	c.611+1G>A		splice_donor_variant, intron_variant	Intron 5 of 27	ENST00000413689.6	NP_001092874.1
SCN5A	NM_000335.5	c.611+1G>A		splice_donor_variant, intron_variant	Intron 5 of 27	ENST00000423572.7	NP_000326.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SCN5A	ENST00000413689.6	c.611+1G>A		splice_donor_variant, intron_variant	Intron 5 of 27	5	NM_001099404.2	ENSP00000410257.1
SCN5A	ENST00000423572.7	c.611+1G>A		splice_donor_variant, intron_variant	Intron 5 of 27	1	NM_000335.5	ENSP00000398266.2

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152224 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000207

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000211 AC: 3 AN: 1423906 Hom.: 0 Cov.: 32 AF XY: 0.00000426 AC XY: 3 AN XY: 704660

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 32590

American (AMR) AF: 0.00 AC: 0 AN: 37944

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25430

East Asian (EAS) AF: 0.00 AC: 0 AN: 37604

South Asian (SAS) AF: 0.00 AC: 0 AN: 81280

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 51192

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5728

European-Non Finnish (NFE) AF: 0.00000274 AC: 3 AN: 1092984

Other (OTH) AF: 0.00 AC: 0 AN: 59154

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.095309), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152224 Hom.: 0 Cov.: 33 AF XY: 0.0000134 AC XY: 1 AN XY: 74372

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 41464

American (AMR) AF: 0.00 AC: 0 AN: 15288

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5196

South Asian (SAS) AF: 0.000207 AC: 1 AN: 4834

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10626

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68022

Other (OTH) AF: 0.00 AC: 0 AN: 2094

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

Alfa AF: 0.00000497 Hom.: 0

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:8 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:3

Feb 25, 2025

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Identified in patients with Long QT syndrome and Brugada syndrome referred for genetic testing at GeneDx and in published literature (PMID: 20129283, 24606995, 29709101, 30690642, 31737537, 34461752); Not observed at significant frequency in large population cohorts (gnomAD); Canonical splice site variant in a gene for which loss-of-function is a known mechanism of disease; This variant is associated with the following publications: (PMID: 20129283, 25525159, 31737537, 24606995, 29709101, 30690642, 34461752) -

Oct 24, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects a donor splice site in intron 5 of the SCN5A gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in SCN5A are known to be pathogenic (PMID: 20129283, 22789973). This variant is not present in population databases (gnomAD no frequency). Disruption of this splice site has been observed in individuals with Brugada syndrome (PMID: 20129283, 29709101). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 201427). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -

Mar 01, 2025

CeGaT Center for Human Genetics Tuebingen

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

SCN5A: PS4, PVS1:Strong, PM2 -

Brugada syndrome 1 Pathogenic:2

May 06, 2021

Victorian Clinical Genetics Services, Murdoch Childrens Research Institute

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as Pathogenic. Following criteria are met: 0103 - Loss of function and gain of function are both known mechanisms of disease in this gene. Loss of function is usually associated with Brugada syndrome 1 (MIM#601144) and sick sinus syndrome (SSS) (MIM#608567), whereas gain of function is usually associated with long QT syndrome (LQTS) (MIM#603830). Dilated cardiomyopathy 1E (DCM) (MIM#601154) can be caused by variants with either a loss- or gain of function mechanism (PMID: 29798782). However, some variants simultaneously result in both a loss- and gain of function effect, and have been observed in patients with LQTS, Brugada syndrome or SSS, and patients with a blended phenotype. Additionally, different studies have shown conflicting mechanisms in association with atrial fibrillation (MIM#614022) (PMIDs: 29806494, 19167345, 26798387). (I) 0108 - This gene is associated with both recessive and dominant disease. Most conditions associated with this gene are dominantly inherited, however SSS can be caused by recessive variants (OMIM). (I) 0112 - The condition associated with this gene has incomplete penetrance. Among individuals with a SCN5A pathogenic variant, aproximately 20%-30% have an ECG diagnostic of Brugada syndrome and approximately 80% manifest the characteristic ECG changes when challenged with a sodium channel blocker (PMID: 20301690). (I) 0211 - Canonical splice site variant without proven consequence on splicing (no functional evidence available). (SP) 0251 - This variant is heterozygous. (I) 0302 - Variant is present in gnomAD (v3) <0.001 for a dominant condition (1 heterozygote, 0 homozygotes). (SP) 0505 - Abnormal splicing is predicted by in silico tools and affected nucleotide is highly conserved. (SP) 0705 - No comparable canonical splice site variants have previous evidence for pathogenicity. (I) 0801 - This variant has strong previous evidence of pathogenicity in unrelated individuals. This variant has been classified as likely pathogenic or pathogenic in ClinVar and has been primarily reported in individuals with Brugada syndrome, although it has also been identified in one individual with Romano-Ward syndrome and another with atrial flutter and sinus node dysfunction (ClinVar; PMIDs: 20129283, 24606995, 26111534, 29709101, 29884292). (SP) 0905 - No published segregation evidence has been identified for this variant. (I) 1007 - No published functional evidence has been identified for this variant. (I) 1208 - Inheritance information for this variant is not currently available in this individual. (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -

May 24, 2017

Center For Human Genetics And Laboratory Diagnostics, Dr. Klein, Dr. Rost And Colleagues

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Brugada syndrome Pathogenic:1

Oct 30, 2023

All of Us Research Program, National Institutes of Health

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant disrupts a canonical splice site and is predicted to result in abnormal splicing. Aberrant splicing and/or loss of function is an established mechanism of disease. This prediction has not been confirmed by functional studies. This variant has been reported in multiple individuals with Brugada syndrome and long QT syndrome (PMID: 20129283, 24606995, 29709101, 29884292, 32893267). This variant is absent from or rare in large population databases, including the Genome Aggregation Database (http://gnomad.broadinstitute.org/). -

Cardiovascular phenotype Pathogenic:1

Jun 10, 2025

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.611+1G>A intronic pathogenic mutation results from a G to A substitution one nucleotide after coding exon 4 of the SCN5A gene. Alterations that disrupt the canonical splice site are expected to result in aberrant splicing. In silico splice site analysis predicts that this alteration will weaken the native splice donor site. The resulting transcript is predicted to be in-frame and is not expected to trigger nonsense-mediated mRNAdecay; however, direct evidence is unavailable. The exact functional effect of the altered amino acid sequence is unknown; however, the impacted region is critical for protein function (Ambry internal data). This alteration has been described in individuals and families with Brugada syndrome; of note, at least one individual had a co-occurring SCN5A alteration also detected, and one reportedly unaffected carrier was also described (Kapplinger JD et al. Heart Rhythm, 2010 Jan;7:33-46; Robyns T et al. Ann Noninvasive Electrocardiol, 2018 09;23:e12548; Marschall C et al. Cardiovasc Diagn Ther, 2019 Oct;9:S292-S298) This variant has also been observed in a long QT syndrome cohort; however, clinical details were limited (Christiansen M et al. BMC Med Genet, 2014 Mar;15:31). This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). Based on the supporting evidence, this alteration is interpreted as a disease-causing mutation. -

Cardiac arrhythmia Pathogenic:1

Jan 16, 2024

Color Diagnostics, LLC DBA Color Health

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant (also known as IVS5+1G>A in published literature) causes a G to A nucleotide substitution at the +1 position of intron 5 of the SCN5A gene. Splice site prediction tools predict that this variant may have a significant impact on RNA splicing. Although this prediction has not been confirmed in published RNA studies, this variant is expected to result in an absent or disrupted protein product. This variant has been reported in about ten individuals affected with Brugada syndrome (PMID: 20129283, 29709101, 29884292, 32893267), in two young individuals affected with sinus node dysfunction (PMID: 26111534, 37746560), in an individual affected with mitral valve dilatation (PMID: 36143288), and in an individual affected with long QT syndrome (PMID 24606995). This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). Loss of SCN5A function is a known mechanism of disease (clinicalgenome.org). Based on the available evidence, this variant is classified as Pathogenic. -

SCN5A-related disorder Other:1

-

GenomeConnect - Invitae Patient Insights Network

Significance: not provided

Review Status: no classification provided

Collection Method: phenotyping only

Variant interpreted as Pathogenic and reported on 06-19-2020 by Invitae. GenomeConnect-Invitae Patient Insights Network assertions are reported exactly as they appear on the patient-provided report from the testing laboratory. Registry team members make no attempt to reinterpret the clinical significance of the variant. Phenotypic details are available under supporting information. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.41
CADD	Pathogenic	34
DANN	Uncertain	1.0
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.84
FATHMM_MKL	Pathogenic	0.99	D
PhyloP100		6.1
GERP RS		4.1
Mutation Taster		=0/100	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		0.92		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.92		Position offset: 1

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

Other links and lift over

dbSNP: rs794728843; hg19: chr3-38662333; COSMIC: COSV61142858;