NM_001099404.2:c.1126C>T

Variant names:

• chr3-38606683-G-A
• rs199473100
• NM_001099404.2:c.1126C>T

Variant summary

Our verdict is Pathogenic. The variant received 11 ACMG points: 11P and 0B. PM1 PM2 PM5 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:4 U:1 O:1
• Conservation: PhyloP100: 2.87
• Publications: 9 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: Orphanet, ClinGen
• Brugada syndrome 1

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

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

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

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

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

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P, Ambry Genetics
• progressive familial heart block, type 1A

  Inheritance: AD, SD Classification: STRONG, MODERATE Submitted by: Genomics England PanelApp, Ambry Genetics
• sick sinus syndrome 1

  Inheritance: AR, AD Classification: STRONG, LIMITED Submitted by: Labcorp Genetics (formerly Invitae)
• 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
• congenital heart disease

  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 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, 12 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 chr3-38606682-C-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 67639.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• 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 VariationId is 67638.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001099404.2. 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
	SCN5A	NM_001099404.2	MANE Plus Clinical	c.1126C>T	p.Arg376Cys	missense	Exon 9 of 28	NP_001092874.1	H9KVD2
	SCN5A	NM_000335.5	MANE Select	c.1126C>T	p.Arg376Cys	missense	Exon 9 of 28	NP_000326.2
	SCN5A	NM_198056.3		c.1126C>T	p.Arg376Cys	missense	Exon 9 of 28	NP_932173.1	Q14524-1

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SCN5A	ENST00000413689.6	TSL:5 MANE Plus Clinical	c.1126C>T	p.Arg376Cys	missense	Exon 9 of 28	ENSP00000410257.1	H9KVD2
	SCN5A	ENST00000423572.7	TSL:1 MANE Select	c.1126C>T	p.Arg376Cys	missense	Exon 9 of 28	ENSP00000398266.2	Q14524-2
	SCN5A	ENST00000333535.9	TSL:1	c.1126C>T	p.Arg376Cys	missense	Exon 9 of 28	ENSP00000328968.4	Q14524-1

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

⚠️ 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: 33470

American (AMR) AF: 0.00 AC: 0 AN: 44632

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26108

East Asian (EAS) AF: 0.00 AC: 0 AN: 39694

South Asian (SAS) AF: 0.00 AC: 0 AN: 86170

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53110

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 0.00000180 AC: 2 AN: 1111716

Other (OTH) AF: 0.00 AC: 0 AN: 60358

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.00233887), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 33

ClinVar

ClinVar submissions

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
2	-	-	not provided (3)
-	1	-	Brugada syndrome 1 (1)
1	-	-	Cardiovascular phenotype (1)
1	-	-	not specified (1)

Computational scores

Source: dbNSFP v4.9

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
DEOGEN2	Pathogenic	0.96	D
Eigen	Uncertain	0.58
Eigen_PC	Uncertain	0.55
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Pathogenic	0.98	D
M_CAP	Pathogenic	0.84	D
MetaRNN	Pathogenic	0.95	D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Uncertain	2.8	M
PhyloP100		2.9
PrimateAI	Uncertain	0.69	T
PROVEAN	Pathogenic	-5.0	D
REVEL	Pathogenic	0.94
Sift	Uncertain	0.0010	D
Sift4G	Uncertain	0.0030	D
Polyphen		1.0	D
Vest4		0.89
MutPred		0.77		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
Mutation Taster		=0/100	disease causing (ClinVar)

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