rs199472696

Variant names:

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM2PM5PP3_StrongPP5_Very_Strong

The NM_000218.3(KCNQ1):c.520C>T(p.Arg174Cys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000031 in 1,612,454 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R174H) has been classified as Pathogenic.

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 33)

Exomes 𝑓: 0.0000021 ( 0 hom. )

Consequence

KCNQ1
NM_000218.3 missense

Scores

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:12O:1

Conservation

PhyloP100: 3.56

Variant links:

Genes affected

KCNQ1 (HGNC:6294): (potassium voltage-gated channel subfamily Q member 1) This gene encodes a voltage-gated potassium channel required for repolarization phase of the cardiac action potential. This protein can form heteromultimers with two other potassium channel proteins, KCNE1 and KCNE3. Mutations in this gene are associated with hereditary long QT syndrome 1 (also known as Romano-Ward syndrome), Jervell and Lange-Nielsen syndrome, and familial atrial fibrillation. This gene exhibits tissue-specific imprinting, with preferential expression from the maternal allele in some tissues, and biallelic expression in others. This gene is located in a region of chromosome 11 amongst other imprinted genes that are associated with Beckwith-Wiedemann syndrome (BWS), and itself has been shown to be disrupted by chromosomal rearrangements in patients with BWS. Alternatively spliced transcript variants have been found for this gene. [provided by RefSeq, Aug 2011]

KCNQ1 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Pathogenic. Variant got 16 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PM5

Other missense variant is known to change same aminoacid residue: Variant chr11-2570671-G-A is described in Lovd as [Pathogenic].

PP3

MetaRNN computational evidence supports a deleterious effect, 0.993

PP5

Variant 11-2570670-C-T is Pathogenic according to our data. Variant chr11-2570670-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 53058.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr11-2570670-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNQ1	NM_000218.3 link	c.520C>T	p.Arg174Cys	missense_variant	Exon 3 of 16	ENST00000155840.12	NP_000209.2	P51787-1Q96AI9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	UniProt
KCNQ1	ENST00000155840.12 link	c.520C>T	p.Arg174Cys	missense_variant	Exon 3 of 16	1	NM_000218.3	ENSP00000155840.2	P51787-1
KCNQ1	ENST00000335475.6 link	c.139C>T	p.Arg47Cys	missense_variant	Exon 3 of 16	1		ENSP00000334497.5	P51787-2
KCNQ1	ENST00000496887.7 link	c.259C>T	p.Arg87Cys	missense_variant	Exon 4 of 16	5		ENSP00000434560.2	E9PPZ0
KCNQ1	ENST00000646564.2 link	c.478-12765C>T		intron_variant	Intron 2 of 10			ENSP00000495806.2	A0A2R8YEQ9

Frequencies

GnomAD3 genomes

AF:

0.0000131

AC:

AN:

152172

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000654

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.00000401

AC:

AN:

249462

Hom.:

AF XY:

0.00000739

AC XY:

AN XY:

135368

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000290

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000205

AC:

AN:

1460282

Hom.:

Cov.:

AF XY:

0.00000275

AC XY:

AN XY:

726530

show subpopulations

Gnomad4 AFR exome

AF:

0.0000597

Gnomad4 AMR exome

AF:

0.0000224

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:

0.00

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.0000131

AC:

AN:

152172

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74330

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.0000654

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000147

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.0000113

ExAC

AF:

0.00000824

AC:

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:12Other:1

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Long QT syndrome 1

Pathogenic:3

Aug 01, 2023

Molecular Genetics Laboratory - Cardiogenetics, CHU de Nantes

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Feb 01, 2016

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: The c.520C>T (p.R174C) in KCNQ1 gene is a missense variant that involves a conserved nucleotide and 5/5 in silico tools predict deleterious outcome. The variant is present in the control population dataset of ExAC at a low frequency (0.0008%) which does not exceed the maximum allele frequency for a pathogenic KCNQ1 variant (0.01%). This variant has been reported in the literature in multiple affected individuals presented with elongated QTc interval, including one homozygous pt with severe arrhythmic presentation. Other alterations of the same codon, p.R174H, p.R174L and p.R174P have been reported in pts with LQTS. Functional studies showed p.R174C alters the normal channel activity. In addition, several reputable databases/clinical laboratories classified the variant as Pathogenic. Therefore, this variant was classified as Pathogenic. -

Nov 27, 2022

Johns Hopkins Genomics, Johns Hopkins University

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This KCNQ1 variant (rs199472696) is rare (<0.1%) in a large population dataset (gnomAD: 1/249462 total alleles; 0.0004%; no homozygotes) and has been reported in ClinVar5. This variant has been reported in the literature in multiple unrelated individuals affected with long QT syndrome. Alterations of the same codon have also been reported in individuals with LQT1. Experimental studies have shown that this amino acid substitution (p.Arg174Cys) adversely affects KCNQ1 channel function. Bioinformatic analysis predicts that this missense variant would not affect normal exon 3 splicing, although this has not been confirmed experimentally to our knowledge. We consider c.520C>T to be pathogenic. -

not provided

Pathogenic:3

Mar 01, 2025

CeGaT Center for Human Genetics Tuebingen

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

KCNQ1: PS4, PM1, PM2, PM5, PS3:Moderate -

Dec 14, 2021

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (Lek et al., 2016); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Published in vitro functional studies demonstrate a damaging effect as the p.(R174C) variant impairs potassium channel regulation and function (Chouabe et al., 1997; Matavel et al., 2010; Wu et al., 2018); Reported in ClinVar as a pathogenic variant (ClinVar Variant ID# 53058; Landrum et al., 2016); This variant is associated with the following publications: (PMID: 9312006, 23130128, 10973849, 15840476, 9386136, 26986070, 26907222, 29532034, 22581653, 19841300, 19716085, 19934648, 23392653, 27251404, 23728945, 26669661, 19815527, 27761162, 29037160, 29033053, 29449639, 11668638, 31737537, 32383558) -

Nov 02, 2021

Mayo Clinic Laboratories, Mayo Clinic

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

PP3, PM2_supporting, PM3, PS3, PS4_moderate -

Long QT syndrome

Pathogenic:3

Sep 10, 2015

Clinical Molecular Genetics Laboratory, Johns Hopkins All Children's Hospital

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Nov 24, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces arginine, which is basic and polar, with cysteine, which is neutral and slightly polar, at codon 174 of the KCNQ1 protein (p.Arg174Cys). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This missense change has been observed in individuals with long QT syndrome (PMID: 9386136, 11668638, 15840476, 19716085, 23130128, 23392653). ClinVar contains an entry for this variant (Variation ID: 53058). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is expected to disrupt KCNQ1 protein function with a positive predictive value of 95%. Experimental studies have shown that this missense change affects KCNQ1 function (PMID: 9312006, 19934648). For these reasons, this variant has been classified as Pathogenic. -

Aug 01, 2024

All of Us Research Program, National Institutes of Health

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.520C>T (p.Arg174Cys) variant in the KCNQ1 gene is located on the exon 3 of the KCNQ1 gene and is predicted to replace arginine with cysteine at codon 174 of the KCNQ1 protein (p.Arg174Cys). This variant has been identified in multiple individuals with long QT syndrome (LQTS) (PMID: 11668638, 23130128, 27251404, 29449639) or referred for LQTS genetic testing (PMID: 15840476, 19716085). This variant has also been reported in homozygous and compound heterozygous states in individuals affected with Jervell and Lange-Nielsen syndrome (PMID: 23392653, 29037160). A different missense substitution affecting the same amino acid residue, p.Arg174His, has been determined to be pathogenic in ClinVar based on the ACMG guideline. Experimental studies have shown that this missense change affects KCNQ1 function (PMID: 29449639, 9312006, 19934648). This variant is present at a very low frequency (1/249462) in the general population according to gnomAD. In silico prediction algorithm suggests that this variant may have deleterious impact on protein structure and function (REVEL score ?0.75). Therefore, the c.520C>T (p.Arg174Cys) variant in the KCNQ1 gene has been classified as pathogenic. -

Beckwith-Wiedemann syndrome;C1837014:Atrial fibrillation, familial, 3;C1865019:Short QT syndrome type 2;C4551509:Jervell and Lange-Nielsen syndrome 1;C4551647:Long QT syndrome 1

Pathogenic:1

Oct 11, 2021

Fulgent Genetics, Fulgent Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Cardiovascular phenotype

Pathogenic:1

Dec 28, 2021

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.R174C pathogenic mutation (also known as c.520C>T), located in coding exon 3 of the KCNQ1 gene, results from a C to T substitution at nucleotide position 520. The arginine at codon 174 is replaced by cysteine, an amino acid with highly dissimilar properties, and is located in the S2/S3 transmembrane-spanning region. This variant has been reported in long QT syndrome (LQTS) cohorts and LQTS genetic testing cohorts, where some cases had limited details provided (Donger C et al. Circulation. 1997;96(9):2778-81; Splawski I et al. Circulation. 2000;102(10):1178-85; Tester DJ. Heart Rhythm. 2005;2(5):507-17; Couderc JP et al. J Am Heart Assoc. 2012;1:e000570; Miyazaki et al. JACC: Clin Electrophys. 2016;(2)3:266-76; Westphal DS et al. Mol Genet Genomic Med, 2020 09;8:e1300). This variant has also been reported in the homozygous and compound heterozygous states in patients with severe LQTS presentation and Jervell and Lange-Nielsen syndrome (Giudicessi JR et al. Circ Cardiovasc Genet. 2013;6(2):193-200; Uysal F et al. BMC Med Genet. 2017 10;18:114). This variant was also detected in two siblings with LQTS who had additional co-occurring variants in other arrhythmia-related genes; family members heterozygous for p.R174C with QTc values in the normal range were also described (Wu J et al. Sci Rep, 2018 02;8:3129). Functional studies have reported this alteration to disrupt regulation of ion channel activation and lead to impaired ion channel function (Chouabe C et al. EMBO J. 1997;16(17):5472-9; Matavel A et al. Channels (Austin). 2010;4(1):3-11; Huang H et al. Sci Adv, 2018 03;4:eaar2631). Furthermore, other variants affecting this amino acid (p.R174H, p.R174P, and p.R174L) have also been reported in LQTS cohorts (Lupoglazoff JM et al. J. Am Coll Cardiol. 2004;43(5):826-30; Napolitano C et al. JAMA. 2005; 294:2975-80; Aziz PF et al. Circ Arrhythm Electrophysiol. 2011;4:867-73). 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

Jul 10, 2024

Color Diagnostics, LLC DBA Color Health

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This missense variant replaces arginine with cysteine at codon 174 of the KCNQ1 protein. This variant is found within the highly conserved cytoplasmic linker region (a.a. 169-196) between transmembrane domains S2 and S3. Rare non-truncating variants in this region have been shown to be significantly overrepresented in individuals with long QT syndrome (PMID: 32893267). Functional studies have shown that this variant results in a severe trafficking defect, complete loss of surface expression and channel current (PMID: 9312006, 19934648, 29449639, 29532034). This variant has been reported in multiple unrelated individuals affected with long QT syndrome (PMID: 11668638, 23130128, 27251404, 29449639, 2383558, 32893267), as well as in a few individuals suspected of having this condition (PMID: 15840476, 19716085, 38489124). This variant has also been reported in the homozygous and compound heterozygous states in individuals affected with Jervell and Lange-Nielsen syndrome (PMID: 23392653, 29037160, 31427586). This variant has been identified in 1/249462 chromosomes in the general population by the Genome Aggregation Database (gnomAD). Based on the available evidence, this variant is classified as Pathogenic. -

Congenital long QT syndrome

Other:1

Cardiovascular Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

This variant has been reported as associated with Long QT syndrome in the following publications (PMID:9386136;PMID:11668638;PMID:15840476;PMID:19716085;PMID:19934648). This is a literature report, and does not necessarily reflect the clinical interpretation of the Imperial College / Royal Brompton Cardiovascular Genetics laboratory. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.98

BayesDel_addAF

Pathogenic

0.55

BayesDel_noAF

Pathogenic

0.55

CADD

Pathogenic

DANN

Pathogenic

1.0

DEOGEN2

Pathogenic

0.99

.;D;.

Eigen

Pathogenic

0.80

Eigen_PC

Pathogenic

0.68

FATHMM_MKL

Uncertain

0.96

LIST_S2

Pathogenic

1.0

D;D;D

M_CAP

Pathogenic

0.92

MetaRNN

Pathogenic

0.99

D;D;D

MetaSVM

Pathogenic

1.1

MutationAssessor

Pathogenic

4.2

.;H;.

PrimateAI

Pathogenic

0.84

PROVEAN

Pathogenic

-7.5

D;D;D

REVEL

Pathogenic

0.98

Sift

Pathogenic

0.0

D;D;D

Sift4G

Pathogenic

0.0

D;D;D

Polyphen

1.0

.;D;.

Vest4

0.90, 0.87

MutPred

0.97

.;Loss of MoRF binding (P = 0.0045);.;

MVP

0.97

MPC

1.4

ClinPred

1.0

GERP RS

4.4

Varity_R

0.96

gMVP

0.99

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over