NM_000218.3:c.364dupT

Variant names:

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PVS1PP5_Very_Strong

The NM_000218.3(KCNQ1):c.364dupT(p.Cys122LeufsTer163) variant causes a frameshift change. The variant allele was found at a frequency of 0.0000144 in 1,596,406 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000015 ( 0 hom. )

Consequence

KCNQ1
NM_000218.3 frameshift

Scores

Not classified

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:7

Conservation

PhyloP100: 5.34

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.

PVS1

Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.

PP5

Variant 11-2445461-A-AT is Pathogenic according to our data. Variant chr11-2445461-A-AT is described in ClinVar as [Likely_pathogenic]. Clinvar id is 200915.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
KCNQ1	NM_000218.3 link	c.364dupT	p.Cys122LeufsTer163	frameshift_variant	Exon 1 of 16	ENST00000155840.12	NP_000209.2	P51787-1Q96AI9
KCNQ1	NM_001406836.1 link	c.364dupT	p.Cys122LeufsTer163	frameshift_variant	Exon 1 of 15		NP_001393765.1
KCNQ1	NM_001406838.1 link	c.364dupT	p.Cys122LeufsTer161	frameshift_variant	Exon 1 of 11		NP_001393767.1
KCNQ1	NM_001406837.1 link	c.2dupT	p.Met1IlefsTer13	frameshift_variant, start_lost	Exon 1 of 17		NP_001393766.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	UniProt
KCNQ1	ENST00000155840.12 link	c.364dupT	p.Cys122LeufsTer163	frameshift_variant	Exon 1 of 16	1	NM_000218.3	ENSP00000155840.2	P51787-1
KCNQ1	ENST00000345015.4 link	n.141dupT		non_coding_transcript_exon_variant	Exon 1 of 3	1
KCNQ1	ENST00000496887.7 link	c.103dupT	p.Cys35LeufsTer163	frameshift_variant	Exon 2 of 16	5		ENSP00000434560.2	E9PPZ0
KCNQ1	ENST00000646564.2 link	c.364dupT	p.Cys122LeufsTer161	frameshift_variant	Exon 1 of 11			ENSP00000495806.2	A0A2R8YEQ9

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152140

Hom.:

Cov.:

show subpopulations

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

GnomAD3 exomes

AF:

0.0000227

AC:

AN:

219922

Hom.:

AF XY:

0.0000409

AC XY:

AN XY:

122282

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.000168

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000152

AC:

AN:

1444266

Hom.:

Cov.:

AF XY:

0.0000278

AC XY:

AN XY:

718768

show subpopulations

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:

0.000256

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152140

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74326

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.000207

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.00

Gnomad4 OTH

AF:

0.00

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:7

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Long QT syndrome 1

Pathogenic:3

Feb 01, 2013

Arcensus

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Aug 12, 2019

Centre for Mendelian Genomics, University Medical Centre Ljubljana

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was classified as: Pathogenic. The following ACMG criteria were applied in classifying this variant: PVS1,PS1,PP4. -

Mar 04, 2015

Genetic Services Laboratory, University of Chicago

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

KCNQ1-related disorder

Pathogenic:1

May 06, 2024

PreventionGenetics, part of Exact Sciences

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

The KCNQ1 c.364dupT variant is predicted to result in a frameshift and premature protein termination (p.Cys122Leufs*163). This variant has been reported in the heterozygous state in multiple individuals with long QT syndrome and in the homozygous state in an individual with Jervell and Lange-Nielsen syndrome (described as InsG 2025-2026 K121fs/629* in Tester et al. 2005. PubMed ID: 15840476; Table S1, Schwartz et al. 2021. PubMed ID: 34505893; described as c.365insT in Table S1, Kapplinger et al. 2009. PubMed ID: 19716085; Whiffin et al. 2019. PubMed ID: 30609406; Jacobson et al. 2014. PubMed ID: 24665220). This variant is reported in 0.017% of alleles in individuals of South Asian descent in gnomAD. Frameshift variants in KCNQ1 are expected to be pathogenic. This variant is interpreted as pathogenic. -

not provided

Pathogenic:1

Dec 28, 2023

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Frameshift variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss-of-function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 34505893, 28606196, 23631430, 19716085, 30609406, 29625023, 26582918, 15840476) -

Long QT syndrome

Pathogenic:1

Apr 07, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Cys122Leufs*163) in the KCNQ1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in KCNQ1 are known to be pathogenic (PMID: 9323054, 19862833). This variant is present in population databases (rs397508109, gnomAD 0.02%). This premature translational stop signal has been observed in individual(s) with clinical features of long QT syndrome (PMID: 15840476). This variant is also known as Ins G 2025-2026 (K121fs/629*). ClinVar contains an entry for this variant (Variation ID: 200915). For these reasons, this variant has been classified as Pathogenic. -

Cardiovascular phenotype

Pathogenic:1

Jun 18, 2019

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.364dupT pathogenic mutation, located in coding exon 1 of the KCNQ1 gene, results from a duplication of T at nucleotide position 364, causing a translational frameshift with a predicted alternate stop codon (p.C122Lfs*163). This alteration has been detected in the homozygous state in a child of consanguineous parents who was reported to have Jervell and Lange-Nielsen syndrome. The parents were reported to have normal ECGs (Jacobson D et al. Paediatr Child Health, 2014 Mar;19:123-4). This alteration (also referred to as K121fs/629* and 365insT) has also been detected in long QT syndrome genetic testing cohorts; however, details were limited (Tester DJ et al. Heart Rhythm, 2005 May;2:507-17; Kapplinger JD et al. Heart Rhythm, 2009 Sep;6:1297-303). This alteration is expected to result in loss of function by premature protein truncation or nonsense-mediated mRNA decay. As such, this alteration is interpreted as a disease-causing mutation. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

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