NM_000218.3:c.1343C>T

Variant names:

Variant summary

Our verdict is Uncertain significance. The variant received -1 ACMG points: 0P and 1B. BS4_Supporting

This summary comes from the ClinGen Evidence Repository: NM_000218.3(KCNQ1):c.1343C>T is a missense variant ithat substitutes proline with leucine at codon 448 (p.Pro448Leu). This variant is present in gnomAD v.4.1.0 at a maximum allele frequency of 0.00005254, with 62 alleles / 1,179,942 total alleles in the European non-Finnish population, which is higher than the ClinGen Potassium Channel Arrhythmia VCEP PM2_Supporting threshold of <0.00001, but lower than the BS1 threshold of >0.0004 so neither criterion is met. This variant has been reported in at least 1 proband affected with long QT syndrome 1, however, the requirement for 2 unrelated probands has not been reached so the PS4_Supporting code is not yet met (PMID:23392653, PMID:19716085, PMID:25854863). The variant has been observed in a family with long QT syndrome but fails to segregate with the disease phenotype in at least 1 affected member (PMID:23392653; BS4_Supporting). The computational predictor REVEL gives a score of 0.592, which is below the ClinGen Potassium Channel Arrhythmia VCEP PP3 threshold of >0.75 but higher than the BP4 threshold of <0.25 and does not strongly predict a damaging effect on KCNQ1 function. The computational splicing predictor SpliceAI gives a score of 0.00, which is lower than the ClinGen Potassium Channel Arrhythmia VCEP PP3 threshold of >0.5 and does not strongly predict a damaging effect on KCNQ1 splicing. In summary, this variant meets the criteria to be classified as a variant of uncertain significance for long QT syndrome 1 based on the ACMG/AMP criteria applied, as specified by the ClinGen Potassium Channel Arrhythmia VCEP: BS4_Supporting. (VCEP specifications version 1.0.0; date of approval 03/04/2025). LINK:https://erepo.genome.network/evrepo/ui/classification/CA005629/MONDO:0100316/112

Frequency

Genomes: 𝑓 0.000059 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000038 ( 0 hom. )

Consequence

KCNQ1
NM_000218.3 missense

Scores

Clinical Significance

Uncertain significance reviewed by expert panel U:10B:3O:1

Conservation

PhyloP100: -0.179

Publications

48 publications found

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 Gene-Disease associations (from GenCC):

long QT syndrome
Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
long QT syndrome 1
Inheritance: AD, AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P
Jervell and Lange-Nielsen syndrome
Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
Jervell and Lange-Nielsen syndrome 1
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae)
atrial fibrillation, familial, 3
Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
short QT syndrome
Inheritance: AD Classification: STRONG, SUPPORTIVE Submitted by: ClinGen, Orphanet
short QT syndrome type 2
Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P
familial atrial fibrillation
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
Jervell and Lange-Nielsen syndrome
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
hypertrophic cardiomyopathy
Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

KCNQ1 links:

ENSG00000296223 (HGNC:):

ENSG00000296223 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received -1 ACMG points.

BS4

For more information check the summary or visit ClinGen Evidence Repository.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000218.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
KCNQ1	NM_000218.3	MANE Select	c.1343C>T	p.Pro448Leu	missense	Exon 10 of 16	NP_000209.2
KCNQ1	NM_001406836.1		c.1247C>T	p.Pro416Leu	missense	Exon 9 of 15	NP_001393765.1
KCNQ1	NM_001406837.1		c.1073C>T	p.Pro358Leu	missense	Exon 11 of 17	NP_001393766.1

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
KCNQ1	ENST00000155840.12	TSL:1 MANE Select	c.1343C>T	p.Pro448Leu	missense	Exon 10 of 16	ENSP00000155840.2	P51787-1
KCNQ1	ENST00000335475.6	TSL:1	c.962C>T	p.Pro321Leu	missense	Exon 10 of 16	ENSP00000334497.5	P51787-2
KCNQ1	ENST00000910997.1		c.1340C>T	p.Pro447Leu	missense	Exon 10 of 16	ENSP00000581056.1

Frequencies

GnomAD3 genomes

AF:

0.0000592

AC:

AN:

152086

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:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.000132

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000200

AC:

AN:

250376

AF XY:

0.0000221

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 FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000265

Gnomad OTH exome

AF:

0.000327

GnomAD4 exome

AF:

0.0000376

AC:

AN:

1461180

Hom.:

Cov.:

AF XY:

0.0000371

AC XY:

AN XY:

726868

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33472

American (AMR)

AF:

0.00

AC:

AN:

44704

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26128

East Asian (EAS)

AF:

0.00

AC:

AN:

39694

South Asian (SAS)

AF:

0.00

AC:

AN:

86190

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53132

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5566

European-Non Finnish (NFE)

AF:

0.0000477

AC:

AN:

1111936

Other (OTH)

AF:

0.0000331

AC:

AN:

60358

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.470

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000592

AC:

AN:

152086

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74286

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41426

American (AMR)

AF:

0.00

AC:

AN:

15274

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3466

East Asian (EAS)

AF:

0.00

AC:

AN:

5158

South Asian (SAS)

AF:

0.00

AC:

AN:

4822

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10618

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.000132

AC:

AN:

68006

Other (OTH)

AF:

0.00

AC:

AN:

2090

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.475

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.0000711

Hom.:

Bravo

AF:

0.0000453

EpiCase

AF:

0.000109

EpiControl

AF:

0.00

ClinVar

ClinVar submissions

Significance:Uncertain significance

Revision:reviewed by expert panel

View on ClinVar

Pathogenic

VUS

Benign

Condition

not specified (3)

Long QT syndrome (2)

Long QT syndrome 1 (2)

Atrial fibrillation, familial, 3 (1)

Cardiac arrhythmia (1)

Cardiovascular phenotype (1)

Jervell and Lange-Nielsen syndrome 1 (1)

not provided (1)

Short QT syndrome type 2 (1)

Congenital long QT syndrome (1)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.068

CardioboostArm

Benign

0.047

BayesDel_addAF

Pathogenic

0.17

BayesDel_noAF

Uncertain

0.070

CADD

Benign

4.9

(source)

DANN

Uncertain

0.98

DEOGEN2

Uncertain

0.52

Eigen

Benign

-0.86

Eigen_PC

Benign

-0.82

FATHMM_MKL

Benign

0.033

LIST_S2

Benign

0.68

M_CAP

Uncertain

0.28

MetaRNN

Benign

0.17

MetaSVM

Uncertain

0.61

MutationAssessor

Benign

0.34

PhyloP100

-0.18

PrimateAI

Benign

0.25

PROVEAN

Benign

-1.4

REVEL

Uncertain

0.59

Sift

Benign

0.076

Sift4G

Benign

0.33

Polyphen

0.0

Vest4

0.69

MutPred

0.33

Loss of catalytic residue at P447 (P = 0.0102)

MVP

0.85

MPC

0.38

ClinPred

0.042

GERP RS

4.1

Varity_R

0.041

gMVP

0.31

Mutation Taster

=35/65

disease causing

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over