rs199472801

Positions:

• chr11-2776038-A-G

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM1 PM2 PP3_Strong PP5_Very_Strong

The NM_000218.3(KCNQ1):​c.1669A>G​(p.Lys557Glu) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: KCNQ1 NM_000218.3 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3 O:1
• Conservation: PhyloP100: 6.87

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]

ACMG classification

Verdict is Pathogenic. Variant got 16 ACMG points.

• PM1: In a region_of_interest Interaction with KCNE1 C-terminus (size 37) in uniprot entity KCNQ1_HUMAN there are 36 pathogenic changes around while only 1 benign (97%) in NM_000218.3
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.981
• PP5: Variant 11-2776038-A-G is Pathogenic according to our data. Variant chr11-2776038-A-G is described in ClinVar as [Pathogenic]. Clinvar id is 67047.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr11-2776038-A-G is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCNQ1	NM_000218.3	c.1669A>G	p.Lys557Glu	missense_variant	13/16	ENST00000155840.12	NP_000209.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KCNQ1	ENST00000155840.12	c.1669A>G	p.Lys557Glu	missense_variant	13/16	1	NM_000218.3	ENSP00000155840	P1
KCNQ1	ENST00000335475.6	c.1288A>G	p.Lys430Glu	missense_variant	13/16	1		ENSP00000334497
KCNQ1	ENST00000496887.7	c.1312A>G	p.Lys438Glu	missense_variant	13/16	5		ENSP00000434560
KCNQ1	ENST00000646564.2	c.1129A>G	p.Lys377Glu	missense_variant	8/11			ENSP00000495806

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1412462 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 697676

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: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Apr 26, 2017

The K557E variant in the KCNQ1 gene has been reported in a large kindred of Dutch ancestry with LQTS-associated features (Spätjens et al., 2014). Moreover, the variant was de novo in the proband from this kindred, and non-paternity was excluded. In relatives, the variant segregated with moderate QTc prolongation (i.e. average 476+/-13ms) at rest, which was significantly augmented during exercise (i.e. >550ms). K557E has also been reported in additional individuals with LQTS and/or referred for LQTS testing (Jongbloed et al., 2002; Kapplinger et al., 2009; Barsheshet et al., 2012). The K557E variant is not observed in large population cohorts (Lek et al., 2016; 1000 Genomes Consortium et al., 2015; Exome Variant Server). The K557E variant is a non-conservative amino acid substitution, which is likely to impact secondary protein structure as these residues differ in polarity, charge, size and/or other properties. This substitution occurs at a position that is conserved across species, and in silico analysis predicts this variant is probably damaging to the protein structure/function. Furthermore, in vitro functional analysis of the KCNQ1-associated potassium channel showed that, in the presence of K557E, there was a decrease in current density, a voltage-right shift of channel activation, a faster current decline, and a weaker interaction with the KCNE1-associated protein, as compared to wild-type (Heijman et al., 2012, Spätjens et al., 2014, Dvir et al., 2014). -

Long QT syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 05, 2020

For these reasons, this variant has been classified as Pathogenic. This variant has been reported to affect KCNQ1 protein function (PMID: 25139741, 25037568). This variant has been observed in individual(s) with long QT syndrome (PMID: 25139741, 12402336). In at least one individual the variant was observed to be de novo. It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 67047). This variant is not present in population databases (ExAC no frequency). This sequence change replaces lysine with glutamic acid at codon 557 of the KCNQ1 protein (p.Lys557Glu). The lysine residue is highly conserved and there is a small physicochemical difference between lysine and glutamic acid. -

Cardiovascular phenotype Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Feb 12, 2024

The p.K557E pathogenic mutation (also known as c.1669A>G), located in coding exon 13 of the KCNQ1 gene, results from an A to G substitution at nucleotide position 1669. The lysine at codon 557 is replaced by glutamic acid, an amino acid with similar properties. This variant was observed to co-segregate with long QT syndrome in eight relatives in a four-generation family (Jongbloed R et al. Hum Mutat. 2002;20(5):382-91; Spätjens RL et al Cardiovasc Res. 2014;104(1):216-25). In a study of long QT syndrome clinical genetic testing, this alteration was reported in one patient (Kapplinger JD et al. Heart Rhythm. 2009;6(9):1297-303). Additionally, in vitro functional analyses indicated this variant adversely affects the voltage-gated potassium ion channel, resulting in decreased current density, prolongation of the channel activation threshold, and accelerated channel deactivation (Dvir M et al. J Cell Sci. 2014;127(Pt18):3943-55; Spätjens RL et al Cardiovasc Res. 2014;104(1):216-25). This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Based on the supporting evidence, this alteration is interpreted as a disease-causing mutation. -

Congenital long QT syndrome Other:1

not provided, no classification provided

literature only

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

-

This variant has been reported as associated with Long QT syndrome in the following publications (PMID:12402336;PMID:19716085). 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	1.0
BayesDel_addAF	Pathogenic	0.55	D
BayesDel_noAF	Pathogenic	0.55
CADD	Pathogenic	30
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.99	D;.;.
Eigen	Pathogenic	0.75
Eigen_PC	Uncertain	0.65
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	D;D;D
M_CAP	Pathogenic	0.90	D
MetaRNN	Pathogenic	0.98	D;D;D
MetaSVM	Pathogenic	0.96	D
MutationAssessor	Pathogenic	3.0	M;.;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Pathogenic	0.80	T
PROVEAN	Uncertain	-3.5	D;.;D
REVEL	Pathogenic	0.95
Sift	Pathogenic	0.0	D;.;D
Sift4G	Uncertain	0.0030	D;.;D
Polyphen		1.0	D;.;D
Vest4		0.97
MutPred		0.88		Loss of MoRF binding (P = 6e-04);.;.;
MVP		0.98
MPC		1.4
ClinPred		1.0	D
GERP RS		3.8
Varity_R		0.92
gMVP		0.98

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

Other links and lift over

dbSNP: rs199472801; hg19: chr11-2797268;