11-2583477-A-G

Position:

• chr11-2583477-A-G

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_000218.3(KCNQ1):​c.964A>G​(p.Thr322Ala) 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 Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T322K) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: KCNQ1 NM_000218.3 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6 O:1
• Conservation: PhyloP100: 6.95

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 18 ACMG points.

• PM1: In a topological_domain Extracellular (size 6) in uniprot entity KCNQ1_HUMAN there are 10 pathogenic changes around while only 0 benign (100%) in NM_000218.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr11-2583478-C-A is described in Lovd as [Pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.986
• PP5: Variant 11-2583477-A-G is Pathogenic according to our data. Variant chr11-2583477-A-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 53149.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr11-2583477-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.964A>G	p.Thr322Ala	missense_variant	7/16	ENST00000155840.12	NP_000209.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KCNQ1	ENST00000155840.12	c.964A>G	p.Thr322Ala	missense_variant	7/16	1	NM_000218.3	ENSP00000155840.2
KCNQ1	ENST00000335475.6	c.583A>G	p.Thr195Ala	missense_variant	7/16	1		ENSP00000334497.5
KCNQ1	ENST00000496887.7	c.703A>G	p.Thr235Ala	missense_variant	8/16	5		ENSP00000434560.2
KCNQ1	ENST00000646564.2	c.520A>G	p.Thr174Ala	missense_variant	3/11			ENSP00000495806.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:6 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Mayo Clinic Laboratories, Mayo Clinic	Apr 14, 2022	PP3, PM2, PS3, PS4 -
Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Jan 07, 2022	Not observed at significant frequency in large population cohorts (gnomAD); Published functional studies demonstrate a damaging effect as this variant results in suppression of the potassium current (Burgess et al., 2012; Rothenberg et al., 2016); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Reported in ClinVar as a pathogenic variant (ClinVar Variant ID# 53149); This variant is associated with the following publications: (PMID: 24269949, 15851119, 15840476, 23092362, 19815527, 19716085, 22949429, 12877697, 22199116, 19841300, 15466642, 28491751, 31737537, 32383558, 30219255) -

Long QT syndrome Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Oct 25, 2022	This variant disrupts the p.Thr322 amino acid residue in KCNQ1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 16414944, 17470695, 18400097, 19716085, 23092362). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. Experimental studies have shown that this missense change affects KCNQ1 function (PMID: 23092362, 28491751). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt KCNQ1 protein function. ClinVar contains an entry for this variant (Variation ID: 53149). This missense change has been observed in individuals with long QT syndrome (LQTS) (PMID: 19716085, 22949429, 23092362). It has also been observed to segregate with disease in related individuals. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces threonine, which is neutral and polar, with alanine, which is neutral and non-polar, at codon 322 of the KCNQ1 protein (p.Thr322Ala). -
Pathogenic, criteria provided, single submitter	clinical testing	All of Us Research Program, National Institutes of Health	Jun 07, 2024	The c.964A>G (p.Thr322Ala) variant in the KCNQ1 gene replaces threonine with alanine in codon 322. This variant has been reported in individuals with long QT syndrome (PMID: 29884292, 15840476, 12877697 , 15466642, 19716085, 22199116, 23631430, 19841300, 18452873). Functional data indicates a deleterious impact of this variant on protein function (PMID: 21320432, 20399767). This variant is absent in the general population database, gnomAD. Computational evidence suggests that this missense variant is expected to disrupt KCNQ1 protein function (REVEL 0.974). Other variants that disrupt this amino acid have been interpreted as pathogenic (ClinVar ID: 53151, 200830). ClinVar contains an entry for this variant (Variation ID: 53149 ). Based on the available evidence, the c.964A>G (p.Thr322Ala) variant of KCNQ1 is classified as pathogenic. -

Long QT syndrome 1 Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Center For Human Genetics And Laboratory Diagnostics, Dr. Klein, Dr. Rost And Colleagues

May 16, 2020

- -

Cardiovascular phenotype Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

May 28, 2023

The p.T322A variant (also known as c.964A>G), located in coding exon 7 of the KCNQ1 gene, results from an A to G substitution at nucleotide position 964. The threonine at codon 322 is replaced by alanine, an amino acid with similar properties, and is located in the transmembrane spanning pore/S6 region of the protein. This alteration has been reported in individuals with long QT syndrome (Nemec J et al. Pacing Clin Electrophysiol, 2003 Aug;26:1660-7; Choi G et al. Circulation, 2004 Oct;110:2119-24; Tester DJ et al. Heart Rhythm, 2005 May;2:507-17; Kapa S et al. Circulation, 2009 Nov;120:1752-60; Kapplinger JD et al. Heart Rhythm, 2009 Sep;6:1297-303; Giudicessi JR et al. Circ Cardiovasc Genet, 2012 Oct;5:519-28; Marschall C et al. Cardiovasc Diagn Ther, 2019 Oct;9:S292-S298; Westphal DS et al. Mol Genet Genomic Med, 2020 09;8:e1300). Additionally, in vitro studies suggest that this alteration results in abnormal protein function (Burgess DE et al. Biochemistry, 2012 Nov;51:9076-85). 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 majority of available evidence to date, this variant is likely to be pathogenic. -

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:12877697;PMID:15466642;PMID:15840476;PMID:19716085;PMID:19841300). 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	0.93
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.57
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.99	D;.;.
Eigen	Pathogenic	0.73
Eigen_PC	Uncertain	0.63
FATHMM_MKL	Uncertain	0.77	D
LIST_S2	Uncertain	0.88	D;D;D
M_CAP	Pathogenic	0.86	D
MetaRNN	Pathogenic	0.99	D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.4	M;.;.
PrimateAI	Uncertain	0.73	T
PROVEAN	Pathogenic	-4.5	D;.;D
REVEL	Pathogenic	0.97
Sift	Uncertain	0.0010	D;.;D
Sift4G	Uncertain	0.0040	D;.;D
Polyphen		1.0	D;.;D
Vest4		0.90
MutPred		0.93		Gain of catalytic residue at T322 (P = 0.0065);.;.;
MVP		0.98
MPC		1.1
ClinPred		1.0	D
GERP RS		3.9
Varity_R		0.94
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

Other links and lift over

dbSNP: rs199472754; hg19: chr11-2604707;