rs199472707

Variant names:

• chr11-2571397-C-T
• rs199472707
• NM_000218.3:c.677C>T

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1 PM2 PP3_Strong

The NM_000218.3(KCNQ1):​c.677C>T​(p.Ala226Val) variant causes a missense change involving the alteration of a conserved nucleotide. 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 Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: not found (cov: 33)
• Consequence: KCNQ1 NM_000218.3 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:3 O:1
• Conservation: PhyloP100: 7.47

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 Likely_pathogenic. Variant got 8 ACMG points.

• PM1: In a transmembrane_region Helical; Voltage-sensor; Name=Segment S4 (size 22) in uniprot entity KCNQ1_HUMAN there are 26 pathogenic changes around while only 0 benign (100%) in NM_000218.3
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.983

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNQ1	NM_000218.3	c.677C>T	p.Ala226Val	missense_variant	Exon 4 of 16	ENST00000155840.12	NP_000209.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNQ1	ENST00000155840.12	c.677C>T	p.Ala226Val	missense_variant	Exon 4 of 16	1	NM_000218.3	ENSP00000155840.2
KCNQ1	ENST00000335475.6	c.296C>T	p.Ala99Val	missense_variant	Exon 4 of 16	1		ENSP00000334497.5
KCNQ1	ENST00000496887.7	c.416C>T	p.Ala139Val	missense_variant	Exon 5 of 16	5		ENSP00000434560.2
KCNQ1	ENST00000646564.2	c.478-12038C>T		intron_variant	Intron 2 of 10			ENSP00000495806.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:3 Other:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Long QT syndrome Uncertain:2

Mar 05, 2024

All of Us Research Program, National Institutes of Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Apr 15, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces alanine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 226 of the KCNQ1 protein (p.Ala226Val). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with long QT syndrome (PMID: 15234419, 24606995; Invitae). ClinVar contains an entry for this variant (Variation ID: 67097). 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 with a positive predictive value of 95%. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Cardiovascular phenotype Pathogenic:1

Sep 02, 2022

Ambry Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.A226V variant (also known as c.677C>T), located in coding exon 4 of the KCNQ1 gene, results from a C to T substitution at nucleotide position 677. The alanine at codon 226 is replaced by valine, an amino acid with similar properties. This alteration has been detected in several individuals with long QT syndrome (LQTS) (Shimizu W et al. J. Am. Coll. Cardiol., 2004 Jul;44:117-25; Horigome H et al. Circ Arrhythm Electrophysiol, 2011 Aug;4:456-64; Jons C et al. J. Cardiovasc. Electrophysiol., 2009 Aug;20:859-65; Christiansen M et al. BMC Med. Genet., 2014 Mar;15:31). 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. -

not provided Uncertain:1

Nov 01, 2017

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

A variant of uncertain significance has been identified in the KCNQ1 gene. The A226V variant has been reported in association with LQTS (Moss et al., 2007); however, additional clinical information was not provided. Additionally, this variant has been reported in patients with fetal arrhythmia who did not have a definitive diagnosis of LQTS (Mitchell et al., 2012; Cuneo et al., 2013). The A226V variant is not observed in large population cohorts (Lek et al., 2016). Located in the voltage sensor S4 domain, this substitution occurs at a position that is conserved across species. In silico analysis predicts this variant is probably damaging to the protein structure/function. However, the A226V variant is a conservative amino acid substitution, which is not likely to impact secondary protein structure as these residues share similar properties. -

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:15234419;PMID:17470695). 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	Uncertain	0.50
BayesDel_addAF	Pathogenic	0.51	D
BayesDel_noAF	Pathogenic	0.49
CADD	Uncertain	26
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.97	.;D;.
Eigen	Uncertain	0.50
Eigen_PC	Uncertain	0.48
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.98	D;D;D
M_CAP	Pathogenic	0.83	D
MetaRNN	Pathogenic	0.98	D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Benign	1.1	.;L;.
PrimateAI	Pathogenic	0.85	D
PROVEAN	Uncertain	-3.9	D;D;D
REVEL	Pathogenic	0.94
Sift	Uncertain	0.0040	D;D;D
Sift4G	Uncertain	0.026	D;D;D
Polyphen		1.0	.;D;.
Vest4		0.95, 0.91
MutPred		0.85		.;Loss of sheet (P = 0.0063);.;
MVP		0.98
MPC		1.2
ClinPred		0.99	D
GERP RS		4.3
Varity_R		0.74
gMVP		0.95

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: rs199472707; hg19: chr11-2592627; COSMIC: COSV50129661;