11-2572105-G-T

Position:

• chr11-2572105-G-T

Variant summary

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

The ENST00000155840.12(KCNQ1):​c.776G>T​(p.Arg259Leu) 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 Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R259H) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: KCNQ1 ENST00000155840.12 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3 O:1
• Conservation: PhyloP100: 9.14

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 hotspot region, there are 9 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 11 uncertain in ENST00000155840.12
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr11-2572104-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 53100.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.989
• PP5: Variant 11-2572105-G-T is Pathogenic according to our data. Variant chr11-2572105-G-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 53102.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr11-2572105-G-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCNQ1	NM_000218.3	c.776G>T	p.Arg259Leu	missense_variant	5/16	ENST00000155840.12	NP_000209.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KCNQ1	ENST00000155840.12	c.776G>T	p.Arg259Leu	missense_variant	5/16	1	NM_000218.3	ENSP00000155840	P1
KCNQ1	ENST00000335475.6	c.395G>T	p.Arg132Leu	missense_variant	5/16	1		ENSP00000334497
KCNQ1	ENST00000496887.7	c.515G>T	p.Arg172Leu	missense_variant	6/16	5		ENSP00000434560
KCNQ1	ENST00000646564.2	c.478-11330G>T		intron_variant				ENSP00000495806

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1457986 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 725428

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/Likely 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

Sep 08, 2022

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 22949429, 23392653, 31737537, 22456477, 21185501, 25525159, 28483220, 19490272, 25929701, 15466642, 18752142, 19841300, 15840476, 19716085, 26675252) -

Long QT syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 31, 2024

This sequence change replaces arginine, which is basic and polar, with leucine, which is neutral and non-polar, at codon 259 of the KCNQ1 protein (p.Arg259Leu). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individuals with long QT syndrome (PMID: 15466642, 19490272, 19841300, 23392653, 26675252). ClinVar contains an entry for this variant (Variation ID: 53102). 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%. This variant disrupts the p.Arg259 amino acid residue in KCNQ1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 11021476, 16922724, 21350584, 23158531, 24291113, 26346102). 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. -

Cardiovascular phenotype Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Nov 30, 2022

The p.R259L variant (also known as c.776G>T), located in coding exon 5 of the KCNQ1 gene, results from a G to T substitution at nucleotide position 776. The arginine at codon 259 is replaced by leucine, an amino acid with dissimilar properties. This variant has been previously reported in a case indicated as having clinically "definite" long QT syndrome (LQTS), and has also been reported in multiple unrelated individuals referred for long QT syndrome (LQTS) genetic testing, although in some cases clinical details were limited and some reports may overlap (Choi G et al. Circulation. 2004;110(15):2119-24; Tester DJ et al. Heart Rhythm. 2005;2(5):507-17; Berge KE et al. Scand J Clin Lab Invest. 2008;68(5):362-8; Jons C et al. J Cardiovasc Electrophysiol. 2009;20(8):859-65; Kapa S et al. Circulation. 2009;120(18):1752-60). This variant was also reported in an individual with LQTS who carried a second KCNQ1 alteration (Giudicessi JR et al. Circ Cardiovasc Genet. 2013;6(2):193-200). This variant co-occurred in trans with a second KCNQ1 alteration in an individual with Jervell and Lange-Nielsen syndrome (Torrado M et al. NPJ Genom Med. 2021 Mar;6(1):21). In addition, another alteration affecting this amino acid (p.R259H, c.776G>A) has also been reported in association with LQTS (Millat G et al. Clin Genet. 2006;70(3):214-27). 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:15466642;PMID:15840476;PMID:18752142;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	0.99
BayesDel_addAF	Pathogenic	0.53	D
BayesDel_noAF	Pathogenic	0.52
CADD	Pathogenic	29
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.98	.;D;.
Eigen	Uncertain	0.57
Eigen_PC	Uncertain	0.50
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Pathogenic	0.98	D;D;D
M_CAP	Pathogenic	0.96	D
MetaRNN	Pathogenic	0.99	D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Benign	2.0	.;M;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Pathogenic	0.83	D
PROVEAN	Pathogenic	-6.9	D;D;D
REVEL	Pathogenic	0.95
Sift	Uncertain	0.0070	D;D;D
Sift4G	Uncertain	0.0070	D;D;D
Polyphen		0.98, 0.99	.;D;D
Vest4		0.94, 0.94
MutPred		0.91		.;Loss of helix (P = 0.0304);.;
MVP		0.98
MPC		1.3
ClinPred		0.99	D
GERP RS		4.0
Varity_R		0.89
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: rs199472720; hg19: chr11-2593335;