rs199472710

Positions:

• chr11-2572033-T-A

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.704T>A​(p.Ile235Asn) 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 (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I235V) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: KCNQ1 NM_000218.3 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:2 O:1
• Conservation: PhyloP100: 5.80

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 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
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr11-2572032-A-G is described in Lovd as [Likely_pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.984
• PP5: Variant 11-2572033-T-A is Pathogenic according to our data. Variant chr11-2572033-T-A is described in ClinVar as [Pathogenic]. Clinvar id is 53088.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr11-2572033-T-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCNQ1	NM_000218.3	c.704T>A	p.Ile235Asn	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.704T>A	p.Ile235Asn	missense_variant	5/16	1	NM_000218.3	ENSP00000155840.2
KCNQ1	ENST00000335475.6	c.323T>A	p.Ile108Asn	missense_variant	5/16	1		ENSP00000334497.5
KCNQ1	ENST00000496887.7	c.443T>A	p.Ile148Asn	missense_variant	6/16	5		ENSP00000434560.2
KCNQ1	ENST00000646564.2	c.478-11402T>A		intron_variant				ENSP00000495806.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Long QT syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Feb 18, 2022

For these reasons, this variant has been classified as Pathogenic. Experimental studies have shown that this missense change affects KCNQ1 function (PMID: 19590188, 24269949). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive. ClinVar contains an entry for this variant (Variation ID: 53088). This missense change has been observed in individuals with long QT syndrome (PMID: 18452873, 22949429, 24269949). 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 isoleucine, which is neutral and non-polar, with asparagine, which is neutral and polar, at codon 235 of the KCNQ1 protein (p.Ile235Asn). -

Cardiac arrhythmia Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Aug 31, 2021

Variant summary: KCNQ1 c.704T>A (p.Ile235Asn) results in a non-conservative amino acid change located in the Ion transport domain (IPR005821; voltage sensor transmembrane domain S4 in Henrion_2009) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 248876 control chromosomes (gnomAD). c.704T>A has been reported in the literature in multiple individuals affected with Long QT Syndrome as well as ten individuals with concealed LQT1 in one family (Choi_2004, Johnson_2008, Bartos_2013). These data indicate that the variant is very likely to be associated with disease. Functional studies report experimental evidence evaluating an impact on protein function and this variant effect results in reducing KCNQ1 channel currents in a dominant-negative manner and impaired Protein Kinase A response of slow delayed rectifier potassium channels. One ClinVar submitter (evaluation after 2014) cites the variant as pathogenic. Based on the evidence outlined above, the variant was classified as 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:19590188;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	1.0
BayesDel_addAF	Pathogenic	0.39	D
BayesDel_noAF	Pathogenic	0.32
CADD	Pathogenic	27
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.99	.;D;.
Eigen	Uncertain	0.53
Eigen_PC	Uncertain	0.44
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	1.0	D;D;D
M_CAP	Pathogenic	0.93	D
MetaRNN	Pathogenic	0.98	D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.1	.;M;.
PrimateAI	Pathogenic	0.91	D
PROVEAN	Pathogenic	-6.7	D;D;D
REVEL	Pathogenic	0.95
Sift	Pathogenic	0.0	D;D;D
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		0.98, 0.68	.;D;P
Vest4		0.98
MutPred		0.89		.;Gain of methylation at R231 (P = 0.0409);.;
MVP		1.0
MPC		1.4
ClinPred		1.0	D
GERP RS		4.2
Varity_R		0.97
gMVP		1.0

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: rs199472710; hg19: chr11-2593263;