11-2777002-G-C

Position:

• chr11-2777002-G-C

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PS1 PM1 PM2 PM5 PP3_Strong PP5_Moderate

The NM_000218.3(KCNQ1):​c.1702G>C​(p.Gly568Arg) 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. 13/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★). Another nucleotide change resulting in same amino acid change has been previously reported as Pathogenicin Lovd. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G568A) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: KCNQ1 NM_000218.3 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 7.70

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.

• PS1: Transcript NM_000218.3 (KCNQ1) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in Lovd
• 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
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr11-2777003-G-C is described in Lovd as [Pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.991
• PP5: Variant 11-2777002-G-C is Pathogenic according to our data. Variant chr11-2777002-G-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 570319.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCNQ1	NM_000218.3	c.1702G>C	p.Gly568Arg	missense_variant	14/16	ENST00000155840.12	NP_000209.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KCNQ1	ENST00000155840.12	c.1702G>C	p.Gly568Arg	missense_variant	14/16	1	NM_000218.3	ENSP00000155840	P1
KCNQ1	ENST00000335475.6	c.1321G>C	p.Gly441Arg	missense_variant	14/16	1		ENSP00000334497
KCNQ1	ENST00000496887.7	c.1345G>C	p.Gly449Arg	missense_variant	14/16	5		ENSP00000434560
KCNQ1	ENST00000646564.2	c.1162G>C	p.Gly388Arg	missense_variant	9/11			ENSP00000495806

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Long QT syndrome Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Feb 20, 2018

This sequence change replaces glycine with arginine at codon 568 of the KCNQ1 protein (p.Gly568Arg). The glycine residue is highly conserved and there is a moderate physicochemical difference between glycine and arginine. This variant is not present in population databases (ExAC no frequency). This variant has been reported to segregate with long QT syndrome in a family and has been reported in individuals with this condition (PMID: 23392653, 22456477). Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C15"). In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. Other missense substitutions at this codon (p.Gly568Glu and p.Gly568Ala) have been reported in individuals affected with long QT syndrome (PMID: 27041096, 12702160). A different variant (c.1702G>A) giving rise to the same protein effect observed here (p.Gly568Arg) has been reported in an individual affected with long QT syndrome (PMID: 22956155). This suggests that the glycine residue is critical for KCNQ1 protein function. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.57
CADD	Pathogenic	29
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.98	D;.;.
Eigen	Pathogenic	0.73
Eigen_PC	Uncertain	0.63
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.95	D;D;D
M_CAP	Pathogenic	0.89	D
MetaRNN	Pathogenic	0.99	D;D;D
MetaSVM	Pathogenic	0.86	D
MutationAssessor	Pathogenic	3.0	M;.;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Pathogenic	0.80	T
PROVEAN	Pathogenic	-7.0	D;.;D
REVEL	Pathogenic	0.94
Sift	Pathogenic	0.0	D;.;D
Sift4G	Pathogenic	0.0	D;.;D
Polyphen		0.99	D;.;D
Vest4		0.85
MutPred		0.95		Gain of MoRF binding (P = 0.0073);.;.;
MVP		0.97
MPC		1.3
ClinPred		1.0	D
GERP RS		4.0
Varity_R		0.91
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: rs199472807; hg19: chr11-2798232;