rs794728522

Positions:

• chr11-2583538-T-A
• chr11-2583538-T-C

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PM1 PM2 PM5 PP3_Strong PP5

The NM_000218.3(KCNQ1):​c.1025T>A​(p.Leu342His) 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). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. L342F) has been classified as Pathogenic.

• 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:1
• Conservation: PhyloP100: 7.52

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 11 ACMG points.

• PM1: In a helix (size 19) in uniprot entity KCNQ1_HUMAN there are 35 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 chr11-2583537-C-T is described in Lovd as [Pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.984
• PP5: Variant 11-2583538-T-A is Pathogenic according to our data. Variant chr11-2583538-T-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 405269.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCNQ1	NM_000218.3	c.1025T>A	p.Leu342His	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.1025T>A	p.Leu342His	missense_variant	7/16	1	NM_000218.3	ENSP00000155840	P1
KCNQ1	ENST00000335475.6	c.644T>A	p.Leu215His	missense_variant	7/16	1		ENSP00000334497
KCNQ1	ENST00000496887.7	c.764T>A	p.Leu255His	missense_variant	8/16	5		ENSP00000434560
KCNQ1	ENST00000646564.2	c.581T>A	p.Leu194His	missense_variant	3/11			ENSP00000495806

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 33

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Cardiovascular phenotype Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Dec 28, 2020

The p.L342H variant (also known as c.1025T>A), located in coding exon 7 of the KCNQ1 gene, results from a T to A substitution at nucleotide position 1025. The leucine at codon 342 is replaced by histidine, an amino acid with similar properties, and is located in the S6 transmembrane region. Another likely pathogenic variant affecting this codon (p.L342F, c.1024C>T) has been reported in association with long QT syndrome (Donger C et al. Circulation. 1997;96:2778-81; Hedley PL et al. Cardiovasc J Afr. 2013;24:231-7). Based on internal structural analysis, p.L342H is predicted to destabilize the local protein structure. This variant was not reported in population-based 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. -

Long QT syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jun 12, 2017

In summary, this variant is a novel missense change with uncertain impact on protein function. It has been classified as a Variant of Uncertain Significance. 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, but these predictions have not been confirmed by published functional studies. This variant identified in the KCNQ1 gene is located in the transmembrane S6 region of the resulting protein (PMID: 19841300, 25348405). For more information about the location of this variant, please visit www.invitae.com/KCNQ1-topology. It is unclear how this variant impacts the function of this protein. This variant has not been reported in the literature in individuals with a KCNQ1-related disease. ClinVar contains an entry for this variant (Variation ID: 405269). This variant is not present in population databases (ExAC no frequency). This sequence change replaces leucine with histidine at codon 342 of the KCNQ1 protein (p.Leu342His). The leucine residue is highly conserved and there is a moderate physicochemical difference between leucine and histidine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.59
CADD	Pathogenic	32
DANN	Uncertain	0.98
DEOGEN2	Pathogenic	0.99	D;.;.
Eigen	Pathogenic	0.76
Eigen_PC	Uncertain	0.63
FATHMM_MKL	Uncertain	0.78	D
LIST_S2	Uncertain	0.88	D;D;D
M_CAP	Pathogenic	0.97	D
MetaRNN	Pathogenic	0.98	D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.9	H;.;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Pathogenic	0.89	D
PROVEAN	Pathogenic	-6.6	D;.;D
REVEL	Pathogenic	0.97
Sift	Pathogenic	0.0	D;.;D
Sift4G	Pathogenic	0.0	D;.;D
Polyphen		1.0	D;.;D
Vest4		0.96
MutPred		0.85		Loss of stability (P = 0.0159);.;.;
MVP		1.0
MPC		1.3
ClinPred		1.0	D
GERP RS		3.9
Varity_R		0.99
gMVP		0.97

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: rs794728522; hg19: chr11-2604768;