chr11-2662023-G-A

Position:

• chr11-2662023-G-A

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 0P and 2B. BP4_Moderate

The NM_000218.3(KCNQ1):​c.1456G>A​(p.Ala486Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000171 in 1,461,882 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.000017 (0 hom.)
• Consequence: KCNQ1 NM_000218.3 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:7 B:1
• Conservation: PhyloP100: 2.39

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]

KCNQ1OT1 (HGNC:6295): (KCNQ1 opposite strand/antisense transcript 1) Human chromosomal region 11p15.5 contains two clusters of epigenetically-regulated genes that are expressed from only one chromosome in a parent-of-origin manner. Each cluster, or imprinted domain, is regulated by a functionally independent imprinting control region (ICR). The human CDKN1C/KCNQ1OT1 domain is regulated by an ICR located in an intron of KCNQ1, and contains at least eight genes that are expressed exclusively or preferentially from the maternally-inherited allele. The DNA of the ICR is specifically methylated on the maternally-inherited chromosome, and unmethylated on the paternally-inherited chromosome. The ICR contains the promoter of the KCNQ1OT1 gene that is exclusively expressed from the paternal allele. The KCNQ1OT1 transcript is the antisense to the KCNQ1 gene and is a unspliced long non-coding RNA. It interacts with chromatin and regulates transcription of multiple target genes through epigenetic modifications. The transcript is abnormally expressed from both chromosomes in most patients with Beckwith-Wiedemann syndrome, and the transcript also plays an important role in colorectal carcinogenesis. [provided by RefSeq, Apr 2012]

ACMG classification

Verdict is Likely_benign. Variant got -2 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.14065948).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCNQ1	NM_000218.3	c.1456G>A	p.Ala486Thr	missense_variant	11/16	ENST00000155840.12	NP_000209.2
KCNQ1OT1	NR_002728.3	n.37976C>T		non_coding_transcript_exon_variant	1/1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KCNQ1	ENST00000155840.12	c.1456G>A	p.Ala486Thr	missense_variant	11/16	1	NM_000218.3	ENSP00000155840	P1
KCNQ1OT1	ENST00000710656.1	n.376-20908C>T		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.0000358 AC: 9 AN: 251412 Hom.: 0 AF XY: 0.0000294 AC XY: 4 AN XY: 135886

Gnomad AFR exome AF: 0.0000615

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad SAS exome AF: 0.000196

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000880

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000171 AC: 25 AN: 1461882 Hom.: 0 Cov.: 34 AF XY: 0.0000193 AC XY: 14 AN XY: 727242

Gnomad4 AFR exome AF: 0.0000597

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000756

Gnomad4 SAS exome AF: 0.0000812

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000899

Gnomad4 OTH exome AF: 0.0000331

GnomAD4 genome Cov.: 33

Alfa AF: 0.0000761 Hom.: 0

Bravo AF: 0.0000189

ExAC AF: 0.0000412 AC: 5

EpiCase AF: 0.000109

EpiControl AF: 0.00

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:7 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Mar 05, 2021	- -
Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Oct 29, 2019	In silico analysis, which includes protein predictors and evolutionary conservation, supports that this variant does not alter protein structure/function; Has not been previously published as pathogenic or benign to our knowledge -

Long QT syndrome Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	All of Us Research Program, National Institutes of Health	Aug 28, 2023	This missense variant replaces alanine with threonine at codon 486 of the KCNQ1 protein. Computational prediction is inconclusive regarding the impact of this variant on protein structure and function (internally defined REVEL score threshold 0.5 < inconclusive < 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has not been reported in individuals affected with cardiovascular disorders in the literature. This variant has been identified in 9/251412 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -
Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jan 25, 2024	This sequence change replaces alanine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 486 of the KCNQ1 protein (p.Ala486Thr). This variant is present in population databases (rs753256800, gnomAD 0.02%). This variant has not been reported in the literature in individuals affected with KCNQ1-related conditions. ClinVar contains an entry for this variant (Variation ID: 925996). 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 not expected to disrupt KCNQ1 protein function with a negative predictive value of 80%. 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. -

Beckwith-Wiedemann syndrome;C1837014:Atrial fibrillation, familial, 3;C1865019:Short QT syndrome type 2;C4551509:Jervell and Lange-Nielsen syndrome 1;C4551647:Long QT syndrome 1 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Fulgent Genetics, Fulgent Genetics

Dec 03, 2021

- -

KCNQ1-related disorder Uncertain:1

Uncertain significance, no assertion criteria provided

clinical testing

PreventionGenetics, part of Exact Sciences

Mar 26, 2024

The KCNQ1 c.1456G>A variant is predicted to result in the amino acid substitution p.Ala486Thr. To our knowledge, this variant has not been reported in the literature. This variant is reported in 0.020% of alleles in individuals of South Asian descent in gnomAD. At this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

Cardiac arrhythmia Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Color Diagnostics, LLC DBA Color Health

Jan 23, 2023

This missense variant replaces alanine with threonine at codon 486 of the KCNQ1 protein. Computational prediction is inconclusive regarding the impact of this variant on protein structure and function (internally defined REVEL score threshold 0.5 < inconclusive < 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has not been reported in individuals affected with cardiovascular disorders in the literature. This variant has been identified in 9/251412 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -

Cardiovascular phenotype Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Ambry Genetics

May 20, 2024

This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.078
BayesDel_addAF	Benign	-0.034	T
BayesDel_noAF	Uncertain	-0.010
CADD	Benign	17
DANN	Benign	0.91
DEOGEN2	Benign	0.34	T;.;.
Eigen	Benign	-0.81
Eigen_PC	Benign	-0.80
FATHMM_MKL	Benign	0.43	N
LIST_S2	Benign	0.80	T;T;T
M_CAP	Pathogenic	0.35	D
MetaRNN	Benign	0.14	T;T;T
MetaSVM	Pathogenic	0.98	D
MutationAssessor	Benign	1.0	L;.;.
MutationTaster	Benign	1.0	N;N
PrimateAI	Benign	0.47	T
PROVEAN	Benign	-0.29	N;.;N
REVEL	Uncertain	0.53
Sift	Benign	0.12	T;.;T
Sift4G	Benign	0.40	T;.;T
Polyphen		0.083	B;.;B
Vest4		0.20
MVP		0.89
MPC		0.39
ClinPred		0.032	T
GERP RS		1.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.031
gMVP		0.37

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: rs753256800; hg19: chr11-2683253;