21-34449393-T-C

Variant names:

• chr21-34449393-T-C
• rs199473359
• NM_000219.6:c.242A>G

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM1 PM2 PP3_Moderate

The NM_000219.6(KCNE1):​c.242A>G​(p.Tyr81Cys) 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 Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. Y81S) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 18)
• Consequence: KCNE1 NM_000219.6 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3 O:1
• Conservation: PhyloP100: 6.81
• Publications: 10 publications found

Genes affected

KCNE1 (HGNC:6240): (potassium voltage-gated channel subfamily E regulatory subunit 1) The product of this gene belongs to the potassium channel KCNE family. Potassium ion channels are essential to many cellular functions and show a high degree of diversity, varying in their electrophysiologic and pharmacologic properties. This gene encodes a transmembrane protein known to associate with the product of the KVLQT1 gene to form the delayed rectifier potassium channel. Mutation in this gene are associated with both Jervell and Lange-Nielsen and Romano-Ward forms of long-QT syndrome. Alternatively spliced transcript variants encoding the same protein have been identified. [provided by RefSeq, Jul 2008]

KCNE1 Gene-Disease associations (from GenCC):

• long QT syndrome 5

  Inheritance: AD Classification: DEFINITIVE, STRONG, LIMITED Submitted by: ClinGen, G2P, Labcorp Genetics (formerly Invitae), Ambry Genetics
• Jervell and Lange-Nielsen syndrome 2

  Inheritance: AR Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P, PanelApp Australia
• Jervell and Lange-Nielsen syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• atrial fibrillation

  Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics

ACMG classification

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 2 benign, 108 uncertain in NM_000219.6
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.933

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNE1	NM_000219.6	c.242A>G	p.Tyr81Cys	missense_variant	Exon 4 of 4	ENST00000399286.3	NP_000210.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNE1	ENST00000399286.3	c.242A>G	p.Tyr81Cys	missense_variant	Exon 4 of 4	1	NM_000219.6	ENSP00000382226.2

Frequencies

GnomAD3 genomes Cov.: 18

GnomAD2 exomes AF: 0.00000795 AC: 2 AN: 251436 AF XY: 0.0000147

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000109

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 18

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000189

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:1

Aug 23, 2019

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Published functional studies suggest a dominant negative effect (Wu et al., 2006); Reported in ClinVar as a variant of uncertain significance but additional evidence is not available (ClinVar Variant ID# 132671; Landrum et al., 2016); In silico analysis, which includes protein predictors and evolutionary conservation, supports a deleterious effect; Not observed at a significant frequency in large population cohorts (Lek et al., 2016); This variant is associated with the following publications: (PMID: 16945797, 22581653, 16945798, 24710009, 17341399, 16155735, 30530868) -

Long QT syndrome Uncertain:1

Sep 01, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces tyrosine with cysteine at codon 81 of the KCNE1 protein (p.Tyr81Cys). The tyrosine residue is highly conserved and there is a large physicochemical difference between tyrosine and cysteine. This variant is not present in population databases (ExAC no frequency). This missense change has been observed in individual(s) with long QT syndrome (PMID: 16155735). ClinVar contains an entry for this variant (Variation ID: 132671). 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. Experimental studies have shown that this missense change affects KCNE1 function (PMID: 16945797). 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. -

Cardiovascular phenotype Uncertain:1

Aug 13, 2019

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.242A>G (p.Y81C) alteration is located in exon 3 (coding exon 1) of the KCNE1 gene. This alteration results from a A to G substitution at nucleotide position 242, causing the tyrosine (Y) at amino acid position 81 to be replaced by a cysteine (C). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Congenital long QT syndrome Other:1

-

Cardiovascular Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

This variant has been reported as associated with Long QT syndrome in the following publications (PMID:16155735;PMID:16945797). 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	0.87
BayesDel_addAF	Pathogenic	0.27	D
BayesDel_noAF	Pathogenic	0.49
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.95	D;D;D;D;D;D;D;D
Eigen	Pathogenic	0.69
Eigen_PC	Uncertain	0.58
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Benign	0.85	.;.;D;.;.;.;.;.
M_CAP	Uncertain	0.22	D
MetaRNN	Pathogenic	0.93	D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Uncertain	2.8	M;M;M;M;M;M;M;M
PhyloP100		6.8
PrimateAI	Uncertain	0.77	T
PROVEAN	Pathogenic	-8.4	D;.;.;D;D;D;D;D
REVEL	Pathogenic	0.92
Sift	Pathogenic	0.0	D;.;.;D;D;D;D;D
Sift4G	Pathogenic	0.0	D;D;D;D;D;D;D;D
Polyphen		1.0	D;D;D;D;D;D;D;D
Vest4		0.93
MutPred		0.68		Loss of phosphorylation at Y81 (P = 0.0215);Loss of phosphorylation at Y81 (P = 0.0215);Loss of phosphorylation at Y81 (P = 0.0215);Loss of phosphorylation at Y81 (P = 0.0215);Loss of phosphorylation at Y81 (P = 0.0215);Loss of phosphorylation at Y81 (P = 0.0215);Loss of phosphorylation at Y81 (P = 0.0215);Loss of phosphorylation at Y81 (P = 0.0215);
MVP		0.93
MPC		0.48
ClinPred		1.0	D
GERP RS		5.2
Varity_R		0.40
gMVP		0.96
Mutation Taster		=0/100	disease causing

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

Other links and lift over

dbSNP: rs199473359; hg19: chr21-35821691;