21-34449414-G-C

Position:

• chr21-34449414-G-C

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM2 PM5 PP3

The NM_000219.6(KCNE1):​c.221C>G​(p.Ser74Trp) 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 Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. S74A) has been classified as Benign.

• Frequency: Genomes: not found (cov: 17)
• Consequence: KCNE1 NM_000219.6 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 8.49

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 5 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr21-34449414-G-A is described in Lovd as [Pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.818

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCNE1	NM_000219.6	c.221C>G	p.Ser74Trp	missense_variant	4/4	ENST00000399286.3	NP_000210.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KCNE1	ENST00000399286.3	c.221C>G	p.Ser74Trp	missense_variant	4/4	1	NM_000219.6	ENSP00000382226	P1

Frequencies

GnomAD3 genomes Cov.: 17

GnomAD4 exome Cov.: 29

GnomAD4 genome Cov.: 17

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Long QT syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 28, 2023

This variant is not present in population databases (gnomAD no frequency). 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. 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 expected to disrupt KCNE1 protein function. ClinVar contains an entry for this variant (Variation ID: 409231). This variant has not been reported in the literature in individuals affected with KCNE1-related conditions. This sequence change replaces serine, which is neutral and polar, with tryptophan, which is neutral and slightly polar, at codon 74 of the KCNE1 protein (p.Ser74Trp). -

Cardiovascular phenotype Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Dec 21, 2020

The p.S74W variant (also known as c.221C>G), located in coding exon 1 of the KCNE1 gene, results from a C to G substitution at nucleotide position 221. The serine at codon 74 is replaced by tryptophan, an amino acid with highly dissimilar properties. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.80
BayesDel_addAF	Pathogenic	0.38	D
BayesDel_noAF	Pathogenic	0.42
CADD	Uncertain	26
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.94	D;D;D;D;D;D;D;D
Eigen	Pathogenic	0.75
Eigen_PC	Uncertain	0.66
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.89	.;.;D;.;.;.;.;.
M_CAP	Pathogenic	0.36	D
MetaRNN	Pathogenic	0.82	D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Uncertain	2.8	M;M;M;M;M;M;M;M
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D;D;D;D;D
PrimateAI	Uncertain	0.69	T
PROVEAN	Pathogenic	-5.0	D;.;.;D;D;D;D;D
REVEL	Pathogenic	0.84
Sift	Uncertain	0.0010	D;.;.;D;D;D;D;D
Sift4G	Pathogenic	0.0010	D;D;D;D;D;D;D;D
Polyphen		1.0	D;D;D;D;D;D;D;D
Vest4		0.58
MutPred		0.50		Loss of disorder (P = 0);Loss of disorder (P = 0);Loss of disorder (P = 0);Loss of disorder (P = 0);Loss of disorder (P = 0);Loss of disorder (P = 0);Loss of disorder (P = 0);Loss of disorder (P = 0);
MVP		0.97
MPC		0.50
ClinPred		1.0	D
GERP RS		5.2
Varity_R		0.72
gMVP		0.75

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: rs74315446; hg19: chr21-35821712;