21-34370504-A-T

Variant names:

• chr21-34370504-A-T
• rs758038035
• NM_172201.2:c.26A>T

Variant summary

Our verdict is Likely benign. The variant received -4 ACMG points: 2P and 6B. PM2 BP4_Moderate BS2

The NM_172201.2(KCNE2):​c.26A>T​(p.Gln9Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000342 in 1,461,888 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 17/22 in silico tools predict a benign 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. Q9E) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000034 (0 hom.)
• Consequence: KCNE2 NM_172201.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.20

Genes affected

KCNE2 (HGNC:6242): (potassium voltage-gated channel subfamily E regulatory subunit 2) Voltage-gated potassium (Kv) channels represent the most complex class of voltage-gated ion channels from both functional and structural standpoints. Their diverse functions include regulating neurotransmitter release, heart rate, insulin secretion, neuronal excitability, epithelial electrolyte transport, smooth muscle contraction, and cell volume. This gene encodes a member of the potassium channel, voltage-gated, isk-related subfamily. This member is a small integral membrane subunit that assembles with the KCNH2 gene product, a pore-forming protein, to alter its function. This gene is expressed in heart and muscle and the gene mutations are associated with cardiac arrhythmia. [provided by RefSeq, Jul 2008]

ENSG00000225555 (HGNC:):

ACMG classification

Our verdict: Likely_benign. The variant received -4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.109643996).
• BS2: High AC in GnomAdExome4 at 5 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNE2	NM_172201.2	c.26A>T	p.Gln9Leu	missense_variant	Exon 2 of 2	ENST00000290310.4	NP_751951.1
LOC105372791	NR_188571.1	n.783T>A		non_coding_transcript_exon_variant	Exon 2 of 3
LOC105372791	NR_188572.1	n.783T>A		non_coding_transcript_exon_variant	Exon 2 of 2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNE2	ENST00000290310.4	c.26A>T	p.Gln9Leu	missense_variant	Exon 2 of 2	1	NM_172201.2	ENSP00000290310.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000342 AC: 5 AN: 1461888 Hom.: 0 Cov.: 31 AF XY: 0.00000550 AC XY: 4 AN XY: 727244

African (AFR) AF: 0.00 AC: 0 AN: 33478

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000450 AC: 5 AN: 1112008

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Long QT syndrome 6 Uncertain:1

Dec 13, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glutamine, which is neutral and polar, with leucine, which is neutral and non-polar, at codon 9 of the KCNE2 protein (p.Gln9Leu). 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. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. 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 tolerated. This variant has not been reported in the literature in individuals affected with KCNE2-related conditions. This variant is not present in population databases (gnomAD no frequency). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.10
BayesDel_addAF	Benign	-0.039	T
BayesDel_noAF	Benign	-0.29
CADD	Benign	11
DANN	Benign	0.72
DEOGEN2	Benign	0.26	T
Eigen	Benign	-0.85
Eigen_PC	Benign	-0.73
FATHMM_MKL	Benign	0.14	N
LIST_S2	Benign	0.49	T
M_CAP	Benign	0.041	D
MetaRNN	Benign	0.11	T
MetaSVM	Benign	-0.68	T
MutationAssessor	Benign	1.7	L
PhyloP100		1.2
PrimateAI	Benign	0.27	T
PROVEAN	Benign	0.38	N
REVEL	Benign	0.16
Sift	Benign	0.26	T
Sift4G	Benign	0.43	T
Polyphen		0.0	B
Vest4		0.15
MutPred		0.50		Loss of disorder (P = 0.09);
MVP		0.74
MPC		0.10
ClinPred		0.11	T
GERP RS		3.2
Varity_R		0.059
gMVP		0.86
Mutation Taster		=69/31	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.11		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

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Other links and lift over

dbSNP: rs758038035; hg19: chr21-35742803;