rs199473549

Positions:

• chr7-150958094-C-A

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The ENST00000262186.10(KCNH2):​c.881G>T​(p.Gly294Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000176 in 1,135,536 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. G294R) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000018 (0 hom.)
• Consequence: KCNH2 ENST00000262186.10 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2 O:1
• Conservation: PhyloP100: 0.442

Genes affected

KCNH2 (HGNC:6251): (potassium voltage-gated channel subfamily H member 2) This gene encodes a component of a voltage-activated potassium channel found in cardiac muscle, nerve cells, and microglia. Four copies of this protein interact with one copy of the KCNE2 protein to form a functional potassium channel. Mutations in this gene can cause long QT syndrome type 2 (LQT2). Transcript variants encoding distinct isoforms have been identified. [provided by RefSeq, May 2022]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCNH2	NM_000238.4	c.881G>T	p.Gly294Val	missense_variant	4/15	ENST00000262186.10	NP_000229.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KCNH2	ENST00000262186.10	c.881G>T	p.Gly294Val	missense_variant	4/15	1	NM_000238.4	ENSP00000262186	P1
KCNH2	ENST00000532957.5	n.1104G>T		non_coding_transcript_exon_variant	4/9	2
KCNH2	ENST00000684241.1	n.1714G>T		non_coding_transcript_exon_variant	2/13

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000176 AC: 2 AN: 1135536 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 542114

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000105

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2 Other:1

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

Nov 01, 2023

This sequence change replaces glycine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 294 of the KCNH2 protein (p.Gly294Val). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with clinical features of KCNH2-related conditions (PMID: 15913580). ClinVar contains an entry for this variant (Variation ID: 67539). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be tolerated. Experimental studies have shown that this missense change does not substantially affect KCNH2 function (PMID: 29752375). 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. -

Short QT syndrome type 1;C3150943:Long QT syndrome 2 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Fulgent Genetics, Fulgent Genetics

Jul 20, 2021

- -

SUDDEN INFANT DEATH SYNDROME Other:1

not provided, no classification provided

literature only

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

-

This variant has been reported as associated with Sudden infant death syndrome in the following publications (PMID:15913580). 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	Benign	0.14
BayesDel_addAF	Pathogenic	0.23	D
BayesDel_noAF	Uncertain	0.090
CADD	Benign	22
DANN	Benign	0.97
DEOGEN2	Benign	0.39	T;T
Eigen	Benign	-0.37
Eigen_PC	Benign	-0.29
FATHMM_MKL	Benign	0.13	N
LIST_S2	Benign	0.80	T;T
M_CAP	Pathogenic	0.54	D
MetaRNN	Uncertain	0.47	T;T
MetaSVM	Uncertain	0.52	D
MutationAssessor	Benign	0.0	N;.
MutationTaster	Benign	0.59	N;N;N
PrimateAI	Pathogenic	0.92	D
PROVEAN	Benign	-1.8	N;.
REVEL	Uncertain	0.64
Sift	Uncertain	0.0090	D;.
Sift4G	Benign	0.20	T;T
Polyphen		0.15	B;.
Vest4		0.41
MutPred		0.42		Loss of loop (P = 0.0603);.;
MVP		0.92
MPC		1.7
ClinPred		0.25	T
GERP RS		3.4
Varity_R		0.27
gMVP		0.65

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: rs199473549; hg19: chr7-150655182;