rs794728494

Positions:

• chr7-150974783-C-A
• chr7-150974783-C-G
• chr7-150974783-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM1 PM2

The NM_000238.4(KCNH2):​c.235G>T​(p.Ala79Ser) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 34)
• Consequence: KCNH2 NM_000238.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.146

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 4 ACMG points.

• PM1: In a helix (size 11) in uniprot entity KCNH2_HUMAN there are 7 pathogenic changes around while only 0 benign (100%) in NM_000238.4
• 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.235G>T	p.Ala79Ser	missense_variant	2/15	ENST00000262186.10	NP_000229.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KCNH2	ENST00000262186.10	c.235G>T	p.Ala79Ser	missense_variant	2/15	1	NM_000238.4	ENSP00000262186	P1
KCNH2	ENST00000532957.5	n.458G>T		non_coding_transcript_exon_variant	2/9	2

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 34

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Long QT syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Mar 18, 2017

This variant identified in the KCNH2 gene is located in the cytoplasmic N-terminal region of the resulting protein (PMID: 19841300, 25348405). For more information about the location of this variant, please visit www.invitae.com/KCNH2-topology. It is unclear how this variant impacts the function of this protein. In summary, this variant is a novel missense change that is not predicted to affect protein function. There is no indication that it causes disease, but the available evidence is currently insufficient to prove that conclusively. Therefore, it has been classified as a Variant of Uncertain Significance. 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, but these predictions have not been confirmed by published functional studies. This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with a KCNH2-related disease. This sequence change replaces alanine with serine at codon 79 of the KCNH2 protein (p.Ala79Ser). The alanine residue is weakly conserved and there is a moderate physicochemical difference between alanine and serine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.11
BayesDel_addAF	Uncertain	0.080	D
BayesDel_noAF	Benign	-0.12
CADD	Pathogenic	27
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.68	D;D
Eigen	Benign	-0.44
Eigen_PC	Benign	-0.34
FATHMM_MKL	Benign	0.76	D
LIST_S2	Uncertain	0.94	D;D
M_CAP	Pathogenic	0.98	D
MetaRNN	Uncertain	0.60	D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Benign	0.57	N;.
MutationTaster	Benign	0.72	D;D
PrimateAI	Pathogenic	0.85	D
PROVEAN	Benign	-1.2	N;.
REVEL	Uncertain	0.48
Sift	Uncertain	0.0050	D;.
Sift4G	Uncertain	0.036	D;D
Polyphen		0.0	B;.
Vest4		0.50
MutPred		0.46		Gain of phosphorylation at A79 (P = 0.0427);.;
MVP		0.63
MPC		1.0
ClinPred		0.75	D
GERP RS		4.4
Varity_R		0.45
gMVP		0.91

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: rs794728494; hg19: chr7-150671871;