rs76420733

chr7-150947821-G-Achr7-150947821-G-C

Variant summary

Our verdict is Likely benign. Variant got -6 ACMG points: 0P and 6B. BP4_Moderate BS2

The NM_000238.4(KCNH2):c.2750C>T(p.Pro917Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000315 in 1,526,048 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. P917P) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.000053 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000029 (0 hom.)
• Consequence: KCNH2 NM_000238.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:8 B:1 O:1
• Conservation: PhyloP100: 0.0840

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 Likely_benign. Variant got -6 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.20010555).
• BS2: High AC in GnomAd at 8 AD,Digenic gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
KCNH2	NM_000238.4	c.2750C>T	p.Pro917Leu	missense_variant	12/15	ENST00000262186.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KCNH2	ENST00000262186.10	c.2750C>T	p.Pro917Leu	missense_variant	12/15	1	NM_000238.4	P1
KCNH2	ENST00000330883.9	c.1730C>T	p.Pro577Leu	missense_variant	8/11	1
KCNH2	ENST00000684241.1	n.3583C>T		non_coding_transcript_exon_variant	10/13

Frequencies

GnomAD3 genomes AF: 0.0000526 AC: 8 AN: 152046 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000483

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000655

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000735

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000569 AC: 7 AN: 122966 Hom.: 0 AF XY: 0.0000893 AC XY: 6 AN XY: 67184

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000860

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.000167

Gnomad NFE exome AF: 0.0000660

Gnomad OTH exome AF: 0.000263

GnomAD4 exome AF: 0.0000291 AC: 40 AN: 1374002 Hom.: 0 Cov.: 36 AF XY: 0.0000354 AC XY: 24 AN XY: 677108

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.000204

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.0000568

Gnomad4 NFE exome AF: 0.0000261

Gnomad4 OTH exome AF: 0.0000524

GnomAD4 genome AF: 0.0000526 AC: 8 AN: 152046 Hom.: 0 Cov.: 33 AF XY: 0.0000404 AC XY: 3 AN XY: 74266

Gnomad4 AFR AF: 0.0000483

Gnomad4 AMR AF: 0.0000655

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000735

Gnomad4 OTH AF: 0.00

Bravo AF: 0.0000453

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:8 Benign:1 Other:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not specified Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Jun 23, 2016	Variant identified in a genome or exome case(s) and assessed due to predicted null impact of the variant or pathogenic assertions in the literature or databases. Disclaimer: This variant has not undergone full assessment. The following are preliminary notes: Reported in 2 probands but also found in controls - Multiple reports question pathogenicity; ClinVar: 2 VUS -
Uncertain significance, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Jun 15, 2020	Variant summary: KCNH2 c.2750C>T (p.Pro917Leu) results in a non-conservative amino acid change in the encoded protein sequence. Three of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 8e-05 in 124454 control chromosomes. This frequency is not significantly higher than expected for a pathogenic variant in KCNH2 causing Arrhythmia (8e-05 vs 0.0001), allowing no conclusion about variant significance. c.2750C>T has been reported in the literature in individuals affected with Arrhythmia (Splawski_2000, Moss_2002, Shimizu_2009). These report(s) do not provide unequivocal conclusions about association of the variant with Arrhythmia. At least one publication reports experimental evidence evaluating an impact on protein function. These results showed no damaging effect of this variant (Jou_2013). Five clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation (likely benign n=1, VUS n=4). Based on the evidence outlined above, the variant was classified as VUS-possibly benign. -

Long QT syndrome Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Invitae	Nov 02, 2023	This sequence change replaces proline, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 917 of the KCNH2 protein (p.Pro917Leu). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This missense change has been observed in individual(s) with Long QT syndrome (PMID: 10973849, 11854117, 19926013). ClinVar contains an entry for this variant (Variation ID: 67432). Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Not Available"; PolyPhen-2: "Benign"; Align-GVGD: "Not Available". The leucine amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect protein function. Experimental studies have shown that this missense change does not substantially affect KCNH2 function (PMID: 23303164). 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. -
Uncertain significance, criteria provided, single submitter	clinical testing	All of Us Research Program, National Institutes of Health	Feb 05, 2024	This missense variant replaces proline with leucine at codon 917 of the KCNH2 protein. Computational prediction is inconclusive regarding the impact of this variant on protein structure and function (internally defined REVEL score threshold 0.5 < inconclusive < 0.7, PMID: 27666373). Splice site prediction tools suggest that this variant may not impact RNA splicing. A functional study has shown that this variant does not alter the channel function in zebrafish cardiac assay (PMID: 23303164). This variant has been reported in two individuals affected with long QT syndrome (PMID: 10973849, 11854117), as well as in unaffected controls (PMID: 17161064, 19841300). This variant has been identified in 7/122966 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -

not provided Uncertain:1 Other:1

Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Nov 02, 2023	In silico analysis supports that this missense variant does not alter protein structure/function; This variant is associated with the following publications: (PMID: 19841300, 14661677, 11854117, 22949429, 31493592, 17161064, 23303164, 19926013, 10973849) -
not provided, no classification provided	literature only	Cardiovascular Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust	-	This variant has been reported in the following publications (PMID:10973849;PMID:11854117;PMID:14661677;PMID:17161064;PMID:19841300). -

Long QT syndrome 2 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Apr 27, 2017

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). Publications were found based on this search. However, the evidence from the literature, in combination with allele frequency data from public databases where available, was not sufficient to rule this variant in or out of causing disease. Therefore, this variant is classified as a variant of unknown 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

Aug 04, 2021

- -

Cardiac arrhythmia Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Color Diagnostics, LLC DBA Color Health

Feb 23, 2023

This missense variant replaces proline with leucine at codon 917 of the KCNH2 protein. Computational prediction is inconclusive regarding the impact of this variant on protein structure and function (internally defined REVEL score threshold 0.5 < inconclusive < 0.7, PMID: 27666373). A functional study has shown that this variant does not alter the channel function in zebrafish cardiac assay (PMID: 23303164). This variant has been reported in two individuals affected with long QT syndrome (PMID: 10973849, 11854117), as well as in unaffected controls (PMID: 17161064, 19841300). This variant has been identified in 7/122966 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -

Cardiovascular phenotype Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Jul 11, 2018

This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.079
CardioboostArm	Benign	0.00030
BayesDel_addAF	Pathogenic	0.25	D
BayesDel_noAF	Uncertain	0.12
Cadd	Benign	20
Dann	Uncertain	0.99
Eigen	Benign	-0.76
Eigen_PC	Benign	-0.64
FATHMM_MKL	Benign	0.36	N
LIST_S2	Benign	0.72	T;T
M_CAP	Uncertain	0.15	D
MetaRNN	Benign	0.20	T;T
MetaSVM	Uncertain	0.0066	D
MutationTaster	Benign	1.0	N;N;N
PrimateAI	Uncertain	0.53	T
PROVEAN	Benign	-1.7	N;N
REVEL	Uncertain	0.56
Sift	Benign	0.30	T;T
Sift4G	Benign	0.11	T;T
Polyphen		0.0	B;B
Vest4		0.21
MutPred		0.76		.;Loss of glycosylation at P917 (P = 0.0342);
MVP		0.99
MPC		0.18
ClinPred		0.030	T
GERP RS		1.0
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.071
gMVP		0.71

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: rs76420733; hg19: chr7-150644909;