rs199472995

Positions:

• chr7-150950246-C-A

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM1 PM2 PP3_Strong PP5_Very_Strong

The NM_000238.4(KCNH2):​c.2320G>T​(p.Asp774Tyr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,044 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 30)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: KCNH2 NM_000238.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4 O:1
• Conservation: PhyloP100: 7.90

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]

KCNH2 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 16 ACMG points.

• PM1: In a binding_site (size 100) in uniprot entity KCNH2_HUMAN there are 17 pathogenic changes around while only 0 benign (100%) in NM_000238.4
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.994
• PP5: Variant 7-150950246-C-A is Pathogenic according to our data. Variant chr7-150950246-C-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 67385.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr7-150950246-C-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCNH2	NM_000238.4	c.2320G>T	p.Asp774Tyr	missense_variant	9/15	ENST00000262186.10	NP_000229.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KCNH2	ENST00000262186.10	c.2320G>T	p.Asp774Tyr	missense_variant	9/15	1	NM_000238.4	ENSP00000262186.5

Frequencies

GnomAD3 genomes Cov.: 30

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461044 Hom.: 0 Cov.: 39 AF XY: 0.00 AC XY: 0 AN XY: 726780

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: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 30

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Feb 08, 2019	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	GeneDx	May 10, 2017	The D774Y likely pathogenic variant in the KCNH2 gene has been reported previously in multiple unrelated patients with LQTS and has not been detected in over 1,500 reference alleles (Tester et al., 2005; Chung et al., 2007; Kapplinger et al, 2009). In addition, Obeyesekere et al. (2012), observed the D774Y variant in three individuals with a history of sudden cardiac death and prolonged end-recovery QTc.D774Y occurs in the S6/cyclic nucleotide-binding domain of the resultant protein, where many other pathogenic missense variants have been reported in association with LQTS (Stenson et al., 2014). According to the NHLBI Exome Sequencing Project, D774Y was not observed in approximately 6,500 individuals from European and African American backgrounds, indicating that it is not a common variant in these populations. In silico analysis predicts this variant is probably damaging to the protein structure/function. Nevertheless, the D774Y variant results in a conservative amino acid substitution, which is not likely to impact secondary structure as these residues share similar properties.In summary, the D774Y variant is a strong candidate to be pathogenic -

Long QT syndrome 2 Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Blueprint Genetics

Apr 20, 2015

- -

Long QT syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jul 08, 2023

This sequence change replaces aspartic acid, which is acidic and polar, with tyrosine, which is neutral and polar, at codon 774 of the KCNH2 protein (p.Asp774Tyr). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individuals with long QT syndrome (PMID: 15840476, 17905336, 22429796). ClinVar contains an entry for this variant (Variation ID: 67385). 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 disruptive. Experimental studies have shown that this missense change affects KCNH2 function (PMID: 25417810). For these reasons, this variant has been classified as Pathogenic. -

Congenital long QT 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 Long QT syndrome in the following publications (PMID:15840476;PMID:17905336;PMID:19716085;PMID:22429796). 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	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.58
CADD	Pathogenic	32
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.98	.;D;D
Eigen	Pathogenic	0.93
Eigen_PC	Pathogenic	0.81
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Pathogenic	0.99	D;D;D
M_CAP	Pathogenic	0.85	D
MetaRNN	Pathogenic	0.99	D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.3	.;H;.
PrimateAI	Uncertain	0.75	T
PROVEAN	Pathogenic	-8.8	D;D;.
REVEL	Pathogenic	0.99
Sift	Pathogenic	0.0	D;D;.
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		1.0	D;D;.
Vest4		0.98
MutPred		0.93		.;Gain of catalytic residue at L769 (P = 0.0497);.;
MVP		1.0
MPC		2.4
ClinPred		1.0	D
GERP RS		4.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.93
gMVP		0.97

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.13		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: rs199472995; hg19: chr7-150647334;