chr7-150951802-G-A

Variant names:

• chr7-150951802-G-A
• rs199472915
• NM_000238.4:c.1591C>T

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PM1 PM2 PM5 PP3_Strong PP5

The NM_000238.4(KCNH2):​c.1591C>T​(p.Arg531Trp) variant causes a missense change. The variant allele was found at a frequency of 0.000000695 in 1,439,356 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R531Q) has been classified as Pathogenic.

• Frequency:
  • Genomes: not found (cov: 34)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: KCNH2 NM_000238.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:6 U:1 O:1
• Conservation: PhyloP100: 5.26

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 Pathogenic. Variant got 11 ACMG points.

• PM1: In a transmembrane_region Helical; Voltage-sensor; Name=Segment S4 (size 20) in uniprot entity KCNH2_HUMAN there are 5 pathogenic changes around while only 0 benign (100%) in NM_000238.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr7-150951801-C-T is described in Lovd as [Pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.991
• PP5: Variant 7-150951802-G-A is Pathogenic according to our data. Variant chr7-150951802-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 67218.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=4, Uncertain_significance=1, Pathogenic=2, not_provided=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNH2	NM_000238.4	c.1591C>T	p.Arg531Trp	missense_variant	Exon 7 of 15	ENST00000262186.10	NP_000229.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNH2	ENST00000262186.10	c.1591C>T	p.Arg531Trp	missense_variant	Exon 7 of 15	1	NM_000238.4	ENSP00000262186.5

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome AF: 6.95e-7 AC: 1 AN: 1439356 Hom.: 0 Cov.: 36 AF XY: 0.00 AC XY: 0 AN XY: 712158

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: 9.11e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 34

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:6 Uncertain:1 Other:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Long QT syndrome 2 Pathogenic:2

Sep 21, 2024

Victorian Clinical Genetics Services, Murdoch Childrens Research Institute

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as Pathogenic. Following criteria are met: 0103 - Dominant negative and loss of function are known mechanisms of disease in this gene and are associated with Long QT syndrome 2 (MIM#613688). Gain of function is also a known mechanism associated with Short QT syndrome 1 (MIM#609620) (OMIM, PMID: 10753933, 21777565). (I) 0107 - This gene is associated with autosomal dominant disease. (I) 0112 - The condition associated with this gene has incomplete penetrance (PMID: 20301308). (I) 0200 - Variant is predicted to result in a missense amino acid change from arginine to tryptophan. (I) 0251 - This variant is heterozygous. (I) 0301 - Variant is absent from gnomAD (both v2 and v3). (SP) 0501 - Missense variant consistently predicted to be damaging by multiple in silico tools or highly conserved with a major amino acid change. (SP) 0602 - Variant is located in a hotspot region or cluster of pathogenic variants (DECIPHER). (SP) 0704 - Another missense variant comparable to the one identified in this case has limited previous evidence for pathogenicity. An alternative change to a glutamine has been reported in an individual with LQTS (PMID: 10973849). (SP) 0801 -This variant has strong previous evidence of pathogenicity in unrelated individuals. It has been reported in multiple individuals with LQTS (PMID: 19716085, 25967940, 28532774, 32893267, 35911527) and sudden death cases (PMID: 19804510; 35091851). In addition, it has been classified as likely pathogenic/pathogenic in ClinVar, including one VUS classification dated 2020. (SP) 0905 - No published segregation evidence has been identified for this variant. (I) 1002 - This variant has moderate functional evidence supporting abnormal protein function. Functional studies have demonstrated altered channel current activation and inactivation (PMID: 16166152, 23546015). (SP) 1208 - Inheritance information for this variant is not currently available in this individual. (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -

May 16, 2023

Illumina Laboratory Services, Illumina

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The KCNH2 c.1591C>T (p.Arg531Trp) missense variant has been identified in four individuals with a phenotype consistent with long QT syndrome (LQTS) and in two individuals with sudden cardiac death (PMID: 19716085; 19804510; 23631430; 28532774; 35091851). Additionally, a different amino acid substitution at the same codon (p.Arg531Gln) has been reported in an individual with LQTS (PMID: 10973849). This variant is not observed in version 2.1.1 or version 3.1.2 of the Genome Aggregation Database. The p.Arg531Trp variant is located in the transmembrane segment 4 domain that contains several highly conserved arginine residues that are important for normal Kv11.1 gating. A functional study conducted in human cell lines demonstrated that this variant dramatically altered Kv11.1 gating (PMID: 23546015). Based on the available evidence, the c.1591C>T (p.Arg531Trp) variant is classified as likely pathogenic for long QT syndrome. -

not provided Pathogenic:2

Jun 27, 2024

GeneDx

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Identified in multiple unrelated patients with LQTS or sudden cardiac death referred for genetic testing at GeneDx and in the published literature (PMID: 35091851, 19716085, 19804510, 28532774); Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 22581653, 26105569, 28532774, 19804510, 23631430, 23980196, 25417810, 25967940, 16166152, 23546015, 36525500, 35091851, 19716085, 32893267) -

Jul 15, 2018

Mayo Clinic Laboratories, Mayo Clinic

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

PM1, PS4_moderate, PM2_supporting, PP3, PP2, PS3_supporting -

Long QT syndrome Pathogenic:2

Sep 03, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

For these reasons, this variant has been classified as Pathogenic. Experimental studies have shown that this missense change affects KCNH2 function (PMID: 23546015). 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. ClinVar contains an entry for this variant (Variation ID: 67218). This missense change has been observed in individuals with long QT syndrome (PMID: 19716085, 28532774; Invitae). It has also been observed to segregate with disease in related individuals. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces arginine, which is basic and polar, with tryptophan, which is neutral and slightly polar, at codon 531 of the KCNH2 protein (p.Arg531Trp). -

Sep 16, 2024

All of Us Research Program, National Institutes of Health

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This missense variant replaces arginine with tryptophan at codon 531 of the KCNH2 protein. This variant is found within the highly conserved transmembrane S4 domain (a.a. 521-541). Rare nontruncating variants in this region have been shown to be significantly overrepresented in individuals with long QT syndrome (PMID: 32893267). Functional studies have shown that this variant causes trafficking deficiency in cardiomyocytes differentiated from human induced pluripotent stem cells (hiPSCs) and impairs potassium channel function in several in vitro cell systems (PMID: 16166152, 23546015, 36525500). This variant has been reported in at least seven unrelated individuals affected with or suspected of having long QT syndrome (PMID: 19716085, 19804510, 23631430, 28532774, 32893267, Clinvar SCV000827271.5) and in another individual affected with sudden cardiac death (PMID: 35091851). This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). Based on the available evidence, this variant is classified as Likely Pathogenic. -

not specified Uncertain:1

Nov 02, 2020

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: KCNH2 c.1591C>T (p.Arg531Trp) results in a non-conservative amino acid change located in the Ion transport domain (S4 domain, Kapplinger_2009) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 238752 control chromosomes (gnomAD and publication data). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.1591C>T has been reported in the literature in individuals affected with Long QT syndrome (Kapplinger_2009, Schmitt_2009, Lieve_2013, Ebbrahim_2017). These reports do not provide unequivocal conclusions about association of the variant with Arrhythmia. Functional studies report this variant altered channel current activation and inactivation (Subbiah_2005, McBride_2013). One ClinVar submitter (evaluation after 2014) cites the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Congenital long QT syndrome Other:1

-

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

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

This variant has been reported as associated with Long QT syndrome in the following publications (PMID:19716085). 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	0.56	D
BayesDel_noAF	Pathogenic	0.56
CADD	Pathogenic	29
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.99	.;D;D
Eigen	Pathogenic	0.79
Eigen_PC	Uncertain	0.63
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Pathogenic	1.0	D;D;D
M_CAP	Pathogenic	0.96	D
MetaRNN	Pathogenic	0.99	D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	4.3	.;H;.
PrimateAI	Pathogenic	0.90	D
PROVEAN	Pathogenic	-7.7	D;D;.
REVEL	Pathogenic	0.95
Sift	Pathogenic	0.0	D;D;.
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		1.0	D;D;.
Vest4		0.97
MutPred		0.94		.;Gain of catalytic residue at L529 (P = 0.011);.;
MVP		1.0
MPC		2.2
ClinPred		1.0	D
GERP RS		4.1
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.96
gMVP		1.0

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: rs199472915; hg19: chr7-150648890; COSMIC: COSV51226669;