7-150974822-A-G

Variant names:

• chr7-150974822-A-G
• rs199473416
• NM_000238.4:c.196T>C

Variant summary

Our verdict is Pathogenic. The variant received 11 ACMG points: 11P and 0B. PM1 PM2 PM5 PP2 PP3_Strong

The NM_000238.4(KCNH2):​c.196T>C​(p.Cys66Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 14/23 in silico tools predict a damaging outcome for this variant. 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. C66Y) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 34)
• Consequence: KCNH2 NM_000238.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 9.13
• Publications: 13 publications found

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 Gene-Disease associations (from GenCC):

• long QT syndrome

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• long QT syndrome 2

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, G2P
• short QT syndrome

  Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: Orphanet, ClinGen
• short QT syndrome type 1

  Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE Submitted by: Labcorp Genetics (formerly Invitae), G2P, Ambry Genetics
• Brugada syndrome

  Inheritance: AD Classification: MODERATE, NO_KNOWN Submitted by: ClinGen, Genomics England PanelApp

ACMG classification

Our verdict: Pathogenic. The variant received 11 ACMG points.

• PM1: In a hotspot region, there are 16 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 18 uncertain 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 chr7-150974821-C-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 545688.
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 158 curated pathogenic missense variants (we use a threshold of 10). The gene has 38 curated benign missense variants. Gene score misZ: 3.3724 (above the threshold of 3.09). Trascript score misZ: 2.4846 (below the threshold of 3.09). GenCC associations: The gene is linked to long QT syndrome 2, Brugada syndrome, short QT syndrome type 1, short QT syndrome, long QT syndrome.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.973

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNH2	NM_000238.4	c.196T>C	p.Cys66Arg	missense_variant	Exon 2 of 15	ENST00000262186.10	NP_000229.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNH2	ENST00000262186.10	c.196T>C	p.Cys66Arg	missense_variant	Exon 2 of 15	1	NM_000238.4	ENSP00000262186.5
KCNH2	ENST00000713710.1	c.196T>C	p.Cys66Arg	missense_variant	Exon 2 of 15			ENSP00000519013.1
KCNH2	ENST00000532957.5	n.419T>C		non_coding_transcript_exon_variant	Exon 2 of 9	2
KCNH2	ENST00000713700.1	n.154T>C		non_coding_transcript_exon_variant	Exon 2 of 9

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

Aug 03, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant identified in the KCNH2 gene is located in the cytoplasmic PAS region of the resulting protein (PMID: 19841300). 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. This sequence change replaces cysteine with arginine at codon 66 of the KCNH2 protein (p.Cys66Arg). The cysteine residue is weakly conserved and there is a large physicochemical difference between cysteine and arginine. 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. A different missense substitution at this codon (p.Cys66Gly) has been determined to be pathogenic (PMID: 11854117, 25417810, 10973849, 23303164, 10187793). This suggests that the cysteine residue is critical for KCNH2 protein function and that other missense substitutions at this position may also be pathogenic. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). In summary, this variant is a rare missense change that affects a residue required for adequate protein function, which is suggestive of pathogenicity. However, the available evidence is currently insufficient to prove that conclusively. Therefore, it has been classified as a Variant of Uncertain Significance.

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
CardioboostArm	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.57
CADD	Pathogenic	32
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.99	D;D
Eigen	Pathogenic	0.75
Eigen_PC	Uncertain	0.60
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.98	D;D
M_CAP	Pathogenic	0.98	D
MetaRNN	Pathogenic	0.97	D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	4.4	H;.
PhyloP100		9.1
PrimateAI	Pathogenic	0.97	D
PROVEAN	Pathogenic	-8.1	D;.
REVEL	Pathogenic	0.89
Sift	Uncertain	0.0010	D;.
Sift4G	Pathogenic	0.0010	D;D
Vest4		0.93
ClinPred		1.0	D
GERP RS		4.4
Varity_R		0.99
gMVP		1.0
Mutation Taster		=3/97	disease causing

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

Other links and lift over

dbSNP: rs199473416; hg19: chr7-150671910;