rs199473420

Positions:

• chr7-150974807-C-A
• chr7-150974807-C-G
• chr7-150974807-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM2 PM5 PP3_Strong

The NM_000238.4(KCNH2):​c.211G>T​(p.Gly71Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic 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. G71R) has been classified as 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: 2.67

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 Likely_pathogenic. Variant got 8 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr7-150974807-C-G is described in Lovd as [Pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.942

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCNH2	NM_000238.4	c.211G>T	p.Gly71Trp	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.211G>T	p.Gly71Trp	missense_variant	2/15	1	NM_000238.4	ENSP00000262186.5
KCNH2	ENST00000532957.5	n.434G>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 12, 2022

This missense change has been observed in individuals with long QT syndrome (PMID: 26496715, 29497013; Invitae). 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. This variant disrupts the p.Gly71 amino acid residue in KCNH2. Other variant(s) that disrupt this residue have been observed in individuals with KCNH2-related conditions (PMID: 23631430), which suggests that this may be a clinically significant amino acid residue. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). ClinVar contains an entry for this variant (Variation ID: 853484). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glycine, which is neutral and non-polar, with tryptophan, which is neutral and slightly polar, at codon 71 of the KCNH2 protein (p.Gly71Trp). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.54	D
BayesDel_noAF	Pathogenic	0.54
CADD	Pathogenic	33
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.98	D;D
Eigen	Pathogenic	0.68
Eigen_PC	Uncertain	0.50
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Pathogenic	1.0	D;D
M_CAP	Pathogenic	0.98	D
MetaRNN	Pathogenic	0.94	D;D
MetaSVM	Pathogenic	0.96	D
MutationAssessor	Pathogenic	4.5	H;.
PrimateAI	Pathogenic	0.95	D
PROVEAN	Pathogenic	-5.4	D;.
REVEL	Pathogenic	0.86
Sift	Pathogenic	0.0	D;.
Sift4G	Pathogenic	0.0	D;D
Polyphen		1.0	D;.
Vest4		0.79
MutPred		0.69		Loss of disorder (P = 0.0361);.;
MVP		1.0
MPC		2.3
ClinPred		1.0	D
GERP RS		4.4
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: rs199473420; hg19: chr7-150671895;