7-150974761-A-G

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM1 PM2 PM5 PP3_Strong

The NM_000238.4(KCNH2):c.257T>C(p.Leu86Pro) 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. 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. L86R) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 34)
• Consequence: KCNH2 NM_000238.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3 O:1
• Conservation: PhyloP100: 9.04

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 10 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 15 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 chr7-150974761-A-C is described in ClinVar as [Pathogenic]. Clinvar id is 67414.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.993

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
KCNH2	NM_000238.4	c.257T>C	p.Leu86Pro	missense_variant	2/15	ENST00000262186.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KCNH2	ENST00000262186.10	c.257T>C	p.Leu86Pro	missense_variant	2/15	1	NM_000238.4	P1
KCNH2	ENST00000532957.5	n.480T>C		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:3 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Dec 31, 2020

Reported in one individual referred for LQTS genetic testing; no patient-specific data were described (Kapplinger et al., 2009); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Not observed in large population cohorts (Lek et al., 2016); This variant is associated with the following publications: (PMID: 19716085, 25417810, 22581653, 32475984) -

Long QT syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Mar 01, 2023

This variant is not present in population databases (gnomAD no frequency). This sequence change replaces leucine, which is neutral and non-polar, with proline, which is neutral and non-polar, at codon 86 of the KCNH2 protein (p.Leu86Pro). This missense change has been observed in individual(s) with KCNH2-conditions (PMID: 19716085). ClinVar contains an entry for this variant (Variation ID: 67413). 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, 32475984). 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. -

Cardiovascular phenotype Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Mar 28, 2018

The c.257T>C (p.L86P) alteration is located in exon 2 (coding exon 2) of the KCNH2 gene. This alteration results from a T to C substitution at nucleotide position 257, causing the leucine (L) at amino acid position 86 to be replaced by a proline (P). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

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: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
CardioboostArm	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.59
Cadd	Pathogenic	32
Dann	Uncertain	1.0
DEOGEN2	Pathogenic	0.98	D;D
Eigen	Uncertain	0.65
Eigen_PC	Uncertain	0.53
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.93	D;D
M_CAP	Pathogenic	0.99	D
MetaRNN	Pathogenic	0.99	D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	4.2	H;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Pathogenic	0.96	D
PROVEAN	Pathogenic	-4.5	D;.
REVEL	Pathogenic	0.96
Sift	Pathogenic	0.0	D;.
Sift4G	Pathogenic	0.0010	D;D
Polyphen		0.39	B;.
Vest4		0.94
MutPred		0.97		Gain of disorder (P = 0.0218);.;
MVP		1.0
MPC		2.5
ClinPred		1.0	D
GERP RS		4.4
Varity_R		0.99
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: rs199472851; hg19: chr7-150671849;