NM_000238.4:c.1700T>C

Variant names:

• chr7-150951693-A-G
• rs199473519
• NM_000238.4:c.1700T>C

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1 PM2 PP3_Strong

The NM_000238.4(KCNH2):​c.1700T>C​(p.Ile567Thr) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,820 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 Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 34)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: KCNH2 NM_000238.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2 O:1
• Conservation: PhyloP100: 7.17

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 Likely_pathogenic. Variant got 8 ACMG points.

• PM1: In a transmembrane_region Helical; Name=Segment S5 (size 20) in uniprot entity KCNH2_HUMAN there are 14 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, 0.986

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNH2	NM_000238.4	c.1700T>C	p.Ile567Thr	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.1700T>C	p.Ile567Thr	missense_variant	Exon 7 of 15	1	NM_000238.4	ENSP00000262186.5

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461820 Hom.: 0 Cov.: 34 AF XY: 0.00000138 AC XY: 1 AN XY: 727222

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: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 34

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Long QT syndrome Uncertain:1

Oct 30, 2020

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. This variant has been observed in individuals affected with long QT syndrome (PMID: 19862833, 23158531, Invitae). ClinVar contains an entry for this variant (Variation ID: 67241). This variant is not present in population databases (ExAC no frequency). This sequence change replaces isoleucine with threonine at codon 567 of the KCNH2 protein (p.Ile567Thr). The isoleucine residue is highly conserved and there is a moderate physicochemical difference between isoleucine and threonine. -

Cardiovascular phenotype Uncertain:1

Jan 14, 2019

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.1700T>C (p.I567T) alteration is located in exon 7 (coding exon 7) of the KCNH2 gene. This alteration results from a T to C substitution at nucleotide position 1700, causing the isoleucine (I) at amino acid position 567 to be replaced by a threonine (T). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

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:19862833). 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	0.99
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.58
CADD	Uncertain	26
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.97	.;D;D
Eigen	Pathogenic	0.70
Eigen_PC	Uncertain	0.59
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Pathogenic	0.98	D;D;D
M_CAP	Pathogenic	0.96	D
MetaRNN	Pathogenic	0.99	D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.5	.;H;.
PrimateAI	Pathogenic	0.86	D
PROVEAN	Pathogenic	-4.9	D;D;.
REVEL	Pathogenic	0.92
Sift	Pathogenic	0.0	D;D;.
Sift4G	Pathogenic	0.0010	D;D;D
Polyphen		1.0	D;D;.
Vest4		0.96
MutPred		0.87		.;Loss of stability (P = 0.0219);.;
MVP		0.99
MPC		2.4
ClinPred		1.0	D
GERP RS		3.2
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.90
gMVP		0.96

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: rs199473519; hg19: chr7-150648781;