rs199473547

chr7-150945441-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_000238.4(KCNH2):c.3404G>A(p.Arg1135His) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000319 in 1,568,264 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. R1135C) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: KCNH2 NM_000238.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2 O:1
• Conservation: PhyloP100: 2.40

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 Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
KCNH2	NM_000238.4	c.3404G>A	p.Arg1135His	missense_variant	15/15	ENST00000262186.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KCNH2	ENST00000262186.10	c.3404G>A	p.Arg1135His	missense_variant	15/15	1	NM_000238.4	P1
KCNH2	ENST00000330883.9	c.2384G>A	p.Arg795His	missense_variant	11/11	1
KCNH2	ENST00000684241.1	n.4237G>A		non_coding_transcript_exon_variant	13/13

Frequencies

GnomAD3 genomes AF: 0.0000131 AC: 2 AN: 152134 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000241

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000212 AC: 3 AN: 1416130 Hom.: 0 Cov.: 31 AF XY: 0.00000286 AC XY: 2 AN XY: 700202

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: 0.00000276

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.0000131 AC: 2 AN: 152134 Hom.: 0 Cov.: 33 AF XY: 0.0000269 AC XY: 2 AN XY: 74320

Gnomad4 AFR AF: 0.0000241

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000843 Hom.: 0

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

AiLife Diagnostics, AiLife Diagnostics

Feb 18, 2022

- -

Long QT syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Sep 02, 2022

This sequence change replaces arginine, which is basic and polar, with histidine, which is basic and polar, at codon 1135 of the KCNH2 protein (p.Arg1135His). This variant is present in population databases (rs199473547, gnomAD 0.01%). This missense change has been observed in individual(s) with clinical features of KCNH2-related conditions (PMID: 18692916). ClinVar contains an entry for this variant (Variation ID: 67493). 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 tolerated. Experimental studies have shown that this missense change affects KCNH2 function (PMID: 18692916). 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. -

Short 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 Short QT syndrome in the following publications (PMID:18692916;PMID:19174314). 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	Uncertain	0.38
CardioboostArm	Benign	0.018
BayesDel_addAF	Pathogenic	0.38	D
BayesDel_noAF	Pathogenic	0.31
Cadd	Uncertain	24
Dann	Uncertain	1.0
Eigen	Uncertain	0.26
Eigen_PC	Uncertain	0.30
FATHMM_MKL	Uncertain	0.76	D
LIST_S2	Uncertain	0.91	D;D
M_CAP	Pathogenic	0.48	D
MetaRNN	Uncertain	0.48	T;T
MetaSVM	Pathogenic	0.87	D
MutationTaster	Benign	0.99	D;D;D
PrimateAI	Uncertain	0.74	T
PROVEAN	Benign	-0.59	N;N
REVEL	Pathogenic	0.72
Sift	Benign	0.73	T;T
Sift4G	Benign	0.38	T;T
Polyphen		1.0	D;D
Vest4		0.21
MutPred		0.75		.;Loss of sheet (P = 0.1158);
MVP		0.97
MPC		0.21
ClinPred		0.90	D
GERP RS		4.8
Varity_R		0.10
gMVP		0.54

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: rs199473547; hg19: chr7-150642529;