rs199472880

Positions:

• chr7-150958110-C-G
• chr7-150958110-C-T

Variant summary

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

The NM_000238.4(KCNH2):​c.865G>C​(p.Glu289Gln) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000262 in 1,144,896 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. E289K) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000026 (0 hom.)
• Consequence: KCNH2 NM_000238.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 1.69

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.865G>C	p.Glu289Gln	missense_variant	4/15	ENST00000262186.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KCNH2	ENST00000262186.10	c.865G>C	p.Glu289Gln	missense_variant	4/15	1	NM_000238.4	P1
KCNH2	ENST00000532957.5	n.1088G>C		non_coding_transcript_exon_variant	4/9	2
KCNH2	ENST00000684241.1	n.1698G>C		non_coding_transcript_exon_variant	2/13

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000262 AC: 3 AN: 1144896 Hom.: 0 Cov.: 31 AF XY: 0.00000365 AC XY: 2 AN XY: 548150

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: 0.00000313

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Long QT syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jul 17, 2023

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. 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. ClinVar contains an entry for this variant (Variation ID: 1764220). This variant has not been reported in the literature in individuals affected with KCNH2-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glutamic acid, which is acidic and polar, with glutamine, which is neutral and polar, at codon 289 of the KCNH2 protein (p.Glu289Gln). -

Cardiovascular phenotype Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Oct 25, 2023

The p.E289Q variant (also known as c.865G>C), located in coding exon 4 of the KCNH2 gene, results from a G to C substitution at nucleotide position 865. The glutamic acid at codon 289 is replaced by glutamine, an amino acid with highly similar properties. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.32
BayesDel_addAF	Pathogenic	0.27	D
BayesDel_noAF	Pathogenic	0.15
CADD	Uncertain	24
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.51	D;T
Eigen	Uncertain	0.33
Eigen_PC	Uncertain	0.33
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Uncertain	0.92	D;D
M_CAP	Pathogenic	0.95	D
MetaRNN	Uncertain	0.51	D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Benign	1.6	L;.
MutationTaster	Benign	0.99	D;D;D
PrimateAI	Pathogenic	0.95	D
PROVEAN	Benign	-1.3	N;.
REVEL	Pathogenic	0.76
Sift	Uncertain	0.0080	D;.
Sift4G	Benign	0.37	T;T
Polyphen		0.97	D;.
Vest4		0.22
MutPred		0.49		Gain of MoRF binding (P = 0.0297);.;
MVP		0.94
MPC		1.8
ClinPred		0.90	D
GERP RS		3.8
Varity_R		0.28
gMVP		0.66

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: rs199472880; hg19: chr7-150655198;