NM_000238.4:c.927C>G

Variant names:

• chr7-150957492-G-C
• rs775056804
• NM_000238.4:c.927C>G

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 2P and 1B. PM2 BP4

The NM_000238.4(KCNH2):​c.927C>G​(p.His309Gln) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000658 in 151,866 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
• Consequence: KCNH2 NM_000238.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 0.515

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 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.26980925).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNH2	NM_000238.4	c.927C>G	p.His309Gln	missense_variant	Exon 5 of 15	ENST00000262186.10	NP_000229.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNH2	ENST00000262186.10	c.927C>G	p.His309Gln	missense_variant	Exon 5 of 15	1	NM_000238.4	ENSP00000262186.5
KCNH2	ENST00000532957.5	n.1150C>G		non_coding_transcript_exon_variant	Exon 5 of 9	2
KCNH2	ENST00000684241.1	n.1760C>G		non_coding_transcript_exon_variant	Exon 3 of 13

Frequencies

GnomAD3 genomes AF: 0.00000658 AC: 1 AN: 151866 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

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 Cov.: 32

GnomAD4 genome AF: 0.00000658 AC: 1 AN: 151866 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74184

Gnomad4 AFR AF: 0.00

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

Bravo AF: 0.00000756

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Long QT syndrome Uncertain:2

Oct 02, 2023

All of Us Research Program, National Institutes of Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This missense variant replaces histidine with glutamine at codon 309 of the KCNH2 protein. Computational prediction is inconclusive regarding the impact of this variant on protein structure and function (internally defined REVEL score threshold 0.5 < inconclusive < 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has not been reported in individuals affected with KCNH2-related disorders in the literature. This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -

Mar 10, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces histidine, which is basic and polar, with glutamine, which is neutral and polar, at codon 309 of the KCNH2 protein (p.His309Gln). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with KCNH2-related conditions. 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 tolerated. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.15
BayesDel_addAF	Pathogenic	0.18	D
BayesDel_noAF	Uncertain	0.030
CADD	Benign	22
DANN	Benign	0.96
DEOGEN2	Benign	0.37	T;T
Eigen	Benign	-0.35
Eigen_PC	Benign	-0.19
FATHMM_MKL	Uncertain	0.85	D
LIST_S2	Benign	0.74	T;T
M_CAP	Uncertain	0.26	D
MetaRNN	Benign	0.27	T;T
MetaSVM	Uncertain	0.58	D
MutationAssessor	Benign	1.4	L;.
PrimateAI	Pathogenic	0.85	D
PROVEAN	Benign	-1.6	N;.
REVEL	Pathogenic	0.65
Sift	Benign	0.031	D;.
Sift4G	Benign	0.17	T;T
Polyphen		0.15	B;.
Vest4		0.25
MutPred		0.52		Loss of loop (P = 0.0073);.;
MVP		0.85
MPC		1.2
ClinPred		0.41	T
GERP RS		4.0
Varity_R		0.11
gMVP		0.54

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.080		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: rs775056804; hg19: chr7-150654580;