NM_000238.4:c.2766delG

Variant names:

• chr7-150947804-GC-G
• rs1554424403
• NM_000238.4:c.2766delG

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000238.4(KCNH2):​c.2766delG​(p.Pro923ArgfsTer51) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 33)
• Consequence: KCNH2 NM_000238.4 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 0.481

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 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 7-150947804-GC-G is Pathogenic according to our data. Variant chr7-150947804-GC-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 495746.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr7-150947804-GC-G is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNH2	NM_000238.4	c.2766delG	p.Pro923ArgfsTer51	frameshift_variant	Exon 12 of 15	ENST00000262186.10	NP_000229.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNH2	ENST00000262186.10	c.2766delG	p.Pro923ArgfsTer51	frameshift_variant	Exon 12 of 15	1	NM_000238.4	ENSP00000262186.5
KCNH2	ENST00000330883.9	c.1746delG	p.Pro583ArgfsTer51	frameshift_variant	Exon 8 of 11	1		ENSP00000328531.4
KCNH2	ENST00000684241.1	n.3599delG		non_coding_transcript_exon_variant	Exon 10 of 13

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 36

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Cardiovascular phenotype Pathogenic:2

Nov 27, 2018

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.2766delG pathogenic mutation, located in coding exon 12 of the KCNH2 gene, results from a deletion of one nucleotide at nucleotide position 2766, causing a translational frameshift with a predicted alternate stop codon (p.P923Rfs*51). This alteration has been reported in one individual from a long QT syndrome testing cohort (Tester DJ et al. Heart Rhythm, 2005 May;2:507-17). In addition to the clinical data presented in the literature, this alteration is expected to result in loss of function by premature protein truncation or nonsense-mediated mRNA decay. As such, this alteration is interpreted as a disease-causing mutation. -

Jul 10, 2017

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: The KCNH2 c.2766delG (p.Pro923Argfs) variant results in a premature termination codon, predicted to cause a truncated or absent KCNH2 protein due to nonsense mediated decay, which are commonly known mechanisms for disease. Truncations downstream of this position have been classified as likely pathogenic/pathogenic by our laboratory (e.g. c.2959_2960delCT (p.Leu987fs) and c.3107dupG (p.Asp1037fs). This variant is absent in 11608 control chromosomes (ExAC and publication controls). A publication, Tester_2005, cites the variant in an affected individual for LQTS. A functional study, Hsueh_2008, indicates the variant to cause reduced current amplitude and faster inactivation. Therefore, taking all available lines of evidence into consideration, the variant of interest has been classified as "Likely Pathogenic." -

not provided Pathogenic:1

Oct 15, 2019

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Reported in a patient referred for LQTS genetic testing; however, additional clinical information was not provided (Tester et al., 2005); Not observed in large population cohorts (Lek et al., 2016); Frameshift variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss-of-function is a known mechanism of disease; This variant is associated with the following publications: (PMID: 18593567, 15840476, 19841300) -

Computational scores

Source: dbNSFP v4.3

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: rs1554424403; hg19: chr7-150644892;