rs1554425320

Variant names:

• chr7-150950421-CTG-TT
• rs1554425320
• NM_000238.4:c.2146-3_2146-1delCAGinsAA

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_000238.4(KCNH2):​c.2146-3_2146-1delCAGinsAA variant causes a splice acceptor, splice region, intron change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Likely pathogenic (★).

• Frequency: Genomes: not found (cov: 30)
• Consequence: KCNH2 NM_000238.4 splice_acceptor, splice_region, intron
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 7.98
• Publications: 0 publications found

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]

KCNH2 Gene-Disease associations (from GenCC):

• long QT syndrome

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• long QT syndrome 2

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, G2P
• short QT syndrome

  Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: Orphanet, ClinGen
• short QT syndrome type 1

  Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE Submitted by: Labcorp Genetics (formerly Invitae), G2P, Ambry Genetics
• Brugada syndrome

  Inheritance: AD Classification: MODERATE, NO_KNOWN Submitted by: ClinGen, Genomics England PanelApp

ACMG classification

Our verdict: Pathogenic. The variant received 12 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, Cryptic splice site detected, with MaxEntScore 5.7, offset of 1, new splice context is: tgcccccaccctgccccaAGtgc. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 7-150950421-CTG-TT is Pathogenic according to our data. Variant chr7-150950421-CTG-TT is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 456902.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNH2	NM_000238.4	c.2146-3_2146-1delCAGinsAA		splice_acceptor_variant, splice_region_variant, intron_variant	Intron 8 of 14	ENST00000262186.10	NP_000229.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNH2	ENST00000262186.10	c.2146-3_2146-1delCAGinsAA		splice_acceptor_variant, splice_region_variant, intron_variant	Intron 8 of 14	1	NM_000238.4	ENSP00000262186.5

Frequencies

GnomAD3 genomes Cov.: 30

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 30

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Long QT syndrome Pathogenic:1

Jan 26, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, donor and acceptor splice site variants are typically loss-of-function (PMID: 16199547), and loss-of-function variants in KCNH2 are known to be pathogenic (PMID: 19862833). However, without additional functional and/or genetic data, this variant has been classified as Likely Pathogenic. This variant has not been reported in the literature in individuals with a KCNH2-related disease. This variant is a complex sequence change that results in the deletion of 3 nucleotides and the insertion of 2 nucleotides. It affects an acceptor splice site in intron 8 of the KCNH2 gene. It is expected to disrupt RNA splicing and likely results in an absent or disrupted protein product. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
PhyloP100		8.0

Splicing

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs1554425320; hg19: chr7-150647509;