chr1-40784200-C-CG

Variant names:

• chr1-40784200-C-CG
• rs1168470485
• NM_004700.4:c.110dupG

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PVS1 PM2 PP5

The NM_004700.4(KCNQ4):​c.110dupG​(p.Gly38ArgfsTer198) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000136 in 147,406 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: 𝑓 0.000014 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000019 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: KCNQ4 NM_004700.4 frameshift
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:1
• Conservation: PhyloP100: 1.66

Genes affected

KCNQ4 (HGNC:6298): (potassium voltage-gated channel subfamily Q member 4) The protein encoded by this gene forms a potassium channel that is thought to play a critical role in the regulation of neuronal excitability, particularly in sensory cells of the cochlea. The current generated by this channel is inhibited by M1 muscarinic acetylcholine receptors and activated by retigabine, a novel anti-convulsant drug. The encoded protein can form a homomultimeric potassium channel or possibly a heteromultimeric channel in association with the protein encoded by the KCNQ3 gene. Defects in this gene are a cause of nonsyndromic sensorineural deafness type 2 (DFNA2), an autosomal dominant form of progressive hearing loss. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Pathogenic. Variant got 11 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 1-40784200-C-CG is Pathogenic according to our data. Variant chr1-40784200-C-CG is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 3343127.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=1, Pathogenic=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNQ4	NM_004700.4	c.110dupG	p.Gly38ArgfsTer198	frameshift_variant	Exon 1 of 14	ENST00000347132.10	NP_004691.2
KCNQ4	NM_172163.3	c.110dupG	p.Gly38ArgfsTer198	frameshift_variant	Exon 1 of 13		NP_751895.1
KCNQ4	XM_047434057.1	c.110dupG	p.Gly38ArgfsTer198	frameshift_variant	Exon 1 of 13		XP_047290013.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNQ4	ENST00000347132.10	c.110dupG	p.Gly38ArgfsTer198	frameshift_variant	Exon 1 of 14	1	NM_004700.4	ENSP00000262916.6
KCNQ4	ENST00000509682.6	c.110dupG	p.Gly38ArgfsTer198	frameshift_variant	Exon 1 of 13	5		ENSP00000423756.2

Frequencies

GnomAD3 genomes AF: 0.0000136 AC: 2 AN: 147406 Hom.: 0 Cov.: 32

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: 0.0000303

Gnomad OTH AF: 0.00

GnomAD4 exome Data not reliable, filtered out with message: AS_VQSR AF: 0.0000185 AC: 18 AN: 971506 Hom.: 0 Cov.: 24 AF XY: 0.0000151 AC XY: 7 AN XY: 464262

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: 0.0000199

Gnomad4 OTH exome AF: 0.0000283

GnomAD4 genome AF: 0.0000136 AC: 2 AN: 147406 Hom.: 0 Cov.: 32 AF XY: 0.0000139 AC XY: 1 AN XY: 71708

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: 0.0000303

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.0000113

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Pathogenic:1 Uncertain:1

Nov 19, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Gly38Argfs*198) in the KCNQ4 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in KCNQ4 are known to be pathogenic (PMID: 23717403). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate insufficient coverage at this position in the gnomAD database. This variant has not been reported in the literature in individuals affected with KCNQ4-related conditions. For these reasons, this variant has been classified as Pathogenic. -

Jan 30, 2024

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Frameshift variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss-of-function is not a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); Has not been previously published as pathogenic or benign to our knowledge -

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: rs1168470485; hg19: chr1-41249872;