1-40819438-TCTC-T

Position:

• chr1-40819438-TCTC-T

Variant summary

Our verdict is Pathogenic. Variant got 13 ACMG points: 13P and 0B. PM1 PM2 PM4_Supporting PP5_Very_Strong

The NM_004700.4(KCNQ4):​c.806_808delCCT​(p.Ser269del) variant causes a disruptive inframe deletion change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000342 in 1,461,712 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★★). Synonymous variant affecting the same amino acid position (i.e. S269S) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0000034 (0 hom.)
• Consequence: KCNQ4 NM_004700.4 disruptive_inframe_deletion
• Clinical Significance: Pathogenic reviewed by expert panel P:4 U:1
• Conservation: PhyloP100: 0.805

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]

KCNQ4 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 13 ACMG points.

• PM1: In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 7 uncertain in NM_004700.4
• PM2: Very rare variant in population databases, with high coverage
• PM4: Nonframeshift variant in NON repetitive region in NM_004700.4. Strenght limited to Supporting due to length of the change: 1aa.
• PP5: Variant 1-40819438-TCTC-T is Pathogenic according to our data. Variant chr1-40819438-TCTC-T is described in ClinVar as [Pathogenic]. Clinvar id is 208366.Status of the report is reviewed_by_expert_panel, 3 stars. Variant chr1-40819438-TCTC-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCNQ4	NM_004700.4	c.806_808delCCT	p.Ser269del	disruptive_inframe_deletion	5/14	ENST00000347132.10	NP_004691.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KCNQ4	ENST00000347132.10	c.806_808delCCT	p.Ser269del	disruptive_inframe_deletion	5/14	1	NM_004700.4	ENSP00000262916.6
KCNQ4	ENST00000509682.6	c.806_808delCCT	p.Ser269del	disruptive_inframe_deletion	5/13	5		ENSP00000423756.2
KCNQ4	ENST00000443478.3	c.491_493delCCT	p.Ser164del	disruptive_inframe_deletion	4/13	5		ENSP00000406735.3
KCNQ4	ENST00000506017.1	n.125_127delCCT		non_coding_transcript_exon_variant	2/11	2

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 0.00000342 AC: 5 AN: 1461712 Hom.: 0 AF XY: 0.00000275 AC XY: 2 AN XY: 727180

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: 0.00000360

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 31

Bravo AF: 0.00000378

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:4 Uncertain:1

Revision: reviewed by expert panel

Submissions by phenotype

not provided Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Jul 11, 2023	Published functional studies demonstrate a damaging effect (Lee et al., 2021); In-frame deletion of 1 amino acid in a non-repeat region; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 20301388, 23399560, 33367117, 23443030, 34316018, 23717403, 30311386) -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Oct 24, 2023	This variant, c.806_808del, results in the deletion of 1 amino acid(s) of the KCNQ4 protein (p.Ser269del), but otherwise preserves the integrity of the reading frame. This variant is not present in population databases (gnomAD no frequency). This variant has been observed in individuals with autosomal dominant non-syndromic deafness (PMID: 23399560, 23443030). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 208366). For these reasons, this variant has been classified as Pathogenic. -

Autosomal dominant nonsyndromic hearing loss 2A Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

ClinVar Staff, National Center for Biotechnology Information (NCBI)

Aug 20, 2015

- -

Nonsyndromic genetic hearing loss Pathogenic:1

Pathogenic, reviewed by expert panel

curation

ClinGen Hearing Loss Variant Curation Expert Panel

Jun 27, 2023

The c.803_805CCT[1] (aka c.806_808del) variant is predicted to cause a change in the length of the protein due to an in-frame deletion of 1 amino acid (p.Ser269del). It is absent from gnomAD v2.1.1 (PM2_Supporting). The variant has been reported in at least 5 probands with autosomal dominant hearing loss (PS4_Supporting; PMID: 23399560, 23443030, 34316018, LMM unpublished data SCV000967428.1). The variant has been observed to segregate with hearing loss in 12 affected individuals from 1 family (PP1_Strong; PMID: 23443030). This variant causes a change in the length of the protein due to an in-frame deletion between the S5 membrane-spanning domain and the pore region, which is important for protein function (PM4, PMID: 23717403). Patch-clamp studies in HEK293T cells revealed significantly reduced whole-cell potassium currents, and KCNQ openers did not rescue KCNQ4 mutant channels (PMID: 34316018, PS3_Moderate). In summary, this variant meets criteria to be classified as pathogenic for autosomal dominant nonsyndromic hearing loss. ACMG/AMP Criteria applied as specified by the ClinGen Hearing Loss VCEP: PP1_Strong, PM4, PS3_Moderate, PM2_Supporting, PS4_Supporting. (VCEP specifications version 2; 06.27.2023). -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Feb 26, 2018

Variant classified as Uncertain Significance - Favor Pathogenic. The p.Ser269del variant in KCNQ4 has been reported in 2 individuals with bilateral sloping hear ing loss and segregated with disease in 9 affected relatives from 1 family (Wata be 2013, Abdelfatah 2013). However, there was one individual with a similar hear ing loss pattern and two additional individuals with other forms of hearing loss that did not harbor the variant, as well as 7 family members with hearing loss on the other side of the family that did not harbor the variant (Abdelfatah 2013 ). The p.Ser269del variant was absent from large population studies and is repor ted in ClinVar (Variation ID# 204595). This variant is a deletion of 1 amino aci d at position 269 and is not predicted to alter the protein reading-frame. In su mmary, while there is some suspicion for a pathogenic role, the clinical signifi cance of the p.Ser269del variant is uncertain. ACMG/AMP Criteria applied: PP1_St rong, PM2, PS4_Supporting, BS4. -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs797044966; hg19: chr1-41285110;