20-63442482-G-C

Variant names:

• chr20-63442482-G-C
• rs74315392
• NM_172107.4:c.740C>G
• KCNQ2 p.Ser247Trp

GermlineCancer (beta)

Variant summary

Our verdict is Pathogenic.

>+14 Pathogenic

-7

-6

-1

0

+5

+6

+9

+10

BenignB

Likely BenignLB

UncertainVUS

Likely PathogenicLP

PathogenicP

The variant received 17 classification points (ACMG Germline Pathogenicity v2019): 17P and 0B. PS3PM1PM2PM5PP2PP3_ModeratePP5_Strong

The NM_172107.4(KCNQ2):c.740C>G (p.Ser247Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant is absent from the gnomAD population database at sites with sufficient sequencing coverage. In-silico predictor (REVEL) classifies this variant as likely damaging/oncogenic. Splicing prediction tools (SpliceAI) predict no significant impact on normal splicing. Variant has been reported in ClinVar as Pathogenic/Likely Pathogenic (★★). ClinVar reports functional evidence for this variant: "SCV001224511: Experimental studies have shown that this missense change affects KCNQ2 function (PMID:12742592)." and additional evidence is available in ClinVar. A different missense at the same amino acid position has been reported as Pathogenic/Likely Pathogenic in ClinVar: p.S247P: Likely_pathogenic (ClinVar VariationId 813771, 1 star) Other variants at the same amino acid position have been reported in ClinVar (not pathogenic): p.S247*: not_provided (ClinVar VariationId 21799); p.S247= (synonymous): Likely_benign (ClinVar VariationId 339335, 1 star) This exact variant is curated in the UniProt human variants database as Uncertain Significance.

• Frequency: Genomes: not found (cov: 29)
• Consequence: KCNQ2 NM_172107.4 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3 O:1
• Conservation: PhyloP100: 6.63
• Publications: 24 publications found

Genes affected

KCNQ2 (HGNC:6296): (potassium voltage-gated channel subfamily Q member 2) The M channel is a slowly activating and deactivating potassium channel that plays a critical role in the regulation of neuronal excitability. The M channel is formed by the association of the protein encoded by this gene and a related protein encoded by the KCNQ3 gene, both integral membrane proteins. M channel currents are inhibited by M1 muscarinic acetylcholine receptors and activated by retigabine, a novel anti-convulsant drug. Defects in this gene are a cause of benign familial neonatal convulsions type 1 (BFNC), also known as epilepsy, benign neonatal type 1 (EBN1). At least five transcript variants encoding five different isoforms have been found for this gene. [provided by RefSeq, Jul 2008]

KCNQ2 Gene-Disease associations (from GenCC):

• complex neurodevelopmental disorder

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: ClinGen, PanelApp Australia
• developmental and epileptic encephalopathy, 7

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: PanelApp Australia, Labcorp Genetics (formerly Invitae), G2P, Orphanet
• neonatal encephalopathy with non-epileptic myoclonus

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• neonatal-onset developmental and epileptic encephalopathy

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: PanelApp Australia, ClinGen
• seizures, benign familial neonatal, 1

  Inheritance: AD Classification: DEFINITIVE Submitted by: G2P
• seizures, benign familial neonatal, 2

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
• benign familial infantile epilepsy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• benign familial neonatal-infantile seizures

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• benign neonatal seizures

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• malignant migrating partial seizures of infancy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

Classification according to ACMG Germline Pathogenicity v2019

Our verdict: Pathogenic. The variant received 17 points.

• PS3: Well-established functional study supports damaging effect (PS3); SCV001224511: Experimental studies have shown that this missense change affects KCNQ2 function (PMID: 12742592).; SCV004170645: Published functional studies demonstrate a damaging effect showing a reduction of the channel current (Dedek et al., 2003)
• PM1: Missense neighbourhood hotspot (≥2 P/LP within ±8 AA, OR ≥ 5 vs. background) — PM1; In-domain: 0 pathogenic, 0 benign rare missense variants.; ±8 AA neighbourhood: 27 pathogenic, 0 benign (OR vs. background: 275.0).
• PM2: Absent from gnomAD (AD/XL gene) — PM2; Absent from gnomAD at well-covered site (MOI: AD/XL) (threshold 0.0001) — PM2 moderate.
• PM5: Different pathogenic missense at same AA residue in ClinVar (PM5); ClinVar contains a germline Pathogenic/Likely Pathogenic entry at the same amino acid position with a different amino acid change: p.S247P: Likely_pathogenic (ClinVar VariationId 813771, 1 star); Other variants at the same amino acid residue (not pathogenic): p.S247*: not_provided (ClinVar VariationId 21799); p.S247= (synonymous): Likely_benign (ClinVar VariationId 339335, 1 star)
• PP2: Missense in gene constrained for missense variation where missense is common disease mechanism (PP2); Missense in a gene constrained for missense variation (gnomAD Z-score: 3.708). ClinVar shows strong pathogenic missense enrichment: 441 P/LP and 43 B/LB missense entries (ratio 10.3×).
• PP3: Germline meta computational scorer (REVEL/MetaRNN/BayesDel) predicts damaging effect — moderate evidence (PP3); Splicing verdict: not pathogenic.; Germline computational verdict: pathogenic (Moderate).
• PP5: ClinVar 2-star pathogenic — strong (PP5); ClinVar germline classification: Pathogenic/Likely Pathogenic, 2 star(s).

Variant Effect in Transcripts

Automated classification analysis was done for transcript: NM_172107.4. You can select a different transcript below to see updated classification assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	KCNQ2	NM_172107.4	MANE Select	c.740C>G	p.Ser247Trp	missense	Exon 5 of 17	NP_742105.1	O43526-1
	KCNQ2	NM_001382235.1		c.740C>G	p.Ser247Trp	missense	Exon 5 of 17	NP_001369164.1	A0A9L9PXL0
	KCNQ2	NM_172106.3		c.740C>G	p.Ser247Trp	missense	Exon 5 of 16	NP_742104.1	O43526-2

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	KCNQ2	ENST00000359125.7	TSL:1 MANE Select	c.740C>G	p.Ser247Trp	missense	Exon 5 of 17	ENSP00000352035.2	O43526-1
	KCNQ2	ENST00000626839.2	TSL:1	c.740C>G	p.Ser247Trp	missense	Exon 5 of 16	ENSP00000486706.1	O43526-2
	KCNQ2	ENST00000344462.8	TSL:1	c.740C>G	p.Ser247Trp	missense	Exon 5 of 16	ENSP00000339611.4	O43526-4

Frequencies

GnomAD3 genomes Cov.: 29

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 29

ClinVar

ClinVar submissions

Significance: Pathogenic

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
1	-	-	Developmental and epileptic encephalopathy, 7 (1)
1	-	-	Early-infantile DEE (1)
1	-	-	not provided (1)
-	-	-	Seizures, benign familial neonatal, 2 (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.58
CADD	Pathogenic	33
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.66	D
Eigen	Pathogenic	0.69
Eigen_PC	Uncertain	0.54
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Pathogenic	1.0	D
M_CAP	Pathogenic	0.84	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.6	H
PhyloP100		6.6
PrimateAI	Pathogenic	0.92	D
PROVEAN	Pathogenic	-6.3	D
REVEL	Pathogenic	0.86
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Varity_R		0.98
gMVP		1.0
Mutation Taster		=0/100	disease causing (ClinVar)

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

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

Other links and lift over

dbSNP: rs74315392;

hg19: chr20-62073835;

ACMG debug oncogenicity

ACGS debug oncogenicity

ACMG debug germline

Submit to ClinVar