chr20-63442428-G-A

Variant names:

• chr20-63442428-G-A
• rs587777219
• NM_172107.4:c.794C>T

Variant summary

Our verdict is Pathogenic. The variant received 19 ACMG points: 19P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Very_Strong

The NM_172107.4(KCNQ2):​c.794C>T​(p.Ala265Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A265P) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 29)
• Consequence: KCNQ2 NM_172107.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:13 O:1
• Conservation: PhyloP100: 9.77
• Publications: 18 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 Submitted by: ClinGen
• developmental and epileptic encephalopathy, 7

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

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

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

  Inheritance: AD Classification: DEFINITIVE Submitted by: G2P
• undetermined early-onset epileptic encephalopathy

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• 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

ACMG classification

Our verdict: Pathogenic. The variant received 19 ACMG points.

• PM1: In a hotspot region, there are 31 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 11 uncertain in NM_172107.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr20-63442429-C-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 197891.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP2: Missense variant in the KCNQ2 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 319 curated pathogenic missense variants (we use a threshold of 10). The gene has 78 curated benign missense variants. Gene score misZ: 4.0411 (above the threshold of 3.09). Trascript score misZ: 3.6968 (above the threshold of 3.09). GenCC associations: The gene is linked to benign familial infantile epilepsy, malignant migrating partial seizures of infancy, developmental and epileptic encephalopathy, 7, benign familial neonatal-infantile seizures, benign neonatal seizures, neonatal-onset developmental and epileptic encephalopathy, complex neurodevelopmental disorder, seizures, benign familial neonatal, 2, seizures, benign familial neonatal, 1, neonatal encephalopathy with non-epileptic myoclonus.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.944
• PP5: Variant 20-63442428-G-A is Pathogenic according to our data. Variant chr20-63442428-G-A is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 120176.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

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

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	KCNQ2	NM_172107.4	MANE Select	c.794C>T	p.Ala265Val	missense	Exon 5 of 17	NP_742105.1	O43526-1
	KCNQ2	NM_001382235.1		c.794C>T	p.Ala265Val	missense	Exon 5 of 17	NP_001369164.1	A0A9L9PXL0
	KCNQ2	NM_172106.3		c.794C>T	p.Ala265Val	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.794C>T	p.Ala265Val	missense	Exon 5 of 17	ENSP00000352035.2	O43526-1
	KCNQ2	ENST00000626839.2	TSL:1	c.794C>T	p.Ala265Val	missense	Exon 5 of 16	ENSP00000486706.1	O43526-2
	KCNQ2	ENST00000344462.8	TSL:1	c.794C>T	p.Ala265Val	missense	Exon 5 of 16	ENSP00000339611.4	O43526-4

Frequencies

GnomAD3 genomes Cov.: 29

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 29

Alfa AF: 0.0000152 Hom.: 0

ClinVar

ClinVar submissions

Significance: Pathogenic/Likely pathogenic

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
4	-	-	Developmental and epileptic encephalopathy, 7 (5)
3	-	-	not provided (3)
1	-	-	Developmental and epileptic encephalopathy (1)
1	-	-	Inborn genetic diseases (1)
1	-	-	Intellectual disability (1)
1	-	-	KCNQ2-related disorder (1)
1	-	-	Seizure (1)
1	-	-	Seizures, benign familial neonatal, 1;C3150986:Developmental and epileptic encephalopathy, 7 (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.53	D
BayesDel_noAF	Pathogenic	0.53
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.46	T
Eigen	Uncertain	0.24
Eigen_PC	Benign	0.21
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Pathogenic	0.66	D
MetaRNN	Pathogenic	0.94	D
MetaSVM	Pathogenic	0.92	D
MutationAssessor	Uncertain	2.7	M
PhyloP100		9.8
PrimateAI	Pathogenic	0.87	D
PROVEAN	Uncertain	-3.6	D
REVEL	Pathogenic	0.82
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0010	D
Polyphen		0.78	P
Vest4		0.87
MutPred		0.76		Loss of disorder (P = 0.0801)
MVP		1.0
MPC		2.3
ClinPred		0.99	D
GERP RS		3.4
Varity_R		0.82
gMVP		0.99
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

Other links and lift over

dbSNP: rs587777219; hg19: chr20-62073781; COSMIC: COSV60431805; COSMIC: COSV60431805;