NM_172107.4:c.619C>T

Variant names:

• chr20-63444730-G-A
• rs74315391
• NM_172107.4:c.619C>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.619C>T​(p.Arg207Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000689 in 1,451,022 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R207Q) has been classified as Pathogenic.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: KCNQ2 NM_172107.4 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:10 O:1
• Conservation: PhyloP100: 3.32
• Publications: 25 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: Orphanet, Labcorp Genetics (formerly Invitae), G2P
• 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
• 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 32 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 5 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 chr20-63444729-C-T is described in ClinVar as Pathogenic. ClinVar VariationId is 7391.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, 0.99
• PP5: Variant 20-63444730-G-A is Pathogenic according to our data. Variant chr20-63444730-G-A is described in ClinVar as Pathogenic. ClinVar VariationId is 7386.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

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	KCNQ2	NM_172107.4	MANE Select	c.619C>T	p.Arg207Trp	missense	Exon 4 of 17	NP_742105.1
	KCNQ2	NM_001382235.1		c.619C>T	p.Arg207Trp	missense	Exon 4 of 17	NP_001369164.1
	KCNQ2	NM_172106.3		c.619C>T	p.Arg207Trp	missense	Exon 4 of 16	NP_742104.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	KCNQ2	ENST00000359125.7	TSL:1 MANE Select	c.619C>T	p.Arg207Trp	missense	Exon 4 of 17	ENSP00000352035.2
	KCNQ2	ENST00000626839.2	TSL:1	c.619C>T	p.Arg207Trp	missense	Exon 4 of 16	ENSP00000486706.1
	KCNQ2	ENST00000344462.8	TSL:1	c.619C>T	p.Arg207Trp	missense	Exon 4 of 16	ENSP00000339611.4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.89e-7 AC: 1 AN: 1451022 Hom.: 0 Cov.: 32 AF XY: 0.00000139 AC XY: 1 AN XY: 720642

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33414

American (AMR) AF: 0.00 AC: 0 AN: 42996

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25856

East Asian (EAS) AF: 0.00 AC: 0 AN: 39296

South Asian (SAS) AF: 0.00 AC: 0 AN: 84228

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 51512

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5742

European-Non Finnish (NFE) AF: 9.03e-7 AC: 1 AN: 1107936

Other (OTH) AF: 0.00 AC: 0 AN: 60042

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 33

Alfa AF: 0.00000575 Hom.: 0

ClinVar

ClinVar submissions as Germline

Significance: Pathogenic

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
3	-	-	not provided (3)
1	-	-	Developmental and epileptic encephalopathy (1)
1	-	-	Developmental and epileptic encephalopathy, 7 (1)
1	-	-	Inborn genetic diseases (1)
1	-	-	Seizure (1)
1	-	-	Seizures, benign familial neonatal, 1 (2)
1	-	-	Seizures, benign familial neonatal, 1, and/or myokymia (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	1.0
BayesDel_addAF	Pathogenic	0.54	D
BayesDel_noAF	Pathogenic	0.54
CADD	Pathogenic	27
DANN	Pathogenic	1.0
DEOGEN2	Uncertain	0.66	D
Eigen	Uncertain	0.44
Eigen_PC	Uncertain	0.30
FATHMM_MKL	Uncertain	0.89	D
LIST_S2	Pathogenic	1.0	D
M_CAP	Pathogenic	0.93	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.8	H
PhyloP100		3.3
PrimateAI	Pathogenic	0.90	D
PROVEAN	Pathogenic	-7.1	D
REVEL	Pathogenic	0.94
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.96
MutPred		0.95		Gain of catalytic residue at Q204 (P = 0.0581)
MVP		1.0
MPC		2.8
ClinPred		1.0	D
GERP RS		1.8
PromoterAI		-0.027	Neutral
Varity_R		0.96
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

Other links and lift over

dbSNP: rs74315391; hg19: chr20-62076083;