Genetic Variant KCNQ2:p.Pro777Arg (chr20-63406933-G-C) – ACMG Classification: Benign (-17 pts)

Variant summary

Our verdict is Benign. The variant received -17 ACMG points: 3P and 20B. PM1PP2BP4_StrongBP6_Very_StrongBS1BS2

The NM_172107.4(KCNQ2):c.2330C>G(p.Pro777Arg) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000121 in 1,600,288 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P777S) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.000092 ( 0 hom., cov: 33)

Exomes 𝑓: 0.00012 ( 0 hom. )

Consequence

KCNQ2
NM_172107.4 missense

Scores

Clinical Significance

Likely benign criteria provided, multiple submitters, no conflicts B:3

Conservation

PhyloP100: 0.398

Publications

3 publications found

Variant links:

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, G2P, 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

KCNQ2 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Benign. The variant received -17 ACMG points.

PM1

In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 2 benign, 12 uncertain in NM_172107.4

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.

BP4

Computational evidence support a benign effect (MetaRNN=0.038796812).

BP6

Variant 20-63406933-G-C is Benign according to our data. Variant chr20-63406933-G-C is described in ClinVar as Likely_benign. ClinVar VariationId is 205851.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

BS1

Variant frequency is greater than expected in population nfe. GnomAdExome4 allele frequency = 0.000124 (179/1448062) while in subpopulation NFE AF = 0.000153 (170/1108002). AF 95% confidence interval is 0.000134. There are 0 homozygotes in GnomAdExome4. There are 86 alleles in the male GnomAdExome4 subpopulation. Median coverage is 36. This position passed quality control check.

BS2

High AC in GnomAd4 at 14 AD gene.

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

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
KCNQ2	NM_172107.4	MANE Select	c.2330C>G	p.Pro777Arg	missense	Exon 17 of 17	NP_742105.1	O43526-1
KCNQ2	NM_001382235.1		c.2384C>G	p.Pro795Arg	missense	Exon 17 of 17	NP_001369164.1	A0A9L9PXL0
KCNQ2	NM_172106.3		c.2276C>G	p.Pro759Arg	missense	Exon 16 of 16	NP_742104.1	O43526-2

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
KCNQ2	ENST00000359125.7	TSL:1 MANE Select	c.2330C>G	p.Pro777Arg	missense	Exon 17 of 17	ENSP00000352035.2	O43526-1
KCNQ2	ENST00000626839.2	TSL:1	c.2276C>G	p.Pro759Arg	missense	Exon 16 of 16	ENSP00000486706.1	O43526-2
KCNQ2	ENST00000344462.8	TSL:1	c.2237C>G	p.Pro746Arg	missense	Exon 16 of 16	ENSP00000339611.4	O43526-4

Frequencies

GnomAD3 genomes

AF:

0.0000920

AC:

AN:

152226

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000724

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000131

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:

0.000132

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000726

AC:

AN:

220390

AF XY:

0.0000823

show subpopulations

Gnomad AFR exome

AF:

0.000221

Gnomad AMR exome

AF:

0.0000610

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.000102

Gnomad OTH exome

AF:

0.000181

GnomAD4 exome

AF:

0.000124

AC:

179

AN:

1448062

Hom.:

Cov.:

AF XY:

0.000119

AC XY:

AN XY:

719732

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33340

American (AMR)

AF:

0.0000686

AC:

AN:

43714

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

25936

East Asian (EAS)

AF:

0.00

AC:

AN:

39254

South Asian (SAS)

AF:

0.00

AC:

AN:

85036

European-Finnish (FIN)

AF:

0.00

AC:

AN:

47144

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5750

European-Non Finnish (NFE)

AF:

0.000153

AC:

170

AN:

1108002

Other (OTH)

AF:

0.000100

AC:

AN:

59886

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.499

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000920

AC:

AN:

152226

Hom.:

Cov.:

AF XY:

0.0000807

AC XY:

AN XY:

74372

show subpopulations

African (AFR)

AF:

0.0000724

AC:

AN:

41460

American (AMR)

AF:

0.000131

AC:

AN:

15292

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5198

South Asian (SAS)

AF:

0.00

AC:

AN:

4838

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10626

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.000132

AC:

AN:

68020

Other (OTH)

AF:

0.00

AC:

AN:

2094

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.525

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.000154

Hom.:

Bravo

AF:

0.000106

ESP6500AA

AF:

0.000229

AC:

ESP6500EA

AF:

0.00

AC:

ExAC

AF:

0.0000999

AC:

ClinVar

ClinVar submissions as Germline

Significance:Likely benign

Revision:criteria provided, multiple submitters, no conflicts

View on ClinVar

Pathogenic

VUS

Benign

Condition

Developmental and epileptic encephalopathy (1)

Inborn genetic diseases (1)

not provided (1)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.077

BayesDel_addAF

Benign

-0.20

BayesDel_noAF

Benign

-0.27

CADD

Benign

5.9

(source)

DANN

Benign

0.17

DEOGEN2

Benign

0.0023

Eigen

Benign

-1.4

Eigen_PC

Benign

-1.4

FATHMM_MKL

Benign

0.098

LIST_S2

Uncertain

0.86

M_CAP

Benign

0.049

MetaRNN

Benign

0.039

MetaSVM

Benign

-1.0

MutationAssessor

Benign

0.55

PhyloP100

0.40

PrimateAI

Uncertain

0.54

PROVEAN

Benign

-1.0

REVEL

Benign

0.065

Sift

Benign

1.0

Sift4G

Benign

0.65

Polyphen

0.029

Vest4

0.033

MVP

0.69

MPC

0.66

ClinPred

0.0042

GERP RS

-2.0

Varity_R

0.030

gMVP

0.23

Mutation Taster

=98/2

polymorphism

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over