20-63419626-G-A

Position:

chr20-63419626-G-A

Variant summary

Our verdict is Benign. Variant got -9 ACMG points: 1P and 10B. PP2BP4BP6BS1BS2

The NM_172107.4(KCNQ2):c.1294C>T(p.Arg432Cys) variant causes a missense change. The variant allele was found at a frequency of 0.0000323 in 1,610,588 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: 𝑓 0.000085 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000027 ( 0 hom. )

Consequence

KCNQ2
NM_172107.4 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:2B:1

Conservation

PhyloP100: 4.27

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 links:

KCNQ2 (HGNC:):

KCNQ2 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Benign. Variant got -9 ACMG points.

PP2

Missense variant in gene, where missense usually causes diseases (based on misZ statistic), KCNQ2. . Gene score misZ 4.0411 (greater than the threshold 3.09). Trascript score misZ 3.6968 (greater than threshold 3.09). GenCC has associacion of gene with seizures, benign familial neonatal, 1, neonatal-onset developmental and epileptic encephalopathy, benign familial neonatal-infantile seizures, benign neonatal seizures, malignant migrating partial seizures of infancy, neonatal encephalopathy with non-epileptic myoclonus, complex neurodevelopmental disorder, seizures, benign familial neonatal, 2, developmental and epileptic encephalopathy, 7, benign familial infantile epilepsy.

BP4

Computational evidence support a benign effect (MetaRNN=0.268776).

BP6

Variant 20-63419626-G-A is Benign according to our data. Variant chr20-63419626-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 575399.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=1, Uncertain_significance=2}.

BS1

Variant frequency is greater than expected in population afr. gnomad4 allele frequency = 0.0000854 (13/152258) while in subpopulation AFR AF= 0.000265 (11/41470). AF 95% confidence interval is 0.000149. There are 0 homozygotes in gnomad4. There are 7 alleles in male gnomad4 subpopulation. Median coverage is 33. This position pass quality control queck.

BS2

High AC in GnomAd4 at 13 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCNQ2	NM_172107.4 linkuse as main transcript	c.1294C>T	p.Arg432Cys	missense_variant	12/17	ENST00000359125.7	NP_742105.1	O43526-1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KCNQ2	ENST00000359125.7 linkuse as main transcript	c.1294C>T	p.Arg432Cys	missense_variant	12/17	1	NM_172107.4	ENSP00000352035.2		O43526-1

Frequencies

GnomAD3 genomes

AF:

0.0000854

AC:

AN:

152258

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.000265

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000654

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:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000328

AC:

AN:

243560

Hom.:

AF XY:

0.0000227

AC XY:

AN XY:

132030

show subpopulations

Gnomad AFR exome

AF:

0.000129

Gnomad AMR exome

AF:

0.0000294

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.0000337

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000364

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000267

AC:

AN:

1458330

Hom.:

Cov.:

AF XY:

0.0000248

AC XY:

AN XY:

725132

show subpopulations

Gnomad4 AFR exome

AF:

0.000329

Gnomad4 AMR exome

AF:

0.0000225

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.0000351

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.0000198

Gnomad4 OTH exome

AF:

0.0000332

GnomAD4 genome

AF:

0.0000854

AC:

AN:

152258

Hom.:

Cov.:

AF XY:

0.0000941

AC XY:

AN XY:

74390

show subpopulations

Gnomad4 AFR

AF:

0.000265

Gnomad4 AMR

AF:

0.0000654

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000147

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000711

Hom.:

Bravo

AF:

0.0000756

ESP6500AA

AF:

0.000227

AC:

ESP6500EA

AF:

0.00

AC:

ExAC

AF:

0.0000330

AC:

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:2Benign:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not specified

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Sep 03, 2024

Variant summary: KCNQ2 c.1294C>T (p.Arg432Cys) results in a non-conservative amino acid change in the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 3.2e-05 in 1610588 control chromosomes. This frequency is not significantly higher than estimated for a pathogenic variant in KCNQ2 causing KCNQ2-Related Disorders, allowing no conclusion about variant significance. c.1294C>T has been reported in the literature in at-least one individual affected with childhood epilepsy (example: Lee_2019). These report(s) do not provide unequivocal conclusions about association of the variant with KCNQ2-Related Disorders. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publication has been ascertained in the context of this evaluation (PMID: 31199083). ClinVar contains an entry for this variant (Variation ID: 575399). Based on the evidence outlined above, the variant was classified as uncertain significance. -

Early infantile epileptic encephalopathy with suppression bursts

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Dec 30, 2023

This sequence change replaces arginine, which is basic and polar, with cysteine, which is neutral and slightly polar, at codon 432 of the KCNQ2 protein (p.Arg432Cys). This variant is present in population databases (rs368720575, gnomAD 0.02%). This missense change has been observed in individual(s) with epilepsy (PMID: 31199083). ClinVar contains an entry for this variant (Variation ID: 575399). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant¬†is likely to be tolerated. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Inborn genetic diseases

Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Ambry Genetics

Aug 03, 2018

This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.083

BayesDel_addAF

Benign

-0.018

BayesDel_noAF

Uncertain

-0.020

CADD

Pathogenic

DANN

Uncertain

1.0

DEOGEN2

Benign

0.29

Eigen

Benign

0.10

Eigen_PC

Uncertain

0.23

FATHMM_MKL

Uncertain

0.86

LIST_S2

Benign

0.23

M_CAP

Uncertain

0.21

MetaRNN

Benign

0.27

MetaSVM

Uncertain

0.78

MutationAssessor

Benign

0.34

PrimateAI

Benign

0.35

PROVEAN

Benign

-1.9

REVEL

Uncertain

0.39

Sift

Benign

0.038

Sift4G

Uncertain

0.054

Polyphen

0.66

Vest4

0.31

MVP

0.54

MPC

0.96

ClinPred

0.16

GERP RS

3.8

Varity_R

0.15

gMVP

0.29

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

LitVar

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over