chr20-63406948-G-A

Position:

chr20-63406948-G-A

Variant summary

Our verdict is Likely benign. Variant got -5 ACMG points: 1P and 6B. PP2BP4_ModerateBS2

The NM_172107.4(KCNQ2):c.2315C>T(p.Pro772Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000158 in 1,583,636 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

Frequency

Genomes: 𝑓 0.000026 ( 0 hom., cov: 34)

Exomes 𝑓: 0.000015 ( 0 hom. )

Consequence

KCNQ2
NM_172107.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:2

Conservation

PhyloP100: 1.49

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:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Likely_benign. Variant got -5 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=0.0916633).

BS2

High AC in GnomAdExome4 at 21 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCNQ2	NM_172107.4 linkuse as main transcript	c.2315C>T	p.Pro772Leu	missense_variant	17/17	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.2315C>T	p.Pro772Leu	missense_variant	17/17	1	NM_172107.4	ENSP00000352035.2		O43526-1

Frequencies

GnomAD3 genomes

AF:

0.0000263

AC:

AN:

152196

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.000288

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.000207

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000364

AC:

AN:

192192

Hom.:

AF XY:

0.0000377

AC XY:

AN XY:

106222

show subpopulations

Gnomad AFR exome

AF:

0.0000887

Gnomad AMR exome

AF:

0.0000330

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.0000661

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000482

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000147

AC:

AN:

1431440

Hom.:

Cov.:

AF XY:

0.0000141

AC XY:

AN XY:

710220

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.0000478

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.0000260

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.0000164

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.0000263

AC:

AN:

152196

Hom.:

Cov.:

AF XY:

0.0000403

AC XY:

AN XY:

74352

show subpopulations

Gnomad4 AFR

AF:

0.0000241

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.000288

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.000207

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000147

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.0000227

ExAC

AF:

0.0000336

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

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

Oct 27, 2023

Variant summary: KCNQ2 c.2315C>T (p.Pro772Leu) results in a non-conservative amino acid change in the encoded protein sequence. Four of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 3.6e-05 in 192192 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.2315C>T has been reported in the literature as a VUS in the heterozygous state in a setting of WES in an individual affected with epilepsy who also had other putatively pathogenic variants reported in epilepsy-related genes (Al Anazi_2022). This report does 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: 36539902). One submitter has cited a clinical-significance assessment for this variant to ClinVar after 2014 and has classified the variant as uncertain significance. 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

Aug 14, 2023

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. 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. ClinVar contains an entry for this variant (Variation ID: 530457). This variant has not been reported in the literature in individuals affected with KCNQ2-related conditions. This variant is present in population databases (rs774206764, gnomAD 0.006%). This sequence change replaces proline, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 772 of the KCNQ2 protein (p.Pro772Leu). -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.071

BayesDel_addAF

Benign

-0.15

BayesDel_noAF

Benign

-0.25

CADD

Benign

DANN

Benign

0.85

DEOGEN2

Benign

0.0082

.;T;T;T;.;.

Eigen

Benign

-0.99

Eigen_PC

Benign

-1.0

FATHMM_MKL

Benign

0.24

LIST_S2

Benign

0.78

T;T;T;T;T;T

M_CAP

Uncertain

0.12

MetaRNN

Benign

0.092

T;T;T;T;T;T

MetaSVM

Benign

-1.1

MutationAssessor

Benign

0.69

.;.;N;.;.;.

PrimateAI

Uncertain

0.62

PROVEAN

Benign

-0.61

.;.;N;.;N;D

REVEL

Benign

0.038

Sift

Benign

0.73

.;.;T;.;T;T

Sift4G

Benign

0.70

T;.;T;T;T;T

Polyphen

0.49

P;.;P;.;P;B

Vest4

0.049

MVP

0.66

MPC

0.81

ClinPred

0.012

GERP RS

1.6

Varity_R

0.017

gMVP

0.20

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