chr8-132129876-C-T

Variant names:

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2BP4_Strong

The NM_004519.4(KCNQ3):c.2005G>A(p.Ala669Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,461,892 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 0.0000027 ( 0 hom. )

Consequence

KCNQ3
NM_004519.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: 0.249

Publications

1 publications found

Variant links:

Genes affected

KCNQ3 (HGNC:6297): (potassium voltage-gated channel subfamily Q member 3) This gene encodes a protein that functions in the regulation of neuronal excitability. The encoded protein forms an M-channel by associating with the products of the related KCNQ2 or KCNQ5 genes, which both encode integral membrane proteins. M-channel currents are inhibited by M1 muscarinic acetylcholine receptors and are activated by retigabine, a novel anti-convulsant drug. Defects in this gene are a cause of benign familial neonatal convulsions type 2 (BFNC2), also known as epilepsy, benign neonatal type 2 (EBN2). Alternative splicing of this gene results in multiple transcript variants. [provided by RefSeq, May 2014]

KCNQ3 Gene-Disease associations (from GenCC):

seizures, benign familial neonatal, 2
Inheritance: AD Classification: STRONG, MODERATE Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae)
benign familial infantile epilepsy
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
benign neonatal seizures
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
genetic developmental and epileptic encephalopathy
Inheritance: AR Classification: LIMITED Submitted by: Ambry Genetics

KCNQ3 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (MetaRNN=0.053486705).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNQ3	NM_004519.4 link	c.2005G>A	p.Ala669Thr	missense_variant	Exon 15 of 15	ENST00000388996.10	NP_004510.1	O43525-1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNQ3	ENST00000388996.10 link	c.2005G>A	p.Ala669Thr	missense_variant	Exon 15 of 15	1	NM_004519.4	ENSP00000373648.3		O43525-1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD2 exomes

AF:

0.00000795

AC:

AN:

251494

AF XY:

0.0000147

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000578

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000274

AC:

AN:

1461892

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

727248

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.0000224

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.00

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53420

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00000270

AC:

AN:

1112010

Other (OTH)

AF:

0.00

AC:

AN:

60396

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.538

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

Cov.:

Alfa

AF:

0.0000282

Hom.:

Bravo

AF:

0.00000756

ExAC

AF:

0.00000824

AC:

EpiCase

AF:

0.0000545

EpiControl

AF:

0.0000593

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Benign neonatal seizures

Uncertain:1

Oct 15, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

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. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated. This variant has not been reported in the literature in individuals affected with KCNQ3-related conditions. This variant is present in population databases (rs201812160, ExAC 0.009%). This sequence change replaces alanine with threonine at codon 669 of the KCNQ3 protein (p.Ala669Thr). The alanine residue is weakly conserved and there is a small physicochemical difference between alanine and threonine. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.064

BayesDel_addAF

Benign

-0.21

BayesDel_noAF

Benign

-0.37

CADD

Benign

1.5

(source)

DANN

Benign

0.76

DEOGEN2

Benign

0.24

T;.;.;.;.

Eigen

Benign

-1.0

Eigen_PC

Benign

-0.99

FATHMM_MKL

Benign

0.11

LIST_S2

Benign

0.71

T;T;T;T;T

M_CAP

Uncertain

0.086

MetaRNN

Benign

0.053

T;T;T;T;T

MetaSVM

Uncertain

0.41

MutationAssessor

Benign

0.55

N;.;.;.;.

PhyloP100

0.25

PrimateAI

Benign

0.23

PROVEAN

Benign

-0.43

N;.;N;N;.

REVEL

Benign

0.19

Sift

Benign

0.41

T;.;T;T;.

Sift4G

Benign

0.42

T;T;T;T;.

Polyphen

0.0

B;.;.;B;.

Vest4

0.040

MutPred

0.25

Gain of phosphorylation at A669 (P = 0.0264);.;.;.;.;

MVP

0.54

MPC

0.096

ClinPred

0.031

GERP RS

2.6

Varity_R

0.040

gMVP

0.20

Mutation Taster

=99/1

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

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over