20-63445276-C-A

Position:

• chr20-63445276-C-A

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP2 PP3_Moderate PP5

The NM_172107.4(KCNQ2):​c.476G>T​(p.Gly159Val) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (no stars).

• Frequency: Genomes: not found (cov: 34)
• Consequence: KCNQ2 NM_172107.4 missense
• Clinical Significance: Likely pathogenic no assertion criteria provided P:1
• Conservation: PhyloP100: 6.01

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]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• 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.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.926
• PP5: Variant 20-63445276-C-A is Pathogenic according to our data. Variant chr20-63445276-C-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 438297.Status of the report is no_assertion_criteria_provided, 0 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCNQ2	NM_172107.4	c.476G>T	p.Gly159Val	missense_variant	3/17	ENST00000359125.7	NP_742105.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KCNQ2	ENST00000359125.7	c.476G>T	p.Gly159Val	missense_variant	3/17	1	NM_172107.4	ENSP00000352035	A1

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 34

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: no assertion criteria provided

Submissions by phenotype

Developmental and epileptic encephalopathy, 7 Pathogenic:1

Likely pathogenic, no assertion criteria provided

clinical testing

Molecular Genetics Laboratory, BC Children's and BC Women's Hospitals

Mar 27, 2017

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.54	D
BayesDel_noAF	Pathogenic	0.54
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.48	.;.;T;T;D;D;T;.;.;.
Eigen	Uncertain	0.50
Eigen_PC	Uncertain	0.37
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	1.0	D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.94	D
MetaRNN	Pathogenic	0.93	D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.1	M;.;.;.;.;M;.;M;M;M
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D;D;D;D;D
PrimateAI	Uncertain	0.78	T
PROVEAN	Pathogenic	-8.0	.;.;.;.;D;D;.;D;D;D
REVEL	Pathogenic	0.86
Sift	Pathogenic	0.0	.;.;.;.;D;D;.;D;D;D
Sift4G	Pathogenic	0.0	D;D;D;D;D;D;D;D;D;D
Polyphen		1.0	D;.;.;.;.;D;.;D;D;.
Vest4		0.91
MutPred		0.63		Loss of helix (P = 0.0444);Loss of helix (P = 0.0444);Loss of helix (P = 0.0444);Loss of helix (P = 0.0444);Loss of helix (P = 0.0444);Loss of helix (P = 0.0444);.;Loss of helix (P = 0.0444);Loss of helix (P = 0.0444);Loss of helix (P = 0.0444);
MVP		0.98
MPC		3.2
ClinPred		1.0	D
GERP RS		3.8
Varity_R		0.87
gMVP		0.98

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.13		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

Other links and lift over

dbSNP: rs1057516081; hg19: chr20-62076629;