rs1057516077

Positions:

• chr20-63446793-G-A
• chr20-63446793-G-C

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.341C>T​(p.Thr114Ile) variant causes a missense change involving the alteration of a conserved nucleotide. 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: 32)
• Consequence: KCNQ2 NM_172107.4 missense
• Clinical Significance: Likely pathogenic no assertion criteria provided P:1 O:1
• Conservation: PhyloP100: 7.76

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 (HGNC:):

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, 0.921
• PP5: Variant 20-63446793-G-A is Pathogenic according to our data. Variant chr20-63446793-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 369742.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.341C>T	p.Thr114Ile	missense_variant	2/17	ENST00000359125.7	NP_742105.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KCNQ2	ENST00000359125.7	c.341C>T	p.Thr114Ile	missense_variant	2/17	1	NM_172107.4	ENSP00000352035.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1 Other:1

Revision: no assertion criteria provided

Submissions by phenotype

KCNQ2-related disorder Pathogenic:1

Likely pathogenic, no assertion criteria provided

clinical testing

PreventionGenetics, part of Exact Sciences

Nov 28, 2023

The KCNQ2 c.341C>T variant is predicted to result in the amino acid substitution p.Thr114Ile. This variant was reported to occur de novo in an individual with early onset epileptic encephalopathy (case #1654 in Saitsu et al 2012. PubMed ID: 22926866). A different amino acid substitution at this position (c.340A>G, p.Thr114Ala) was reported in a patient with benign familial neonatal epilepsy (Grinton et al 2015. PubMed ID: 25982755). This variant has not been reported in a large population database (http://gnomad.broadinstitute.org), indicating this variant is rare. This variant is interpreted as likely pathogenic. -

Developmental and epileptic encephalopathy, 7 Other:1

not provided, no classification provided

literature only

GeneReviews

-

Likely EE (epileptic encephalopathy) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.56
CADD	Pathogenic	30
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.48	.;.;T;T;D;D;.;.;.
Eigen	Pathogenic	0.74
Eigen_PC	Uncertain	0.64
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Pathogenic	0.99	D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.96	D
MetaRNN	Pathogenic	0.92	D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Uncertain	2.8	M;.;.;.;.;M;M;M;M
PrimateAI	Pathogenic	0.89	D
PROVEAN	Pathogenic	-5.1	.;.;.;.;D;D;D;D;D
REVEL	Pathogenic	0.90
Sift	Pathogenic	0.0	.;.;.;.;D;D;D;D;D
Sift4G	Pathogenic	0.0	D;D;D;D;D;D;D;D;D
Polyphen		1.0	D;.;.;.;.;D;D;D;.
Vest4		0.97
MutPred		0.57		Loss of disorder (P = 0.05);Loss of disorder (P = 0.05);Loss of disorder (P = 0.05);Loss of disorder (P = 0.05);Loss of disorder (P = 0.05);Loss of disorder (P = 0.05);Loss of disorder (P = 0.05);Loss of disorder (P = 0.05);Loss of disorder (P = 0.05);
MVP		0.99
MPC		2.4
ClinPred		1.0	D
GERP RS		3.9
Varity_R		0.92
gMVP		0.97

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

Other links and lift over

dbSNP: rs1057516077; hg19: chr20-62078146;