rs796052626

Variant names:

• chr20-63444721-G-A
• rs796052626
• NM_172107.4:c.628C>T

Variant summary

Our verdict is Pathogenic. Variant got 17 ACMG points: 17P and 0B. PM1 PM2 PM5 PP2 PP3_Moderate PP5_Very_Strong

The NM_172107.4(KCNQ2):​c.628C>T​(p.Arg210Cys) 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. 13/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R210H) has been classified as Pathogenic.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: KCNQ2 NM_172107.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4 O:1
• Conservation: PhyloP100: 9.79

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 Pathogenic. Variant got 17 ACMG points.

• PM1: In a transmembrane_region Helical; Voltage-sensor; Name=Segment S4 (size 22) in uniprot entity KCNQ2_HUMAN there are 15 pathogenic changes around while only 0 benign (100%) in NM_172107.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr20-63444720-C-T is described in Lovd as [Pathogenic].
• PP2: Missense variant in the KCNQ2 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 319 curated pathogenic missense variants (we use a threshold of 10). The gene has 78 curated benign missense variants. Gene score misZ: 4.0411 (above the threshold of 3.09). Trascript score misZ: 3.6968 (above the threshold of 3.09). GenCC associations: The gene is linked to 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, 0.933
• PP5: Variant 20-63444721-G-A is Pathogenic according to our data. Variant chr20-63444721-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 205873.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNQ2	NM_172107.4	c.628C>T	p.Arg210Cys	missense_variant	Exon 4 of 17	ENST00000359125.7	NP_742105.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNQ2	ENST00000359125.7	c.628C>T	p.Arg210Cys	missense_variant	Exon 4 of 17	1	NM_172107.4	ENSP00000352035.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1449454 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 719682

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Developmental and epileptic encephalopathy, 7 Pathogenic:1 Other:1

Dec 24, 2021

Baylor Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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GeneReviews

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

EE (epileptic encephalopathy) -

Early infantile epileptic encephalopathy with suppression bursts Pathogenic:1

Dec 21, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces arginine, which is basic and polar, with cysteine, which is neutral and slightly polar, at codon 210 of the KCNQ2 protein (p.Arg210Cys). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with KCNQ2-related benign familial neonatal epilepsy (PMID: 28602030). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 205873). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt KCNQ2 protein function with a positive predictive value of 95%. This variant disrupts the p.Arg210 amino acid residue in KCNQ2. Other variant(s) that disrupt this residue have been determined to be pathogenic (Invitae). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -

Seizures, benign familial neonatal, 1 Pathogenic:1

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Centre de Biologie Pathologie Génétique, Centre Hospitalier Universitaire de Lille

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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Intellectual disability Pathogenic:1

Dec 01, 2017

Diagnostic Laboratory, Strasbourg University Hospital

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

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Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.59
CADD	Pathogenic	34
DANN	Pathogenic	1.0
DEOGEN2	Uncertain	0.60	.;.;D;D;D;T;D;D;.;.;.;.
Eigen	Pathogenic	0.86
Eigen_PC	Pathogenic	0.75
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.95	D
MetaRNN	Pathogenic	0.93	D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.8	H;.;.;.;.;.;H;.;H;H;H;.
PrimateAI	Pathogenic	0.91	D
PROVEAN	Pathogenic	-7.2	.;.;.;.;D;.;D;.;D;D;D;.
REVEL	Pathogenic	0.94
Sift	Pathogenic	0.0	.;.;.;.;D;.;D;.;D;D;D;.
Sift4G	Pathogenic	0.0	D;D;D;D;D;.;D;D;D;D;D;D
Polyphen		1.0	D;.;.;.;.;.;D;.;D;D;.;.
Vest4		0.95
MutPred		0.64		Loss of MoRF binding (P = 0.0148);Loss of MoRF binding (P = 0.0148);Loss of MoRF binding (P = 0.0148);Loss of MoRF binding (P = 0.0148);Loss of MoRF binding (P = 0.0148);.;Loss of MoRF binding (P = 0.0148);.;Loss of MoRF binding (P = 0.0148);Loss of MoRF binding (P = 0.0148);Loss of MoRF binding (P = 0.0148);.;
MVP		0.99
MPC		3.3
ClinPred		1.0	D
GERP RS		4.0
Varity_R		0.96
gMVP		0.99

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: rs796052626; hg19: chr20-62076074; COSMIC: COSV60433067; COSMIC: COSV60433067;