20-63444720-C-G

Variant names:

• chr20-63444720-C-G
• rs886041262
• NM_172107.4:c.629G>C

Variant summary

Our verdict is Pathogenic. The variant received 17 ACMG points: 17P and 0B. PM1 PM2 PM5 PP2 PP3_Moderate PP5_Very_Strong

The NM_172107.4(KCNQ2):​c.629G>C​(p.Arg210Pro) 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 (★★). 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)
• Consequence: KCNQ2 NM_172107.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 4.90
• Publications: 19 publications found

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 Gene-Disease associations (from GenCC):

• complex neurodevelopmental disorder

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• developmental and epileptic encephalopathy, 7

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Labcorp Genetics (formerly Invitae), G2P
• neonatal encephalopathy with non-epileptic myoclonus

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• neonatal-onset developmental and epileptic encephalopathy

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• seizures, benign familial neonatal, 1

  Inheritance: AD Classification: DEFINITIVE Submitted by: G2P
• seizures, benign familial neonatal, 2

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
• benign familial infantile epilepsy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• benign familial neonatal-infantile seizures

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• benign neonatal seizures

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• malignant migrating partial seizures of infancy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 17 ACMG points.

• PM1: In a hotspot region, there are 31 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 4 uncertain 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 ClinVar as Pathogenic. ClinVar VariationId is 279931.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• 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 benign familial infantile epilepsy, malignant migrating partial seizures of infancy, developmental and epileptic encephalopathy, 7, benign familial neonatal-infantile seizures, benign neonatal seizures, neonatal-onset developmental and epileptic encephalopathy, complex neurodevelopmental disorder, seizures, benign familial neonatal, 2, seizures, benign familial neonatal, 1, neonatal encephalopathy with non-epileptic myoclonus.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.93
• PP5: Variant 20-63444720-C-G is Pathogenic according to our data. Variant chr20-63444720-C-G is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 280614.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.629G>C	p.Arg210Pro	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.629G>C	p.Arg210Pro	missense_variant	Exon 4 of 17	1	NM_172107.4	ENSP00000352035.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:3

May 25, 2018

Genetic Services Laboratory, University of Chicago

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Oct 30, 2023

Revvity Omics, Revvity

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Dec 27, 2016

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The R210P variant has not been published as a pathogenic variant, nor has it been reported as a benign variant to our knowledge. However, different missense variants at the same position (R210C, R210H) have been reported previously in association with KCNQ2-related disorders (Stenson et al., 2014). The R210P variant was not observed in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. The R210P variant is a non-conservative amino acid substitution, which is likely to impact secondary protein structure as these residues differ in polarity, charge, size and/or other properties. This substitution occurs at a conserved position predicted to be within the voltage-sensor transmembrane segment S4 of the protein, and multiple missense variants in nearby residues have been reported in the Human Gene Mutation Database in association with KCNQ2-related disorders (Stenson et al., 2014), supporting the functional importance of this region of the protein. Therefore, the R210P variant is considered to be a pathogenic variant -

Developmental and epileptic encephalopathy Pathogenic:1

Aug 09, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. This variant disrupts the p.Arg210 amino acid residue in KCNQ2. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 24107868, 24371303, 25880994, 26446091, 28283543). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. 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. ClinVar contains an entry for this variant (Variation ID: 280614). This variant has not been reported in the literature in individuals affected with KCNQ2-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces arginine, which is basic and polar, with proline, which is neutral and non-polar, at codon 210 of the KCNQ2 protein (p.Arg210Pro). -

Developmental and epileptic encephalopathy, 7 Pathogenic:1

Mar 09, 2017

HudsonAlpha Institute for Biotechnology, HudsonAlpha Institute for Biotechnology

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: research

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.55	D
BayesDel_noAF	Pathogenic	0.55
CADD	Pathogenic	33
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.52	.;.;D;D;D;T;D;D;.;.;.;.
Eigen	Uncertain	0.56
Eigen_PC	Uncertain	0.52
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.98	D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.96	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;.
PhyloP100		4.9
PrimateAI	Pathogenic	0.89	D
PROVEAN	Pathogenic	-6.3	.;.;.;.;D;.;D;.;D;D;D;.
REVEL	Pathogenic	0.93
Sift	Uncertain	0.0010	.;.;.;.;D;.;D;.;D;D;D;.
Sift4G	Uncertain	0.0020	D;D;D;D;D;.;D;D;D;D;D;D
Polyphen		0.92	P;.;.;.;.;.;P;.;P;P;.;.
Vest4		0.94
MutPred		0.67		Loss of MoRF binding (P = 0.0075);Loss of MoRF binding (P = 0.0075);Loss of MoRF binding (P = 0.0075);Loss of MoRF binding (P = 0.0075);Loss of MoRF binding (P = 0.0075);.;Loss of MoRF binding (P = 0.0075);.;Loss of MoRF binding (P = 0.0075);Loss of MoRF binding (P = 0.0075);Loss of MoRF binding (P = 0.0075);.;
MVP		0.99
MPC		3.4
ClinPred		1.0	D
GERP RS		4.0
PromoterAI		0.012	Neutral
Varity_R		0.99
gMVP		1.0
Mutation Taster		=0/100	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs886041262; hg19: chr20-62076073;