rs1057516099

Positions:

• chr20-63439624-C-T

Variant summary

Our verdict is Pathogenic. Variant got 19 ACMG points: 19P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Very_Strong

The NM_172107.4(KCNQ2):​c.901G>A​(p.Gly301Ser) 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 Pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G301D) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: KCNQ2 NM_172107.4 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:9 O:1
• Conservation: PhyloP100: 7.73

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 Pathogenic. Variant got 19 ACMG points.

• PM1: In a transmembrane_region Helical; Name=Segment S6 (size 20) in uniprot entity KCNQ2_HUMAN there are 10 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 chr20-63439623-C-T is described in Lovd as [Pathogenic].
• 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, 0.956
• PP5: Variant 20-63439624-C-T is Pathogenic according to our data. Variant chr20-63439624-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 369770.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr20-63439624-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCNQ2	NM_172107.4	c.901G>A	p.Gly301Ser	missense_variant	6/17	ENST00000359125.7	NP_742105.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KCNQ2	ENST00000359125.7	c.901G>A	p.Gly301Ser	missense_variant	6/17	1	NM_172107.4	ENSP00000352035.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:9 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Developmental and epileptic encephalopathy, 7 Pathogenic:5 Other:1

Pathogenic, criteria provided, single submitter	research	Al Jalila Children’s Genomics Center, Al Jalila Childrens Speciality Hospital	Oct 04, 2024	PS2, PM2, PS3, PM5 -
not provided, no classification provided	literature only	GeneReviews	-	EE (epileptic encephalopathy) -
Pathogenic, criteria provided, single submitter	clinical testing	3billion	Oct 02, 2021	Same nucleotide change resulting in same amino acid change has been previously reported as de novoo (ClinVar ID: VCV000369770.5, PMID: 27864847, PS2). The missense variant is located in a mutational hot spot and/or well-established functional domain in which established pathogenic variants have been reported (PM1). It is not observed in the gnomAD v2.1.1 dataset (PM2). A different missense change (p.Gly301Asp) at the same codon has been reported as pathogenic (ClinVar ID: VCV000431095.3). The variant was observed as assumed (i.e. paternity and maternity not confirmed) de novoo (3billion dataset, PM6). In silico tool predictions suggest damaging effect of the variant on gene or gene product (REVEL: 0.944, 3Cnet: 0.943, PP3). Therefore, this variant is classified as pathogenic according to the recommendation of ACMG/AMP guideline. -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	Victorian Clinical Genetics Services, Murdoch Childrens Research Institute	Oct 19, 2020	Based on the classification scheme VCGS_Germline_v1.3.3, this variant is classified as Pathogenic. Following criteria are met: 0103 - Dominant negative and loss of function are known mechanisms of disease in this gene and are associated with early infantile epileptic encephalopathy 7 (EEIE) (MIM#613720) (PMID: 24318194). (I) 0107 - This gene is associated with autosomal dominant disease. (I) 0200 - Variant is predicted to result in a missense amino acid change from glycine to serine. (I) 0251 - This variant is heterozygous. (I) 0301 - Variant is absent from gnomAD (both v2 and v3). (SP) 0501 - Missense variant consistently predicted to be damaging by multiple in silico tools or highly conserved with a major amino acid change. (SP) 0603 - Missense variant in a region that is highly intolerant to missense variation (high constraint region in DECIPHER). (SP) 0703 - Other missense variants comparable to the one identified in this case have moderate previous evidence for pathogenicity. Two alternative missense changes (p.Gly301Ser, p.Gly301Val) have been reported as pathogenic, likely pathogenic and as a VUS (ClinVar, LOVD). One report notes the patient was de novo. (SP) 0801 - This variant has strong previous evidence of pathogenicity in unrelated individuals. This variant has been reported as pathogenic and likely pathogenic, and has been observed in several de novo patients with EEIE (ClinVar, LOVD, PMID 25959266). (SP) 1203 - This variant has been shown to be de novo in the proband (parental status confirmed) (by trio analysis). (SP) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -
Pathogenic, criteria provided, single submitter	clinical testing	Institute of Human Genetics, University of Leipzig Medical Center	Feb 12, 2024	Criteria applied: PS2,PS4,PM5_STR,PM1,PM2_SUP,PP3 -

not provided Pathogenic:2

Pathogenic, no assertion criteria provided	clinical testing	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -
Pathogenic, no assertion criteria provided	clinical testing	Genome Diagnostics Laboratory, University Medical Center Utrecht	-	- -

Early infantile epileptic encephalopathy with suppression bursts Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Mar 26, 2023

For these reasons, this variant has been classified as Pathogenic. 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: 369770). This missense change has been observed in individual(s) with KCNQ2-related epilepsy (PMID: 27864847, 31418850). In at least one individual the variant was observed to be de novo. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glycine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 301 of the KCNQ2 protein (p.Gly301Ser). -

Epileptic encephalopathy Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Neurogenetics Laboratory - MEYER, AOU Meyer

Nov 16, 2016

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.57
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.49	.;.;T;T;D;T;D;T;.;.;.
Eigen	Uncertain	0.58
Eigen_PC	Uncertain	0.45
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.97	D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.93	D
MetaRNN	Pathogenic	0.96	D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.1	M;.;.;.;.;.;M;.;M;M;M
PrimateAI	Pathogenic	0.87	D
PROVEAN	Pathogenic	-5.5	.;.;.;.;D;.;D;.;D;D;D
REVEL	Pathogenic	0.92
Sift	Uncertain	0.0010	.;.;.;.;D;.;D;.;D;D;D
Sift4G	Uncertain	0.029	D;D;D;D;D;.;D;D;D;D;D
Polyphen		1.0	D;.;.;.;.;.;D;.;D;D;.
Vest4		0.97
MutPred		0.74		Loss of sheet (P = 0.1907);Loss of sheet (P = 0.1907);Loss of sheet (P = 0.1907);Loss of sheet (P = 0.1907);Loss of sheet (P = 0.1907);.;Loss of sheet (P = 0.1907);.;Loss of sheet (P = 0.1907);Loss of sheet (P = 0.1907);Loss of sheet (P = 0.1907);
MVP		0.99
MPC		2.8
ClinPred		1.0	D
GERP RS		4.0
Varity_R		0.93
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: rs1057516099; hg19: chr20-62070977; COSMIC: COSV60432245; COSMIC: COSV60432245;