rs796052620

Positions:

• chr20-63444766-A-G

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.583T>C​(p.Ser195Pro) 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. S195C) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: KCNQ2 NM_172107.4 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3 O:1
• Conservation: PhyloP100: 9.13

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 19 ACMG points.

• PM1: In a hotspot region, there are 11 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 7 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 chr20-63444765-G-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 982654.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP2: Missense variant where missense usually causes diseases, KCNQ2
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.943
• PP5: Variant 20-63444766-A-G is Pathogenic according to our data. Variant chr20-63444766-A-G is described in ClinVar as [Pathogenic]. Clinvar id is 205866.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
KCNQ2	NM_172107.4	c.583T>C	p.Ser195Pro	missense_variant	4/17	ENST00000359125.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KCNQ2	ENST00000359125.7	c.583T>C	p.Ser195Pro	missense_variant	4/17	1	NM_172107.4	A1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Inborn genetic diseases Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Mar 09, 2016

worked up for close match - no RD needed until we see in house. -

Early infantile epileptic encephalopathy with suppression bursts Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Aug 10, 2022

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: 205866). This missense change has been observed in individual(s) with clinical features of KCNQ2-related conditions (PMID: 24107868; Invitae). 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 serine, which is neutral and polar, with proline, which is neutral and non-polar, at codon 195 of the KCNQ2 protein (p.Ser195Pro). -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Sep 17, 2012

p.Ser195Pro (TCT>CCT):c.583 T>C in exon 4 of the KCNQ2 gene (NM_172107.2)The Ser195Pro missense change has not been published as a mutation, nor has it been reported as a benign polymorphism to our knowledge. The NHLBI ESP Exome Variant Project has not identified Ser195Pro in approximately 6,500 individuals of European or African American ethnicity, indicating that it is not a common benign variant in these populations. The amino acid substitution is non-conservative, as a polar Serine is replaced by a non-polar Proline, and the gain of a bulky Proline residue may alter the secondary structure of the protein. Ser195Pro alters a highly conserved position in the linker region between the S3 and S4 transmembrane segments of the protein. Some in silico algorithms predict Ser195Pro may be damaging to protein structure/function, although one model suggests it is benign. Therefore, based on the currently available information, it is unclear whether Ser195Pro is a disease-causing mutation or a rare benign variant. The variant is found in INFANT-EPI panel(s). -

Developmental and epileptic encephalopathy, 7 Other:1

not provided, no classification provided

literature only

GeneReviews

-

Infantile spasms -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.55	D
BayesDel_noAF	Pathogenic	0.56
CADD	Pathogenic	28
DANN	Uncertain	1.0
Eigen	Uncertain	0.21
Eigen_PC	Benign	0.15
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Pathogenic	0.97	D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.88	D
MetaRNN	Pathogenic	0.94	D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Uncertain	2.3	M;.;.;.;.;.;M;.;M;M;M;.
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D;D;D;D;D
PrimateAI	Pathogenic	0.86	D
Sift4G	Uncertain	0.0020	D;D;D;D;D;.;D;D;D;D;D;D
Polyphen		0.99	D;.;.;.;.;.;D;.;D;D;.;.
Vest4		0.99
MutPred		0.73		Loss of MoRF binding (P = 0.0556);Loss of MoRF binding (P = 0.0556);Loss of MoRF binding (P = 0.0556);Loss of MoRF binding (P = 0.0556);Loss of MoRF binding (P = 0.0556);.;Loss of MoRF binding (P = 0.0556);.;Loss of MoRF binding (P = 0.0556);Loss of MoRF binding (P = 0.0556);Loss of MoRF binding (P = 0.0556);.;
MVP		1.0
MPC		3.2
ClinPred		1.0	D
GERP RS		3.9
Varity_R		0.93
gMVP		1.0

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs796052620; hg19: chr20-62076119;