rs118192207

Variant names:

• chr20-63442449-T-A
• rs118192207
• NM_172107.4:c.773A>T

Your query was ambiguous. Multiple possible variants found:

• chr20-63442449-T-A
• chr20-63442449-T-C

Variant summary

Our verdict is Likely pathogenic. The variant received 9 ACMG points: 9P and 0B. PM1 PM2 PM5 PP2 PP3_Moderate

The NM_172107.4(KCNQ2):​c.773A>T​(p.Asn258Ile) 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 Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. N258S) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 29)
• Consequence: KCNQ2 NM_172107.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.84
• Publications: 1 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: Likely_pathogenic. The variant received 9 ACMG points.

• PM1: In a hotspot region, there are 30 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 9 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 chr20-63442450-T-C is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 4071957.Status of the report is criteria_provided_single_submitter, 1 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, 0.875

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNQ2	NM_172107.4	c.773A>T	p.Asn258Ile	missense_variant	Exon 5 of 17	ENST00000359125.7	NP_742105.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNQ2	ENST00000359125.7	c.773A>T	p.Asn258Ile	missense_variant	Exon 5 of 17	1	NM_172107.4	ENSP00000352035.2

Frequencies

GnomAD3 genomes Cov.: 29

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 29

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Seizures, benign familial neonatal, 1;C3150986:Developmental and epileptic encephalopathy, 7 Uncertain:1

-

Center for Genomics, Ann and Robert H. Lurie Children's Hospital of Chicago

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant has been reported in the literature in at least 1 individual with Lennox-Gastaut syndrome (Na 2020 PMID:32139178, Kim 2021 PMID:32917465). This variant is not present in large control databases. Evolutionary conservation and computational predictive tools suggest that this variant may impact the protein. Of note, other variants at this position have been reported in association with disease (p.Asn258Ser). In summary, data on this variant is suspicious for disease, but requires further evidence for pathogenicity. Therefore, the clinical significance of this variant is uncertain -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.41	D
BayesDel_noAF	Pathogenic	0.35
CADD	Pathogenic	28
DANN	Uncertain	0.99
DEOGEN2	Benign	0.41	.;.;T;T;D;T;D;T;.;.;.;.
Eigen	Uncertain	0.34
Eigen_PC	Uncertain	0.31
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.89	D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.69	D
MetaRNN	Pathogenic	0.88	D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.5	M;.;.;.;.;.;M;.;M;M;M;.
PhyloP100		7.8
PrimateAI	Uncertain	0.75	T
PROVEAN	Pathogenic	-7.1	.;.;.;.;D;.;D;.;D;D;D;.
REVEL	Pathogenic	0.80
Sift	Uncertain	0.0020	.;.;.;.;D;.;D;.;D;D;D;.
Sift4G	Uncertain	0.0060	D;D;D;D;D;.;D;D;D;D;D;D
Polyphen		0.68	P;.;.;.;.;.;P;.;P;P;.;.
Vest4		0.84
MutPred		0.61		Loss of disorder (P = 0.0064);Loss of disorder (P = 0.0064);Loss of disorder (P = 0.0064);Loss of disorder (P = 0.0064);Loss of disorder (P = 0.0064);.;Loss of disorder (P = 0.0064);.;Loss of disorder (P = 0.0064);Loss of disorder (P = 0.0064);Loss of disorder (P = 0.0064);.;
MVP		0.98
MPC		2.8
ClinPred		0.99	D
GERP RS		3.4
Varity_R		0.93
gMVP		1.0
Mutation Taster		=0/100	disease causing

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: rs118192207; hg19: chr20-62073802;