rs796052650

Variant names:

• chr20-63413574-G-A
• rs796052650
• NM_172107.4:c.1639C>T

Your query was ambiguous. Multiple possible variants found:

• chr20-63413574-G-A
• chr20-63413574-G-C
• chr20-63413574-G-T

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.1639C>T​(p.Arg547Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000685 in 1,459,140 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. R547Q) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: KCNQ2 NM_172107.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6 O:1
• Conservation: PhyloP100: 0.0970
• Publications: 9 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

LOC105372724 (HGNC:):

ACMG classification

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

• PM1: In a hotspot region, there are 20 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 12 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 chr20-63413573-C-A is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 2005878.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, 0.893
• PP5: Variant 20-63413574-G-A is Pathogenic according to our data. Variant chr20-63413574-G-A is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 205912.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.1639C>T	p.Arg547Trp	missense_variant	Exon 15 of 17	ENST00000359125.7	NP_742105.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNQ2	ENST00000359125.7	c.1639C>T	p.Arg547Trp	missense_variant	Exon 15 of 17	1	NM_172107.4	ENSP00000352035.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1459140 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 725938

African (AFR) AF: 0.00 AC: 0 AN: 33444

American (AMR) AF: 0.00 AC: 0 AN: 44720

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.00 AC: 0 AN: 39690

South Asian (SAS) AF: 0.00 AC: 0 AN: 86226

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52282

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5692

European-Non Finnish (NFE) AF: 9.00e-7 AC: 1 AN: 1110626

Other (OTH) AF: 0.00 AC: 0 AN: 60328

GnomAD4 genome Cov.: 33

Alfa AF: 0.00 Hom.: 0

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:6 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:4

Aug 14, 2024

Mayo Clinic Laboratories, Mayo Clinic

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

PP1, PP2, PP3, PM2, PS4_moderate

Sep 02, 2016

Center for Pediatric Genomic Medicine, Children's Mercy Hospital and Clinics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Nov 06, 2024

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 28717674, 29655203, 34474328, 35401395, 29455050, 27602407, 39141400, 23360469, 37593999, 38074073)

Nov 01, 2017

CeGaT Center for Human Genetics Tuebingen

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Seizures, benign familial neonatal, 1 Pathogenic:1 Other:1

Aug 29, 2024

3billion

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The variant is observed at an extremely low frequency in the gnomAD v4.0.0 dataset (total allele frequency: <0.001%). Predicted Consequence/Location: Missense variant In silico tool predictions suggest damaging effect of the variant on gene or gene product [REVEL: 0.79 (>=0.6, sensitivity 0.68 and specificity 0.92); 3Cnet: 0.99 (>=0.6, sensitivity 0.72 and precision 0.9)]. The same nucleotide change resulting in the same amino acid change has been previously reported as pathogenic/likely pathogenic with strong evidence (ClinVar ID: VCV000205912 /PMID: 23360469). The variant has been observed in at least two similarly affected unrelated individuals (PMID: 23360469, 29655203, 34474328). Different missense changes at the same codon (p.Arg547Gly, p.Arg547Leu) have been reported as pathogenic/likely pathogenic with strong evidence (ClinVar ID: VCV000226112, VCV002005878). Therefore, this variant is classified as Pathogenic according to the recommendation of ACMG/AMP guideline.

GeneReviews

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

BFNE (benign familial neonatal epilepsy)

Developmental and epileptic encephalopathy Pathogenic:1

May 23, 2024

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 tryptophan, which is neutral and slightly polar, at codon 547 of the KCNQ2 protein (p.Arg547Trp). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individuals with benign familial neonatal-infantile seizures (PMID: 23360469, 29655203; Invitae). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 205912). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. For these reasons, this variant has been classified as Pathogenic.

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.87
BayesDel_addAF	Pathogenic	0.47	D
BayesDel_noAF	Pathogenic	0.43
CADD	Benign	23
DANN	Uncertain	1.0
DEOGEN2	Benign	0.0	.;.;T;T;D;T;D;T;.;.;T
Eigen	Benign	-0.27
Eigen_PC	Benign	-0.38
FATHMM_MKL	Benign	0.66	D
LIST_S2	Uncertain	0.95	D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.97	D
MetaRNN	Pathogenic	0.89	D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Benign	0.0	.;.;.;.;.;.;M;.;.;.;.
PhyloP100		0.097
PrimateAI	Pathogenic	0.89	D
PROVEAN	Benign	0.0	.;.;.;.;D;.;D;.;D;.;.
REVEL	Benign	0.0
Sift	Pathogenic	0.0	.;.;.;.;D;.;D;.;D;.;.
Sift4G	Pathogenic	0.0010	D;D;D;D;D;.;D;D;D;D;D
Vest4		0.85
ClinPred		1.0	D
GERP RS		-1.1
Varity_R		0.89
gMVP		0.96
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: rs796052650; hg19: chr20-62044927; COSMIC: COSV60557310; COSMIC: COSV60557310;