chr20-63433842-T-C

Variant names:

• chr20-63433842-T-C
• rs1057516111
• NM_172107.4:c.1085A>G

Variant summary

Our verdict is Likely pathogenic. The variant received 9 ACMG points: 9P and 0B. PM1 PM2 PP2 PP3_Moderate PP5_Moderate

The NM_172107.4(KCNQ2):​c.1085A>G​(p.Tyr362Cys) variant causes a missense change involving the alteration of a non-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 Likely pathogenic (★). Synonymous variant affecting the same amino acid position (i.e. Y362Y) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 33)
• Consequence: KCNQ2 NM_172107.4 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1 O:1
• Conservation: PhyloP100: 2.81
• Publications: 3 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

ENSG00000293847 (HGNC:):

ACMG classification

Our verdict: Likely_pathogenic. The variant received 9 ACMG points.

• PM1: In a hotspot region, there are 13 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
• 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, 0.867
• PP5: Variant 20-63433842-T-C is Pathogenic according to our data. Variant chr20-63433842-T-C is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 369784.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCNQ2	NM_172107.4	c.1085A>G	p.Tyr362Cys	missense_variant	Exon 8 of 17	ENST00000359125.7	NP_742105.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNQ2	ENST00000359125.7	c.1085A>G	p.Tyr362Cys	missense_variant	Exon 8 of 17	1	NM_172107.4	ENSP00000352035.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1 Other:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Pathogenic:1

Jun 13, 2023

Mayo Clinic Laboratories, Mayo Clinic

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

PP1_moderate, PP2, PP3, PP4, PM2_moderate -

Seizures, benign familial neonatal, 1 Other:1

-

GeneReviews

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

BFNE (benign familial neonatal epilepsy) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.53
BayesDel_addAF	Pathogenic	0.42	D
BayesDel_noAF	Pathogenic	0.37
CADD	Pathogenic	29
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.48	.;.;T;T;T;T;D;T;.;.;.
Eigen	Uncertain	0.45
Eigen_PC	Uncertain	0.46
FATHMM_MKL	Uncertain	0.91	D
LIST_S2	Uncertain	0.95	D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.86	D
MetaRNN	Pathogenic	0.87	D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Uncertain	2.4	M;.;.;.;.;.;M;.;M;M;M
PhyloP100		2.8
PrimateAI	Uncertain	0.77	T
PROVEAN	Pathogenic	-5.2	.;.;.;.;D;.;D;.;D;D;D
REVEL	Pathogenic	0.92
Sift	Uncertain	0.0050	.;.;.;.;D;.;D;.;D;D;T
Sift4G	Uncertain	0.040	D;T;T;T;T;.;D;T;T;T;T
Polyphen		1.0	D;.;.;.;.;.;D;.;D;D;.
Vest4		0.92
MutPred		0.47		Loss of phosphorylation at Y362 (P = 0.0654);Loss of phosphorylation at Y362 (P = 0.0654);Loss of phosphorylation at Y362 (P = 0.0654);Loss of phosphorylation at Y362 (P = 0.0654);Loss of phosphorylation at Y362 (P = 0.0654);.;Loss of phosphorylation at Y362 (P = 0.0654);.;Loss of phosphorylation at Y362 (P = 0.0654);Loss of phosphorylation at Y362 (P = 0.0654);Loss of phosphorylation at Y362 (P = 0.0654);
MVP		0.99
MPC		3.0
ClinPred		0.99	D
GERP RS		4.9
Varity_R		0.79
gMVP		0.97
Mutation Taster		=0/100	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs1057516111; hg19: chr20-62065195;