NM_172107.4:c.757G>A

Variant names:

• chr20-63442465-C-T
• rs1057516093
• NM_172107.4:c.757G>A

Variant summary

Our verdict is Likely pathogenic. The variant received 9 ACMG points: 9P and 0B. PM1 PM2 PM5 PP2 PP5_Moderate

The NM_172107.4(KCNQ2):​c.757G>A​(p.Ala253Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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. A253P) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 29)
• Consequence: KCNQ2 NM_172107.4 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1 O:1
• Conservation: PhyloP100: 7.73
• 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

ACMG classification

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

• PM1: In a hotspot region, there are 26 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 chr20-63442465-C-G is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 1708357.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.
• PP5: Variant 20-63442465-C-T is Pathogenic according to our data. Variant chr20-63442465-C-T is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 369761.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.757G>A	p.Ala253Thr	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.757G>A	p.Ala253Thr	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: Likely pathogenic

Submissions summary: Pathogenic:1 Other:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

Dec 23, 2022

Institute of Human Genetics, University of Leipzig Medical Center

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

_x000D_ Criteria applied: PM5_STR, PM1, PS4_SUP, PM2_SUP, PP3 -

-

GeneReviews

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

Uncertain severity -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.69
BayesDel_addAF	Pathogenic	0.23	D
BayesDel_noAF	Uncertain	0.090
CADD	Pathogenic	26
DANN	Uncertain	1.0
DEOGEN2	Benign	0.35	.;.;T;T;D;T;D;T;.;.;.;.
Eigen	Benign	0.10
Eigen_PC	Benign	0.17
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.96	D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.51	D
MetaRNN	Uncertain	0.69	D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Uncertain	2.8	M;.;.;.;.;.;M;.;M;M;M;.
PhyloP100		7.7
PrimateAI	Uncertain	0.78	T
PROVEAN	Benign	-1.8	.;.;.;.;N;.;N;.;N;N;N;.
REVEL	Pathogenic	0.68
Sift	Uncertain	0.023	.;.;.;.;D;.;D;.;D;D;D;.
Sift4G	Benign	0.091	T;T;T;T;T;.;T;T;T;T;T;T
Polyphen		0.23	B;.;.;.;.;.;B;.;B;B;.;.
Vest4		0.86
MutPred		0.50		Gain of methylation at K255 (P = 0.0975);Gain of methylation at K255 (P = 0.0975);Gain of methylation at K255 (P = 0.0975);Gain of methylation at K255 (P = 0.0975);Gain of methylation at K255 (P = 0.0975);.;Gain of methylation at K255 (P = 0.0975);.;Gain of methylation at K255 (P = 0.0975);Gain of methylation at K255 (P = 0.0975);Gain of methylation at K255 (P = 0.0975);.;
MVP		0.92
MPC		2.0
ClinPred		0.97	D
GERP RS		3.4
Varity_R		0.37
gMVP		0.98
Mutation Taster		=0/100	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.050		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: rs1057516093; hg19: chr20-62073818;