NM_172107.4:c.773A>T

Variant names:

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

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PM1 PM2 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 (★).

• 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

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 Likely_pathogenic. Variant got 7 ACMG points.

• PM1: In a region_of_interest Mediates interaction with SLC5A3 (size 101) in uniprot entity KCNQ2_HUMAN there are 33 pathogenic changes around while only 0 benign (100%) 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 seizures, benign familial neonatal, 1, neonatal-onset developmental and epileptic encephalopathy, benign familial neonatal-infantile seizures, benign neonatal seizures, malignant migrating partial seizures of infancy, neonatal encephalopathy with non-epileptic myoclonus, complex neurodevelopmental disorder, seizures, benign familial neonatal, 2, developmental and epileptic encephalopathy, 7, benign familial infantile epilepsy.
• 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

Apr 14, 2022

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;.
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

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

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr20-62073802;