chr20-63439675-A-C

Position:

• chr20-63439675-A-C

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PM2 PP2 PP5

The NM_172107.4(KCNQ2):​c.850T>G​(p.Tyr284Asp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Pathogenic (no stars).

• Frequency: Genomes: not found (cov: 33)
• Consequence: KCNQ2 NM_172107.4 missense
• Clinical Significance: Pathogenic no assertion criteria provided P:1 O:1
• Conservation: PhyloP100: 1.60

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 (HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 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 gene, where missense usually causes diseases (based on misZ statistic), KCNQ2. . Gene score misZ 4.0411 (greater than the threshold 3.09). Trascript score misZ 3.6968 (greater than threshold 3.09). GenCC has associacion of gene with 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.
• PP5: Variant 20-63439675-A-C is Pathogenic according to our data. Variant chr20-63439675-A-C is described in ClinVar as [Pathogenic]. Clinvar id is 219234.Status of the report is no_assertion_criteria_provided, 0 stars. Variant chr20-63439675-A-C is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCNQ2	NM_172107.4	c.850T>G	p.Tyr284Asp	missense_variant	6/17	ENST00000359125.7	NP_742105.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KCNQ2	ENST00000359125.7	c.850T>G	p.Tyr284Asp	missense_variant	6/17	1	NM_172107.4	ENSP00000352035.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1 Other:1

Revision: no assertion criteria provided

Submissions by phenotype

Developmental and epileptic encephalopathy, 7 Pathogenic:1

Pathogenic, no assertion criteria provided

clinical testing

NeuroMeGen, Hospital Clinico Santiago de Compostela

-

- -

Complex neurodevelopmental disorder Other:1

not provided, no classification provided

literature only

Channelopathy-Associated Epilepsy Research Center

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- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.96
BayesDel_addAF	Pathogenic	0.27	D
BayesDel_noAF	Pathogenic	0.26
CADD	Pathogenic	27
DANN	Uncertain	0.99
Eigen	Uncertain	0.41
Eigen_PC	Uncertain	0.35
FATHMM_MKL	Uncertain	0.81	D
LIST_S2	Benign	0.12	T
M_CAP	Pathogenic	0.82	D
MetaRNN	Uncertain	0.74	D
Sift4G	Benign	0.31	T
MVP		0.79
ClinPred		0.98	D
GERP RS		4.0

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

Publications

LitVar

Other links and lift over

dbSNP: rs864321706; hg19: chr20-62071028; COSMIC: COSV60434144; COSMIC: COSV60434144;