rs397507449

Variant names:

• chr20-63433808-C-T
• rs397507449
• ENST00000344425.8:c.1119G>A

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 10P and 2B. PVS1 PM2 BP6_Moderate

The NM_172107.4(KCNQ2):​c.1118+1G>A variant causes a splice donor, intron 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. 1/1 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Benign (★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: KCNQ2 NM_172107.4 splice_donor, intron
• Clinical Significance: Benign criteria provided, single submitter B:1 O:1
• Conservation: PhyloP100: 7.22

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 8 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• BP6: Variant 20-63433808-C-T is Benign according to our data. Variant chr20-63433808-C-T is described in ClinVar as [Benign]. Clinvar id is 21758.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.1118+1G>A		splice_donor_variant, intron_variant	Intron 8 of 16	ENST00000359125.7	NP_742105.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCNQ2	ENST00000359125.7	c.1118+1G>A		splice_donor_variant, intron_variant	Intron 8 of 16	1	NM_172107.4	ENSP00000352035.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Significance: Benign

Submissions summary: Benign:1 Other:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

May 28, 2019

Mendelics

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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GeneReviews

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

BNE (benign neonatal epilepsy) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.34
CADD	Pathogenic	28
DANN	Uncertain	1.0
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.96
FATHMM_MKL	Uncertain	0.92	D
GERP RS		4.9

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.96		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.96		Position offset: 1

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs397507449; hg19: chr20-62065161;