8-132180246-G-T

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Moderate

The NM_004519.4(KCNQ3):c.688C>A(p.Arg230Ser) variant causes a missense change. 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 Pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R230C) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: KCNQ3 NM_004519.4 missense
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 6.79

Genes affected

KCNQ3 (HGNC:6297): (potassium voltage-gated channel subfamily Q member 3) This gene encodes a protein that functions in the regulation of neuronal excitability. The encoded protein forms an M-channel by associating with the products of the related KCNQ2 or KCNQ5 genes, which both encode integral membrane proteins. M-channel currents are inhibited by M1 muscarinic acetylcholine receptors and are activated by retigabine, a novel anti-convulsant drug. Defects in this gene are a cause of benign familial neonatal convulsions type 2 (BFNC2), also known as epilepsy, benign neonatal type 2 (EBN2). Alternative splicing of this gene results in multiple transcript variants. [provided by RefSeq, May 2014]

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 3 uncertain in NM_004519.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr8-132180246-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 205963.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.978
• PP5: Variant 8-132180246-G-T is Pathogenic according to our data. Variant chr8-132180246-G-T is described in ClinVar as [Pathogenic]. Clinvar id is 978934.Status of the report is criteria_provided_single_submitter, 1 stars. Variant chr8-132180246-G-T is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
KCNQ3	NM_004519.4	c.688C>A	p.Arg230Ser	missense_variant	4/15	ENST00000388996.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KCNQ3	ENST00000388996.10	c.688C>A	p.Arg230Ser	missense_variant	4/15	1	NM_004519.4	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Intellectual disability Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Diagnostic Laboratory, Strasbourg University Hospital

Apr 20, 2020

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Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.57
Cadd	Pathogenic	27
Dann	Uncertain	1.0
DEOGEN2	Pathogenic	0.97	D;.;.;.;.
Eigen	Pathogenic	0.87
Eigen_PC	Pathogenic	0.82
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Pathogenic	1.0	D;D;D;D;D
M_CAP	Pathogenic	0.70	D
MetaRNN	Pathogenic	0.98	D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.4	M;.;.;.;.
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Pathogenic	0.91	D
PROVEAN	Pathogenic	-5.7	D;.;D;D;.
REVEL	Pathogenic	0.96
Sift	Pathogenic	0.0	D;.;D;D;.
Sift4G	Pathogenic	0.0010	D;D;D;D;.
Polyphen		1.0	D;.;.;D;.
Vest4		0.94
MutPred		0.88		Loss of MoRF binding (P = 0.017);.;.;Loss of MoRF binding (P = 0.017);.;
MVP		1.0
MPC		2.2
ClinPred		1.0	D
GERP RS		5.5
Varity_R		0.97
gMVP		0.99

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

LitVar

Other links and lift over

dbSNP: rs796052676; hg19: chr8-133192493;