8-132175472-T-C

Variant names:

• chr8-132175472-T-C
• rs118192248
• NM_004519.4:c.914A>G

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PM1 PM2 PM5 PP3_Strong

The NM_004519.4(KCNQ3):​c.914A>G​(p.Asp305Gly) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000657 in 152,190 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. D305H) has been classified as Uncertain significance.

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
• Consequence: KCNQ3 NM_004519.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2 O:1
• Conservation: PhyloP100: 8.02
• Publications: 6 publications found

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]

KCNQ3 Gene-Disease associations (from GenCC):

• complex neurodevelopmental disorder

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• seizures, benign familial neonatal, 2

  Inheritance: AD Classification: STRONG, MODERATE Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae)
• self-limited familial neonatal epilepsy

  Inheritance: AD Classification: MODERATE Submitted by: ClinGen
• benign familial infantile epilepsy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• benign neonatal seizures

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• genetic developmental and epileptic encephalopathy

  Inheritance: AR Classification: LIMITED Submitted by: Ambry Genetics, ClinGen

ACMG classification

Our verdict: Pathogenic. The variant received 10 ACMG points.

• PM1: In a hotspot region, there are 8 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 8 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 chr8-132175473-C-A is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 427162.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.958

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_004519.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	KCNQ3	NM_004519.4	MANE Select	c.914A>G	p.Asp305Gly	missense	Exon 5 of 15	NP_004510.1	O43525-1
	KCNQ3	NM_001204824.2		c.554A>G	p.Asp185Gly	missense	Exon 5 of 15	NP_001191753.1	O43525-2

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	KCNQ3	ENST00000388996.10	TSL:1 MANE Select	c.914A>G	p.Asp305Gly	missense	Exon 5 of 15	ENSP00000373648.3	O43525-1
	KCNQ3	ENST00000519445.5	TSL:5	c.914A>G	p.Asp305Gly	missense	Exon 5 of 15	ENSP00000428790.1	E7ET42
	KCNQ3	ENST00000521134.6	TSL:2	c.554A>G	p.Asp185Gly	missense	Exon 5 of 15	ENSP00000429799.1	O43525-2

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152190 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000241

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 32

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152190 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74358

African (AFR) AF: 0.0000241 AC: 1 AN: 41456

American (AMR) AF: 0.00 AC: 0 AN: 15288

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3468

East Asian (EAS) AF: 0.00 AC: 0 AN: 5176

South Asian (SAS) AF: 0.00 AC: 0 AN: 4834

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10624

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68026

Other (OTH) AF: 0.00 AC: 0 AN: 2090

Alfa AF: 0.00 Hom.: 0

ClinVar

ClinVar submissions

Significance: Uncertain significance

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
-	1	-	Benign neonatal seizures (1)
-	1	-	not specified (1)
-	-	-	Seizures, benign familial neonatal, 2 (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.58
CADD	Pathogenic	34
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.98	D
Eigen	Pathogenic	0.88
Eigen_PC	Pathogenic	0.83
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Pathogenic	0.54	D
MetaRNN	Pathogenic	0.96	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.1	M
PhyloP100		8.0
PrimateAI	Pathogenic	0.83	D
PROVEAN	Pathogenic	-6.7	D
REVEL	Pathogenic	0.99
Sift	Pathogenic	0.0	D
Sift4G	Uncertain	0.0030	D
Polyphen		1.0	D
Vest4		0.98
MutPred		0.83		Gain of catalytic residue at A304 (P = 0.0463)
MVP		1.0
MPC		2.3
ClinPred		1.0	D
GERP RS		5.5
Varity_R		0.97
gMVP		0.99
Mutation Taster		=4/96	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.28		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.28		Position offset: 1

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

Other links and lift over

dbSNP: rs118192248; hg19: chr8-133187719;