rs185511111

Positions:

• chr8-132129996-C-A
• chr8-132129996-C-G
• chr8-132129996-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_004519.4(KCNQ3):​c.1885G>T​(p.Val629Phe) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000658 in 152,052 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
• Consequence: KCNQ3 NM_004519.4 missense, splice_region
• Scores: Splicing: ADA: 0.9998
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 7.37

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 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.936

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCNQ3	NM_004519.4	c.1885G>T	p.Val629Phe	missense_variant, splice_region_variant	15/15	ENST00000388996.10	NP_004510.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KCNQ3	ENST00000388996.10	c.1885G>T	p.Val629Phe	missense_variant, splice_region_variant	15/15	1	NM_004519.4	ENSP00000373648.3

Frequencies

GnomAD3 genomes AF: 0.00000658 AC: 1 AN: 152052 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000242

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: 0.00000658 AC: 1 AN: 152052 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74270

Gnomad4 AFR AF: 0.0000242

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Inborn genetic diseases Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Feb 28, 2018

The p.V629F variant (also known as c.1885G>T) is located in coding exon 15 of the KCNQ3 gene. The valine at codon 629 is replaced by phenylalanine, an amino acid with highly similar properties. This change occurs in the first base pair of coding exon 15. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Nov 01, 2013

p.Val629Phe (GTT>TTT): c.1885 G>T in exon 15 of the KCNQ3 gene. The Val629Phe missense change in the KCNQ3 has not been published as a mutation, nor has it been reported as a benign polymorphism to our knowledge. It was not observed in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. This variant is a conservative substitution of one uncharged, non-polar amino acid for another. It alters a highly conserved position in the C-terminal region of the protein. In silico analysis predicts this variant is probably damaging to the protein structure/function. Therefore, based on the currently available information, it is unclear whether Val629Phe is a disease-causing mutation or a rare benign variant. The variant is found in INFANT-EPI panel(s). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.95
BayesDel_addAF	Pathogenic	0.50	D
BayesDel_noAF	Pathogenic	0.48
CADD	Pathogenic	34
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.98	D;.;.;.;.
Eigen	Pathogenic	0.82
Eigen_PC	Pathogenic	0.80
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.97	D;D;D;D;D
M_CAP	Pathogenic	0.73	D
MetaRNN	Pathogenic	0.94	D;D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Uncertain	2.8	M;.;.;.;.
PrimateAI	Benign	0.40	T
PROVEAN	Pathogenic	-4.4	D;.;D;D;.
REVEL	Pathogenic	0.92
Sift	Uncertain	0.0010	D;.;D;D;.
Sift4G	Pathogenic	0.0010	D;D;D;D;.
Polyphen		1.0	D;.;.;D;.
Vest4		0.77
MutPred		0.71		Loss of MoRF binding (P = 0.1128);.;.;.;.;
MVP		0.92
MPC		0.58
ClinPred		0.99	D
GERP RS		5.7
Varity_R		0.81
gMVP		0.84

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.96
SpliceAI score (max)		0.060		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: rs185511111; hg19: chr8-133142243;