chr8-132480350-G-A

Variant names:

• chr8-132480350-G-A
• rs761977947
• NM_004519.4:c.183C>T

Variant summary

Our verdict is Likely benign. The variant received -5 ACMG points: 2P and 7B. PM2 BP4_Strong BP6_Moderate BP7

The NM_004519.4(KCNQ3):​c.183C>T​(p.Ala61Ala) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★). Synonymous variant affecting the same amino acid position (i.e. A61A) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: KCNQ3 NM_004519.4 synonymous
• Clinical Significance: Likely benign criteria provided, single submitter B:1
• Conservation: PhyloP100: -1.27
• Publications: 0 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):

• seizures, benign familial neonatal, 2

  Inheritance: AD Classification: STRONG, MODERATE Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae)
• 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

ACMG classification

Our verdict: Likely_benign. The variant received -5 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.72).
• BP6: Variant 8-132480350-G-A is Benign according to our data. Variant chr8-132480350-G-A is described in ClinVar as Likely_benign. ClinVar VariationId is 2157102.Status of the report is criteria_provided_single_submitter, 1 stars.
• BP7: Synonymous conserved (PhyloP=-1.27 with no splicing effect.

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

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	KCNQ3	NM_004519.4	MANE Select	c.183C>T	p.Ala61Ala	synonymous	Exon 1 of 15	NP_004510.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	KCNQ3	ENST00000388996.10	TSL:1 MANE Select	c.183C>T	p.Ala61Ala	synonymous	Exon 1 of 15	ENSP00000373648.3
	KCNQ3	ENST00000519445.5	TSL:5	c.183C>T	p.Ala61Ala	synonymous	Exon 1 of 15	ENSP00000428790.1
	KCNQ3	ENST00000519589.1	TSL:2	n.-40C>T		upstream_gene	N/A

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Data not reliable, filtered out with message: AS_VQSR AF: 6.93e-7 AC: 1 AN: 1443226 Hom.: 0 Cov.: 33 AF XY: 0.00000139 AC XY: 1 AN XY: 717484

African (AFR) AF: 0.00 AC: 0 AN: 32742

American (AMR) AF: 0.00 AC: 0 AN: 43942

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25754

East Asian (EAS) AF: 0.00 AC: 0 AN: 38794

South Asian (SAS) AF: 0.00 AC: 0 AN: 84498

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 45316

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5510

European-Non Finnish (NFE) AF: 9.03e-7 AC: 1 AN: 1106982

Other (OTH) AF: 0.00 AC: 0 AN: 59688

GnomAD4 genome Cov.: 33

ClinVar

ClinVar submissions as Germline

Significance: Likely benign

Revision: criteria provided, single submitter

Pathogenic	VUS	Benign	Condition
-	-	1	Benign neonatal seizures (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.72
CADD	Benign	9.3
DANN	Benign	0.84
PhyloP100		-1.3
PromoterAI		-0.026	Neutral

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

Other links and lift over

dbSNP: rs761977947; hg19: chr8-133492597;