rs140712277

chr20-63445350-G-A

Variant summary

Our verdict is Benign. Variant got -15 ACMG points: 0P and 15B. BP4_Strong BP6_Moderate BP7 BS1 BS2

The NM_172107.4(KCNQ2):c.402C>T(p.Ile134=) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000279 in 1,613,694 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★).

• Frequency:
  • Genomes: 𝑓 0.00013 (0 hom., cov: 34)
  • Exomes 𝑓: 0.000017 (0 hom.)
• Consequence: KCNQ2 NM_172107.4 synonymous
• Clinical Significance: Likely benign criteria provided, single submitter B:1
• Conservation: PhyloP100: 0.285

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 Benign. Variant got -15 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.48).
• BP6: Variant 20-63445350-G-A is Benign according to our data. Variant chr20-63445350-G-A is described in ClinVar as [Likely_benign]. Clinvar id is 413253.Status of the report is criteria_provided_single_submitter, 1 stars.
• BP7: Synonymous conserved (PhyloP=0.285 with no splicing effect.
• BS1: Variant frequency is greater than expected in population afr. gnomad4 allele frequency = 0.000131 (20/152350) while in subpopulation AFR AF= 0.000433 (18/41576). AF 95% confidence interval is 0.000279. There are 0 homozygotes in gnomad4. There are 12 alleles in male gnomad4 subpopulation. Median coverage is 34. This position pass quality control queck.
• BS2: High AC in GnomAd at 20 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
KCNQ2	NM_172107.4	c.402C>T	p.Ile134=	synonymous_variant	3/17	ENST00000359125.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KCNQ2	ENST00000359125.7	c.402C>T	p.Ile134=	synonymous_variant	3/17	1	NM_172107.4	A1

Frequencies

GnomAD3 genomes AF: 0.000131 AC: 20 AN: 152232 Hom.: 0 Cov.: 34

Gnomad AFR AF: 0.000434

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000654

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: 0.0000147

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000359 AC: 9 AN: 250632 Hom.: 0 AF XY: 0.0000442 AC XY: 6 AN XY: 135734

Gnomad AFR exome AF: 0.000247

Gnomad AMR exome AF: 0.0000868

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000177

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000171 AC: 25 AN: 1461344 Hom.: 0 Cov.: 32 AF XY: 0.0000179 AC XY: 13 AN XY: 726954

Gnomad4 AFR exome AF: 0.000299

Gnomad4 AMR exome AF: 0.0000447

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000899

Gnomad4 OTH exome AF: 0.0000331

GnomAD4 genome AF: 0.000131 AC: 20 AN: 152350 Hom.: 0 Cov.: 34 AF XY: 0.000161 AC XY: 12 AN XY: 74500

Gnomad4 AFR AF: 0.000433

Gnomad4 AMR AF: 0.0000653

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000329 Hom.: 0

Bravo AF: 0.000102

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Likely benign

Submissions summary: Benign:1

Revision: criteria provided, single submitter

Submissions by phenotype

Early infantile epileptic encephalopathy with suppression bursts Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Invitae

Dec 27, 2023

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Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.48
Cadd	Benign	9.0
Dann	Benign	0.77

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs140712277; hg19: chr20-62076703; COSMIC: COSV100609195; COSMIC: COSV100609195;