rs200872349

chr20-63419614-G-Achr20-63419614-G-C

Variant summary

Our verdict is Likely benign. Variant got -6 ACMG points: 0P and 6B. BP4 BP6 BS2

The NM_172107.4(KCNQ2):c.1301+5C>T variant causes a splice donor 5th base, intron change. The variant allele was found at a frequency of 0.0000236 in 1,609,060 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.000046 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000021 (0 hom.)
• Consequence: KCNQ2 NM_172107.4 splice_donor_5th_base, intron
• Scores: Splicing: ADA: 0.3421
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:1
• Conservation: PhyloP100: 4.88

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 Likely_benign. Variant got -6 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.15).
• BP6: Variant 20-63419614-G-A is Benign according to our data. Variant chr20-63419614-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 205904.We mark this variant Likely_benign, oryginal submissions are: {Uncertain_significance=1, Likely_benign=1}.
• BS2: High AC in GnomAd at 7 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
KCNQ2	NM_172107.4	c.1301+5C>T		splice_donor_5th_base_variant, intron_variant		ENST00000359125.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KCNQ2	ENST00000359125.7	c.1301+5C>T		splice_donor_5th_base_variant, intron_variant		1	NM_172107.4	A1

Frequencies

GnomAD3 genomes AF: 0.0000460 AC: 7 AN: 152248 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000241

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000654

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000385

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000441

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000498 AC: 12 AN: 240736 Hom.: 0 AF XY: 0.0000767 AC XY: 10 AN XY: 130338

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000593

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000506

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000919

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000213 AC: 31 AN: 1456694 Hom.: 0 Cov.: 31 AF XY: 0.0000262 AC XY: 19 AN XY: 724156

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000679

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000203

Gnomad4 SAS exome AF: 0.0000118

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000153

Gnomad4 OTH exome AF: 0.0000332

GnomAD4 genome AF: 0.0000459 AC: 7 AN: 152366 Hom.: 0 Cov.: 33 AF XY: 0.0000537 AC XY: 4 AN XY: 74510

Gnomad4 AFR AF: 0.0000240

Gnomad4 AMR AF: 0.0000653

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.000386

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000441

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000329 Hom.: 0

Bravo AF: 0.0000453

Asia WGS AF: 0.000577 AC: 2 AN: 3478

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Early infantile epileptic encephalopathy with suppression bursts Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Nov 27, 2023

This sequence change falls in intron 12 of the KCNQ2 gene. It does not directly change the encoded amino acid sequence of the KCNQ2 protein. It affects a nucleotide within the consensus splice site. This variant is present in population databases (rs200872349, gnomAD 0.05%). This variant has not been reported in the literature in individuals affected with KCNQ2-related conditions. ClinVar contains an entry for this variant (Variation ID: 205904). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant is not likely to affect RNA splicing. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

not specified Benign:1

Likely benign, criteria provided, single submitter

clinical testing

GeneDx

Dec 21, 2017

This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.15
Cadd	Uncertain	24
Dann	Uncertain	0.98

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.34
dbscSNV1_RF	Benign	0.44
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: rs200872349; hg19: chr20-62050967;