2-166039428-G-A

Position:

• chr2-166039428-G-A

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_001165963.4(SCN1A):​c.2584C>T​(p.Arg862*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: SCN1A NM_001165963.4 stop_gained
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:7
• Conservation: PhyloP100: 0.700

Genes affected

SCN1A (HGNC:10585): (sodium voltage-gated channel alpha subunit 1) Voltage-dependent sodium channels are heteromeric complexes that regulate sodium exchange between intracellular and extracellular spaces and are essential for the generation and propagation of action potentials in muscle cells and neurons. Each sodium channel is composed of a large pore-forming, glycosylated alpha subunit and two smaller beta subunits. This gene encodes a sodium channel alpha subunit, which has four homologous domains, each of which contains six transmembrane regions. Allelic variants of this gene are associated with generalized epilepsy with febrile seizures and epileptic encephalopathy. Alternative splicing results in multiple transcript variants. The RefSeq Project has decided to create four representative RefSeq records. Three of the transcript variants are supported by experimental evidence and the fourth contains alternate 5' untranslated exons, the exact combination of which have not been experimentally confirmed for the full-length transcript. [provided by RefSeq, Oct 2015]

SCN1A (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 2-166039428-G-A is Pathogenic according to our data. Variant chr2-166039428-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 189857.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr2-166039428-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SCN1A	NM_001165963.4	c.2584C>T	p.Arg862*	stop_gained	17/29	ENST00000674923.1	NP_001159435.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SCN1A	ENST00000674923.1	c.2584C>T	p.Arg862*	stop_gained	17/29		NM_001165963.4	ENSP00000501589.1
SCN1A	ENST00000303395.9	c.2584C>T	p.Arg862*	stop_gained	16/28	5		ENSP00000303540.4
SCN1A	ENST00000375405.7	c.2551C>T	p.Arg851*	stop_gained	14/26	5		ENSP00000364554.3
SCN1A	ENST00000409050.1	c.2500C>T	p.Arg834*	stop_gained	14/26	5		ENSP00000386312.1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1405258 Hom.: 0 Cov.: 36 AF XY: 0.00 AC XY: 0 AN XY: 701242

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 31

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:7

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:4

Pathogenic, criteria provided, single submitter	clinical testing	Mayo Clinic Laboratories, Mayo Clinic	Jul 21, 2021	PM2, PS4_moderate, PVS1 -
Pathogenic, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Apr 01, 2020	- -
Pathogenic, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	May 19, 2014	- -
Pathogenic, no assertion criteria provided	clinical testing	Genetics and Genomic Medicine Centre, NeuroGen Healthcare, NeuroGen Healthcare	Apr 23, 2023	- -

Severe myoclonic epilepsy in infancy Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Neuberg Centre For Genomic Medicine, NCGM	-	The stop gained p.R862* in SCN1A (NM_001165963.4) has been reported previously in individuals affected with Idiopathic childhood epilepsies (Orrico et al, 2009). The p.R862* variant is novel (not in any individuals) in gnomAD Exomes and is novel (not in any individuals) in 1000 Genomes. This variant is predicted to cause loss of normal protein function through protein truncation. The p.R862* variant is a loss of function variant in the gene SCN1A, which is intolerant of Loss of Function variants. The nucleotide change in SCN1A is predicted as conserved by GERP++ and PhyloP across 100 vertebrates. For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	research	Center for Bioinformatics, Peking University	Dec 20, 2014	- -

Early infantile epileptic encephalopathy with suppression bursts Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Nov 02, 2023

This sequence change creates a premature translational stop signal (p.Arg862*) in the SCN1A gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in SCN1A are known to be pathogenic (PMID: 17347258, 18930999). This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with SCN1A-related conditions (PMID: 19522081, 29056246). ClinVar contains an entry for this variant (Variation ID: 189857). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.59
CADD	Pathogenic	38
DANN	Uncertain	1.0
Eigen	Uncertain	0.56
Eigen_PC	Uncertain	0.38
FATHMM_MKL	Uncertain	0.92	D
Vest4		0.97
GERP RS		2.6

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs397514459; hg19: chr2-166895938; COSMIC: COSV57665384; COSMIC: COSV57665384;