rs1553561016

Variant names:

• chr2-166073619-C-T
• rs1553561016
• NM_001165963.4:c.3G>A

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_001165963.4(SCN1A):​c.3G>A​(p.Met1?) variant causes a start lost change involving the alteration of a 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 (★).

• Frequency: Genomes: not found (cov: 31)
• Consequence: SCN1A NM_001165963.4 start_lost
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 7.89

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-AS1 (HGNC:54069): (SCN1A and SCN9A antisense RNA 1)

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PVS1: Start lost variant, next in-frame start position is after 7 pathogenic variants. Next in-frame start position is after 72 codons. Genomic position: 166073408. Lost 0.035 part of the original CDS.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 2-166073619-C-T is Pathogenic according to our data. Variant chr2-166073619-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 530490.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SCN1A	NM_001165963.4	c.3G>A	p.Met1?	start_lost	Exon 4 of 29	ENST00000674923.1	NP_001159435.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SCN1A	ENST00000674923.1	c.3G>A	p.Met1?	start_lost	Exon 4 of 29		NM_001165963.4	ENSP00000501589.1
SCN1A	ENST00000303395.9	c.3G>A	p.Met1?	start_lost	Exon 3 of 28	5		ENSP00000303540.4
SCN1A	ENST00000375405.7	c.3G>A	p.Met1?	start_lost	Exon 1 of 26	5		ENSP00000364554.3
SCN1A	ENST00000409050.1	c.3G>A	p.Met1?	start_lost	Exon 1 of 26	5		ENSP00000386312.1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 31

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Early infantile epileptic encephalopathy with suppression bursts Pathogenic:1

Oct 26, 2019

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects the initiator methionine of the SCN1A mRNA. The next in-frame methionine is located at codon 72. This variant is not present in population databases (ExAC no frequency). This variant has been observed to be de novo in an individual with clinical features of Dravet syndrome (Invitae). Different variants (c.1A>T and c.2T>C) giving rise to a loss of the initiator codon, have been reported in individuals affected with Dravet syndrome (PMID: 21248271, 18930999). 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	0.53
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.78	.;.;.;D;.;.;D;.;.;.;.
Eigen	Uncertain	0.67
Eigen_PC	Pathogenic	0.73
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.90	D;D;D;D;.;D;.;.;D;D;.
M_CAP	Pathogenic	0.84	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	0.93	D
PROVEAN	Uncertain	-2.6	.;.;.;D;.;.;D;.;D;D;.
REVEL	Pathogenic	0.86
Sift	Pathogenic	0.0	.;.;.;D;.;.;D;.;D;D;.
Sift4G	Uncertain	0.013	.;.;.;D;.;.;D;.;D;D;.
Polyphen		0.86	.;.;.;.;P;.;.;P;P;.;.
Vest4		0.92, 0.90, 0.85, 0.75
MutPred		0.92		Gain of sheet (P = 0.0827);Gain of sheet (P = 0.0827);Gain of sheet (P = 0.0827);Gain of sheet (P = 0.0827);Gain of sheet (P = 0.0827);Gain of sheet (P = 0.0827);Gain of sheet (P = 0.0827);Gain of sheet (P = 0.0827);Gain of sheet (P = 0.0827);Gain of sheet (P = 0.0827);Gain of sheet (P = 0.0827);
MVP		0.98
ClinPred		1.0	D
GERP RS		5.8
Varity_R		0.83
gMVP		0.35

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

Publications

LitVar

Other links and lift over

dbSNP: rs1553561016; hg19: chr2-166930129;