2-166037860-C-G

Variant names:

• chr2-166037860-C-G
• rs1041924436
• NM_001165963.4:c.2862G>C

Variant summary

Our verdict is Pathogenic. The variant received 14 ACMG points: 14P and 0B. PS1 PM1 PM2 PM5 PP2 PP3 PP5_Moderate

The NM_001165963.4(SCN1A):​c.2862G>C​(p.Glu954Asp) variant causes a missense 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 (★). Another nucleotide change resulting in the same amino acid substitution has been previously reported as Likely pathogenic in ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. E954G) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: SCN1A NM_001165963.4 missense
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 1.84
• Publications: 0 publications found

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

Our verdict: Pathogenic. The variant received 14 ACMG points.

• PS1: Transcript NM_001165963.4 (SCN1A) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in ClinVar.
• PM1: In a hotspot region, there are 32 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 6 uncertain in NM_001165963.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr2-166037861-T-C is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 2020613.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP2: Missense variant in the SCN1A gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 848 curated pathogenic missense variants (we use a threshold of 10). The gene has 89 curated benign missense variants. Gene score misZ: 5.2206 (above the threshold of 3.09). Trascript score misZ: 7.6022 (above the threshold of 3.09). GenCC associations: The gene is linked to familial or sporadic hemiplegic migraine, myoclonic-astatic epilepsy, arthrogryposis, Dravet syndrome, malignant migrating partial seizures of infancy, generalized epilepsy with febrile seizures plus, type 2, migraine, familial hemiplegic, 3, developmental and epileptic encephalopathy, 6A, familial hemiplegic migraine, generalized epilepsy with febrile seizures plus, genetic developmental and epileptic encephalopathy, Lennox-Gastaut syndrome.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.814
• PP5: Variant 2-166037860-C-G is Pathogenic according to our data. Variant chr2-166037860-C-G is described in ClinVar as Pathogenic. ClinVar VariationId is 1071810.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.2862G>C	p.Glu954Asp	missense_variant	Exon 18 of 29	ENST00000674923.1	NP_001159435.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SCN1A	ENST00000674923.1	c.2862G>C	p.Glu954Asp	missense_variant	Exon 18 of 29		NM_001165963.4	ENSP00000501589.1
SCN1A	ENST00000303395.9	c.2862G>C	p.Glu954Asp	missense_variant	Exon 17 of 28	5		ENSP00000303540.4
SCN1A	ENST00000375405.7	c.2829G>C	p.Glu943Asp	missense_variant	Exon 15 of 26	5		ENSP00000364554.3
SCN1A	ENST00000409050.2	c.2778G>C	p.Glu926Asp	missense_variant	Exon 17 of 28	5		ENSP00000386312.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Developmental and epileptic encephalopathy Pathogenic:1

Jun 19, 2020

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

For these reasons, this variant has been classified as Pathogenic. A different variant (c.2862G>T) giving rise to the same protein effect observed here (p.Glu954Asp) has been determined to be pathogenic (Invitae). This suggests that this variant is also likely to be causative of disease. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. This variant has not been reported in the literature in individuals with SCN1A-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change replaces glutamic acid with aspartic acid at codon 954 of the SCN1A protein (p.Glu954Asp). The glutamic acid residue is highly conserved and there is a small physicochemical difference between glutamic acid and aspartic acid. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.96
BayesDel_addAF	Pathogenic	0.33	D
BayesDel_noAF	Pathogenic	0.23
CADD	Benign	22
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.97	.;.;.;D;.;.;D;.;.;.
Eigen	Uncertain	0.24
Eigen_PC	Uncertain	0.25
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Uncertain	0.95	D;D;D;D;.;D;.;.;D;D
M_CAP	Pathogenic	0.74	D
MetaRNN	Pathogenic	0.81	D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	0.90	D
MutationAssessor	Uncertain	2.3	.;.;.;M;.;.;M;.;.;.
PhyloP100		1.8
PrimateAI	Pathogenic	0.79	T
PROVEAN	Uncertain	-2.9	.;.;.;D;.;.;D;.;D;D
REVEL	Pathogenic	0.77
Sift	Pathogenic	0.0	.;.;.;D;.;.;D;.;D;D
Sift4G	Uncertain	0.034	.;.;.;D;.;.;D;.;D;D
Polyphen		0.99, 0.18	.;.;.;D;B;.;D;B;B;.
Vest4		0.73, 0.80, 0.81, 0.82
MutPred		0.56		.;Loss of helix (P = 0.0041);.;Loss of helix (P = 0.0041);.;.;Loss of helix (P = 0.0041);.;.;.;
MVP		0.85
MPC		2.5
ClinPred		0.99	D
GERP RS		3.4
Varity_R		0.82
gMVP		0.99
Mutation Taster		=11/89	disease causing

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: rs1041924436; hg19: chr2-166894370;