rs121918751

chr2-165991841-A-C

Variant summary

Our verdict is Pathogenic. Variant got 19 ACMG points: 19P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Very_Strong

The NM_001165963.4(SCN1A):c.5434T>G(p.Trp1812Gly) variant causes a missense 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. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. W1812C) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: SCN1A NM_001165963.4 missense
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:2 O:1
• Conservation: PhyloP100: 9.32

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)

LOC102724058 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 19 ACMG points.

• PM1: In a hotspot region, there are 6 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 10 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 chr2-165991839-C-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 546874.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP2: Missense variant where missense usually causes diseases, SCN1A
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.976
• PP5: Variant 2-165991841-A-C is Pathogenic according to our data. Variant chr2-165991841-A-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 68662.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SCN1A	NM_001165963.4	c.5434T>G	p.Trp1812Gly	missense_variant	29/29	ENST00000674923.1
LOC102724058	NR_110598.1	n.176-23772A>C		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SCN1A	ENST00000674923.1	c.5434T>G	p.Trp1812Gly	missense_variant	29/29		NM_001165963.4	P4
SCN1A-AS1	ENST00000651574.1	n.193-23772A>C		intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Mar 02, 2017

The W1812G missense variant in the SCN1A gene has been reported previously as a denovo variant in an individual with severe myoclonic epilepsy in infancy (SMEI) (Fujiwaraet al., 2003). It was not observed in approximately 6,500 individuals of European andAfrican American ancestry in the NHLBI Exome Sequencing Project, indicating it is not acommon benign variant in these populations. The W1812G variant is a semi-conservativeamino acid substitution, which may impact secondary protein structure as these residuesdiffer in some properties. This substitution occurs at a position that is conserved acrossspecies, and different missense variants in the same residue (W1812S, W1812R) havebeen reported previously as de novo in association with SCN1A-related disorders(SCN1A Variant Database). In silico analysis predicts this variant is probably damaging tothe protein structure/function. Therefore, we consider the W1812G variant to be pathogenic. -

Seizure Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Genetic Services Laboratory, University of Chicago

Sep 03, 2014

- -

Severe myoclonic epilepsy in infancy Other:1

not provided, no classification provided

literature only

UniProtKB/Swiss-Prot

-

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.57
Cadd	Pathogenic	30
Dann	Uncertain	0.98
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.95
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Pathogenic	0.97	D;D;D;D;.;.;.;D;D
M_CAP	Pathogenic	0.98	D
MetaRNN	Pathogenic	0.98	D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Pathogenic	0.86	D
Polyphen		1.0	.;.;.;.;D;.;D;D;.
Vest4		0.91, 0.96, 0.96, 0.93
MutPred		0.79		.;.;.;Gain of disorder (P = 0.0037);.;Gain of disorder (P = 0.0037);.;.;.;
MVP		0.99
MPC		2.3
ClinPred		1.0	D
GERP RS		5.8
Varity_R		0.91
gMVP		1.0

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: rs121918751; hg19: chr2-166848351;