NM_001165963.4:c.5171C>T

Variant names:

• chr2-165992104-G-A
• rs1553520319
• NM_001165963.4:c.5171C>T

Variant summary

Our verdict is Pathogenic. The variant received 11 ACMG points: 11P and 0B. PM1 PM2 PM5 PP2 PP3_Moderate PP5_Moderate

The NM_001165963.4(SCN1A):​c.5171C>T​(p.Ala1724Val) 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 variant affecting the same amino acid position, but resulting in a different missense (i.e. A1724P) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 31)
• Consequence: SCN1A NM_001165963.4 missense
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 3.04
• 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)

LOC102724058 (HGNC:):

ACMG classification

Our verdict: Pathogenic. The variant received 11 ACMG points.

• PM1: In a hotspot region, there are 23 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 chr2-165992105-C-G is described in ClinVar as Pathogenic. ClinVar VariationId is 3065909.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, 0.889
• PP5: Variant 2-165992104-G-A is Pathogenic according to our data. Variant chr2-165992104-G-A is described in ClinVar as Pathogenic. ClinVar VariationId is 530420.Status of the report is criteria_provided_single_submitter, 1 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001165963.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SCN1A	NM_001165963.4	MANE Select	c.5171C>T	p.Ala1724Val	missense	Exon 29 of 29	NP_001159435.1
	SCN1A	NM_001202435.3		c.5171C>T	p.Ala1724Val	missense	Exon 28 of 28	NP_001189364.1
	SCN1A	NM_001353948.2		c.5171C>T	p.Ala1724Val	missense	Exon 27 of 27	NP_001340877.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SCN1A	ENST00000674923.1	MANE Select	c.5171C>T	p.Ala1724Val	missense	Exon 29 of 29	ENSP00000501589.1
	SCN1A	ENST00000303395.9	TSL:5	c.5171C>T	p.Ala1724Val	missense	Exon 28 of 28	ENSP00000303540.4
	SCN1A	ENST00000375405.7	TSL:5	c.5138C>T	p.Ala1713Val	missense	Exon 26 of 26	ENSP00000364554.3

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

Developmental and epileptic encephalopathy Pathogenic:1

Apr 15, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces alanine with valine at codon 1724 of the SCN1A protein (p.Ala1724Val). The alanine residue is highly conserved and there is a small physicochemical difference between alanine and valine. This variant is not present in population databases (ExAC no frequency). This variant has been observed in individual(s) with SCN1A-related conditions (PMID: 31302675, 31273778). In at least one individual the variant was observed to be de novo. ClinVar contains an entry for this variant (Variation ID: 530420). Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C15"). This variant disrupts the p.Ala1724 amino acid residue in SCN1A. Other variant(s) that disrupt this residue have been observed in individuals with SCN1A-related conditions (PMID: 28012175, 30185235), which suggests that this may be a clinically significant amino acid residue. For these reasons, this variant has been classified as Pathogenic.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.33	D
BayesDel_noAF	Pathogenic	0.24
CADD	Uncertain	25
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.98	D
Eigen	Pathogenic	0.91
Eigen_PC	Pathogenic	0.84
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Pathogenic	0.86	D
MetaRNN	Pathogenic	0.89	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.9	H
PhyloP100		3.0
PrimateAI	Pathogenic	0.88	D
PROVEAN	Uncertain	-3.6	D
REVEL	Pathogenic	0.82
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.58
MutPred		0.68		Loss of helix (P = 0.2022)
MVP		0.93
MPC		1.7
ClinPred		1.0	D
GERP RS		5.8
Varity_R		0.77
gMVP		0.98
Mutation Taster		=2/98	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: rs1553520319; hg19: chr2-166848614;