2-166002577-A-T

Variant names:

• chr2-166002577-A-T
• rs772400574
• NM_001165963.4:c.4179T>A

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 7P and 2B. PM1 PM2 PM5 PP2 BP4_Moderate

The NM_001165963.4(SCN1A):​c.4179T>A​(p.His1393Gln) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000031 in 1,611,882 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. H1393P) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: SCN1A NM_001165963.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.211

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 Uncertain_significance. Variant got 5 ACMG points.

• PM1: In a topological_domain Extracellular (size 51) in uniprot entity SCN1A_HUMAN there are 14 pathogenic changes around while only 0 benign (100%) 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 chrnull-null-null-null is described in UniProt as null.
• 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 migraine, familial hemiplegic, 3, familial hemiplegic migraine, Dravet syndrome, malignant migrating partial seizures of infancy, generalized epilepsy with febrile seizures plus, myoclonic-astatic epilepsy, developmental and epileptic encephalopathy, developmental and epileptic encephalopathy, 6, familial or sporadic hemiplegic migraine, arthrogryposis, Lennox-Gastaut syndrome, generalized epilepsy with febrile seizures plus, type 2.
• BP4: Computational evidence support a benign effect (MetaRNN=0.112268895).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SCN1A	NM_001165963.4	c.4179T>A	p.His1393Gln	missense_variant	Exon 24 of 29	ENST00000674923.1	NP_001159435.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SCN1A	ENST00000674923.1	c.4179T>A	p.His1393Gln	missense_variant	Exon 24 of 29		NM_001165963.4	ENSP00000501589.1
SCN1A	ENST00000303395.9	c.4179T>A	p.His1393Gln	missense_variant	Exon 23 of 28	5		ENSP00000303540.4
SCN1A	ENST00000375405.7	c.4146T>A	p.His1382Gln	missense_variant	Exon 21 of 26	5		ENSP00000364554.3
SCN1A	ENST00000409050.1	c.4095T>A	p.His1365Gln	missense_variant	Exon 21 of 26	5		ENSP00000386312.1

Frequencies

GnomAD3 genomes AF: 0.00000659 AC: 1 AN: 151746 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1460136 Hom.: 0 Cov.: 31 AF XY: 0.00000413 AC XY: 3 AN XY: 726386

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: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.0000332

GnomAD4 genome AF: 0.00000659 AC: 1 AN: 151746 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74094

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Early infantile epileptic encephalopathy with suppression bursts Uncertain:1

Jun 27, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt SCN1A protein function. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. This variant disrupts the p.His1393 amino acid residue in SCN1A. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 17129991, 28084635). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. ClinVar contains an entry for this variant (Variation ID: 530500). This missense change has been observed in individuals with clinical features of SCN1A-related conditions (Invitae). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces histidine, which is basic and polar, with glutamine, which is neutral and polar, at codon 1393 of the SCN1A protein (p.His1393Gln). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.17
BayesDel_addAF	Uncertain	0.039	T
BayesDel_noAF	Benign	-0.18
CADD	Benign	19
DANN	Benign	0.84
DEOGEN2	Uncertain	0.62	.;.;D;.;.;D;.;.;.
Eigen	Benign	-0.84
Eigen_PC	Benign	-0.65
FATHMM_MKL	Benign	0.44	N
LIST_S2	Benign	0.77	T;T;T;.;T;.;.;T;T
M_CAP	Uncertain	0.12	D
MetaRNN	Benign	0.11	T;T;T;T;T;T;T;T;T
MetaSVM	Benign	-0.28	T
MutationAssessor	Benign	-0.38	.;.;N;.;.;N;.;.;.
PrimateAI	Benign	0.46	T
PROVEAN	Benign	0.040	.;.;N;.;.;N;.;N;N
REVEL	Uncertain	0.30
Sift	Benign	0.18	.;.;T;.;.;T;.;T;T
Sift4G	Uncertain	0.018	.;.;D;.;.;D;.;D;D
Polyphen		0.0	.;.;B;B;.;B;B;B;.
Vest4		0.38, 0.39, 0.39, 0.35
MutPred		0.53		.;.;Loss of catalytic residue at H1393 (P = 0.012);.;.;Loss of catalytic residue at H1393 (P = 0.012);.;.;.;
MVP		0.49
MPC		0.78
ClinPred		0.091	T
GERP RS		3.0
Varity_R		0.052
gMVP		0.91

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: rs772400574; hg19: chr2-166859087;