rs886039456

Variant names:

• chr2-166052885-G-C
• rs886039456
• NM_001165963.4:c.661C>G

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PM2 PP3_Strong PP5

The NM_001353961.2(SCN1A):​c.-1765C>G variant causes a 5 prime UTR premature start codon gain change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000031 in 1,612,370 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: SCN1A NM_001353961.2 5_prime_UTR_premature_start_codon_gain
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2 U:1
• Conservation: PhyloP100: 10.0

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 Likely_pathogenic. Variant got 7 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.965
• PP5: Variant 2-166052885-G-C is Pathogenic according to our data. Variant chr2-166052885-G-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 265297.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=2, Uncertain_significance=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SCN1A	NM_001165963.4	c.661C>G	p.Leu221Val	missense_variant	Exon 8 of 29	ENST00000674923.1	NP_001159435.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SCN1A	ENST00000674923.1	c.661C>G	p.Leu221Val	missense_variant	Exon 8 of 29		NM_001165963.4	ENSP00000501589.1
SCN1A	ENST00000303395.9	c.661C>G	p.Leu221Val	missense_variant	Exon 7 of 28	5		ENSP00000303540.4
SCN1A	ENST00000375405.7	c.661C>G	p.Leu221Val	missense_variant	Exon 5 of 26	5		ENSP00000364554.3
SCN1A	ENST00000409050.1	c.661C>G	p.Leu221Val	missense_variant	Exon 5 of 26	5		ENSP00000386312.1

Frequencies

GnomAD3 genomes AF: 0.0000132 AC: 2 AN: 152002 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: 0.0000294

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1460368 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 726484

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: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000270

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.0000132 AC: 2 AN: 152002 Hom.: 0 Cov.: 32 AF XY: 0.0000269 AC XY: 2 AN XY: 74240

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: 0.0000294

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.0000189

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Severe myoclonic epilepsy in infancy;C1858673:Generalized epilepsy with febrile seizures plus, type 2;C1864987:Migraine, familial hemiplegic, 3 Pathogenic:1

Oct 31, 2018

Fulgent Genetics, Fulgent Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided Pathogenic:1

Oct 10, 2022

GeneDx

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); Missense variants in this gene are often considered pathogenic (HGMD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge -

Early infantile epileptic encephalopathy with suppression bursts Uncertain:1

Nov 19, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. 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 expected to disrupt SCN1A protein function. ClinVar contains an entry for this variant (Variation ID: 265297). This variant has not been reported in the literature in individuals affected with SCN1A-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces leucine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 221 of the SCN1A protein (p.Leu221Val). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.95
BayesDel_addAF	Pathogenic	0.55	D
BayesDel_noAF	Pathogenic	0.56
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.99	.;.;D;.;.;D;.;.;.
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Uncertain	0.89	D;D;D;.;D;.;.;D;D
M_CAP	Pathogenic	0.94	D
MetaRNN	Pathogenic	0.96	D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	3.3	.;.;M;M;.;M;M;M;M
PrimateAI	Pathogenic	0.90	D
PROVEAN	Uncertain	-2.9	.;.;D;.;.;D;.;D;D
REVEL	Pathogenic	0.94
Sift	Pathogenic	0.0	.;.;D;.;.;D;.;D;D
Sift4G	Uncertain	0.017	.;.;D;.;.;D;.;D;D
Polyphen		1.0	.;.;D;D;.;D;D;D;.
Vest4		0.83, 0.89, 0.90, 0.87
MutPred		0.83		Gain of MoRF binding (P = 0.1211);Gain of MoRF binding (P = 0.1211);Gain of MoRF binding (P = 0.1211);Gain of MoRF binding (P = 0.1211);Gain of MoRF binding (P = 0.1211);Gain of MoRF binding (P = 0.1211);Gain of MoRF binding (P = 0.1211);Gain of MoRF binding (P = 0.1211);Gain of MoRF binding (P = 0.1211);
MVP		0.99
MPC		1.7
ClinPred		1.0	D
GERP RS		5.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.86
gMVP		0.96

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: rs886039456; hg19: chr2-166909395;