rs886039456

Variant names:

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PM1PM2PM5PP2PP3_StrongPP5

The NM_001165963.4(SCN1A):c.661C>G(p.Leu221Val) variant causes a missense 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). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. L221P) has been classified as Likely pathogenic.

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000021 ( 0 hom. )

Consequence

SCN1A
NM_001165963.4 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2U:1

Conservation

PhyloP100: 10.0

Publications

0 publications found

Variant links:

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 links:

SCN1A-AS1 (HGNC:54069): (SCN1A and SCN9A antisense RNA 1)

SCN1A-AS1 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 12 ACMG points.

PM1

In a hotspot region, there are 21 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 8 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 chr2-166052884-A-G is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 206745.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 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, 0.965

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 VariationId is 265297.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SCN1A	NM_001165963.4 link	c.661C>G	p.Leu221Val	missense_variant	Exon 8 of 29	ENST00000674923.1	NP_001159435.1	P35498-1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	UniProt
SCN1A	ENST00000674923.1 link	c.661C>G	p.Leu221Val	missense_variant	Exon 8 of 29		NM_001165963.4	ENSP00000501589.1	P35498-1
SCN1A	ENST00000303395.9 link	c.661C>G	p.Leu221Val	missense_variant	Exon 7 of 28	5		ENSP00000303540.4	P35498-1
SCN1A	ENST00000375405.7 link	c.661C>G	p.Leu221Val	missense_variant	Exon 5 of 26	5		ENSP00000364554.3	P35498-2
SCN1A	ENST00000409050.2 link	c.661C>G	p.Leu221Val	missense_variant	Exon 7 of 28	5		ENSP00000386312.1	P35498-3

Frequencies

GnomAD3 genomes

AF:

0.0000132

AC:

AN:

152002

Hom.:

Cov.:

show subpopulations

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:

AN:

1460368

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

726484

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33414

American (AMR)

AF:

0.00

AC:

AN:

44540

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26070

East Asian (EAS)

AF:

0.00

AC:

AN:

39640

South Asian (SAS)

AF:

0.00

AC:

AN:

86198

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53348

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5758

European-Non Finnish (NFE)

AF:

0.00000270

AC:

AN:

1111128

Other (OTH)

AF:

0.00

AC:

AN:

60272

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.408

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000132

AC:

AN:

152002

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74240

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41398

American (AMR)

AF:

0.00

AC:

AN:

15222

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3468

East Asian (EAS)

AF:

0.00

AC:

AN:

5182

South Asian (SAS)

AF:

0.00

AC:

AN:

4832

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10616

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000294

AC:

AN:

67968

Other (OTH)

AF:

0.00

AC:

AN:

2088

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.575

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.0000712

Hom.:

Bravo

AF:

0.0000189

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2Uncertain:1

Revision: criteria provided, conflicting classifications

LINK: link

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

May 01, 2025

GeneDx

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); 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 -

Developmental and epileptic encephalopathy

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

BayesDel_noAF

Pathogenic

0.56

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

DEOGEN2

Pathogenic

0.99

.;.;D;.;.;D;.;.;.

Eigen

Pathogenic

1.1

Eigen_PC

Pathogenic

1.0

FATHMM_MKL

Pathogenic

1.0

LIST_S2

Uncertain

0.89

D;D;D;.;D;.;.;D;D

M_CAP

Pathogenic

0.94

MetaRNN

Pathogenic

0.96

D;D;D;D;D;D;D;D;D

MetaSVM

Pathogenic

1.0

MutationAssessor

Pathogenic

3.3

.;.;M;M;.;M;M;M;M

PhyloP100

PrimateAI

Pathogenic

0.90

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

GERP RS

5.8

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.86

gMVP

0.96

Mutation Taster

=3/97

disease causing (ClinVar)

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over