dbSNP rs121918784: SCN1A:p.Arg859Cys (chr2-166039437-G-A) – ACMG Classification: Pathogenic (17 pts)

Variant summary

Our verdict is Pathogenic. The variant received 17 ACMG points: 17P and 0B. PM1PM5PP2PP3_StrongPP5_Very_Strong

The NM_001165963.4(SCN1A):c.2575C>T(p.Arg859Cys) variant causes a missense change involving the alteration of a non-conserved nucleotide. In-silico tool predicts a pathogenic outcome for this variant. 13/22 in silico tools predict a damaging 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. R859H) has been classified as Pathogenic.

Frequency

Genomes: 𝑓 0.0000067 ( 0 hom., cov: 31)

Exomes 𝑓: 0.0000014 ( 0 hom. )

Failed GnomAD Quality Control

Consequence

SCN1A
NM_001165963.4 missense

Scores

Clinical Significance

Pathogenic criteria provided, multiple submitters, no conflicts P:7O:1

Conservation

PhyloP100: 3.45

Publications

14 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 17 ACMG points.

PM1

In a hotspot region, there are 12 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 12 uncertain in NM_001165963.4

PM5

Other missense variant is known to change same aminoacid residue: Variant chr2-166039436-C-T is described in ClinVar as Pathogenic. ClinVar VariationId is 93639.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, 0.984

PP5

Variant 2-166039437-G-A is Pathogenic according to our data. Variant chr2-166039437-G-A is described in ClinVar as Pathogenic. ClinVar VariationId is 68592.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 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

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
SCN1A	NM_001165963.4	MANE Select	c.2575C>T	p.Arg859Cys	missense	Exon 17 of 29	NP_001159435.1	P35498-1
SCN1A	NM_001202435.3		c.2575C>T	p.Arg859Cys	missense	Exon 16 of 28	NP_001189364.1	P35498-1
SCN1A	NM_001353948.2		c.2575C>T	p.Arg859Cys	missense	Exon 15 of 27	NP_001340877.1	P35498-1

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
SCN1A	ENST00000674923.1	MANE Select	c.2575C>T	p.Arg859Cys	missense	Exon 17 of 29	ENSP00000501589.1	P35498-1
SCN1A	ENST00000303395.9	TSL:5	c.2575C>T	p.Arg859Cys	missense	Exon 16 of 28	ENSP00000303540.4	P35498-1
SCN1A	ENST00000375405.7	TSL:5	c.2542C>T	p.Arg848Cys	missense	Exon 14 of 26	ENSP00000364554.3	P35498-2

Frequencies

GnomAD3 genomes

AF:

0.00000668

AC:

AN:

149732

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:

0.0000148

Gnomad OTH

AF:

0.00

GnomAD4 exome

Data not reliable, filtered out with message: AS_VQSR

AF:

0.00000137

AC:

AN:

1459694

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

726182

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

33406

American (AMR)

AF:

0.00

AC:

AN:

44646

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26074

East Asian (EAS)

AF:

0.0000252

AC:

AN:

39634

South Asian (SAS)

AF:

0.00

AC:

AN:

86008

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53378

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5734

European-Non Finnish (NFE)

AF:

9.00e-7

AC:

AN:

1110504

Other (OTH)

AF:

0.00

AC:

AN:

60310

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.0448430), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.350

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

Data not reliable, filtered out with message: AS_VQSR

AF:

0.00000668

AC:

AN:

149732

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

72854

show subpopulations

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

40710

American (AMR)

AF:

0.00

AC:

AN:

15052

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3460

East Asian (EAS)

AF:

0.00

AC:

AN:

5136

South Asian (SAS)

AF:

0.00

AC:

AN:

4764

European-Finnish (FIN)

AF:

0.00

AC:

AN:

9654

Middle Eastern (MID)

AF:

0.00

AC:

AN:

314

European-Non Finnish (NFE)

AF:

0.0000148

AC:

AN:

67678

Other (OTH)

AF:

0.00

AC:

AN:

2054

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.225

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:

0.00

Hom.:

ClinVar

ClinVar submissions

Significance:Pathogenic

Revision:criteria provided, multiple submitters, no conflicts

View on ClinVar

Pathogenic

VUS

Benign

Condition

Generalized epilepsy with febrile seizures plus, type 2 (3)

Developmental and epileptic encephalopathy (1)

not provided (1)

Seizure (1)

Severe myoclonic epilepsy in infancy (1)

Generalized epilepsy with febrile seizures plus, type 1 (1)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

1.0

BayesDel_addAF

Pathogenic

0.53

BayesDel_noAF

Pathogenic

0.53

CADD

Pathogenic

(source)

DANN

Pathogenic

1.0

DEOGEN2

Pathogenic

0.99

Eigen

Pathogenic

0.90

Eigen_PC

Pathogenic

0.76

FATHMM_MKL

Pathogenic

0.98

LIST_S2

Pathogenic

0.99

M_CAP

Pathogenic

0.93

MetaRNN

Pathogenic

0.98

MetaSVM

Pathogenic

1.0

MutationAssessor

Pathogenic

4.3

PhyloP100

3.5

PrimateAI

Pathogenic

0.86

PROVEAN

Pathogenic

-7.3

REVEL

Pathogenic

0.96

Sift

Pathogenic

0.0

Sift4G

Pathogenic

0.0

Polyphen

1.0

Vest4

0.98

MutPred

0.88

Loss of MoRF binding (P = 0.032)

MVP

1.0

MPC

3.1

ClinPred

1.0

GERP RS

4.8

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.91

gMVP

1.0

Mutation Taster

=1/99

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.080

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

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over