12-51721864-A-T

Variant names:

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 3P and 1B. PM2PP2BP4

The NM_001330260.2(SCN8A):c.1954A>T(p.Ile652Phe) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000187 in 1,602,574 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts 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. I652V) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 31)

Exomes 𝑓: 0.0000014 ( 0 hom. )

Consequence

SCN8A
NM_001330260.2 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:2

Conservation

PhyloP100: 1.98

Publications

1 publications found

Variant links:

Genes affected

SCN8A (HGNC:10596): (sodium voltage-gated channel alpha subunit 8) This gene encodes a member of the sodium channel alpha subunit gene family. The encoded protein forms the ion pore region of the voltage-gated sodium channel. This protein is essential for the rapid membrane depolarization that occurs during the formation of the action potential in excitable neurons. Mutations in this gene are associated with cognitive disability, pancerebellar atrophy and ataxia. Alternate splicing results in multiple transcript variants.[provided by RefSeq, May 2010]

SCN8A Gene-Disease associations (from GenCC):

complex neurodevelopmental disorder
Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
developmental and epileptic encephalopathy, 13
Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P, Ambry Genetics
cognitive impairment with or without cerebellar ataxia
Inheritance: AD Classification: STRONG Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae)
seizures, benign familial infantile, 5
Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
benign familial infantile epilepsy
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
infantile convulsions and choreoathetosis
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
undetermined early-onset epileptic encephalopathy
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
myoclonus, familial, 2
Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics

SCN8A links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PP2

Missense variant in the SCN8A gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 213 curated pathogenic missense variants (we use a threshold of 10). The gene has 45 curated benign missense variants. Gene score misZ: 0.78755 (below the threshold of 3.09). Trascript score misZ: 10.436 (above the threshold of 3.09). GenCC associations: The gene is linked to myoclonus, familial, 2, developmental and epileptic encephalopathy, 13, undetermined early-onset epileptic encephalopathy, benign familial infantile epilepsy, complex neurodevelopmental disorder, seizures, benign familial infantile, 5, cognitive impairment with or without cerebellar ataxia, infantile convulsions and choreoathetosis.

BP4

Computational evidence support a benign effect (MetaRNN=0.41694623).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SCN8A	NM_001330260.2 link	c.1954A>T	p.Ile652Phe	missense_variant	Exon 12 of 27	ENST00000627620.5	NP_001317189.1	Q9UQD0-2Q6B4S4
SCN8A	NM_014191.4 link	c.1954A>T	p.Ile652Phe	missense_variant	Exon 12 of 27	ENST00000354534.11	NP_055006.1	Q9UQD0-1
SCN8A	NM_001177984.3 link	c.1954A>T	p.Ile652Phe	missense_variant	Exon 12 of 26		NP_001171455.1	Q9UQD0-5
SCN8A	NM_001369788.1 link	c.1954A>T	p.Ile652Phe	missense_variant	Exon 12 of 26		NP_001356717.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	UniProt
SCN8A	ENST00000354534.11 link	c.1954A>T	p.Ile652Phe	missense_variant	Exon 12 of 27	1	NM_014191.4	ENSP00000346534.4	Q9UQD0-1
SCN8A	ENST00000627620.5 link	c.1954A>T	p.Ile652Phe	missense_variant	Exon 12 of 27	5	NM_001330260.2	ENSP00000487583.2	Q9UQD0-2
SCN8A	ENST00000599343.5 link	c.1954A>T	p.Ile652Phe	missense_variant	Exon 11 of 26	5		ENSP00000476447.3	Q9UQD0-3
SCN8A	ENST00000355133.7 link	c.1954A>T	p.Ile652Phe	missense_variant	Exon 11 of 25	1		ENSP00000347255.4	Q9UQD0-5

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152226

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

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:

0.00

Gnomad OTH

AF:

0.00

GnomAD4 exome

AF:

0.00000138

AC:

AN:

1450348

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

721954

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33472

American (AMR)

AF:

0.00

AC:

AN:

44720

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26134

East Asian (EAS)

AF:

0.00

AC:

AN:

39696

South Asian (SAS)

AF:

0.00

AC:

AN:

86254

European-Finnish (FIN)

AF:

0.00

AC:

AN:

42222

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00000180

AC:

AN:

1111782

Other (OTH)

AF:

0.00

AC:

AN:

60300

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.475

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:

0.00000657

AC:

AN:

152226

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74370

show subpopulations

African (AFR)

AF:

0.0000241

AC:

AN:

41464

American (AMR)

AF:

0.00

AC:

AN:

15286

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5186

South Asian (SAS)

AF:

0.00

AC:

AN:

4830

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10628

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68040

Other (OTH)

AF:

0.00

AC:

AN:

2094

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.475

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.:

Bravo

AF:

0.00000756

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Inborn genetic diseases

Uncertain:1

Nov 26, 2024

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The c.1954A>T (p.I652F) alteration is located in exon 12 (coding exon 11) of the SCN8A gene. This alteration results from a A to T substitution at nucleotide position 1954, causing the isoleucine (I) at amino acid position 652 to be replaced by a phenylalanine (F). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Developmental and epileptic encephalopathy

Uncertain:1

Jun 05, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces isoleucine, which is neutral and non-polar, with phenylalanine, which is neutral and non-polar, at codon 652 of the SCN8A protein (p.Ile652Phe). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with SCN8A-related conditions. ClinVar contains an entry for this variant (Variation ID: 2174191). 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 SCN8A protein function with a negative predictive value of 95%. 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. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.32

BayesDel_addAF

Uncertain

0.13

BayesDel_noAF

Uncertain

-0.050

CADD

Benign

(source)

DANN

Uncertain

0.99

DEOGEN2

Uncertain

0.77

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

Eigen

Benign

0.029

Eigen_PC

Benign

0.033

FATHMM_MKL

Uncertain

0.82

LIST_S2

Uncertain

0.96

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

M_CAP

Uncertain

0.25

MetaRNN

Benign

0.42

T;T;T;T;T;T;T

MetaSVM

Uncertain

0.53

MutationAssessor

Benign

1.8

.;L;L;L;L;L;.

PhyloP100

2.0

PrimateAI

Uncertain

0.71

PROVEAN

Benign

-2.2

.;N;N;D;.;.;.

REVEL

Uncertain

0.56

Sift

Uncertain

0.0020

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

Sift4G

Benign

0.22

.;T;T;T;T;T;T

Polyphen

0.89, 0.89

.;P;.;.;P;.;.

Vest4

0.52, 0.49, 0.47, 0.61, 0.50

MVP

0.83

MPC

2.0

ClinPred

0.84

GERP RS

2.7

Varity_R

0.31

gMVP

0.75

Mutation Taster

=14/86

disease causing

(source)

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

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