rs187153231

Positions:

• chr12-51746002-A-G
• chr12-51746002-A-T

Variant summary

Our verdict is Likely benign. Variant got -5 ACMG points: 1P and 6B. PP2 BP4_Moderate BS2

The NM_014191.4(SCN8A):​c.2098A>G​(p.Ile700Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000411 in 1,459,256 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/21 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. I700L) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: SCN8A NM_014191.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.87

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]

ACMG classification

Verdict is Likely_benign. Variant got -5 ACMG points.

• PP2: Missense variant where missense usually causes diseases, SCN8A
• BP4: Computational evidence support a benign effect (MetaRNN=0.104394525).
• BS2: High AC in GnomAdExome4 at 6 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SCN8A	NM_001330260.2	c.2098A>G	p.Ile700Val	missense_variant	13/27	ENST00000627620.5
SCN8A	NM_014191.4	c.2098A>G	p.Ile700Val	missense_variant	13/27	ENST00000354534.11
SCN8A	NM_001177984.3	c.2098A>G	p.Ile700Val	missense_variant	13/26
SCN8A	NM_001369788.1	c.2098A>G	p.Ile700Val	missense_variant	13/26

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SCN8A	ENST00000354534.11	c.2098A>G	p.Ile700Val	missense_variant	13/27	1	NM_014191.4	P4
SCN8A	ENST00000627620.5	c.2098A>G	p.Ile700Val	missense_variant	13/27	5	NM_001330260.2	A1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000411 AC: 6 AN: 1459256 Hom.: 0 Cov.: 32 AF XY: 0.00000551 AC XY: 4 AN XY: 725776

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: 0.00000540

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

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

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Nov 24, 2022

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 not expected to disrupt SCN8A protein function. ClinVar contains an entry for this variant (Variation ID: 859199). This variant has not been reported in the literature in individuals affected with SCN8A-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces isoleucine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 700 of the SCN8A protein (p.Ile700Val). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.066
BayesDel_addAF	Benign	-0.017	T
BayesDel_noAF	Benign	-0.26
CADD	Benign	17
DANN	Benign	0.61
DEOGEN2	Benign	0.34	T;.;.;.;.
Eigen	Benign	-0.62
Eigen_PC	Benign	-0.43
FATHMM_MKL	Benign	0.22	N
LIST_S2	Benign	0.79	T;T;.;T;T
M_CAP	Benign	0.033	D
MetaRNN	Benign	0.10	T;T;T;T;T
MetaSVM	Uncertain	-0.18	T
MutationAssessor	Benign	-0.20	N;N;N;.;N
MutationTaster	Benign	0.52	N;N;N
PrimateAI	Benign	0.44	T
PROVEAN	Benign	-0.20	N;N;N;.;.
REVEL	Benign	0.22
Sift	Benign	0.24	T;T;T;.;.
Sift4G	Benign	1.0	T;T;T;T;T
Polyphen		0.0	B;.;.;B;.
Vest4		0.11
MutPred		0.34		Gain of MoRF binding (P = 0.098);Gain of MoRF binding (P = 0.098);Gain of MoRF binding (P = 0.098);.;Gain of MoRF binding (P = 0.098);
MVP		0.45
MPC		0.78
ClinPred		0.17	T
GERP RS		4.0
Varity_R		0.028
gMVP		0.39

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs187153231; hg19: chr12-52139786;