rs879255706

Positions:

• chr12-51806299-A-G

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 5P and 2B. PM1 PM2 PP2 BP4_Moderate

The NM_014191.4(SCN8A):​c.4813A>G​(p.Ile1605Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 13/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: SCN8A NM_014191.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1 O:1
• Conservation: PhyloP100: 0.0990

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 Uncertain_significance. Variant got 3 ACMG points.

• PM1: In a repeat IV (size 297) in uniprot entity SCN8A_HUMAN there are 10 pathogenic changes around while only 1 benign (91%) in NM_014191.4
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), SCN8A. . Gene score misZ 0.78755 (greater than the threshold 3.09). Trascript score misZ 10.278 (greater than threshold 3.09). GenCC has associacion of gene with myoclonus, familial, 2, infantile convulsions and choreoathetosis, cognitive impairment with or without cerebellar ataxia, undetermined early-onset epileptic encephalopathy, complex neurodevelopmental disorder, developmental and epileptic encephalopathy, 13, benign familial infantile epilepsy, seizures, benign familial infantile, 5.
• BP4: Computational evidence support a benign effect (MetaRNN=0.095401496).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SCN8A	NM_001330260.2	c.4813A>G	p.Ile1605Val	missense_variant	27/27	ENST00000627620.5	NP_001317189.1
SCN8A	NM_014191.4	c.4813A>G	p.Ile1605Val	missense_variant	27/27	ENST00000354534.11	NP_055006.1
SCN8A	NM_001177984.3	c.4690A>G	p.Ile1564Val	missense_variant	26/26		NP_001171455.1
SCN8A	NM_001369788.1	c.4690A>G	p.Ile1564Val	missense_variant	26/26		NP_001356717.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SCN8A	ENST00000354534.11	c.4813A>G	p.Ile1605Val	missense_variant	27/27	1	NM_014191.4	ENSP00000346534	P4
SCN8A	ENST00000627620.5	c.4813A>G	p.Ile1605Val	missense_variant	27/27	5	NM_001330260.2	ENSP00000487583	A1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1 Other: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

Labcorp Genetics (formerly Invitae), Labcorp

Jun 22, 2022

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 1605 of the SCN8A protein (p.Ile1605Val). ClinVar contains an entry for this variant (Variation ID: 253291). 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. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated. -

Developmental and epileptic encephalopathy, 13 Other:1

not provided, no classification provided

literature only

GeneReviews

-

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.089
BayesDel_addAF	Uncertain	0.078	D
BayesDel_noAF	Benign	-0.13
CADD	Benign	19
DANN	Benign	0.96
DEOGEN2	Uncertain	0.65	D;.;.;.;.
Eigen	Benign	-0.63
Eigen_PC	Benign	-0.54
FATHMM_MKL	Uncertain	0.84	D
LIST_S2	Benign	0.82	T;T;.;T;T
M_CAP	Benign	0.053	D
MetaRNN	Benign	0.095	T;T;T;T;T
MetaSVM	Uncertain	0.16	D
MutationAssessor	Benign	0.30	N;.;.;.;N
MutationTaster	Benign	0.92	D;D
PrimateAI	Uncertain	0.66	T
PROVEAN	Benign	-0.65	N;N;.;.;.
REVEL	Uncertain	0.37
Sift	Benign	0.19	T;T;.;.;.
Sift4G	Benign	0.25	T;T;T;T;T
Polyphen		0.0050	B;.;.;.;.
Vest4		0.16
MutPred		0.61		Loss of methylation at K1608 (P = 0.1125);.;.;.;Loss of methylation at K1608 (P = 0.1125);
MVP		0.85
MPC		0.91
ClinPred		0.14	T
GERP RS		-0.17
Varity_R		0.032
gMVP		0.69

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

LitVar

Other links and lift over

dbSNP: rs879255706; hg19: chr12-52200083;