rs1555231012

Positions:

• chr12-51806765-T-C

Variant summary

Our verdict is Pathogenic. Variant got 17 ACMG points: 17P and 0B. PM1 PM2 PP2 PP3_Strong PP5_Very_Strong

The NM_014191.4(SCN8A):​c.5279T>C​(p.Met1760Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: SCN8A NM_014191.4 missense
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 8.02

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 Pathogenic. Variant got 17 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.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.962
• PP5: Variant 12-51806765-T-C is Pathogenic according to our data. Variant chr12-51806765-T-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 521651.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SCN8A	NM_001330260.2	c.5279T>C	p.Met1760Thr	missense_variant	27/27	ENST00000627620.5	NP_001317189.1
SCN8A	NM_014191.4	c.5279T>C	p.Met1760Thr	missense_variant	27/27	ENST00000354534.11	NP_055006.1
SCN8A	NM_001177984.3	c.5156T>C	p.Met1719Thr	missense_variant	26/26		NP_001171455.1
SCN8A	NM_001369788.1	c.5156T>C	p.Met1719Thr	missense_variant	26/26		NP_001356717.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SCN8A	ENST00000354534.11	c.5279T>C	p.Met1760Thr	missense_variant	27/27	1	NM_014191.4	ENSP00000346534	P4
SCN8A	ENST00000627620.5	c.5279T>C	p.Met1760Thr	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: Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Inborn genetic diseases Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Jun 28, 2017

The p.M1760T variant (also known as c.5279T>C), located in coding exon 26 of the SCN8A gene, results from a T to C substitution at nucleotide position 5279. The methionine at codon 1760 is replaced by threonine, an amino acid with similar properties. This variant has been determined to be the result of a de novo mutation or germline mosaicism in one family with an isolated case of SCN8A-related neurodevelopmental disorder (Ambry internal data). This variant is located in an functionally critical position (Wu J et al. Science, 2015 Dec;350:aad2395; Veeramah KR et al. Am. J. Hum. Genet., 2012 Mar;90:502-10; Ambry internal data). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Based on the majority of available evidence to date, this variant is likely to be pathogenic. -

Developmental and epileptic encephalopathy, 13 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Mendelics

May 28, 2019

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.59	D
BayesDel_noAF	Pathogenic	0.60
CADD	Pathogenic	27
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.97	D;.;.;.;.
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.91
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.95	D;D;.;D;D
M_CAP	Pathogenic	0.93	D
MetaRNN	Pathogenic	0.96	D;D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	3.9	H;.;.;.;H
MutationTaster	Benign	1.0	D;D
PrimateAI	Pathogenic	0.94	D
PROVEAN	Pathogenic	-5.6	D;D;.;.;.
REVEL	Pathogenic	0.98
Sift	Pathogenic	0.0	D;D;.;.;.
Sift4G	Uncertain	0.013	D;D;D;D;D
Polyphen		0.99	D;.;.;.;.
Vest4		0.92
MutPred		0.79		Loss of stability (P = 0.0359);.;.;.;Loss of stability (P = 0.0359);
MVP		0.99
MPC		2.3
ClinPred		1.0	D
GERP RS		5.3
Varity_R		0.95
gMVP		0.99

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: rs1555231012; hg19: chr12-52200549;