chr12-51806756-T-A

Variant names:

• chr12-51806756-T-A
• rs1555231010
• NM_001330260.2:c.5270T>A

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1 PM2 PP2 PP3_Moderate PP5

The NM_001330260.2(SCN8A):​c.5270T>A​(p.Val1757Asp) 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 (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V1757I) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: SCN8A NM_001330260.2 missense
• Clinical Significance: Likely pathogenic no assertion criteria provided P:1
• 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 Likely_pathogenic. Variant got 8 ACMG points.

• PM1: In a hotspot region, there are 6 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 8 uncertain in NM_001330260.2
• 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, 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, 0.932
• PP5: Variant 12-51806756-T-A is Pathogenic according to our data. Variant chr12-51806756-T-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 559650.Status of the report is no_assertion_criteria_provided, 0 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SCN8A	NM_001330260.2	c.5270T>A	p.Val1757Asp	missense_variant	Exon 27 of 27	ENST00000627620.5	NP_001317189.1
SCN8A	NM_014191.4	c.5270T>A	p.Val1757Asp	missense_variant	Exon 27 of 27	ENST00000354534.11	NP_055006.1
SCN8A	NM_001177984.3	c.5147T>A	p.Val1716Asp	missense_variant	Exon 26 of 26		NP_001171455.1
SCN8A	NM_001369788.1	c.5147T>A	p.Val1716Asp	missense_variant	Exon 26 of 26		NP_001356717.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SCN8A	ENST00000354534.11	c.5270T>A	p.Val1757Asp	missense_variant	Exon 27 of 27	1	NM_014191.4	ENSP00000346534.4
SCN8A	ENST00000627620.5	c.5270T>A	p.Val1757Asp	missense_variant	Exon 27 of 27	5	NM_001330260.2	ENSP00000487583.2
SCN8A	ENST00000599343.5	c.5303T>A	p.Val1768Asp	missense_variant	Exon 26 of 26	5		ENSP00000476447.3
SCN8A	ENST00000355133.7	c.5147T>A	p.Val1716Asp	missense_variant	Exon 25 of 25	1		ENSP00000347255.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: no assertion criteria provided

Submissions by phenotype

SCN8A-related disorder Pathogenic:1

May 04, 2018

Molecular Genetics Laboratory, BC Children's and BC Women's Hospitals

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

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Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.59	D
BayesDel_noAF	Pathogenic	0.61
CADD	Pathogenic	29
DANN	Benign	0.97
DEOGEN2	Pathogenic	0.97	D;.;.;.;.
Eigen	Pathogenic	0.77
Eigen_PC	Uncertain	0.59
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.97	D;D;.;D;D
M_CAP	Pathogenic	0.85	D
MetaRNN	Pathogenic	0.93	D;D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	4.6	H;.;.;.;H
PrimateAI	Pathogenic	0.96	D
PROVEAN	Pathogenic	-6.6	D;D;.;.;.
REVEL	Pathogenic	0.91
Sift	Pathogenic	0.0	D;D;.;.;.
Sift4G	Pathogenic	0.0	D;D;D;D;D
Polyphen		1.0	D;.;.;.;.
Vest4		0.88
MutPred		0.70		Gain of helix (P = 0.0199);.;.;.;Gain of helix (P = 0.0199);
MVP		0.99
MPC		2.8
ClinPred		1.0	D
GERP RS		4.0
Varity_R		0.99
gMVP		1.0

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: rs1555231010; hg19: chr12-52200540;