12-51662852-A-G

Position:

• chr12-51662852-A-G

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP2

The NM_014191.4(SCN8A):​c.35A>G​(p.Asp12Gly) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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. D12E) has been classified 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
• Conservation: PhyloP100: 9.32

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.

• 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.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SCN8A	NM_001330260.2	c.35A>G	p.Asp12Gly	missense_variant	2/27	ENST00000627620.5
SCN8A	NM_014191.4	c.35A>G	p.Asp12Gly	missense_variant	2/27	ENST00000354534.11
SCN8A	NM_001177984.3	c.35A>G	p.Asp12Gly	missense_variant	2/26
SCN8A	NM_001369788.1	c.35A>G	p.Asp12Gly	missense_variant	2/26

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SCN8A	ENST00000354534.11	c.35A>G	p.Asp12Gly	missense_variant	2/27	1	NM_014191.4	P4
SCN8A	ENST00000627620.5	c.35A>G	p.Asp12Gly	missense_variant	2/27	5	NM_001330260.2	A1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Inborn genetic diseases Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

May 26, 2017

The p.D12G variant (also known as c.35A>G), located in coding exon 1 of the SCN8A gene, results from an A to G substitution at nucleotide position 35. The aspartic acid at codon 12 is replaced by glycine, an amino acid with similar properties. This amino acid position is well conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.22
BayesDel_addAF	Pathogenic	0.25	D
BayesDel_noAF	Uncertain	0.13
CADD	Pathogenic	26
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.75	.;D;.;.;.;.
Eigen	Uncertain	0.35
Eigen_PC	Uncertain	0.45
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Benign	0.85	D;D;D;.;D;D
M_CAP	Uncertain	0.21	D
MetaRNN	Uncertain	0.56	D;D;D;D;D;D
MetaSVM	Pathogenic	0.81	D
MutationAssessor	Uncertain	2.9	.;M;M;M;M;M
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Uncertain	0.61	T
PROVEAN	Pathogenic	-4.6	.;D;D;D;.;.
REVEL	Pathogenic	0.65
Sift	Uncertain	0.0030	.;D;D;D;.;.
Sift4G	Uncertain	0.033	.;D;D;D;D;D
Polyphen		0.31	.;B;.;.;.;.
Vest4		0.34, 0.46, 0.44, 0.45, 0.44
MutPred		0.20		Gain of glycosylation at P11 (P = 0.0685);Gain of glycosylation at P11 (P = 0.0685);Gain of glycosylation at P11 (P = 0.0685);Gain of glycosylation at P11 (P = 0.0685);Gain of glycosylation at P11 (P = 0.0685);Gain of glycosylation at P11 (P = 0.0685);
MVP		0.89
MPC		1.3
ClinPred		0.99	D
GERP RS		5.0
Varity_R		0.56
gMVP		0.78

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: rs1565878368; hg19: chr12-52056636;