rs796053228

Positions:

• chr12-51807100-C-G
• chr12-51807100-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM2 PM5 PP2 PP3 PP5_Moderate

The NM_014191.4(SCN8A):​c.5614C>G​(p.Arg1872Gly) 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 pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R1872Q) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: SCN8A NM_014191.4 missense
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 0.565

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.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr12-51807101-G-A is described in Lovd as [Pathogenic].
• 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, 0.788
• PP5: Variant 12-51807100-C-G is Pathogenic according to our data. Variant chr12-51807100-C-G is described in ClinVar as [Pathogenic]. Clinvar id is 426434.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SCN8A	NM_001330260.2	c.5614C>G	p.Arg1872Gly	missense_variant	27/27	ENST00000627620.5	NP_001317189.1
SCN8A	NM_014191.4	c.5614C>G	p.Arg1872Gly	missense_variant	27/27	ENST00000354534.11	NP_055006.1
SCN8A	NM_001177984.3	c.5491C>G	p.Arg1831Gly	missense_variant	26/26		NP_001171455.1
SCN8A	NM_001369788.1	c.5491C>G	p.Arg1831Gly	missense_variant	26/26		NP_001356717.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SCN8A	ENST00000354534.11	c.5614C>G	p.Arg1872Gly	missense_variant	27/27	1	NM_014191.4	ENSP00000346534	P4
SCN8A	ENST00000627620.5	c.5614C>G	p.Arg1872Gly	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: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Jun 13, 2022

Not observed at significant frequency in large population cohorts (gnomAD); Missense variants in this gene are often considered pathogenic (HGMD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This substitution is predicted to be within the C-terminal cytoplasmic domain; Has not been previously published as pathogenic or benign to our knowledge -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.96
BayesDel_addAF	Pathogenic	0.47	D
BayesDel_noAF	Pathogenic	0.44
CADD	Benign	21
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.82	D;.;.;.;.
Eigen	Uncertain	0.22
Eigen_PC	Benign	0.18
FATHMM_MKL	Uncertain	0.87	D
LIST_S2	Uncertain	0.87	D;D;.;D;D
M_CAP	Pathogenic	0.45	D
MetaRNN	Pathogenic	0.79	D;D;D;D;D
MetaSVM	Uncertain	0.72	D
MutationAssessor	Benign	1.3	L;.;.;.;L
MutationTaster	Benign	1.0	D;D
PrimateAI	Pathogenic	0.83	D
PROVEAN	Pathogenic	-5.9	D;D;.;.;.
REVEL	Pathogenic	0.74
Sift	Pathogenic	0.0	D;D;.;.;.
Sift4G	Benign	0.35	T;T;T;T;T
Polyphen		1.0	D;.;.;.;.
Vest4		0.81
MutPred		0.43		Loss of helix (P = 0.028);.;.;.;Loss of helix (P = 0.028);
MVP		0.99
MPC		2.5
ClinPred		0.99	D
GERP RS		1.8
Varity_R		0.91
gMVP		0.97

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: rs796053228; hg19: chr12-52200884; COSMIC: COSV99050261; COSMIC: COSV99050261;