rs750829844

Variant names:

• chr12-51774312-G-A
• rs750829844
• NM_001330260.2:c.3769G>A

Variant summary

Our verdict is Likely benign. The variant received -4 ACMG points: 1P and 5B. PP2 BP4 BS2

The NM_001330260.2(SCN8A):​c.3769G>A​(p.Val1257Ile) variant causes a missense change. The variant allele was found at a frequency of 0.0000236 in 1,613,192 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: 𝑓 0.000026 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000023 (0 hom.)
• Consequence: SCN8A NM_001330260.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 4.05
• Publications: 2 publications found

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]

SCN8A Gene-Disease associations (from GenCC):

• complex neurodevelopmental disorder

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• developmental and epileptic encephalopathy, 13

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P, Ambry Genetics
• cognitive impairment with or without cerebellar ataxia

  Inheritance: AD Classification: STRONG Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae)
• seizures, benign familial infantile, 5

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
• benign familial infantile epilepsy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• infantile convulsions and choreoathetosis

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• undetermined early-onset epileptic encephalopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• myoclonus, familial, 2

  Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics

ACMG classification

Our verdict: Likely_benign. The variant received -4 ACMG points.

• 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, developmental and epileptic encephalopathy, 13, undetermined early-onset epileptic encephalopathy, benign familial infantile epilepsy, complex neurodevelopmental disorder, seizures, benign familial infantile, 5, cognitive impairment with or without cerebellar ataxia, infantile convulsions and choreoathetosis.
• BP4: Computational evidence support a benign effect (MetaRNN=0.35389808).
• BS2: High AC in GnomAdExome4 at 34 AD gene.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001330260.2. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SCN8A	NM_001330260.2	MANE Select	c.3769G>A	p.Val1257Ile	missense	Exon 20 of 27	NP_001317189.1
	SCN8A	NM_014191.4	MANE Plus Clinical	c.3769G>A	p.Val1257Ile	missense	Exon 20 of 27	NP_055006.1
	SCN8A	NM_001177984.3		c.3769G>A	p.Val1257Ile	missense	Exon 20 of 26	NP_001171455.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SCN8A	ENST00000354534.11	TSL:1 MANE Plus Clinical	c.3769G>A	p.Val1257Ile	missense	Exon 20 of 27	ENSP00000346534.4
	SCN8A	ENST00000627620.5	TSL:5 MANE Select	c.3769G>A	p.Val1257Ile	missense	Exon 20 of 27	ENSP00000487583.2
	SCN8A	ENST00000599343.5	TSL:5	c.3802G>A	p.Val1268Ile	missense	Exon 19 of 26	ENSP00000476447.3

Frequencies

GnomAD3 genomes AF: 0.0000263 AC: 4 AN: 152234 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000965

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000280 AC: 7 AN: 250264 AF XY: 0.0000369

Gnomad AFR exome AF: 0.0000623

Gnomad AMR exome AF: 0.0000291

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000353

Gnomad OTH exome AF: 0.000164

GnomAD4 exome AF: 0.0000233 AC: 34 AN: 1460958 Hom.: 0 Cov.: 30 AF XY: 0.0000275 AC XY: 20 AN XY: 726744

African (AFR) AF: 0.000149 AC: 5 AN: 33468

American (AMR) AF: 0.0000672 AC: 3 AN: 44642

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26104

East Asian (EAS) AF: 0.00 AC: 0 AN: 39656

South Asian (SAS) AF: 0.0000232 AC: 2 AN: 86058

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53398

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5760

European-Non Finnish (NFE) AF: 0.0000189 AC: 21 AN: 1111518

Other (OTH) AF: 0.0000497 AC: 3 AN: 60354

GnomAD4 genome AF: 0.0000263 AC: 4 AN: 152234 Hom.: 0 Cov.: 32 AF XY: 0.0000403 AC XY: 3 AN XY: 74370

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.0000965 AC: 4 AN: 41448

American (AMR) AF: 0.00 AC: 0 AN: 15286

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5202

South Asian (SAS) AF: 0.00 AC: 0 AN: 4836

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10624

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68044

Other (OTH) AF: 0.00 AC: 0 AN: 2094

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0.00955443), which strongly suggests a high chance of mosaicism in these individuals.

Alfa AF: 0.0000658 Hom.: 0

Bravo AF: 0.0000453

ExAC AF: 0.0000412 AC: 5

ClinVar

ClinVar submissions as Germline

Significance: Uncertain significance

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
-	1	-	Developmental and epileptic encephalopathy (1)
-	1	-	not provided (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.11
BayesDel_addAF	Uncertain	0.014	T
BayesDel_noAF	Uncertain	-0.040
CADD	Uncertain	26
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.69	D
Eigen	Uncertain	0.23
Eigen_PC	Uncertain	0.36
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Benign	0.84	T
M_CAP	Uncertain	0.12	D
MetaRNN	Benign	0.35	T
MetaSVM	Uncertain	0.69	D
MutationAssessor	Benign	0.69	N
PhyloP100		4.1
PrimateAI	Uncertain	0.79	T
PROVEAN	Benign	-0.94	N
REVEL	Uncertain	0.56
Sift	Uncertain	0.025	D
Sift4G	Benign	0.070	T
Polyphen		0.83	P
Vest4		0.28
MVP		0.86
MPC		0.99
ClinPred		0.19	T
GERP RS		5.0
Varity_R		0.33
gMVP		0.78
Mutation Taster		=51/49	polymorphism

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

Other links and lift over

dbSNP: rs750829844; hg19: chr12-52168096; COSMIC: COSV61976851; COSMIC: COSV61976851;