12-51770005-G-T

Variant names:

• chr12-51770005-G-T
• rs303808
• NM_001330260.2:c.3490+20G>T

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_001330260.2(SCN8A):​c.3490+20G>T variant causes a intron change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 7.3e-7 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: SCN8A NM_001330260.2 intron
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: -0.162
• Publications: 12 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 -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.84).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SCN8A	NM_001330260.2	c.3490+20G>T		intron_variant	Intron 18 of 26	ENST00000627620.5	NP_001317189.1
SCN8A	NM_014191.4	c.3490+20G>T		intron_variant	Intron 18 of 26	ENST00000354534.11	NP_055006.1
SCN8A	NM_001177984.3	c.3490+20G>T		intron_variant	Intron 18 of 25		NP_001171455.1
SCN8A	NM_001369788.1	c.3490+20G>T		intron_variant	Intron 18 of 25		NP_001356717.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SCN8A	ENST00000354534.11	c.3490+20G>T		intron_variant	Intron 18 of 26	1	NM_014191.4	ENSP00000346534.4
SCN8A	ENST00000627620.5	c.3490+20G>T		intron_variant	Intron 18 of 26	5	NM_001330260.2	ENSP00000487583.2
SCN8A	ENST00000599343.5	c.3523+20G>T		intron_variant	Intron 17 of 25	5		ENSP00000476447.3
SCN8A	ENST00000355133.7	c.3490+20G>T		intron_variant	Intron 17 of 24	1		ENSP00000347255.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AS_VQSR AF: 7.34e-7 AC: 1 AN: 1362812 Hom.: 0 Cov.: 21 AF XY: 0.00000148 AC XY: 1 AN XY: 676624

African (AFR) AF: 0.00 AC: 0 AN: 31158

American (AMR) AF: 0.00 AC: 0 AN: 37516

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25044

East Asian (EAS) AF: 0.00 AC: 0 AN: 36990

South Asian (SAS) AF: 0.00 AC: 0 AN: 78838

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 50820

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 4914

European-Non Finnish (NFE) AF: 9.61e-7 AC: 1 AN: 1040548

Other (OTH) AF: 0.00 AC: 0 AN: 56984

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.84
CADD	Benign	0.63
DANN	Benign	0.33
PhyloP100		-0.16

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: rs303808; hg19: chr12-52163789;