12-51790419-A-T

Variant names:

• chr12-51790419-A-T
• rs886041670
• NM_001330260.2:c.4441A>T

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 7P and 1B. PM1 PM2 PM5 PP2 BP4

The NM_001330260.2(SCN8A):​c.4441A>T​(p.Met1481Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,456,064 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. M1481V) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: SCN8A NM_001330260.2 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 9.32
• Publications: 0 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_pathogenic. The variant received 6 ACMG points.

• PM1: In a hotspot region, there are 12 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
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr12-51790419-A-G is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 280470.
• 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=0.42043924).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SCN8A	NM_001330260.2	c.4441A>T	p.Met1481Leu	missense_variant	Exon 25 of 27	ENST00000627620.5	NP_001317189.1
SCN8A	NM_014191.4	c.4441A>T	p.Met1481Leu	missense_variant	Exon 25 of 27	ENST00000354534.11	NP_055006.1
SCN8A	NM_001177984.3	c.4318A>T	p.Met1440Leu	missense_variant	Exon 24 of 26		NP_001171455.1
SCN8A	NM_001369788.1	c.4318A>T	p.Met1440Leu	missense_variant	Exon 24 of 26		NP_001356717.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SCN8A	ENST00000354534.11	c.4441A>T	p.Met1481Leu	missense_variant	Exon 25 of 27	1	NM_014191.4	ENSP00000346534.4
SCN8A	ENST00000627620.5	c.4441A>T	p.Met1481Leu	missense_variant	Exon 25 of 27	5	NM_001330260.2	ENSP00000487583.2
SCN8A	ENST00000599343.5	c.4474A>T	p.Met1492Leu	missense_variant	Exon 24 of 26	5		ENSP00000476447.3
SCN8A	ENST00000355133.7	c.4318A>T	p.Met1440Leu	missense_variant	Exon 23 of 25	1		ENSP00000347255.4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1456064 Hom.: 0 Cov.: 29 AF XY: 0.00 AC XY: 0 AN XY: 724254

African (AFR) AF: 0.0000302 AC: 1 AN: 33144

American (AMR) AF: 0.00 AC: 0 AN: 43228

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25984

East Asian (EAS) AF: 0.00 AC: 0 AN: 39554

South Asian (SAS) AF: 0.00 AC: 0 AN: 84982

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53344

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5746

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1109926

Other (OTH) AF: 0.0000166 AC: 1 AN: 60156

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.69
BayesDel_addAF	Pathogenic	0.21	D
BayesDel_noAF	Uncertain	0.060
CADD	Uncertain	25
DANN	Benign	0.96
DEOGEN2	Uncertain	0.76	D;.;.;.;.
Eigen	Benign	0.097
Eigen_PC	Benign	0.20
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.91	D;D;.;D;D
M_CAP	Pathogenic	0.36	D
MetaRNN	Benign	0.42	T;T;T;T;T
MetaSVM	Uncertain	0.39	D
MutationAssessor	Uncertain	2.2	M;.;.;.;M
PhyloP100		9.3
PrimateAI	Pathogenic	0.93	D
PROVEAN	Uncertain	-2.8	D;D;D;.;.
REVEL	Uncertain	0.54
Sift	Uncertain	0.0010	D;D;D;.;.
Sift4G	Benign	0.31	T;T;T;T;T
Vest4		0.55
ClinPred		0.97	D
GERP RS		3.5
Varity_R		0.69
gMVP		0.94
Mutation Taster		=22/78	disease causing

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: rs886041670; hg19: chr12-52184203;