2-166051830-C-T

Variant names:

• chr2-166051830-C-T
• rs777386001
• NM_001165963.4:c.853G>A

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 5P and 2B. PM1 PM2 PP2 BP4_Moderate

The NM_001165963.4(SCN1A):​c.853G>A​(p.Ala285Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000685 in 1,460,466 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/22 in silico tools predict 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. A285S) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: SCN1A NM_001165963.4 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 1.24
• Publications: 0 publications found

Genes affected

SCN1A (HGNC:10585): (sodium voltage-gated channel alpha subunit 1) Voltage-dependent sodium channels are heteromeric complexes that regulate sodium exchange between intracellular and extracellular spaces and are essential for the generation and propagation of action potentials in muscle cells and neurons. Each sodium channel is composed of a large pore-forming, glycosylated alpha subunit and two smaller beta subunits. This gene encodes a sodium channel alpha subunit, which has four homologous domains, each of which contains six transmembrane regions. Allelic variants of this gene are associated with generalized epilepsy with febrile seizures and epileptic encephalopathy. Alternative splicing results in multiple transcript variants. The RefSeq Project has decided to create four representative RefSeq records. Three of the transcript variants are supported by experimental evidence and the fourth contains alternate 5' untranslated exons, the exact combination of which have not been experimentally confirmed for the full-length transcript. [provided by RefSeq, Oct 2015]

SCN1A-AS1 (HGNC:54069): (SCN1A and SCN9A antisense RNA 1)

ACMG classification

Our verdict: Uncertain_significance. The variant received 3 ACMG points.

• PM1: In a hotspot region, there are 9 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 4 benign, 8 uncertain in NM_001165963.4
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the SCN1A gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 848 curated pathogenic missense variants (we use a threshold of 10). The gene has 89 curated benign missense variants. Gene score misZ: 5.2206 (above the threshold of 3.09). Trascript score misZ: 7.6022 (above the threshold of 3.09). GenCC associations: The gene is linked to familial or sporadic hemiplegic migraine, myoclonic-astatic epilepsy, arthrogryposis, Dravet syndrome, malignant migrating partial seizures of infancy, generalized epilepsy with febrile seizures plus, type 2, migraine, familial hemiplegic, 3, developmental and epileptic encephalopathy, 6A, familial hemiplegic migraine, generalized epilepsy with febrile seizures plus, genetic developmental and epileptic encephalopathy, Lennox-Gastaut syndrome.
• BP4: Computational evidence support a benign effect (MetaRNN=0.17571303).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001165963.4. 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
	SCN1A	NM_001165963.4	MANE Select	c.853G>A	p.Ala285Thr	missense	Exon 9 of 29	NP_001159435.1
	SCN1A	NM_001202435.3		c.853G>A	p.Ala285Thr	missense	Exon 8 of 28	NP_001189364.1
	SCN1A	NM_001353948.2		c.853G>A	p.Ala285Thr	missense	Exon 7 of 27	NP_001340877.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SCN1A	ENST00000674923.1	MANE Select	c.853G>A	p.Ala285Thr	missense	Exon 9 of 29	ENSP00000501589.1
	SCN1A	ENST00000303395.9	TSL:5	c.853G>A	p.Ala285Thr	missense	Exon 8 of 28	ENSP00000303540.4
	SCN1A	ENST00000375405.7	TSL:5	c.853G>A	p.Ala285Thr	missense	Exon 6 of 26	ENSP00000364554.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1460466 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 726566

African (AFR) AF: 0.00 AC: 0 AN: 33394

American (AMR) AF: 0.00 AC: 0 AN: 44584

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26078

East Asian (EAS) AF: 0.00 AC: 0 AN: 39660

South Asian (SAS) AF: 0.00 AC: 0 AN: 86230

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53400

Middle Eastern (MID) AF: 0.000174 AC: 1 AN: 5752

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111076

Other (OTH) AF: 0.00 AC: 0 AN: 60292

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.075
BayesDel_addAF	Uncertain	0.024	T
BayesDel_noAF	Benign	-0.20
CADD	Benign	18
DANN	Benign	0.49
DEOGEN2	Uncertain	0.63	D
Eigen	Benign	-0.66
Eigen_PC	Benign	-0.51
FATHMM_MKL	Benign	0.63	D
LIST_S2	Benign	0.71	T
M_CAP	Benign	0.073	D
MetaRNN	Benign	0.18	T
MetaSVM	Uncertain	-0.28	T
MutationAssessor	Benign	0.035	N
PhyloP100		1.2
PrimateAI	Benign	0.31	T
PROVEAN	Benign	-0.42	N
REVEL	Benign	0.28
Sift	Uncertain	0.0070	D
Sift4G	Benign	0.46	T
Polyphen		0.011	B
Vest4		0.35
MutPred		0.63		Gain of sheet (P = 0.0827)
MVP		0.56
MPC		0.71
ClinPred		0.079	T
GERP RS		1.2
Varity_R		0.12
gMVP		0.73
Mutation Taster		=58/42	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: rs777386001; hg19: chr2-166908340;