2-165388782-C-T

Position:

• chr2-165388782-C-T

Variant summary

Our verdict is Pathogenic. Variant got 17 ACMG points: 17P and 0B. PM1 PM2 PP2 PP3_Strong PP5_Very_Strong

The NM_001040142.2(SCN2A):​c.4976C>T​(p.Ala1659Val) variant causes a missense change involving the alteration of a 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 Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A1659P) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: SCN2A NM_001040142.2 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 7.86

Genes affected

SCN2A (HGNC:10588): (sodium voltage-gated channel alpha subunit 2) Voltage-gated sodium channels are transmembrane glycoprotein complexes composed of a large alpha subunit with four repeat domains, each of which is composed of six membrane-spanning segments, and one or more regulatory beta subunits. Voltage-gated sodium channels function in the generation and propagation of action potentials in neurons and muscle. This gene encodes one member of the sodium channel alpha subunit gene family. Allelic variants of this gene are associated with seizure disorders and autism spectrum disorder. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Nov 2016]

ACMG classification

Verdict is Pathogenic. Variant got 17 ACMG points.

• PM1: In a hotspot region, there are 9 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 3 uncertain in NM_001040142.2
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), SCN2A. . Trascript score misZ 8.7114 (greater than threshold 3.09). GenCC has associacion of gene with seizures, benign familial infantile, 3, Dravet syndrome, benign familial neonatal-infantile seizures, malignant migrating partial seizures of infancy, complex neurodevelopmental disorder, developmental and epileptic encephalopathy, 11, developmental and epileptic encephalopathy, West syndrome, benign familial infantile epilepsy, episodic ataxia, type 9.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.961
• PP5: Variant 2-165388782-C-T is Pathogenic according to our data. Variant chr2-165388782-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 410984.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr2-165388782-C-T is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SCN2A	NM_001040142.2	c.4976C>T	p.Ala1659Val	missense_variant	27/27	ENST00000375437.7
SCN2A	NM_001371246.1	c.4976C>T	p.Ala1659Val	missense_variant	27/27	ENST00000631182.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SCN2A	ENST00000375437.7	c.4976C>T	p.Ala1659Val	missense_variant	27/27	5	NM_001040142.2	P1
SCN2A	ENST00000631182.3	c.4976C>T	p.Ala1659Val	missense_variant	27/27	5	NM_001371246.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Developmental and epileptic encephalopathy, 11 Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	3billion	-	The variant is not observed in the gnomAD v2.1.1 dataset. The variant is located in a mutational hot spot and/or well-established functional domain in which established pathogenic variants have been reported. In silico tool predictions suggest damaging effect of the variant on gene or gene product (REVEL: 0.91; 3Cnet: 0.99). Same nucleotide change resulting in same amino acid change has been previously reported as pathogenic/likely pathogenic with strong evidence (ClinVar ID: VCV000410984). Therefore, this variant is classified as Likely pathogenic according to the recommendation of ACMG/AMP guideline. -
Pathogenic, criteria provided, single submitter	clinical testing	Victorian Clinical Genetics Services, Murdoch Childrens Research Institute	Jul 17, 2023	Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as Pathogenic. Following criteria are met: 0103 - Loss of function and gain of function are known mechanisms of disease in this gene. Variants causing a gain of function result in developmental and epileptic encephalopathy 11 (MIM#613721) or benign familial infantile seizures 3 (MIM#607745), whereas variants causing loss of function result in autism spectrum disorder and/or intellectual disability, with or without childhood-onset seizures (OMIM, PMID: 29691040, PMID: 31904126). 0107 - This gene is associated with autosomal dominant disease. (I) 0200 - Variant is predicted to result in a missense amino acid change from alanine to valine. (I) 0251 - This variant is heterozygous. (I) 0301 - Variant is absent from gnomAD (both v2 and v3). (SP) 0501 - Missense variant consistently predicted to be damaging by multiple in silico tools or highly conserved with a major amino acid change. (SP) 0600 - Variant is located in the annotated Ion transport domain (DECIPHER). (I) 801 - This variant has strong previous evidence of pathogenicity in unrelated individuals. This variant has been reported in multiple individuals with developmental and epileptic encephalopathy (ClinVar, PMID: 35365919). (SP) 1203 - This variant has been shown to be de novo in the proband (parental status confirmed) (by trio analysis). (SP) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -

Seizures, benign familial infantile, 3;C3150987:Developmental and epileptic encephalopathy, 11 Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Aug 16, 2022

This variant is not present in population databases (gnomAD no frequency). This sequence change replaces alanine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 1659 of the SCN2A protein (p.Ala1659Val). This missense change has been observed in individual(s) with clinical features of early infantile epileptic encephalopathy (Invitae). In at least one individual the variant was observed to be de novo. For these reasons, this variant has been classified as Pathogenic. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). ClinVar contains an entry for this variant (Variation ID: 410984). -

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Institute of Medical Genetics and Applied Genomics, University Hospital Tübingen

Oct 23, 2020

- -

Seizures, benign familial infantile, 3 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Beijing Key Laboratry for Genetics of Birth Defects, Beijing Children's Hospital

Feb 28, 2020

- -

Seizure Pathogenic:1

Pathogenic, no assertion criteria provided

clinical testing

Génétique des Maladies du Développement, Hospices Civils de Lyon

Feb 03, 2020

20% mosacism -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.94
BayesDel_addAF	Pathogenic	0.49	D
BayesDel_noAF	Pathogenic	0.46
CADD	Uncertain	23
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.97	D;.;T;.;D;D;.
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.93
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.97	D;.;D;.;.;.;D
M_CAP	Pathogenic	0.85	D
MetaRNN	Pathogenic	0.96	D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	4.4	H;H;.;H;H;H;H
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Pathogenic	0.90	D
PROVEAN	Uncertain	-3.5	D;.;.;.;.;D;D
REVEL	Pathogenic	0.91
Sift	Pathogenic	0.0	D;.;.;.;.;D;D
Sift4G	Pathogenic	0.0010	D;.;.;D;.;D;D
Polyphen		1.0	D;D;.;D;D;D;D
Vest4		0.70
MutPred		0.81		Gain of MoRF binding (P = 0.3999);Gain of MoRF binding (P = 0.3999);.;Gain of MoRF binding (P = 0.3999);Gain of MoRF binding (P = 0.3999);Gain of MoRF binding (P = 0.3999);Gain of MoRF binding (P = 0.3999);
MVP		0.99
ClinPred		1.0	D
GERP RS		5.4
Varity_R		0.96
gMVP		0.99

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: rs1060503101; hg19: chr2-166245292;