2-165373331-G-C

Variant names:

• chr2-165373331-G-C
• rs121917753
• NM_001040142.2:c.3956G>C

Variant summary

Our verdict is Pathogenic. The variant received 19 ACMG points: 19P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Very_Strong

The NM_001040142.2(SCN2A):​c.3956G>C​(p.Arg1319Pro) 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. 13/22 in silico tools predict a damaging 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. R1319Q) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: SCN2A NM_001040142.2 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 10.0
• Publications: 0 publications found

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]

SCN2A Gene-Disease associations (from GenCC):

• complex neurodevelopmental disorder

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen, Illumina
• developmental and epileptic encephalopathy, 11

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Ambry Genetics, Labcorp Genetics (formerly Invitae)
• intellectual disability

  Inheritance: AD Classification: DEFINITIVE Submitted by: G2P
• episodic ataxia, type 9

  Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
• seizures, benign familial infantile, 3

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

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• benign familial neonatal-infantile seizures

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• Dravet syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• genetic developmental and epileptic encephalopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• infantile spasms

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• malignant migrating partial seizures of infancy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 19 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, 4 uncertain in NM_001040142.2
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr2-165373331-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 12880.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP2: Missense variant in the SCN2A gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 362 curated pathogenic missense variants (we use a threshold of 10). The gene has 36 curated benign missense variants. Trascript score misZ: 8.7114 (above the threshold of 3.09). GenCC associations: The gene is linked to genetic developmental and epileptic encephalopathy, episodic ataxia, type 9, seizures, benign familial infantile, 3, complex neurodevelopmental disorder, benign familial neonatal-infantile seizures, Dravet syndrome, infantile spasms, developmental and epileptic encephalopathy, 11, intellectual disability, benign familial infantile epilepsy, malignant migrating partial seizures of infancy.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.942
• PP5: Variant 2-165373331-G-C is Pathogenic according to our data. Variant chr2-165373331-G-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 2203163.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SCN2A	NM_001040142.2	c.3956G>C	p.Arg1319Pro	missense_variant	Exon 21 of 27	ENST00000375437.7	NP_001035232.1
SCN2A	NM_001371246.1	c.3956G>C	p.Arg1319Pro	missense_variant	Exon 21 of 27	ENST00000631182.3	NP_001358175.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SCN2A	ENST00000375437.7	c.3956G>C	p.Arg1319Pro	missense_variant	Exon 21 of 27	5	NM_001040142.2	ENSP00000364586.2
SCN2A	ENST00000631182.3	c.3956G>C	p.Arg1319Pro	missense_variant	Exon 21 of 27	5	NM_001371246.1	ENSP00000486885.1
SCN2A	ENST00000283256.10	c.3956G>C	p.Arg1319Pro	missense_variant	Exon 21 of 27	1		ENSP00000283256.6

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Developmental and epileptic encephalopathy, 11 Pathogenic:1

Jul 17, 2023

Victorian Clinical Genetics Services, Murdoch Childrens Research Institute

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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, PMIDs: 29691040, 31904126). 0107 - This gene is associated with autosomal dominant disease. (I) 0200 - Variant is predicted to result in a missense amino acid change from arginine to proline. (I) 0251 - This variant is heterozygous. (I) 0301 - Variant is absent from gnomAD (both v2 and v3). (SP) 0309 - An alternative amino acid change at the same position has been observed in gnomAD (v2) (1 heterozygote, 0 homozygotes). (I) 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) 0701 - Other missense variants comparable to the one identified in this case have very strong previous evidence for pathogenicity. Alternative missense changes of this arginine residue to glutamine, leucine, and tryptophan have been reported pathogenic by clinical labs in ClinVar and in the literature in individuals with epileptic encephalopathy (PMID: 28379373). (SP) 0801 - This variant has strong previous evidence of pathogenicity in unrelated individuals. This variant has been identified de novo in individuals with intellectual disability and seizures (PMID: 27824329, 31175295). (SP) 0905 - No published segregation evidence has been identified for this variant. (I) 1007 - No published functional evidence has been identified for this variant. (I) 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

Mar 10, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. This variant disrupts the p.Arg1319 amino acid residue in SCN2A. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 15048894, 18479388, 28379373). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. 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"). This missense change has been observed in individual(s) with SCN2A-related conditions (PMID: 27824329, 28191889, 31175295, 33004838). In at least one individual the variant was observed to be de novo. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces arginine, which is basic and polar, with proline, which is neutral and non-polar, at codon 1319 of the SCN2A protein (p.Arg1319Pro). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.57
CADD	Pathogenic	31
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.98	D;.;T;.;D;D;.
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	D;.;D;.;.;.;D
M_CAP	Pathogenic	0.84	D
MetaRNN	Pathogenic	0.94	D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	5.3	H;H;.;H;H;H;H
PhyloP100		10
PrimateAI	Pathogenic	0.94	D
PROVEAN	Pathogenic	-6.2	D;.;.;.;.;D;D
REVEL	Pathogenic	0.94
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		0.95
MutPred		0.72		Loss of MoRF binding (P = 6e-04);Loss of MoRF binding (P = 6e-04);.;Loss of MoRF binding (P = 6e-04);Loss of MoRF binding (P = 6e-04);Loss of MoRF binding (P = 6e-04);Loss of MoRF binding (P = 6e-04);
MVP		1.0
ClinPred		1.0	D
GERP RS		5.9
Varity_R		0.98
gMVP		0.99
Mutation Taster		=8/92	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		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: rs121917753; hg19: chr2-166229841;