2-165309393-T-G

Variant names:

• chr2-165309393-T-G
• rs796053203
• NM_001040142.2:c.647T>G

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.647T>G​(p.Leu216Trp) 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. 12/20 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. L216S) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: SCN2A NM_001040142.2 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 8.02
• Publications: 2 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 18 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 chr2-165309393-T-C is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 2444039.Status of the report is criteria_provided_single_submitter, 1 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, 0.946
• PP5: Variant 2-165309393-T-G is Pathogenic according to our data. Variant chr2-165309393-T-G is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 207088.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.647T>G	p.Leu216Trp	missense_variant	Exon 6 of 27	ENST00000375437.7	NP_001035232.1
SCN2A	NM_001371246.1	c.697+137T>G		intron_variant	Intron 6 of 26	ENST00000631182.3	NP_001358175.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SCN2A	ENST00000375437.7	c.647T>G	p.Leu216Trp	missense_variant	Exon 6 of 27	5	NM_001040142.2	ENSP00000364586.2
SCN2A	ENST00000283256.10	c.647T>G	p.Leu216Trp	missense_variant	Exon 6 of 27	1		ENSP00000283256.6
SCN2A	ENST00000424833.5	c.647T>G	p.Leu216Trp	missense_variant	Exon 6 of 11	1		ENSP00000406454.2
SCN2A	ENST00000631182.3	c.697+137T>G		intron_variant	Intron 6 of 26	5	NM_001371246.1	ENSP00000486885.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

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

Feb 14, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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: 207088). This missense change has been observed in individual(s) with SCN2A-related conditions (PMID: 30109124; Invitae). 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 leucine, which is neutral and non-polar, with tryptophan, which is neutral and slightly polar, at codon 216 of the SCN2A protein (p.Leu216Trp). -

not provided Pathogenic:1

Feb 23, 2012

GeneDx

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The Leu216Trp missense change has not been published as a mutation, nor has it been reported as a benign polymorphism to our knowledge. The NHLBI ESP Exome Variant Project has not identified Leu216Trp in approximately 5,000 individuals of European or African American ethnicity, indicating that it is not a common benign variant in these populations. Although both Leucine and Tryptophan are non-polar, Tryptophan is a larger residue with an aromatic side chain. The Leu216Trp substitution alters a highly conserved position in the S4 segment of the first transmembrane domain of the protein, and a different mutation in this same segment has been published in association with benign familial neonatal-infantile seizures (BFNIS) (Berkovic et al., 2004). Additionally, multiple in silico algorithms predict that Leu216Trp is damaging to protein structure/function. Therefore, Leu216Trp is a strong candidate for a disease-causing mutation, although the possibility that it is a benign variant cannot be excluded at present. The variant is found in INFANT-EPI panel(s). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.58
CADD	Pathogenic	27
DANN	Benign	0.96
DEOGEN2	Pathogenic	0.98	.;D;T;D;D;D
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.91
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	D;D;D;.;.;D
M_CAP	Pathogenic	0.83	D
MetaRNN	Pathogenic	0.95	D;D;D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	4.7	.;H;.;H;H;.
PhyloP100		8.0
PROVEAN	Pathogenic	-5.9	D;D;.;.;D;.
REVEL	Pathogenic	0.90
Sift	Pathogenic	0.0	D;D;.;.;D;.
Sift4G	Pathogenic	0.0	D;D;.;.;D;D
Polyphen		1.0	.;D;.;D;D;.
Vest4		0.93, 0.93
MutPred		0.50		Loss of stability (P = 0.0236);Loss of stability (P = 0.0236);.;Loss of stability (P = 0.0236);Loss of stability (P = 0.0236);.;
MVP		0.98
ClinPred		0.99	D
GERP RS		5.5
Varity_R		0.93
Mutation Taster		=2/98	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs796053203; hg19: chr2-166165903;