2-165323345-C-T

Position:

• chr2-165323345-C-T

Variant summary

Our verdict is Likely benign. Variant got -1 ACMG points: 3P and 4B. PP2 PP3_Moderate BS2

The NM_001040142.2(SCN2A):​c.1861C>T​(p.Arg621Cys) variant causes a missense change. The variant allele was found at a frequency of 0.0000041 in 1,461,878 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R621S) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: SCN2A NM_001040142.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 4.91

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 Likely_benign. Variant got -1 ACMG points.

• PP2: Missense variant where missense usually causes diseases, SCN2A
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.853
• BS2: High AC in GnomAdExome4 at 6 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SCN2A	NM_001040142.2	c.1861C>T	p.Arg621Cys	missense_variant	12/27	ENST00000375437.7
SCN2A	NM_001371246.1	c.1861C>T	p.Arg621Cys	missense_variant	12/27	ENST00000631182.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SCN2A	ENST00000375437.7	c.1861C>T	p.Arg621Cys	missense_variant	12/27	5	NM_001040142.2	P1
SCN2A	ENST00000631182.3	c.1861C>T	p.Arg621Cys	missense_variant	12/27	5	NM_001371246.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 250956 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135664

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000289

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000410 AC: 6 AN: 1461878 Hom.: 0 Cov.: 32 AF XY: 0.00000413 AC XY: 3 AN XY: 727240

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000450

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.0000113

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Seizures, benign familial infantile, 3;C3150987:Developmental and epileptic encephalopathy, 11 Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Invitae	Oct 18, 2022	In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt SCN2A protein function. ClinVar contains an entry for this variant (Variation ID: 207092). This missense change has been observed in individual(s) with Lennox-Gastaut syndrome (Invitae). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This sequence change replaces arginine, which is basic and polar, with cysteine, which is neutral and slightly polar, at codon 621 of the SCN2A protein (p.Arg621Cys). -
Uncertain significance, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Oct 31, 2018	- -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Aug 23, 2013

The R621C variant has not been published as a mutation, nor has it been reported as a benign polymorphism to our knowledge. It was not observed in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. The R621C variant is a non-conservative amino acid substitution, which is likely to impact secondary protein structure as these residues differ in polarity, charge, size and/or other properties. This substitution alters a highly conserved position in the cytoplasmic loop between the first and second homologous domains of the SCN2A protein (Shi et al., 2012), and in silico analysis predicts this variant is probably damaging to the protein structure/function. The variant is found in SCN2A panel(s). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.24
BayesDel_addAF	Pathogenic	0.49	D
BayesDel_noAF	Pathogenic	0.46
CADD	Pathogenic	26
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.85	D;.;T;.;D;D;.
Eigen	Pathogenic	0.88
Eigen_PC	Pathogenic	0.83
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.95	D;.;D;.;.;.;D
M_CAP	Pathogenic	0.34	D
MetaRNN	Pathogenic	0.85	D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	3.3	M;M;.;M;M;M;M
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.63	T
PROVEAN	Pathogenic	-6.3	D;.;.;.;.;D;D
REVEL	Pathogenic	0.77
Sift	Pathogenic	0.0	D;.;.;.;.;D;D
Sift4G	Uncertain	0.0020	D;.;.;D;.;D;D
Polyphen		1.0	D;D;.;D;D;D;D
Vest4		0.79
MutPred		0.37		Loss of solvent accessibility (P = 0.0036);Loss of solvent accessibility (P = 0.0036);.;Loss of solvent accessibility (P = 0.0036);Loss of solvent accessibility (P = 0.0036);Loss of solvent accessibility (P = 0.0036);Loss of solvent accessibility (P = 0.0036);
MVP		0.97
ClinPred		1.0	D
GERP RS		5.6
Varity_R		0.60
gMVP		0.71

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: rs796053205; hg19: chr2-166179855; COSMIC: COSV51853940;