rs757542048

Positions:

• chr2-165389271-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PM2 PP2 PP3

The NM_001040142.2(SCN2A):​c.5465C>T​(p.Ala1822Val) 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 Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: SCN2A NM_001040142.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 7.88

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_pathogenic. Variant got 6 ACMG points.

• PM1: In a topological_domain Cytoplasmic (size 229) in uniprot entity SCN2A_HUMAN there are 7 pathogenic changes around while only 1 benign (88%) 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, 0.806

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
SCN2A	NM_001040142.2	c.5465C>T	p.Ala1822Val	missense_variant	27/27	ENST00000375437.7	NP_001035232.1
SCN2A	NM_001371246.1	c.5465C>T	p.Ala1822Val	missense_variant	27/27	ENST00000631182.3	NP_001358175.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
SCN2A	ENST00000375437.7	c.5465C>T	p.Ala1822Val	missense_variant	27/27	5	NM_001040142.2	ENSP00000364586	P1
SCN2A	ENST00000631182.3	c.5465C>T	p.Ala1822Val	missense_variant	27/27	5	NM_001371246.1	ENSP00000486885

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251252 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135784

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 Data not reliable, filtered out with message: AS_VQSR AF: 6.84e-7 AC: 1 AN: 1461844 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 727220

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

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

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

May 07, 2018

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. This sequence change replaces alanine with valine at codon 1822 of the SCN2A protein (p.Ala1822Val). The alanine residue is highly conserved and there is a small physicochemical difference between alanine and valine. This variant is present in population databases (rs757542048, ExAC 0.009%). This variant has been observed in two related individuals affected with benign familial infantile seizures (PMID: 15048894). ClinVar contains an entry for this variant (Variation ID: 450222). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Jun 29, 2017

A variant of uncertain significance has been identified in the SCN2A gene. The A1822V variant was reported in two members of one family with benign familial infantile seizures; however no additional information was provided (Berkovic et al., 2004). The A1822V variant is not observed at a significant frequency in large population cohorts (Lek et al., 2016; 1000 Genomes Consortium et al., 2015; Exome Variant Server). This substitution alters a conserved position predicted to be within the C-terminal cytoplasmic domain. In silico analysis predicts this variant is probably damaging to the protein structure/function. However, the A1822V variant is a conservative amino acid substitution, which is not likely to impact secondary protein structure as these residues share similar properties. Therefore, based on the currently available information, it is unclear whether this variant is a pathogenic variant or a rare benign variant. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.94
BayesDel_addAF	Pathogenic	0.27	D
BayesDel_noAF	Pathogenic	0.24
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.74	D;.;T;.;D;D;.
Eigen	Pathogenic	0.75
Eigen_PC	Pathogenic	0.78
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Uncertain	0.96	D;.;D;.;.;.;D
M_CAP	Pathogenic	0.63	D
MetaRNN	Pathogenic	0.81	D;D;D;D;D;D;D
MetaSVM	Pathogenic	0.98	D
MutationAssessor	Benign	1.7	L;L;.;L;L;L;L
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.73	T
PROVEAN	Uncertain	-3.7	D;.;.;.;.;D;D
REVEL	Pathogenic	0.80
Sift	Pathogenic	0.0	D;.;.;.;.;D;D
Sift4G	Benign	0.62	T;.;.;T;.;T;T
Polyphen		0.99	D;P;.;P;D;D;P
Vest4		0.70
MutPred		0.44		Loss of catalytic residue at A1822 (P = 0.0668);Loss of catalytic residue at A1822 (P = 0.0668);.;Loss of catalytic residue at A1822 (P = 0.0668);Loss of catalytic residue at A1822 (P = 0.0668);Loss of catalytic residue at A1822 (P = 0.0668);Loss of catalytic residue at A1822 (P = 0.0668);
MVP		0.93
ClinPred		0.96	D
GERP RS		5.6
Varity_R		0.86
gMVP		0.98

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: rs757542048; hg19: chr2-166245781;