8-27463391-T-C

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 2P and 4B. PP3_ModerateBS2

The NM_000742.4(CHRNA2):c.1052A>G(p.Asn351Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000155 in 1,613,952 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. N351T) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000033 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000014 ( 0 hom. )

Consequence

CHRNA2
NM_000742.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:4

Conservation

PhyloP100: 8.02

Variant links:

Genes affected

CHRNA2 (HGNC:1956): (cholinergic receptor nicotinic alpha 2 subunit) Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels formed by a pentameric arrangement of alpha and beta subunits to create distinct muscle and neuronal receptors. Neuronal receptors are found throughout the peripheral and central nervous system where they are involved in fast synaptic transmission. This gene encodes an alpha subunit that is widely expressed in the brain. The proposed structure for nAChR subunits is a conserved N-terminal extracellular domain followed by three conserved transmembrane domains, a variable cytoplasmic loop, a fourth conserved transmembrane domain, and a short C-terminal extracellular region. Mutations in this gene cause autosomal dominant nocturnal frontal lobe epilepsy type 4. Single nucleotide polymorphisms (SNPs) in this gene have been associated with nicotine dependence. [provided by RefSeq, Nov 2009]

CHRNA2 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Likely_benign. Variant got -2 ACMG points.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.936

BS2

High AC in GnomAd at 5 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CHRNA2	NM_000742.4 linkuse as main transcript	c.1052A>G	p.Asn351Ser	missense_variant	6/7	ENST00000407991.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CHRNA2	ENST00000407991.3 linkuse as main transcript	c.1052A>G	p.Asn351Ser	missense_variant	6/7	5	NM_000742.4	P2	Q15822-1

Frequencies

GnomAD3 genomes

AF:

0.0000329

AC:

AN:

151998

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.000207

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00316

Gnomad NFE

AF:

0.0000294

Gnomad OTH

AF:

0.000478

GnomAD3 exomes

AF:

0.0000159

AC:

AN:

250948

Hom.:

AF XY:

0.00000737

AC XY:

AN XY:

135658

show subpopulations

Gnomad AFR exome

AF:

0.0000616

Gnomad AMR exome

AF:

0.0000289

Gnomad ASJ exome

AF:

0.0000995

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.0000327

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000137

AC:

AN:

1461836

Hom.:

Cov.:

AF XY:

0.0000124

AC XY:

AN XY:

727210

show subpopulations

Gnomad4 AFR exome

AF:

0.0000299

Gnomad4 AMR exome

AF:

0.0000224

Gnomad4 ASJ exome

AF:

0.0000765

Gnomad4 EAS exome

AF:

0.0000252

Gnomad4 SAS exome

AF:

0.0000464

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00000989

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.0000329

AC:

AN:

152116

Hom.:

Cov.:

AF XY:

0.0000672

AC XY:

AN XY:

74362

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.000208

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000294

Gnomad4 OTH

AF:

0.000473

Alfa

AF:

0.0000386

Hom.:

Bravo

AF:

0.0000340

ExAC

AF:

0.0000165

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Autosomal dominant nocturnal frontal lobe epilepsy

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Sep 21, 2023

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 CHRNA2 protein function. ClinVar contains an entry for this variant (Variation ID: 575518). This missense change has been observed in at least one individual who was not affected with CHRNA2-related conditions (Invitae). This variant has not been reported in the literature in individuals affected with CHRNA2-related conditions. This variant is present in population databases (rs770305730, gnomAD 0.01%). This sequence change replaces asparagine, which is neutral and polar, with serine, which is neutral and polar, at codon 351 of the CHRNA2 protein (p.Asn351Ser). -

Inborn genetic diseases

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jun 12, 2017

The p.N351S variant (also known as c.1052A>G), located in coding exon 5 of the CHRNA2 gene, results from an A to G substitution at nucleotide position 1052. The asparagine at codon 351 is replaced by serine, an amino acid with highly similar properties. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be tolerated by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

not provided

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Oct 11, 2022

In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge -

Autosomal dominant nocturnal frontal lobe epilepsy 4

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

New York Genome Center

Aug 06, 2021

The inherited missense variant c.1052A>G, p.Asn351Ser in the CHRNA2 gene has not been reported in the available literature.The variant has a 0.003% allele frequency in the gnomAD database (5 out of 151,998 heterozygous alleles), suggesting it is not a common benign variant in the populations represented in this database. In silico analysis support a deleterious effect on the gene or gene product. The variant resides at the Neurotransmitter-gated ion-channel transmembrane region domain. Based on the available evidence, the c.1052A>G, p.Asn351Ser missense variant in the CHRNA2 gene is classified as a variant of uncertain significance. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Uncertain

0.41

BayesDel_addAF

Benign

-0.091

BayesDel_noAF

Benign

-0.19

Cadd

Uncertain

Dann

Uncertain

1.0

DEOGEN2

Pathogenic

0.84

D;.;.

Eigen

Pathogenic

0.87

Eigen_PC

Pathogenic

0.78

FATHMM_MKL

Uncertain

0.94

LIST_S2

Uncertain

0.95

D;D;D

M_CAP

Uncertain

0.15

MetaRNN

Pathogenic

0.94

D;D;D

MetaSVM

Uncertain

0.50

MutationAssessor

Pathogenic

4.2

H;.;.

MutationTaster

Benign

1.0

D;D;D

PrimateAI

Uncertain

0.69

PROVEAN

Pathogenic

-5.0

D;.;D

REVEL

Pathogenic

0.79

Sift

Pathogenic

0.0

D;.;D

Sift4G

Pathogenic

0.0010

D;D;D

Polyphen

1.0

D;.;.

Vest4

0.94

MVP

0.93

MPC

0.65

ClinPred

0.99

GERP RS

4.9

Varity_R

0.94

gMVP

0.81

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.020

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over