NM_000742.4:c.140C>T

Variant names:

Variant summary

Our verdict is Benign. The variant received -7 ACMG points: 0P and 7B. BP4_ModerateBP6BS2

The NM_000742.4(CHRNA2):c.140C>T(p.Thr47Met) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000512 in 1,614,166 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. 15/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. T47T) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.00035 ( 0 hom., cov: 32)

Exomes 𝑓: 0.00053 ( 1 hom. )

Consequence

CHRNA2
NM_000742.4 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:2B:8

Conservation

PhyloP100: 3.10

Publications

3 publications found

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 Gene-Disease associations (from GenCC):

autosomal dominant nocturnal frontal lobe epilepsy 4
Inheritance: AD Classification: STRONG, LIMITED Submitted by: G2P, Illumina, Labcorp Genetics (formerly Invitae)
autosomal dominant nocturnal frontal lobe epilepsy
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
familial sleep-related hypermotor epilepsy
Inheritance: AD Classification: LIMITED Submitted by: ClinGen
benign familial infantile epilepsy
Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

CHRNA2 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Benign. The variant received -7 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.102101505).

BP6

Variant 8-27469915-G-A is Benign according to our data. Variant chr8-27469915-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 204979.We mark this variant Likely_benign, oryginal submission is: [Conflicting_classifications_of_pathogenicity].

BS2

High AC in GnomAd4 at 53 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CHRNA2	NM_000742.4 link	c.140C>T	p.Thr47Met	missense_variant	Exon 3 of 7	ENST00000407991.3	NP_000733.2	Q15822-1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CHRNA2	ENST00000407991.3 link	c.140C>T	p.Thr47Met	missense_variant	Exon 3 of 7	5	NM_000742.4	ENSP00000385026.1		Q15822-1

Frequencies

GnomAD3 genomes

AF:

0.000355

AC:

AN:

152210

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.000121

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000262

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.000282

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.000603

Gnomad OTH

AF:

0.000478

GnomAD2 exomes

AF:

0.000462

AC:

116

AN:

251244

AF XY:

0.000471

show subpopulations

Gnomad AFR exome

AF:

0.000123

Gnomad AMR exome

AF:

0.0000868

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.000139

Gnomad NFE exome

AF:

0.000933

Gnomad OTH exome

AF:

0.000326

GnomAD4 exome

AF:

0.000529

AC:

773

AN:

1461838

Hom.:

Cov.:

AF XY:

0.000484

AC XY:

352

AN XY:

727224

show subpopulations

African (AFR)

AF:

0.0000896

AC:

AN:

33480

American (AMR)

AF:

0.0000671

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.0000252

AC:

AN:

39700

South Asian (SAS)

AF:

0.00

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.000356

AC:

AN:

53364

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.000660

AC:

734

AN:

1112012

Other (OTH)

AF:

0.000215

AC:

AN:

60396

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.477

Heterozygous variant carriers

114

171

228

285

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

AF:

0.000348

AC:

AN:

152328

Hom.:

Cov.:

AF XY:

0.000309

AC XY:

AN XY:

74482

show subpopulations

African (AFR)

AF:

0.000120

AC:

AN:

41586

American (AMR)

AF:

0.000196

AC:

AN:

15306

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5164

South Asian (SAS)

AF:

0.00

AC:

AN:

4828

European-Finnish (FIN)

AF:

0.000282

AC:

AN:

10622

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.000603

AC:

AN:

68028

Other (OTH)

AF:

0.000473

AC:

AN:

2116

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.480

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.000599

Hom.:

Bravo

AF:

0.000329

TwinsUK

AF:

0.000539

AC:

ALSPAC

AF:

0.000778

AC:

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000349

AC:

ExAC

AF:

0.000494

AC:

EpiCase

AF:

0.000382

EpiControl

AF:

0.000771

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:2Benign:8

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Uncertain:2Benign:2

Jan 04, 2018

Eurofins Ntd Llc (ga)

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Dec 13, 2019

GeneDx

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant is associated with the following publications: (PMID: 21703448, 28488083) -

Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center

Significance:Likely benign

Review Status:no assertion criteria provided

Collection Method:clinical testing

- -

May 01, 2019

CeGaT Center for Human Genetics Tuebingen

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Autosomal dominant nocturnal frontal lobe epilepsy 4

Benign:4

Aug 22, 2023

Mendelics

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Jul 28, 2017

Genome Diagnostics Laboratory, University Medical Center Utrecht

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Jan 12, 2018

Illumina Laboratory Services, Illumina

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score and internal cut-off values, a variant classified as benign is not then subjected to further curation. The score for this variant resulted in a classification of benign for this disease. -

Diagnostic Laboratory, Department of Genetics, University Medical Center Groningen

Significance:Likely benign

Review Status:no assertion criteria provided

Collection Method:clinical testing

- -

Autosomal dominant nocturnal frontal lobe epilepsy

Benign:1

Jan 19, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Inborn genetic diseases

Benign:1

Oct 19, 2022

Ambry Genetics

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.096

BayesDel_addAF

Benign

-0.18

BayesDel_noAF

Benign

-0.10

CADD

Benign

(source)

DANN

Benign

0.94

DEOGEN2

Benign

0.14

T;.;.;.;.;.

Eigen

Benign

-0.51

Eigen_PC

Benign

-0.52

FATHMM_MKL

Uncertain

0.76

LIST_S2

Benign

0.55

T;T;T;T;T;T

M_CAP

Benign

0.041

MetaRNN

Benign

0.10

T;T;T;T;T;T

MetaSVM

Benign

-0.91

MutationAssessor

Benign

0.0

N;.;N;.;.;.

PhyloP100

3.1

PrimateAI

Benign

0.39

PROVEAN

Benign

0.58

N;.;N;N;N;D

REVEL

Uncertain

0.40

Sift

Uncertain

0.026

D;.;D;D;D;D

Sift4G

Uncertain

0.051

T;D;D;.;D;.

Polyphen

0.83

P;.;.;.;.;.

Vest4

0.56

MVP

0.76

MPC

0.27

ClinPred

0.036

GERP RS

3.3

Varity_R

0.021

gMVP

0.38

Mutation Taster

=21/79

disease causing

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.14

Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

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NM_000742.4:c.140C>T

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over