chr20-63350095-T-G

Position:

chr20-63350095-T-G

Variant summary

Our verdict is Benign. Variant got -7 ACMG points: 0P and 7B. BP4_ModerateBS1_SupportingBS2

The NM_000744.7(CHRNA4):c.1316A>C(p.Lys439Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000144 in 1,529,994 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: 𝑓 0.000079 ( 0 hom., cov: 33)

Exomes 𝑓: 0.0000073 ( 0 hom. )

Consequence

CHRNA4
NM_000744.7 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:4B:1

Conservation

PhyloP100: 0.305

Variant links:

Genes affected

CHRNA4 (HGNC:1958): (cholinergic receptor nicotinic alpha 4 subunit) This gene encodes a nicotinic acetylcholine receptor, which belongs to a superfamily of ligand-gated ion channels that play a role in fast signal transmission at synapses. These pentameric receptors can bind acetylcholine, which causes an extensive change in conformation that leads to the opening of an ion-conducting channel across the plasma membrane. This protein is an integral membrane receptor subunit that can interact with either nAChR beta-2 or nAChR beta-4 to form a functional receptor. Mutations in this gene cause nocturnal frontal lobe epilepsy type 1. Polymorphisms in this gene that provide protection against nicotine addiction have been described. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Feb 2012]

CHRNA4 links:

CHRNA4 (HGNC:):

CHRNA4 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Benign. Variant got -7 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.12420726).

BS1

Variant frequency is greater than expected in population amr. gnomad4 allele frequency = 0.0000789 (12/152082) while in subpopulation AMR AF= 0.000655 (10/15272). AF 95% confidence interval is 0.000354. There are 0 homozygotes in gnomad4. There are 4 alleles in male gnomad4 subpopulation. Median coverage is 33. This position pass quality control queck. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting

BS2

High AC in GnomAd4 at 12 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CHRNA4	NM_000744.7 linkuse as main transcript	c.1316A>C	p.Lys439Thr	missense_variant	5/6	ENST00000370263.9	NP_000735.1	P43681-1B4DK78Q59FV0
CHRNA4	NM_001256573.2 linkuse as main transcript	c.788A>C	p.Lys263Thr	missense_variant	5/6		NP_001243502.1	P43681Q4VAQ3B4DK78Q59FV0
CHRNA4	NR_046317.2 linkuse as main transcript	n.1525A>C		non_coding_transcript_exon_variant	5/6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CHRNA4	ENST00000370263.9 linkuse as main transcript	c.1316A>C	p.Lys439Thr	missense_variant	5/6	1	NM_000744.7	ENSP00000359285.4		P43681-1

Frequencies

GnomAD3 genomes

AF:

0.0000789

AC:

AN:

152082

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000655

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.000479

GnomAD4 exome

AF:

0.00000726

AC:

AN:

1377912

Hom.:

Cov.:

AF XY:

0.00000444

AC XY:

AN XY:

675374

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.000170

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:

9.36e-7

Gnomad4 OTH exome

AF:

0.0000528

GnomAD4 genome

AF:

0.0000789

AC:

AN:

152082

Hom.:

Cov.:

AF XY:

0.0000538

AC XY:

AN XY:

74290

show subpopulations

Gnomad4 AFR

AF:

0.0000241

Gnomad4 AMR

AF:

0.000655

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.00

Gnomad4 OTH

AF:

0.000479

Bravo

AF:

0.000166

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:4Benign:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Athena Diagnostics	Mar 01, 2019	- -
Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Oct 14, 2019	Not observed at a significant frequency in large population cohorts (Lek et al., 2016); In silico analysis, which includes protein predictors and evolutionary conservation, supports that this variant does not alter protein structure/function; Has not been previously published as pathogenic or benign to our knowledge; This amino acid substitution is not predicted to occur within the transmembrane region of the protein, where the vast majority of pathogenic missense variants have been identified in association with epilepsy (Steinlein et al., 2010) -

Inborn genetic diseases

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jul 24, 2017

The p.K439T variant (also known as c.1316A>C), located in coding exon 5 of the CHRNA4 gene, results from an A to C substitution at nucleotide position 1316. The lysine at codon 439 is replaced by threonine, an amino acid with similar properties. This amino acid position is not well 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. -

Autosomal dominant nocturnal frontal lobe epilepsy 1;C1861063:Tobacco addiction, susceptibility to

Uncertain:1

Uncertain significance, no assertion criteria provided

research

Division of Human Genetics, Children's Hospital of Philadelphia

Apr 14, 2016

- -

Autosomal dominant nocturnal frontal lobe epilepsy

Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Nov 27, 2023

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.068

BayesDel_addAF

Benign

-0.10

BayesDel_noAF

Benign

-0.38

CADD

Benign

6.0

DANN

Benign

0.94

DEOGEN2

Benign

0.29

T;.

Eigen

Benign

-0.93

Eigen_PC

Benign

-1.0

FATHMM_MKL

Benign

0.10

LIST_S2

Benign

0.75

T;T

M_CAP

Uncertain

0.15

MetaRNN

Benign

0.12

T;T

MetaSVM

Benign

-0.89

MutationAssessor

Benign

1.7

L;.

PrimateAI

Benign

0.39

PROVEAN

Benign

-0.90

N;.

REVEL

Benign

0.18

Sift

Benign

0.24

T;.

Sift4G

Benign

0.41

T;T

Polyphen

0.10

B;.

Vest4

0.19

MutPred

0.31

Loss of ubiquitination at K439 (P = 0.0022);.;

MVP

0.87

MPC

0.68

ClinPred

0.30

GERP RS

1.5

Varity_R

0.10

gMVP

0.27

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

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