chr20-63350145-G-A

Position:

chr20-63350145-G-A

Variant summary

Our verdict is Benign. Variant got -14 ACMG points: 0P and 14B. BP4_StrongBP6BP7BS1BS2

The NM_000744.7(CHRNA4):c.1266C>T(p.Cys422=) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000394 in 1,573,308 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

Frequency

Genomes: 𝑓 0.000053 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000038 ( 0 hom. )

Consequence

CHRNA4
NM_000744.7 synonymous

Scores

Clinical Significance

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

Conservation

PhyloP100: 1.96

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:

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ACMG classification

Classification made for transcript

Verdict is Benign. Variant got -14 ACMG points.

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.71).

BP6

Variant 20-63350145-G-A is Benign according to our data. Variant chr20-63350145-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 98312.We mark this variant Likely_benign, oryginal submissions are: {Likely_benign=1, not_provided=1, Uncertain_significance=1}.

BP7

Synonymous conserved (PhyloP=1.96 with no splicing effect.

BS1

Variant frequency is greater than expected in population nfe. gnomad4 allele frequency = 0.0000526 (8/152204) while in subpopulation NFE AF= 0.0000882 (6/68034). AF 95% confidence interval is 0.0000376. There are 0 homozygotes in gnomad4. There are 2 alleles in male gnomad4 subpopulation. Median coverage is 33. This position pass quality control queck.

BS2

High AC in GnomAd4 at 8 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein
CHRNA4	NM_000744.7 linkuse as main transcript	c.1266C>T	p.Cys422=	synonymous_variant	5/6	ENST00000370263.9	NP_000735.1
CHRNA4	NM_001256573.2 linkuse as main transcript	c.738C>T	p.Cys246=	synonymous_variant	5/6		NP_001243502.1
CHRNA4	NR_046317.2 linkuse as main transcript	n.1475C>T		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.1266C>T	p.Cys422=	synonymous_variant	5/6	1	NM_000744.7	ENSP00000359285	P1	P43681-1

Frequencies

GnomAD3 genomes

AF:

0.0000526

AC:

AN:

152204

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000483

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

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:

0.0000882

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000251

AC:

AN:

198894

Hom.:

AF XY:

0.0000372

AC XY:

AN XY:

107416

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

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:

0.0000584

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000380

AC:

AN:

1421104

Hom.:

Cov.:

AF XY:

0.0000456

AC XY:

AN XY:

701656

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

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:

0.0000487

Gnomad4 OTH exome

AF:

0.0000171

GnomAD4 genome

AF:

0.0000526

AC:

AN:

152204

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74360

show subpopulations

Gnomad4 AFR

AF:

0.0000483

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000882

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000571

Hom.:

Bravo

AF:

0.0000491

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1Benign:1Other:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not provided

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Jan 14, 2014

The c.1266 C>T splice site variant in the CHRNA4 gene 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 6,400 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. Multiple in silico algorithms predict that the c.1266 C>T substitution could potentially introduce a new cryptic donor site that may supplant the natural site in exon 5 and lead to abnormal splicing. However, in the absence of RNA/Functional studies the actual effect of the c.1266 C>T sequence change is unknown. Therefore, based on the currently available information, it is unclear whether this variant is a pathogenic mutation or a rare benign variant as mutations in CHRNA4 demonstrate incomplete penetrance (Hirose and Kurahashi, 2012). This variant has been observed to be maternally inherited. The variant is found in CHILD-EPI panel(s). -

Autosomal dominant nocturnal frontal lobe epilepsy

Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Nov 27, 2023

- -

Tobacco use disorder

Other:1

not provided, no classification provided

literature only

Psychiatry Genetics Yale University

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.71

CADD

Benign

3.0

DANN

Benign

0.30

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.010

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